# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.

# Common codegen classes.

import os
import string
import operator

from WebIDL import *
from Configuration import NoSuchDescriptorError, Descriptor

AUTOGENERATED_WARNING_COMMENT = \
    "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n\n"
ADDPROPERTY_HOOK_NAME = '_addProperty'
FINALIZE_HOOK_NAME = '_finalize'
TRACE_HOOK_NAME = '_trace'
CONSTRUCT_HOOK_NAME = '_constructor'
HASINSTANCE_HOOK_NAME = '_hasInstance'

def replaceFileIfChanged(filename, newContents):
    """
    Read a copy of the old file, so that we don't touch it if it hasn't changed.
    Returns True if the file was updated, false otherwise.
    """
    #XXXjdm This doesn't play well with make right now.
    #       Force the file to always be updated, or else changing CodegenRust.py
    #       will cause many autogenerated bindings to be regenerated perpetually
    #       until the result is actually different.

    #oldFileContents = ""
    #try:
    #    oldFile = open(filename, 'rb')
    #    oldFileContents = ''.join(oldFile.readlines())
    #    oldFile.close()
    #except:
    #    pass

    #if newContents == oldFileContents:
    #    return False

    f = open(filename, 'wb')
    f.write(newContents)
    f.close()

    return True

def toStringBool(arg):
    return str(not not arg).lower()

def toBindingNamespace(arg):
    return re.sub("((_workers)?$)", "Binding\\1", arg);

def stripTrailingWhitespace(text):
    tail = '\n' if text.endswith('\n') else ''
    lines = text.splitlines()
    for i in range(len(lines)):
        lines[i] = lines[i].rstrip()
    return '\n'.join(lines) + tail

def MakeNativeName(name):
    return name[0].upper() + name[1:]

builtinNames = {
    IDLType.Tags.bool: 'bool',
    IDLType.Tags.int8: 'i8',
    IDLType.Tags.int16: 'i16',
    IDLType.Tags.int32: 'i32',
    IDLType.Tags.int64: 'i64',
    IDLType.Tags.uint8: 'u8',
    IDLType.Tags.uint16: 'u16',
    IDLType.Tags.uint32: 'u32',
    IDLType.Tags.uint64: 'u64',
    IDLType.Tags.float: 'f32',
    IDLType.Tags.double: 'f64'
}

numericTags = [
    IDLType.Tags.int8, IDLType.Tags.uint8,
    IDLType.Tags.int16, IDLType.Tags.uint16,
    IDLType.Tags.int32, IDLType.Tags.uint32,
    IDLType.Tags.int64, IDLType.Tags.uint64,
    IDLType.Tags.float, IDLType.Tags.double
    ]

class CastableObjectUnwrapper():
    """
    A class for unwrapping an object named by the "source" argument
    based on the passed-in descriptor and storing it in a variable
    called by the name in the "target" argument.

    codeOnFailure is the code to run if unwrapping fails.
    """
    def __init__(self, descriptor, source, target, codeOnFailure, isOptional=False):
        assert descriptor.castable

        self.substitution = { "type" : descriptor.nativeType,
                              "depth": descriptor.interface.inheritanceDepth(),
                              "prototype": "PrototypeList::id::" + descriptor.name,
                              "protoID" : "PrototypeList::id::" + descriptor.name + " as uint",
                              "source" : source,
                              "target" : target,
                              "codeOnFailure" : CGIndenter(CGGeneric(codeOnFailure), 4).define(),
                              "unwrapped_val" : "Some(val)" if isOptional else "val" }
        if descriptor.hasXPConnectImpls:
            # We don't use xpc_qsUnwrapThis because it will always throw on
            # unwrap failure, whereas we want to control whether we throw or
            # not.
            self.substitution["codeOnFailure"] = CGIndenter(CGGeneric(string.Template(
                "${type} *objPtr;\n"
                "xpc_qsSelfRef objRef;\n"
                "JS::Value val = JS::ObjectValue(*${source});\n"
                "nsresult rv = xpc_qsUnwrapArg<${type}>(cx, val, &objPtr, &objRef.ptr, &val);\n"
                "if (NS_FAILED(rv)) {\n"
                "${codeOnFailure}\n"
                "}\n"
                "// We should be castable!\n"
                "MOZ_ASSERT(!objRef.ptr);\n"
                "// We should have an object, too!\n"
                "MOZ_ASSERT(objPtr);\n"
                "${target} = objPtr;").substitute(self.substitution)), 4).define()

    def __str__(self):
        return string.Template(
"""match unwrap_object(${source}, ${prototype}, ${depth}) {
  Ok(val) => ${target} = ${unwrapped_val},
  Err(()) => {
    ${codeOnFailure}
  }
}
""").substitute(self.substitution)

#"""{
#  nsresult rv = UnwrapObject<${protoID}, ${type}>(cx, ${source}, ${target});
#  if (NS_FAILED(rv)) {
#${codeOnFailure}
#  }
#}""").substitute(self.substitution)

class FailureFatalCastableObjectUnwrapper(CastableObjectUnwrapper):
    """
    As CastableObjectUnwrapper, but defaulting to throwing if unwrapping fails
    """
    def __init__(self, descriptor, source, target, isOptional):
        CastableObjectUnwrapper.__init__(self, descriptor, source, target,
                                         "return 0; //XXXjdm return Throw<%s>(cx, rv);" %
                                         toStringBool(not descriptor.workers),
                                         isOptional)

class CGThing():
    """
    Abstract base class for things that spit out code.
    """
    def __init__(self):
        pass # Nothing for now
    def declare(self):
        """Produce code for a header file."""
        assert(False)  # Override me!
    def define(self):
        """Produce code for a cpp file."""
        assert(False) # Override me!

class CGMethodCall(CGThing):
    """
    A class to generate selection of a method signature from a set of
    signatures and generation of a call to that signature.
    """
    def __init__(self, argsPre, nativeMethodName, static, descriptor, method):
        CGThing.__init__(self)

        methodName = '"%s.%s"' % (descriptor.interface.identifier.name, method.identifier.name)

        def requiredArgCount(signature):
            arguments = signature[1]
            if len(arguments) == 0:
                return 0
            requiredArgs = len(arguments)
            while requiredArgs and arguments[requiredArgs-1].optional:
                requiredArgs -= 1
            return requiredArgs

        def getPerSignatureCall(signature, argConversionStartsAt=0, signatureIndex=0):
            return CGPerSignatureCall(signature[0], argsPre, signature[1],
                                      nativeMethodName + '_'*signatureIndex,
                                      static, descriptor,
                                      method, argConversionStartsAt)
            

        signatures = method.signatures()
        if len(signatures) == 1:
            # Special case: we can just do a per-signature method call
            # here for our one signature and not worry about switching
            # on anything.
            signature = signatures[0]
            self.cgRoot = CGList([ CGIndenter(getPerSignatureCall(signature)) ])
            requiredArgs = requiredArgCount(signature)


            if requiredArgs > 0:
                code = (
                    "if (argc < %d) {\n"
                    "  return 0; //XXXjdm throw exception\n"
                    "  //return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, %s);\n"
                    "}" % (requiredArgs, methodName))
                self.cgRoot.prepend(
                    CGWrapper(CGIndenter(CGGeneric(code)), pre="\n", post="\n"))
                    
            return

        # Need to find the right overload
        maxArgCount = method.maxArgCount
        allowedArgCounts = method.allowedArgCounts

        argCountCases = []
        for argCount in allowedArgCounts:
            possibleSignatures = method.signaturesForArgCount(argCount)
            if len(possibleSignatures) == 1:
                # easy case!
                signature = possibleSignatures[0]

                # (possibly) important optimization: if signature[1] has >
                # argCount arguments and signature[1][argCount] is optional and
                # there is only one signature for argCount+1, then the
                # signature for argCount+1 is just ourselves and we can fall
                # through.
                if (len(signature[1]) > argCount and
                    signature[1][argCount].optional and
                    (argCount+1) in allowedArgCounts and
                    len(method.signaturesForArgCount(argCount+1)) == 1):
                    argCountCases.append(
                        CGCase(str(argCount), None, True))
                else:
                    sigIndex = signatures.index(signature)
                    argCountCases.append(
                        CGCase(str(argCount), getPerSignatureCall(signature,
                                                                  signatureIndex=sigIndex)))
                continue

            distinguishingIndex = method.distinguishingIndexForArgCount(argCount)

            # We can't handle unions at the distinguishing index.
            for (returnType, args) in possibleSignatures:
                if args[distinguishingIndex].type.isUnion():
                    raise TypeError("No support for unions as distinguishing "
                                    "arguments yet: %s",
                                    args[distinguishingIndex].location)

            # Convert all our arguments up to the distinguishing index.
            # Doesn't matter which of the possible signatures we use, since
            # they all have the same types up to that point; just use
            # possibleSignatures[0]
            caseBody = [CGGeneric("let argv_start = JS_ARGV(cx, cast::transmute(vp));")]
            caseBody.extend([ CGArgumentConverter(possibleSignatures[0][1][i],
                                                  i, "argv_start", "argc",
                                                  descriptor) for i in
                              range(0, distinguishingIndex) ])

            # Select the right overload from our set.
            distinguishingArg = "(*argv_start.offset(%d))" % distinguishingIndex

            def pickFirstSignature(condition, filterLambda):
                sigs = filter(filterLambda, possibleSignatures)
                assert len(sigs) < 2
                if len(sigs) > 0:
                    if condition is None:
                        caseBody.append(
                            getPerSignatureCall(sigs[0], distinguishingIndex,
                                                possibleSignatures.index(sigs[0])))
                    else:
                        caseBody.append(CGGeneric("if " + condition + " {"))
                        caseBody.append(CGIndenter(
                                getPerSignatureCall(sigs[0], distinguishingIndex,
                                                    possibleSignatures.index(sigs[0]))))
                        caseBody.append(CGGeneric("}"))
                    return True
                return False

            # First check for null or undefined
            pickFirstSignature("%s.isNullOrUndefined()" % distinguishingArg,
                               lambda s: (s[1][distinguishingIndex].type.nullable() or
                                          s[1][distinguishingIndex].type.isDictionary()))

            # Now check for distinguishingArg being an object that implements a
            # non-callback interface.  That includes typed arrays and
            # arraybuffers.
            interfacesSigs = [
                s for s in possibleSignatures
                if (s[1][distinguishingIndex].type.isObject() or
                    s[1][distinguishingIndex].type.isNonCallbackInterface()) ]
            # There might be more than one of these; we need to check
            # which ones we unwrap to.
            
            if len(interfacesSigs) > 0:
                # The spec says that we should check for "platform objects
                # implementing an interface", but it's enough to guard on these
                # being an object.  The code for unwrapping non-callback
                # interfaces and typed arrays will just bail out and move on to
                # the next overload if the object fails to unwrap correctly.  We
                # could even not do the isObject() check up front here, but in
                # cases where we have multiple object overloads it makes sense
                # to do it only once instead of for each overload.  That will
                # also allow the unwrapping test to skip having to do codegen
                # for the null-or-undefined case, which we already handled
                # above.
                caseBody.append(CGGeneric("if JSVAL_IS_OBJECT(%s) {" %
                                          (distinguishingArg)))
                for idx, sig in enumerate(interfacesSigs):
                    caseBody.append(CGIndenter(CGGeneric("loop {")));
                    type = sig[1][distinguishingIndex].type

                    # The argument at index distinguishingIndex can't possibly
                    # be unset here, because we've already checked that argc is
                    # large enough that we can examine this argument.
                    testCode = instantiateJSToNativeConversionTemplate(
                        getJSToNativeConversionTemplate(type, descriptor,
                                                        failureCode="break;",
                                                        isDefinitelyObject=True),
                        {
                            "declName" : "arg%d" % distinguishingIndex,
                            "holderName" : ("arg%d" % distinguishingIndex) + "_holder",
                            "val" : distinguishingArg
                            })

                    # Indent by 4, since we need to indent further than our "do" statement
                    caseBody.append(CGIndenter(testCode, 4));
                    # If we got this far, we know we unwrapped to the right
                    # interface, so just do the call.  Start conversion with
                    # distinguishingIndex + 1, since we already converted
                    # distinguishingIndex.
                    caseBody.append(CGIndenter(
                            getPerSignatureCall(sig, distinguishingIndex + 1, idx), 4))
                    caseBody.append(CGIndenter(CGGeneric("}")))

                caseBody.append(CGGeneric("}"))

            # XXXbz Now we're supposed to check for distinguishingArg being
            # an array or a platform object that supports indexed
            # properties... skip that last for now.  It's a bit of a pain.
            pickFirstSignature("%s.isObject() && IsArrayLike(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s:
                                   (s[1][distinguishingIndex].type.isArray() or
                                    s[1][distinguishingIndex].type.isSequence() or
                                    s[1][distinguishingIndex].type.isObject()))

            # Check for Date objects
            # XXXbz Do we need to worry about security wrappers around the Date?
            pickFirstSignature("%s.isObject() && JS_ObjectIsDate(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s: (s[1][distinguishingIndex].type.isDate() or
                                          s[1][distinguishingIndex].type.isObject()))

            # Check for vanilla JS objects
            # XXXbz Do we need to worry about security wrappers?
            pickFirstSignature("%s.isObject() && !IsPlatformObject(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s: (s[1][distinguishingIndex].type.isCallback() or
                                          s[1][distinguishingIndex].type.isCallbackInterface() or
                                          s[1][distinguishingIndex].type.isDictionary() or
                                          s[1][distinguishingIndex].type.isObject()))

            # The remaining cases are mutually exclusive.  The
            # pickFirstSignature calls are what change caseBody
            # Check for strings or enums
            if pickFirstSignature(None,
                                  lambda s: (s[1][distinguishingIndex].type.isString() or
                                             s[1][distinguishingIndex].type.isEnum())):
                pass
            # Check for primitives
            elif pickFirstSignature(None,
                                    lambda s: s[1][distinguishingIndex].type.isPrimitive()):
                pass
            # Check for "any"
            elif pickFirstSignature(None,
                                    lambda s: s[1][distinguishingIndex].type.isAny()):
                pass
            else:
                # Just throw; we have no idea what we're supposed to
                # do with this.
                caseBody.append(CGGeneric("return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);" %
                                          toStringBool(not descriptor.workers)))

            argCountCases.append(CGCase(str(argCount),
                                        CGList(caseBody, "\n")))

        overloadCGThings = []
        overloadCGThings.append(
            CGGeneric("let argcount = argc.min(&%d);" %
                      maxArgCount))
        overloadCGThings.append(
            CGSwitch("argcount",
                     argCountCases,
                     CGGeneric("return 0; //XXXjdm throw stuff\n//return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, %s);\n" % methodName)))
        #XXXjdm Avoid unreachable statement warnings
        #overloadCGThings.append(
        #    CGGeneric('fail!("We have an always-returning default case");\n'
        #              'return 0;'))
        self.cgRoot = CGWrapper(CGIndenter(CGList(overloadCGThings, "\n")),
                                pre="\n")

    def define(self):
        return self.cgRoot.define()

class FakeCastableDescriptor():
    def __init__(self, descriptor):
        self.castable = True
        self.workers = descriptor.workers
        self.nativeType = descriptor.nativeType
        self.pointerType = descriptor.pointerType
        self.name = descriptor.name
        self.hasXPConnectImpls = descriptor.hasXPConnectImpls
        class FakeInterface:
            def inheritanceDepth(self):
                return descriptor.interface.inheritanceDepth()
        self.interface = FakeInterface()

def dictionaryHasSequenceMember(dictionary):
    return (any(typeIsSequenceOrHasSequenceMember(m.type) for m in
                dictionary.members) or
            (dictionary.parent and
             dictionaryHasSequenceMember(dictionary.parent)))

def typeIsSequenceOrHasSequenceMember(type):
    if type.nullable():
        type = type.inner
    if type.isSequence():
        return True
    if  type.isArray():
        elementType = type.inner
        return typeIsSequenceOrHasSequenceMember(elementType)
    if type.isDictionary():
        return dictionaryHasSequenceMember(type.inner)
    if type.isUnion():
        return any(typeIsSequenceOrHasSequenceMember(m.type) for m in
                   type.flatMemberTypes)
    return False

def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
                                    isDefinitelyObject=False,
                                    isMember=False,
                                    isOptional=False,
                                    invalidEnumValueFatal=True,
                                    defaultValue=None,
                                    treatNullAs="Default",
                                    isEnforceRange=False,
                                    isClamp=False,
                                    exceptionCode=None,
                                    isCallbackReturnValue=False,
                                    sourceDescription="value"):
    """
    Get a template for converting a JS value to a native object based on the
    given type and descriptor.  If failureCode is given, then we're actually
    testing whether we can convert the argument to the desired type.  That
    means that failures to convert due to the JS value being the wrong type of
    value need to use failureCode instead of throwing exceptions.  Failures to
    convert that are due to JS exceptions (from toString or valueOf methods) or
    out of memory conditions need to throw exceptions no matter what
    failureCode is.

    If isDefinitelyObject is True, that means we know the value
    isObject() and we have no need to recheck that.

    if isMember is True, we're being converted from a property of some
    JS object, not from an actual method argument, so we can't rely on
    our jsval being rooted or outliving us in any way.  Any caller
    passing true needs to ensure that it is handled correctly in
    typeIsSequenceOrHasSequenceMember.

    If isOptional is true, then we are doing conversion of an optional
    argument with no default value.

    invalidEnumValueFatal controls whether an invalid enum value conversion
    attempt will throw (if true) or simply return without doing anything (if
    false).

    If defaultValue is not None, it's the IDL default value for this conversion

    If isEnforceRange is true, we're converting an integer and throwing if the
    value is out of range.

    If isClamp is true, we're converting an integer and clamping if the
    value is out of range.

    The return value from this function is a tuple consisting of four things:

    1)  A string representing the conversion code.  This will have template
        substitution performed on it as follows:

          ${val} replaced by an expression for the JS::Value in question
          ${valPtr} is a pointer to the JS::Value in question
          ${holderName} replaced by the holder's name, if any
          ${declName} replaced by the declaration's name
          ${haveValue} replaced by an expression that evaluates to a boolean
                       for whether we have a JS::Value.  Only used when
                       defaultValue is not None.

    2)  A CGThing representing the native C++ type we're converting to
        (declType).  This is allowed to be None if the conversion code is
        supposed to be used as-is.
    3)  A CGThing representing the type of a "holder" (holderType) which will
        hold a possible reference to the C++ thing whose type we returned in #1,
        or None if no such holder is needed.
    4)  A boolean indicating whether the caller has to do optional-argument handling.
        This will only be true if isOptional is true and if the returned template
        expects both declType and holderType to be wrapped in Optional<>, with
        ${declName} and ${holderName} adjusted to point to the Value() of the
        Optional, and Construct() calls to be made on the Optional<>s as needed.

    ${declName} must be in scope before the generated code is entered.

    If holderType is not None then ${holderName} must be in scope
    before the generated code is entered.
    """
    # If we have a defaultValue then we're not actually optional for
    # purposes of what we need to be declared as.
    assert(defaultValue is None or not isOptional)

    # Also, we should not have a defaultValue if we know we're an object
    assert(not isDefinitelyObject or defaultValue is None)

    # If exceptionCode is not set, we'll just rethrow the exception we got.
    # Note that we can't just set failureCode to exceptionCode, because setting
    # failureCode will prevent pending exceptions from being set in cases when
    # they really should be!
    if exceptionCode is None:
        exceptionCode = "return 0;"
    # We often want exceptionCode to be indented, since it often appears in an
    # if body.
    exceptionCodeIndented = CGIndenter(CGGeneric(exceptionCode))

    # Unfortunately, .capitalize() on a string will lowercase things inside the
    # string, which we do not want.
    def firstCap(string):
        return string[0].upper() + string[1:]

    # Helper functions for dealing with failures due to the JS value being the
    # wrong type of value
    # Helper functions for dealing with failures due to the JS value being the
    # wrong type of value
    def onFailureNotAnObject(failureCode):
        return CGWrapper(
            CGGeneric(
                failureCode or
                ('//XXXjdm ThrowErrorMessage(cx, MSG_NOT_OBJECT, "%s");\n'
                 '%s' % (firstCap(sourceDescription), exceptionCode))),
            post="\n")
    def onFailureBadType(failureCode, typeName):
        return CGWrapper(
            CGGeneric(
                failureCode or
                ('//XXXjdm ThrowErrorMessage(cx, MSG_DOES_NOT_IMPLEMENT_INTERFACE, "%s", "%s")\n;'
                 '%s' % (firstCap(sourceDescription), typeName,
                         exceptionCode))),
            post="\n")

    # A helper function for handling default values.  Takes a template
    # body and the C++ code to set the default value and wraps the
    # given template body in handling for the default value.
    def handleDefault(template, setDefault):
        if defaultValue is None:
            return template
        return CGWrapper(
            CGIndenter(CGGeneric(template)),
            pre="if ${haveValue} {\n",
            post=("\n"
                  "} else {\n"
                  "%s;\n"
                  "}" %
                  CGIndenter(CGGeneric(setDefault)).define())).define()

    # A helper function for handling null default values.  Much like
    # handleDefault, but checks that the default value, if it exists, is null.
    def handleDefaultNull(template, codeToSetNull):
        if (defaultValue is not None and
            not isinstance(defaultValue, IDLNullValue)):
            raise TypeError("Can't handle non-null default value here")
        return handleDefault(template, codeToSetNull)

    # A helper function for wrapping up the template body for
    # possibly-nullable objecty stuff
    def wrapObjectTemplate(templateBody, isDefinitelyObject, type,
                           codeToSetNull, failureCode=None):
        if not isDefinitelyObject:
            # Handle the non-object cases by wrapping up the whole
            # thing in an if cascade.
            templateBody = (
                "if JSVAL_IS_OBJECT(${val}) {\n" +
                CGIndenter(CGGeneric(templateBody)).define() + "\n")
            if type.nullable():
                templateBody += (
                    "} else if RUST_JSVAL_IS_NULL(${val}) != 0 || RUST_JSVAL_IS_VOID(${val}) != 0 {\n"
                    "  %s;\n" % codeToSetNull)
            templateBody += (
                "} else {\n" +
                CGIndenter(onFailureNotAnObject(failureCode)).define() +
                "}")
            if type.nullable():
                templateBody = handleDefaultNull(templateBody, codeToSetNull)
            else:
                assert(defaultValue is None)

        return templateBody

    assert not (isEnforceRange and isClamp) # These are mutually exclusive

    if type.isArray():
        raise TypeError("Can't handle array arguments yet")

    if type.isSequence():
        assert not isEnforceRange and not isClamp

        if failureCode is not None:
            raise TypeError("Can't handle sequences when failureCode is not None")
        nullable = type.nullable();
        # Be very careful not to change "type": we need it later
        if nullable:
            elementType = type.inner.inner
        else:
            elementType = type.inner

        # We have to be careful with reallocation behavior for arrays.  In
        # particular, if we have a sequence of elements which are themselves
        # sequences (so nsAutoTArrays) or have sequences as members, we have a
        # problem.  In that case, resizing the outermost nsAutoTarray to the
        # right size will memmove its elements, but nsAutoTArrays are not
        # memmovable and hence will end up with pointers to bogus memory, which
        # is bad.  To deal with this, we disallow sequences, arrays,
        # dictionaries, and unions which contain sequences as sequence item
        # types.  If WebIDL ever adds another container type, we'd have to
        # disallow it as well.
        if typeIsSequenceOrHasSequenceMember(elementType):
            raise TypeError("Can't handle a sequence containing another "
                            "sequence as an element or member of an element.  "
                            "See the big comment explaining why.\n%s" %
                            str(type.location))

        (elementTemplate, elementDeclType,
         elementHolderType, dealWithOptional,
         initialValue) = getJSToNativeConversionTemplate(
            elementType, descriptorProvider, isMember=True)
        if dealWithOptional:
            raise TypeError("Shouldn't have optional things in sequences")
        if elementHolderType is not None:
            raise TypeError("Shouldn't need holders for sequences")

        typeName = CGWrapper(elementDeclType, pre="Sequence< ", post=" >")
        if nullable:
            typeName = CGWrapper(typeName, pre="Nullable< ", post=" >")
            arrayRef = "${declName}.Value()"
        else:
            arrayRef = "${declName}"
        # If we're optional, the const will come from the Optional
        mutableTypeName = typeName
        if not isOptional:
            typeName = CGWrapper(typeName, pre="const ")

        templateBody = ("""JSObject* seq = &${val}.toObject();\n
if (!IsArrayLike(cx, seq)) {
  return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
}
uint32_t length;
// JS_GetArrayLength actually works on all objects
if (!JS_GetArrayLength(cx, seq, &length)) {
  return false;
}
Sequence< %s > &arr = const_cast< Sequence< %s >& >(%s);
if (!arr.SetCapacity(length)) {
  return Throw<%s>(cx, NS_ERROR_OUT_OF_MEMORY);
}
for (uint32_t i = 0; i < length; ++i) {
  jsval temp;
  if (!JS_GetElement(cx, seq, i, &temp)) {
    return false;
  }
""" % (toStringBool(descriptorProvider.workers),
       elementDeclType.define(),
       elementDeclType.define(),
       arrayRef,
       toStringBool(descriptorProvider.workers)))

        templateBody += CGIndenter(CGGeneric(
                string.Template(elementTemplate).substitute(
                    {
                        "val" : "temp",
                        "valPtr": "&temp",
                        "declName" : "(*arr.AppendElement())"
                        }
                    ))).define()

        templateBody += "\n}"
        templateBody = wrapObjectTemplate(templateBody, isDefinitelyObject,
                                          type,
                                          "const_cast< %s & >(${declName}).SetNull()" % mutableTypeName.define())
        return (templateBody, typeName, None, isOptional, None)

    if type.isUnion():
        if isMember:
            raise TypeError("Can't handle unions as members, we have a "
                            "holderType")
        nullable = type.nullable();
        if nullable:
            type = type.inner

        assert(defaultValue is None or
               (isinstance(defaultValue, IDLNullValue) and nullable))

        unionArgumentObj = "${holderName}"
        if isOptional or nullable:
            unionArgumentObj += ".ref()"

        memberTypes = type.flatMemberTypes
        names = []

        interfaceMemberTypes = filter(lambda t: t.isNonCallbackInterface(), memberTypes)
        if len(interfaceMemberTypes) > 0:
            interfaceObject = []
            for memberType in interfaceMemberTypes:
                if type.isGeckoInterface():
                    name = memberType.inner.identifier.name
                else:
                    name = memberType.name
                interfaceObject.append(CGGeneric("(failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext" % (unionArgumentObj, name)))
                names.append(name)
            interfaceObject = CGWrapper(CGList(interfaceObject, " ||\n"), pre="done = ", post=";\n", reindent=True)
        else:
            interfaceObject = None

        arrayObjectMemberTypes = filter(lambda t: t.isArray() or t.isSequence(), memberTypes)
        if len(arrayObjectMemberTypes) > 0:
            assert len(arrayObjectMemberTypes) == 1
            memberType = arrayObjectMemberTypes[0]
            name = memberType.name
            arrayObject = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
            # XXX Now we're supposed to check for an array or a platform object
            # that supports indexed properties... skip that last for now. It's a
            # bit of a pain.
            arrayObject = CGWrapper(CGIndenter(arrayObject),
                                    pre="if (IsArrayLike(cx, &argObj)) {\n",
                                    post="}")
            names.append(name)
        else:
            arrayObject = None

        dateObjectMemberTypes = filter(lambda t: t.isDate(), memberTypes)
        if len(dateObjectMemberTypes) > 0:
            assert len(dateObjectMemberTypes) == 1
            memberType = dateObjectMemberTypes[0]
            name = memberType.name
            dateObject = CGGeneric("%s.SetTo%s(cx, ${val}, ${valPtr});\n"
                                   "done = true;" % (unionArgumentObj, name))
            dateObject = CGWrapper(CGIndenter(dateObject),
                                   pre="if (JS_ObjectIsDate(cx, &argObj)) {\n",
                                   post="\n}")
            names.append(name)
        else:
            dateObject = None

        callbackMemberTypes = filter(lambda t: t.isCallback() or t.isCallbackInterface(), memberTypes)
        if len(callbackMemberTypes) > 0:
            assert len(callbackMemberTypes) == 1
            memberType = callbackMemberTypes[0]
            name = memberType.name
            callbackObject = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
            names.append(name)
        else:
            callbackObject = None

        dictionaryMemberTypes = filter(lambda t: t.isDictionary(), memberTypes)
        if len(dictionaryMemberTypes) > 0:
            raise TypeError("No support for unwrapping dictionaries as member "
                            "of a union")
        else:
            dictionaryObject = None

        if callbackObject or dictionaryObject:
            nonPlatformObject = CGList([callbackObject, dictionaryObject], "\n")
            nonPlatformObject = CGWrapper(CGIndenter(nonPlatformObject),
                                          pre="if (!IsPlatformObject(cx, &argObj)) {\n",
                                          post="\n}")
        else:
            nonPlatformObject = None

        objectMemberTypes = filter(lambda t: t.isObject(), memberTypes)
        if len(objectMemberTypes) > 0:
            object = CGGeneric("%s.SetToObject(&argObj);\n"
                               "done = true;" % unionArgumentObj)
        else:
            object = None

        hasObjectTypes = interfaceObject or arrayObject or dateObject or nonPlatformObject or object
        if hasObjectTypes:
            # If we try more specific object types first then we need to check
            # whether that succeeded before converting to object.
            if object and (interfaceObject or arrayObject or dateObject or nonPlatformObject):
                object = CGWrapper(CGIndenter(object), pre="if (!done) {\n",
                                   post=("\n}"))

            if arrayObject or dateObject or nonPlatformObject:
                # An object can be both an array object and not a platform
                # object, but we shouldn't have both in the union's members
                # because they are not distinguishable.
                assert not (arrayObject and nonPlatformObject)
                templateBody = CGList([arrayObject, dateObject, nonPlatformObject], " else ")
            else:
                templateBody = None
            if interfaceObject:
                if templateBody:
                    templateBody = CGList([templateBody, object], "\n")
                    templateBody = CGWrapper(CGIndenter(templateBody),
                                             pre="if (!done) {\n", post=("\n}"))
                templateBody = CGList([interfaceObject, templateBody], "\n")
            else:
                templateBody = CGList([templateBody, object], "\n")

            if any([arrayObject, dateObject, nonPlatformObject, object]):
                templateBody.prepend(CGGeneric("JSObject& argObj = ${val}.toObject();"))
            templateBody = CGWrapper(CGIndenter(templateBody),
                                     pre="if (${val}.isObject()) {\n",
                                     post="\n}")
        else:
            templateBody = CGGeneric()

        otherMemberTypes = filter(lambda t: t.isString() or t.isEnum(),
                                  memberTypes)
        otherMemberTypes.extend(t for t in memberTypes if t.isPrimitive())
        if len(otherMemberTypes) > 0:
            assert len(otherMemberTypes) == 1
            memberType = otherMemberTypes[0]
            if memberType.isEnum():
                name = memberType.inner.identifier.name
            else:
                name = memberType.name
            other = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
            names.append(name)
            if hasObjectTypes:
                other = CGWrapper(CGIndenter(other), "{\n", post="\n}")
                if object:
                    join = " else "
                else:
                    other = CGWrapper(other, pre="if (!done) ")
                    join = "\n"
                templateBody = CGList([templateBody, other], join)
        else:
            other = None

        templateBody = CGWrapper(templateBody, pre="bool done = false, failed = false, tryNext;\n")
        throw = CGGeneric("if (failed) {\n"
                          "  return false;\n"
                          "}\n"
                          "if (!done) {\n"
                          "  return ThrowErrorMessage(cx, MSG_NOT_IN_UNION, \"%s\");\n"
                          "}" % ", ".join(names))
        templateBody = CGWrapper(CGIndenter(CGList([templateBody, throw], "\n")), pre="{\n", post="\n}")

        typeName = type.name
        argumentTypeName = typeName + "Argument"
        if nullable:
            typeName = "Nullable<" + typeName + " >"
        if isOptional:
            nonConstDecl = "const_cast<Optional<" + typeName + " >& >(${declName})"
        else:
            nonConstDecl = "const_cast<" + typeName + "& >(${declName})"
            typeName = "const " + typeName

        def handleNull(templateBody, setToNullVar, extraConditionForNull=""):
            null = CGGeneric("if (%s${val}.isNullOrUndefined()) {\n"
                             "  %s.SetNull();\n"
                             "}" % (extraConditionForNull, setToNullVar))
            templateBody = CGWrapper(CGIndenter(templateBody), pre="{\n", post="\n}")
            return CGList([null, templateBody], " else ")

        if type.hasNullableType:
            templateBody = handleNull(templateBody, unionArgumentObj)

        declType = CGGeneric(typeName)
        holderType = CGGeneric(argumentTypeName)
        if isOptional:
            mutableDecl = nonConstDecl + ".Value()"
            declType = CGWrapper(declType, pre="const Optional<", post=" >")
            holderType = CGWrapper(holderType, pre="Maybe<", post=" >")
            constructDecl = CGGeneric(nonConstDecl + ".Construct();")
            if nullable:
                constructHolder = CGGeneric("${holderName}.construct(%s.SetValue());" % mutableDecl)
            else:
                constructHolder = CGGeneric("${holderName}.construct(${declName}.Value());")
        else:
            mutableDecl = nonConstDecl
            constructDecl = None
            if nullable:
                holderType = CGWrapper(holderType, pre="Maybe<", post=" >")
                constructHolder = CGGeneric("${holderName}.construct(%s.SetValue());" % mutableDecl)
            else:
                constructHolder = CGWrapper(holderType, post=" ${holderName}(${declName});")
                holderType = None

        templateBody = CGList([constructHolder, templateBody], "\n")
        if nullable:
            if defaultValue:
                assert(isinstance(defaultValue, IDLNullValue))
                valueMissing = "!(${haveValue}) || "
            else:
                valueMissing = ""
            templateBody = handleNull(templateBody, mutableDecl,
                                      extraConditionForNull=valueMissing)
        templateBody = CGList([constructDecl, templateBody], "\n")

        return templateBody.define(), declType, holderType, False, None

    if type.isGeckoInterface():
        assert not isEnforceRange and not isClamp

        descriptor = descriptorProvider.getDescriptor(
            type.unroll().inner.identifier.name)

        if descriptor.interface.isCallback():
            name = descriptor.nativeType
            declType = CGGeneric("Option<%s>" % name);
            conversion = ("  ${declName} = Some(%s::new(JSVAL_TO_OBJECT(${val})));\n" % name)

            template = wrapObjectTemplate(conversion, type,
                                          "${declName} = None",
                                          failureCode)
            return (template, declType, None, isOptional, None)

        # This is an interface that we implement as a concrete class
        # or an XPCOM interface.

        # Allow null pointers for nullable types and old-binding classes
        argIsPointer = type.nullable() or type.unroll().inner.isExternal()

        # Sequences and non-worker callbacks have to hold a strong ref to the
        # thing being passed down.
        forceOwningType = (descriptor.interface.isCallback() and
                           not descriptor.workers) or isMember

        typeName = descriptor.nativeType
        typePtr = descriptor.pointerType + typeName

        # Compute a few things:
        #  - declType is the type we want to return as the first element of our
        #    tuple.
        #  - holderType is the type we want to return as the third element
        #    of our tuple.

        # Set up some sensible defaults for these things insofar as we can.
        holderType = None
        if argIsPointer:
            declType = "Option<" + typePtr + ">"
        else:
            declType = typePtr

        templateBody = ""
        if descriptor.castable:
            if descriptor.prefable:
                raise TypeError("We don't support prefable castable object "
                                "arguments (like %s), because we don't know "
                                "how to handle them being preffed off" %
                                descriptor.interface.identifier.name)
            if descriptor.interface.isConsequential():
                raise TypeError("Consequential interface %s being used as an "
                                "argument but flagged as castable" %
                                descriptor.interface.identifier.name)
            if failureCode is not None:
                templateBody += str(CastableObjectUnwrapper(
                        descriptor,
                        "JSVAL_TO_OBJECT(${val})",
                        "${declName}",
                        failureCode,
                        isOptional or argIsPointer or type.nullable()))
            else:
                templateBody += str(FailureFatalCastableObjectUnwrapper(
                        descriptor,
                        "JSVAL_TO_OBJECT(${val})",
                        "${declName}",
                        isOptional or argIsPointer or type.nullable()))
        elif descriptor.workers:
            templateBody += "${declName} = &${val}.toObject();"
        else:
            templateBody += (
                "match unwrap_value::<" + typePtr + ">(&${val} as *JSVal, "
                "PrototypeList::id::%s, %d) {\n" % (descriptor.name, descriptor.interface.inheritanceDepth() if descriptor.concrete else 0) +
                "  Err(()) => {")
            templateBody += CGIndenter(onFailureBadType(failureCode,
                                                        descriptor.interface.identifier.name)).define()
            templateBody += (
                "  }\n"
                "  Ok(unwrapped) => ${declName} = Some(unwrapped)\n"
                "}\n")

        templateBody = wrapObjectTemplate(templateBody, isDefinitelyObject,
                                          type, "${declName} = None",
                                          failureCode)

        declType = CGGeneric(declType)
        if holderType is not None:
            holderType = CGGeneric(holderType)
        return (templateBody, declType, holderType, isOptional, None)

    if type.isSpiderMonkeyInterface():
        assert not isEnforceRange and not isClamp
        if isMember:
            raise TypeError("Can't handle member arraybuffers or "
                            "arraybuffer views because making sure all the "
                            "objects are properly rooted is hard")
        name = type.name
        # By default, we use a Maybe<> to hold our typed array.  And in the optional
        # non-nullable case we want to pass Optional<TypedArray> to consumers, not
        # Optional<NonNull<TypedArray> >, so jump though some hoops to do that.
        holderType = "Maybe<%s>" % name
        constructLoc = "${holderName}"
        constructMethod = "construct"
        constructInternal = "ref"
        if type.nullable():
            if isOptional:
                declType = "const Optional<" + name + "*>"
            else:
                declType = name + "*"
        else:
            if isOptional:
                declType = "const Optional<" + name + ">"
                # We don't need a holder in this case
                holderType = None
                constructLoc = "(const_cast<Optional<" + name + ">& >(${declName}))"
                constructMethod = "Construct"
                constructInternal = "Value"
            else:
                declType = "NonNull<" + name + ">"
        template = (
            "%s.%s(cx, &${val}.toObject());\n"
            "if (!%s.%s().inited()) {\n"
            "%s" # No newline here because onFailureBadType() handles that
            "}\n" %
            (constructLoc, constructMethod, constructLoc, constructInternal,
             CGIndenter(onFailureBadType(failureCode, type.name)).define()))
        nullableTarget = ""
        if type.nullable():
            if isOptional:
                mutableDecl = "(const_cast<Optional<" + name + "*>& >(${declName}))"
                template += "%s.Construct();\n" % mutableDecl
                nullableTarget = "%s.Value()" % mutableDecl
            else:
                nullableTarget = "${declName}"
            template += "%s = ${holderName}.addr();" % nullableTarget
        elif not isOptional:
            template += "${declName} = ${holderName}.addr();"
        template = wrapObjectTemplate(template, isDefinitelyObject, type,
                                      "%s = NULL" % nullableTarget,
                                      failureCode)

        if holderType is not None:
            holderType = CGGeneric(holderType)
        # We handle all the optional stuff ourselves; no need for caller to do it.
        return (template, CGGeneric(declType), holderType, False, None)

    if type.isString():
        assert not isEnforceRange and not isClamp

        treatAs = {
            "Default": "Default",
            "EmptyString": "Empty",
        }
        if treatNullAs not in treatAs:
            raise TypeError("We don't support [TreatNullAs=%s]" % treatNullAs)
        nullBehavior = treatAs[treatNullAs]

        def getConversionCode(varName, isOptional=False):
            strval = "strval"
            if isOptional:
                strval = "Some(%s)" % strval
            if type.nullable():
                call = "jsval_to_domstring(cx, ${val})"
            else:
                call = "jsval_to_str(cx, ${val}, %s)" % nullBehavior
            conversionCode = (
                "let strval = %s;\n"
                "if strval.is_err() {\n"
                "  return 0;\n"
                "}\n"
                "let strval = strval.unwrap();\n"
                "%s = %s;" % (call, varName, strval))
            if defaultValue is None:
                return conversionCode

            if isinstance(defaultValue, IDLNullValue):
                assert(type.nullable())
                return handleDefault(conversionCode,
                                     "%s.SetNull()" % varName)
            return handleDefault(
                conversionCode,
                ("static data: [u8, ..%s] = [ %s ];\n"
                 "%s = str::from_utf8(data)" %
                 (len(defaultValue.value) + 1,
                  ", ".join(["'" + char + "' as u8" for char in defaultValue.value] + ["0"]),
                  varName)))

        if isMember:
            # We have to make a copy, because our jsval may well not
            # live as long as our string needs to.
            declType = CGGeneric("nsString")
            return (
                "{\n"
                "  FakeDependentString str;\n"
                "%s\n"
                "  ${declName} = str;\n"
                "}\n" % CGIndenter(CGGeneric(getConversionCode("str"))).define(),
                declType, None, isOptional, None)

        declType = "DOMString"
        initialValue = None
        if type.nullable():
            declType = "Option<%s>" % declType

        if isOptional:
            declType = "Option<%s>" % declType
            initialValue = "None"

        return (
            "%s\n" %
            #"const_cast<%s&>(${declName}) = &${holderName};" %
            (getConversionCode("${declName}", isOptional)),
            CGGeneric(declType), None, #CGGeneric("FakeDependentString"),
            False,
            initialValue)

    if type.isEnum():
        assert not isEnforceRange and not isClamp

        if type.nullable():
            raise TypeError("We don't support nullable enumerated arguments "
                            "yet")
        enum = type.inner.identifier.name
        if invalidEnumValueFatal:
            handleInvalidEnumValueCode = "    return 0;\n"
        else:
            handleInvalidEnumValueCode = "    return 1;\n"
            
        template = (
            "{\n"
            #"  int index = FindEnumStringIndex<%(invalidEnumValueFatal)s>(cx, ${val}, %(values)s, \"%(enumtype)s\", &ok);\n"
            "  let result = FindEnumStringIndex(cx, ${val}, %(values)s);\n"
            "  if result.is_err() {\n"
            "%(handleInvalidEnumValueCode)s"
            "  }\n"
            "  let index = result.unwrap();\n"
            "  ${declName} = cast::transmute(index); //XXXjdm need some range checks up in here\n"
            "}" % { "enumtype" : enum,
                      "values" : enum + "Values::strings",
       "invalidEnumValueFatal" : toStringBool(invalidEnumValueFatal),
  "handleInvalidEnumValueCode" : handleInvalidEnumValueCode })

        if defaultValue is not None:
            assert(defaultValue.type.tag() == IDLType.Tags.domstring)
            template = "" #XXXjdm unfinished
            #template = handleDefault(template,
            #                         ("${declName} = %sValues::%s" %
            #                          (enum,
            #                           getEnumValueName(defaultValue.value))))
        return (template, CGGeneric(enum), None, isOptional, None)

    if type.isCallback():
        assert not isEnforceRange and not isClamp

        if isMember:
            raise TypeError("Can't handle member callbacks; need to sort out "
                            "rooting issues")
        # XXXbz we're going to assume that callback types are always
        # nullable and always have [TreatNonCallableAsNull] for now.
        haveCallable = "${val}.isObject() && JS_ObjectIsCallable(cx, &${val}.toObject())"
        if defaultValue is not None:
            assert(isinstance(defaultValue, IDLNullValue))
            haveCallable = "${haveValue} && " + haveCallable
        return (
            "if (%s) {\n"
            "  ${declName} = &${val}.toObject();\n"
            "} else {\n"
            "  ${declName} = NULL;\n"
            "}" % haveCallable,
            CGGeneric("JSObject*"), None, isOptional, None)

    if type.isAny():
        assert not isEnforceRange and not isClamp

        if isMember:
            raise TypeError("Can't handle member 'any'; need to sort out "
                            "rooting issues")
        templateBody = "${declName} = ${val};"
        templateBody = handleDefaultNull(templateBody,
                                         "${declName} = JSVAL_NULL")
        return (templateBody, CGGeneric("JSVal"), None, isOptional, "JSVAL_NULL")

    if type.isObject():
        assert not isEnforceRange and not isClamp

        if isMember:
            raise TypeError("Can't handle member 'object'; need to sort out "
                            "rooting issues")
        template = wrapObjectTemplate("${declName} = &${val}.toObject();",
                                      isDefinitelyObject, type,
                                      "${declName} = NULL",
                                      failureCode)
        if type.nullable():
            declType = CGGeneric("JSObject*")
        else:
            declType = CGGeneric("NonNull<JSObject>")
        return (template, declType, None, isOptional, None)

    if type.isDictionary():
        if failureCode is not None:
            raise TypeError("Can't handle dictionaries when failureCode is not None")
        # There are no nullable dictionaries
        assert not type.nullable()
        # All optional dictionaries always have default values, so we
        # should be able to assume not isOptional here.
        assert not isOptional

        typeName = CGDictionary.makeDictionaryName(type.inner,
                                                   descriptorProvider.workers)
        actualTypeName = typeName
        selfRef = "${declName}"

        declType = CGGeneric(actualTypeName)

        # If we're a member of something else, the const
        # will come from the Optional or our container.
        if not isMember:
            selfRef = "%s" % selfRef

        # We do manual default value handling here, because we
        # actually do want a jsval, and we only handle null anyway
        if defaultValue is not None:
            assert(isinstance(defaultValue, IDLNullValue))
            val = "if ${haveValue} { ${val} } else { JSVAL_NULL }"
        else:
            val = "${val}"

        template = ("%s = %s::new();\n"
                    "if %s.Init(cx, %s) == 0 {\n"
                    "  return 0;\n"
                    "}" % (selfRef, actualTypeName, selfRef, val))

        return (template, declType, None, False, None)

    if type.isVoid():
        assert not isOptional
        # This one only happens for return values, and its easy: Just
        # ignore the jsval.
        return ("", None, None, False, None)

    if not type.isPrimitive():
        raise TypeError("Need conversion for argument type '%s'" % str(type))

    typeName = builtinNames[type.tag()]

    conversionBehavior = "eDefault"
    if isEnforceRange:
        conversionBehavior = "eEnforceRange"
    elif isClamp:
        conversionBehavior = "eClamp"

    if type.nullable():
        dataLoc = "${declName}.SetValue()"
        nullCondition = "(RUST_JSVAL_IS_NULL(${val}) != 0 || RUST_JSVAL_IS_VOID(${val}) != 0)"
        if defaultValue is not None and isinstance(defaultValue, IDLNullValue):
            nullCondition = "!(${haveValue}) || " + nullCondition
        #XXXjdm support conversionBehavior here
        template = (
            "if (%s) {\n"
            "  ${declName} = None;\n"
            "} else {\n"
            "  match JSValConvertible::from_jsval(${val}) {\n"
            "    Some(val_) => ${declName} = Some(val_),\n"
            "    None => return 0\n"
            "  }\n"
           "}" % nullCondition)
        declType = CGGeneric("Option<" + typeName + ">")
    else:
        assert(defaultValue is None or
               not isinstance(defaultValue, IDLNullValue))
        dataLoc = "${declName}"
        #XXXjdm conversionBehavior should be used
        template = (
            "match JSValConvertible::from_jsval(${val}) {\n"
            "  None => return 0,\n"
            "  Some(v) => %s = v\n"
            "}" % (dataLoc,))
        declType = CGGeneric(typeName)
    if (defaultValue is not None and
        # We already handled IDLNullValue, so just deal with the other ones
        not isinstance(defaultValue, IDLNullValue)):
        tag = defaultValue.type.tag()
        if tag in numericTags:
            defaultStr = defaultValue.value
        else:
            assert(tag == IDLType.Tags.bool)
            defaultStr = toStringBool(defaultValue.value)
        template = CGWrapper(CGIndenter(CGGeneric(template)),
                             pre="if ${haveValue} {\n",
                             post=("\n"
                                   "} else {\n"
                                   "  %s = %s;\n"
                                   "}" % (dataLoc, defaultStr))).define()

    initialVal = "false" if typeName == "bool" else ("0 as %s" % typeName)
    if type.nullable():
        initialVal = "Some(%s)" % initialVal
    return (template, declType, None, isOptional, initialVal)

def instantiateJSToNativeConversionTemplate(templateTuple, replacements,
                                            argcAndIndex=None):
    """
    Take a tuple as returned by getJSToNativeConversionTemplate and a set of
    replacements as required by the strings in such a tuple, and generate code
    to convert into stack C++ types.

    If argcAndIndex is not None it must be a dict that can be used to
    replace ${argc} and ${index}, where ${index} is the index of this
    argument (0-based) and ${argc} is the total number of arguments.
    """
    (templateBody, declType, holderType, dealWithOptional, initialValue) = templateTuple

    if dealWithOptional and argcAndIndex is None:
        raise TypeError("Have to deal with optional things, but don't know how")
    if argcAndIndex is not None and declType is None:
        raise TypeError("Need to predeclare optional things, so they will be "
                        "outside the check for big enough arg count!");

    result = CGList([], "\n")
    # Make a copy of "replacements" since we may be about to start modifying it
    replacements = dict(replacements)
    originalHolderName = replacements["holderName"]
    if holderType is not None:
        if dealWithOptional:
            replacements["holderName"] = (
                "const_cast< %s & >(%s.Value())" %
                (holderType.define(), originalHolderName))
            mutableHolderType = CGWrapper(holderType, pre="Optional< ", post=" >")
            holderType = CGWrapper(mutableHolderType, pre="const ")
        tmpresult = [CGGeneric("let "),
                     CGGeneric(originalHolderName),
                     CGGeneric(": "),
                     holderType]
        if initialValue:
            tmpresult += [CGGeneric(" = "),
                          initialValue]
        tmpresult += [CGGeneric(";")]
        result.append(CGList(tmpresult))

    originalDeclName = replacements["declName"]
    if declType is not None:
        if dealWithOptional:
            mutableDeclType = CGWrapper(declType, pre="Option< ", post=" >")
        newDecl = [CGGeneric("let mut "),
                   CGGeneric(originalDeclName),
                   CGGeneric(": "),
                   declType]
        if initialValue:
            newDecl.append(CGGeneric(" = " + initialValue))
        newDecl.append(CGGeneric(";"))
        result.append(CGList(newDecl))

    conversion = CGGeneric(
            string.Template(templateBody).substitute(replacements)
            )

    if argcAndIndex is not None:
        declConstruct = None
        holderConstruct = None

        conversion = CGList(
            [CGGeneric(
                    string.Template("if (${index} < ${argc}) {").substitute(
                        argcAndIndex
                        )),
             declConstruct,
             holderConstruct,
             CGIndenter(conversion),
             CGGeneric("}")],
            "\n")

    result.append(conversion)
    # Add an empty CGGeneric to get an extra newline after the argument
    # conversion.
    result.append(CGGeneric(""))
    return result;

def convertConstIDLValueToJSVal(value):
    if isinstance(value, IDLNullValue):
        return "NullVal"
    tag = value.type.tag()
    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
               IDLType.Tags.uint16, IDLType.Tags.int32]:
        return "IntVal(%s)" % (value.value)
    if tag == IDLType.Tags.uint32:
        return "UintVal(%s)" % (value.value)
    if tag in [IDLType.Tags.int64, IDLType.Tags.uint64]:
        return "DoubleVal(%s)" % (value.value)
    if tag == IDLType.Tags.bool:
        return "BoolVal(true)" if value.value else "BoolVal(false)"
    if tag in [IDLType.Tags.float, IDLType.Tags.double]:
        return "DoubleVal(%s)" % (value.value)
    raise TypeError("Const value of unhandled type: " + value.type)

class CGArgumentConverter(CGThing):
    """
    A class that takes an IDL argument object, its index in the
    argument list, and the argv and argc strings and generates code to
    unwrap the argument to the right native type.
    """
    def __init__(self, argument, index, argv, argc, descriptorProvider,
                 invalidEnumValueFatal=True):
        CGThing.__init__(self)
        self.argument = argument
        if argument.variadic:
            raise TypeError("We don't support variadic arguments yet " +
                            str(argument.location))
        assert(not argument.defaultValue or argument.optional)

        replacer = {
            "index" : index,
            "argc" : argc,
            "argv" : argv
            }
        self.replacementVariables = {
            "declName" : "arg%d" % index,
            "holderName" : ("arg%d" % index) + "_holder"
            }
        self.replacementVariables["val"] = string.Template(
            "(*${argv}.offset(${index}))"
            ).substitute(replacer)
        self.replacementVariables["valPtr"] = (
            "&" + self.replacementVariables["val"])
        if argument.defaultValue:
            self.replacementVariables["haveValue"] = string.Template(
                "${index} < ${argc}").substitute(replacer)
        self.descriptorProvider = descriptorProvider
        if self.argument.optional and not self.argument.defaultValue:
            self.argcAndIndex = replacer
        else:
            self.argcAndIndex = None
        self.invalidEnumValueFatal = invalidEnumValueFatal

    def define(self):
        return instantiateJSToNativeConversionTemplate(
            getJSToNativeConversionTemplate(self.argument.type,
                                            self.descriptorProvider,
                                            isOptional=(self.argcAndIndex is not None),
                                            invalidEnumValueFatal=self.invalidEnumValueFatal,
                                            defaultValue=self.argument.defaultValue,
                                            treatNullAs=self.argument.treatNullAs,
                                            isEnforceRange=self.argument.enforceRange,
                                            isClamp=self.argument.clamp),
            self.replacementVariables,
            self.argcAndIndex).define()

def getWrapTemplateForType(type, descriptorProvider, result, successCode,
                           isCreator, exceptionCode):
    """
    Reflect a C++ value stored in "result", of IDL type "type" into JS.  The
    "successCode" is the code to run once we have successfully done the
    conversion.  The resulting string should be used with string.Template, it
    needs the following keys when substituting: jsvalPtr/jsvalRef/obj.

    Returns (templateString, infallibility of conversion template)
    """
    haveSuccessCode = successCode is not None
    if not haveSuccessCode:
        successCode = "return 1;"

    # We often want exceptionCode to be indented, since it often appears in an
    # if body.
    exceptionCodeIndented = CGIndenter(CGGeneric(exceptionCode))

    def setValue(value, callWrapValue=False):
        """
        Returns the code to set the jsval to value. If "callWrapValue" is true
        JS_WrapValue will be called on the jsval.
        """
        if not callWrapValue:
            tail = successCode
        elif haveSuccessCode:
            tail = ("if JS_WrapValue(cx, ${jsvalPtr}) == 0 {\n" +
                    "  return 0;\n" +
                    "}\n" +
                    successCode)
        else:
            tail = "return JS_WrapValue(cx, cast::transmute(${jsvalPtr}));"
        return ("${jsvalRef} = %s;\n" +
                tail) % (value)

    def wrapAndSetPtr(wrapCall, failureCode=None):
        """
        Returns the code to set the jsval by calling "wrapCall". "failureCode"
        is the code to run if calling "wrapCall" fails 
        """
        if failureCode is None:
            if not haveSuccessCode:
                return wrapCall + ";\n" + "return if (*vp).v != 0 { 1 } else { 0 };"
            failureCode = "return 0;"
        str = ("if !(%s != 0) {\n" +
               CGIndenter(CGGeneric(failureCode)).define() + "\n" +
               "}\n" +
               successCode) % (wrapCall)
        return str
    
    if type is None or type.isVoid():
        return (setValue("JSVAL_VOID"), True)

    if type.isArray():
        raise TypeError("Can't handle array return values yet")

    if type.isSequence():
        if type.nullable():
            # Nullable sequences are Nullable< nsTArray<T> >
            (recTemplate, recInfall) = getWrapTemplateForType(type.inner, descriptorProvider,
                                                              "%s.Value()" % result, successCode,
                                                              isCreator, exceptionCode)
            return ("""
if (%s.IsNull()) {
%s
}
%s""" % (result, CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define(), recTemplate), recInfall)

        # Now do non-nullable sequences.  We use setting the element
        # in the array as our succcess code because when we succeed in
        # wrapping that's what we should do.
        innerTemplate = wrapForType(
            type.inner, descriptorProvider,
            {
                'result' :  "%s[i]" % result,
                'successCode': ("if (!JS_DefineElement(cx, returnArray, i, tmp,\n"
                                "                      NULL, NULL, JSPROP_ENUMERATE)) {\n"
                                "  return false;\n"
                                "}"),
                'jsvalRef': "tmp",
                'jsvalPtr': "&tmp",
                'isCreator': isCreator
                }
            )
        innerTemplate = CGIndenter(CGGeneric(innerTemplate)).define()
        return (("""
uint32_t length = %s.Length();
JSObject *returnArray = JS_NewArrayObject(cx, length, NULL);
if (!returnArray) {
  return false;
}
jsval tmp;
for (uint32_t i = 0; i < length; ++i) {
%s
}\n""" % (result, innerTemplate)) + setValue("JS::ObjectValue(*returnArray)"), False)

    if type.isGeckoInterface():
        descriptor = descriptorProvider.getDescriptor(type.unroll().inner.identifier.name)
        if type.nullable():
            wrappingCode = ("if %s.is_none() {\n" % (result) +
                            CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define() + "\n" +
                            "}\n" +
                            "let mut %s = %s.unwrap();\n" % (result, result))
        else:
            wrappingCode = ""
        if (not descriptor.interface.isExternal() and
            not descriptor.interface.isCallback()):
            wrap = "GetReflector(cx, (%s).reflector(), ${jsvalPtr} as *mut JSVal)" % result
            # We don't support prefable stuff in workers.
            assert(not descriptor.prefable or not descriptor.workers)
            if not descriptor.prefable:
                # Non-prefable bindings can only fail to wrap as a new-binding object
                # if they already threw an exception.  Same thing for
                # non-prefable bindings.
                failed = ("assert!(unsafe { JS_IsExceptionPending(cx) != 0 });\n" +
                          "%s" % exceptionCode)
            else:
                if descriptor.notflattened:
                    raise TypeError("%s is prefable but not flattened; "
                                    "fallback won't work correctly" %
                                    descriptor.interface.identifier.name)
                # Try old-style wrapping for bindings which might be preffed off.
                failed = wrapAndSetPtr("HandleNewBindingWrappingFailure(cx, ${obj}, %s, ${jsvalPtr})" % result)
            wrappingCode += wrapAndSetPtr(wrap, failed)
        else:
            wrap = "GetReflector(cx, (%s).reflector(), ${jsvalPtr} as *mut JSVal)" % result
            wrappingCode += wrapAndSetPtr(wrap)
        return (wrappingCode, False)

    if type.isString():
        if type.nullable():
            return (wrapAndSetPtr("*${jsvalPtr} = domstring_to_jsval(cx, &%s)" % result), False)
        else:
            return (wrapAndSetPtr("*${jsvalPtr} = str_to_jsval(cx, &%s)" % result), False)

    if type.isEnum():
        if type.nullable():
            raise TypeError("We don't support nullable enumerated return types "
                            "yet")
        return ("""assert!((%(result)s as uint) < %(strings)s.len());
let %(resultStr)s: *JSString = JS_NewStringCopyN(cx, ptr::to_unsafe_ptr(&%(strings)s[%(result)s as u32].value[0]) as *i8, %(strings)s[%(result)s as u32].length as libc::size_t);
if %(resultStr)s.is_null() {
  return 0;
}
""" % { "result" : result,
        "resultStr" : result + "_str",
        "strings" : type.inner.identifier.name + "Values::strings" } +
        setValue("RUST_STRING_TO_JSVAL(%s_str)" % result), False)

    if type.isCallback():
        assert not type.isInterface()
        # XXXbz we're going to assume that callback types are always
        # nullable and always have [TreatNonCallableAsNull] for now.
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        # NB: setValue(..., True) calls JS_WrapValue(), so is fallible
        return (setValue("JS::ObjectOrNullValue(%s)" % result, True), False)

    if type.tag() == IDLType.Tags.any:
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        # NB: setValue(..., True) calls JS_WrapValue(), so is fallible
        return (setValue(result, True), False)

    if type.isObject() or type.isSpiderMonkeyInterface():
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        if type.nullable():
            toValue = "RUST_OBJECT_TO_JSVAL(%s)"
        else:
            toValue = "RUST_OBJECT_TO_JSVAL(%s)"
        # NB: setValue(..., True) calls JS_WrapValue(), so is fallible
        return (setValue(toValue % result, True), False)

    if not type.isPrimitive():
        raise TypeError("Need to learn to wrap %s" % type)

    if type.nullable():
        (recTemplate, recInfal) = getWrapTemplateForType(type.inner, descriptorProvider,
                                                         "%s.Value()" % result, successCode,
                                                         isCreator, exceptionCode)
        return ("if (%s.IsNull()) {\n" % result +
                CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define() + "\n" +
                "}\n" + recTemplate, recInfal)
    
    tag = type.tag()
    
    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
               IDLType.Tags.uint16, IDLType.Tags.int32]:
        return (setValue("RUST_INT_TO_JSVAL(%s as i32)" % result), True)

    elif tag in [IDLType.Tags.int64, IDLType.Tags.uint64, IDLType.Tags.float,
                 IDLType.Tags.double]:
        # XXXbz will cast to double do the "even significand" thing that webidl
        # calls for for 64-bit ints?  Do we care?
        return (setValue("RUST_JS_NumberValue(%s as f64)" % result), True)

    elif tag == IDLType.Tags.uint32:
        return (setValue("RUST_UINT_TO_JSVAL(%s)" % result), True)

    elif tag == IDLType.Tags.bool:
        return (setValue("RUST_BOOLEAN_TO_JSVAL(%s as JSBool)" % result), True)

    else:
        raise TypeError("Need to learn to wrap primitive: %s" % type)

def wrapForType(type, descriptorProvider, templateValues):
    """
    Reflect a C++ value of IDL type "type" into JS.  TemplateValues is a dict
    that should contain:

      * 'jsvalRef': a C++ reference to the jsval in which to store the result of
                    the conversion
      * 'jsvalPtr': a C++ pointer to the jsval in which to store the result of
                    the conversion
      * 'obj' (optional): the name of the variable that contains the JSObject to
                          use as a scope when wrapping, if not supplied 'obj'
                          will be used as the name
      * 'result' (optional): the name of the variable in which the C++ value is
                             stored, if not supplied 'result' will be used as
                             the name
      * 'successCode' (optional): the code to run once we have successfully done
                                  the conversion, if not supplied 'return true;'
                                  will be used as the code
      * 'isCreator' (optional): If true, we're wrapping for the return value of
                                a [Creator] method.  Assumed false if not set.
    """
    wrap = getWrapTemplateForType(type, descriptorProvider,
                                  templateValues.get('result', 'result'),
                                  templateValues.get('successCode', None),
                                  templateValues.get('isCreator', False),
                                  templateValues.get('exceptionCode',
                                                     "return 0;"),)[0]

    defaultValues = {'obj': 'obj'}
    return string.Template(wrap).substitute(defaultValues, **templateValues)

def typeNeedsCx(type, retVal=False):
    if type is None:
        return False
    if type.nullable():
        type = type.inner
    if type.isSequence() or type.isArray():
        type = type.inner
    if type.isUnion():
        return any(typeNeedsCx(t) for t in type.unroll().flatMemberTypes)
    if retVal and type.isSpiderMonkeyInterface():
        return True
    return type.isCallback() or type.isAny() or type.isObject()

def memberIsCreator(member):
    return member.getExtendedAttribute("Creator") is not None

# Returns a tuple consisting of a CGThing containing the type of the return
# value, or None if there is no need for a return value, and a boolean signaling
# whether the return value is passed in an out parameter.
def getRetvalDeclarationForType(returnType, descriptorProvider,
                                resultAlreadyAddRefed):
    if returnType is None or returnType.isVoid():
        # Nothing to declare
        return None, False
    if returnType.isPrimitive() and returnType.tag() in builtinNames:
        result = CGGeneric(builtinNames[returnType.tag()])
        if returnType.nullable():
            result = CGWrapper(result, pre="Nullable<", post=">")
        return result, False
    if returnType.isString():
        result = CGGeneric("DOMString")
        if returnType.nullable():
            result = CGWrapper(result, pre="Option<", post=">")
        return result, False
    if returnType.isEnum():
        if returnType.nullable():
            raise TypeError("We don't support nullable enum return values")
        return CGGeneric(returnType.inner.identifier.name), False
    if returnType.isGeckoInterface():
        descriptor = descriptorProvider.getDescriptor(
            returnType.unroll().inner.identifier.name)
        result = CGGeneric(descriptor.nativeType)
        if returnType.nullable():
            result = CGWrapper(result, pre=("Option<" + descriptor.pointerType), post=">")
        else:
            result = CGWrapper(result, pre=descriptor.pointerType)
        return result, False
    if returnType.isCallback():
        # XXXbz we're going to assume that callback types are always
        # nullable for now.
        return CGGeneric("*JSObject"), False
    if returnType.isAny():
        return CGGeneric("JSVal"), False
    if returnType.isObject() or returnType.isSpiderMonkeyInterface():
        return CGGeneric("*JSObject"), False
    if returnType.isSequence():
        nullable = returnType.nullable()
        if nullable:
            returnType = returnType.inner
        # If our result is already addrefed, use the right type in the
        # sequence argument here.
        (result, _) = getRetvalDeclarationForType(returnType.inner,
                                                  descriptorProvider,
                                                  resultAlreadyAddRefed)
        result = CGWrapper(result, pre="nsTArray< ", post=" >")
        if nullable:
            result = CGWrapper(result, pre="Nullable< ", post=" >")
        return result, True
    raise TypeError("Don't know how to declare return value for %s" %
                    returnType)

def isChromeOnly(m):
    return m.getExtendedAttribute("ChromeOnly")

class PropertyDefiner:
    """
    A common superclass for defining things on prototype objects.

    Subclasses should implement generateArray to generate the actual arrays of
    things we're defining.  They should also set self.chrome to the list of
    things exposed to chrome and self.regular to the list of things exposed to
    web pages.  self.chrome must be a superset of self.regular but also include
    all the ChromeOnly stuff.
    """
    def __init__(self, descriptor, name):
        self.descriptor = descriptor
        self.name = name
        # self.prefCacheData will store an array of (prefname, bool*)
        # pairs for our bool var caches.  generateArray will fill it
        # in as needed.
        self.prefCacheData = []
    def hasChromeOnly(self):
        return len(self.chrome) > len(self.regular)
    def hasNonChromeOnly(self):
        return len(self.regular) > 0
    def variableName(self, chrome):
        if chrome and self.hasChromeOnly():
            return "sChrome" + self.name
        if self.hasNonChromeOnly():
            return "s" + self.name
        return "ptr::null()"
    def usedForXrays(self, chrome):
        # We only need Xrays for methods, attributes and constants.  And we only
        # need them for the non-chrome ones if we have no chromeonly things.
        # Otherwise (we have chromeonly attributes) we need Xrays for the chrome
        # methods/attributes/constants.  Finally, in workers there are no Xrays.
        return ((self.name is "Methods" or self.name is "Attributes" or
                 self.name is "Constants") and
                chrome == self.hasChromeOnly() and
                not self.descriptor.workers)

    def __str__(self):
        # We only need to generate id arrays for things that will end
        # up used via ResolveProperty or EnumerateProperties.
        str = self.generateArray(self.regular, self.variableName(False),
                                 self.usedForXrays(False))
        if self.hasChromeOnly():
            str += self.generateArray(self.chrome, self.variableName(True),
                                      self.usedForXrays(True))
        return str

    @staticmethod
    def getControllingPref(interfaceMember):
        prefName = interfaceMember.getExtendedAttribute("Pref")
        if prefName is None:
            return None
        # It's a list of strings
        assert(len(prefName) is 1)
        assert(prefName[0] is not None)
        return prefName[0]

    def generatePrefableArray(self, array, name, specTemplate, specTerminator,
                              specType, getPref, getDataTuple, doIdArrays):
        """
        This method generates our various arrays.

        array is an array of interface members as passed to generateArray

        name is the name as passed to generateArray

        specTemplate is a template for each entry of the spec array

        specTerminator is a terminator for the spec array (inserted every time
          our controlling pref changes and at the end of the array)

        specType is the actual typename of our spec

        getPref is a callback function that takes an array entry and returns
          the corresponding pref value.

        getDataTuple is a callback function that takes an array entry and
          returns a tuple suitable for substitution into specTemplate.
        """

        # We want to generate a single list of specs, but with specTerminator
        # inserted at every point where the pref name controlling the member
        # changes.  That will make sure the order of the properties as exposed
        # on the interface and interface prototype objects does not change when
        # pref control is added to members while still allowing us to define all
        # the members in the smallest number of JSAPI calls.
        assert(len(array) is not 0)
        lastPref = getPref(array[0]) # So we won't put a specTerminator
                                     # at the very front of the list.
        specs = []
        prefableSpecs = []
        if doIdArrays:
            prefableIds = []

        prefableTemplate = '  { true, &%s[%d] }'
        prefCacheTemplate = '&%s[%d].enabled'
        def switchToPref(props, pref):
            # Remember the info about where our pref-controlled
            # booleans live.
            if pref is not None:
                props.prefCacheData.append(
                    (pref, prefCacheTemplate % (name, len(prefableSpecs)))
                    )
            # Set up pointers to the new sets of specs and ids
            # inside prefableSpecs and prefableIds
            prefableSpecs.append(prefableTemplate %
                                 (name + "_specs", len(specs)))

        switchToPref(self, lastPref)

        for member in array:
            curPref = getPref(member)
            if lastPref != curPref:
                # Terminate previous list
                specs.append(specTerminator)
                # And switch to our new pref
                switchToPref(self, curPref)
                lastPref = curPref
            # And the actual spec
            specs.append(specTemplate % getDataTuple(member))
        specs.append(specTerminator)
        prefableSpecs.append("  { false, NULL }");

        arrays = (("static %s: [%s, ..%i] = [\n" +
                   ',\n'.join(specs) + "\n" +
                   "];\n\n") % (name, specType, len(specs)))
                   #+
                   #"static Prefable<%s> %s[] = [\n" +
                   #',\n'.join(prefableSpecs) + "\n" +
                   #"];\n\n")
        if doIdArrays:
            arrays += ("static %s_ids: [jsid, ..%i] = [" % (name, len(specs))) + ", ".join(["JSID_VOID"] * len(specs)) + "];\n\n"
        return arrays

# The length of a method is the maximum of the lengths of the
# argument lists of all its overloads.
def methodLength(method):
    signatures = method.signatures()
    return max([len(arguments) for (retType, arguments) in signatures])

class MethodDefiner(PropertyDefiner):
    """
    A class for defining methods on a prototype object.
    """
    def __init__(self, descriptor, name, static):
        PropertyDefiner.__init__(self, descriptor, name)

        # FIXME https://bugzilla.mozilla.org/show_bug.cgi?id=772822
        #       We should be able to check for special operations without an
        #       identifier. For now we check if the name starts with __
        methods = [m for m in descriptor.interface.members if
                   m.isMethod() and m.isStatic() == static and
                   not m.isIdentifierLess()]
        self.chrome = [{"name": m.identifier.name,
                        "length": methodLength(m),
                        "flags": "JSPROP_ENUMERATE",
                        "pref": PropertyDefiner.getControllingPref(m) }
                       for m in methods]
        self.regular = [{"name": m.identifier.name,
                         "length": methodLength(m),
                         "flags": "JSPROP_ENUMERATE",
                         "pref": PropertyDefiner.getControllingPref(m) }
                        for m in methods if not isChromeOnly(m)]

        # FIXME Check for an existing iterator on the interface first.
        if any(m.isGetter() and m.isIndexed() for m in methods):
            self.chrome.append({"name": 'iterator',
                                "methodInfo": False,
                                "nativeName": "crust::JS_ArrayIterator",
                                "length": 0,
                                "flags": "JSPROP_ENUMERATE",
                                "pref": None })
            self.regular.append({"name": 'iterator',
                                 "methodInfo": False,
                                 "nativeName": "crust::JS_ArrayIterator",
                                 "length": 0,
                                 "flags": "JSPROP_ENUMERATE",
                                 "pref": None })

        #if not descriptor.interface.parent and not static and not descriptor.workers:
        #    self.chrome.append({"name": 'QueryInterface',
        #                        "methodInfo": False,
        #                        "length": 1,
        #                        "flags": "0",
        #                        "pref": None })

        if static:
            if not descriptor.interface.hasInterfaceObject():
                # static methods go on the interface object
                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
        else:
            if not descriptor.interface.hasInterfacePrototypeObject():
                # non-static methods go on the interface prototype object
                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def pref(m):
            return m["pref"]

        def specData(m):
            if m.get("methodInfo", True):
                jitinfo = ("&%s_methodinfo" % m["name"])
                accessor = "genericMethod"
            else:
                jitinfo = "0 as *JSJitInfo"
                accessor = m.get("nativeName", m["name"])
            return (m["name"], accessor, jitinfo, m["length"], m["flags"])

        def stringDecl(m):
            return "static %s_name: [u8, ..%i] = %s;\n" % (m["name"], len(m["name"]) + 1,
                                                         str_to_const_array(m["name"]))
        
        decls = ''.join([stringDecl(m) for m in array])
        return decls + self.generatePrefableArray(
            array, name,
            '  JSFunctionSpec {name: &%s_name as *u8 as *libc::c_char, call: JSNativeWrapper {op: Some(%s), info: %s}, nargs: %s, flags: %s as u16, selfHostedName: 0 as *libc::c_char }',
            '  JSFunctionSpec {name: 0 as *libc::c_char, call: JSNativeWrapper {op: None, info: 0 as *JSJitInfo}, nargs: 0, flags: 0, selfHostedName: 0 as *libc::c_char }',
            'JSFunctionSpec',
            pref, specData, doIdArrays)

class AttrDefiner(PropertyDefiner):
    def __init__(self, descriptor, name):
        PropertyDefiner.__init__(self, descriptor, name)
        self.name = name
        self.chrome = [m for m in descriptor.interface.members if m.isAttr()]
        self.regular = [m for m in self.chrome if not isChromeOnly(m)]

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def flags(attr):
            return "JSPROP_SHARED | JSPROP_ENUMERATE | JSPROP_NATIVE_ACCESSORS"

        def getter(attr):
            native = ("genericLenientGetter" if attr.hasLenientThis()
                      else "genericGetter")
            return ("JSPropertyOpWrapper {op: Some(%(native)s), info: &%(name)s_getterinfo as *JSJitInfo}"
                    % {"name" : attr.identifier.name,
                       "native" : native})

        def setter(attr):
            if attr.readonly:
                return "JSStrictPropertyOpWrapper {op: None, info: 0 as *JSJitInfo}"
            native = ("genericLenientSetter" if attr.hasLenientThis()
                      else "genericSetter")
            return ("JSStrictPropertyOpWrapper {op: Some(%(native)s), info: &%(name)s_setterinfo as *JSJitInfo}"
                    % {"name" : attr.identifier.name,
                       "native" : native})

        def specData(attr):
            return (attr.identifier.name, flags(attr), getter(attr),
                    setter(attr))

        def stringDecl(attr):
            name = attr.identifier.name
            return "static %s_name: [u8, ..%i] = %s;\n" % (name, len(name) + 1,
                                                         str_to_const_array(name))
        
        decls = ''.join([stringDecl(m) for m in array])

        return decls + self.generatePrefableArray(
            array, name,
            '  JSPropertySpec { name: &%s_name as *u8 as *libc::c_char, tinyid: 0, flags: ((%s) & 0xFF) as u8, getter: %s, setter: %s }',
            '  JSPropertySpec { name: 0 as *libc::c_char, tinyid: 0, flags: 0, getter: JSPropertyOpWrapper {op: None, info: 0 as *JSJitInfo}, setter: JSStrictPropertyOpWrapper {op: None, info: 0 as *JSJitInfo} }',
            'JSPropertySpec',
            PropertyDefiner.getControllingPref, specData, doIdArrays)

class ConstDefiner(PropertyDefiner):
    """
    A class for definining constants on the interface object
    """
    def __init__(self, descriptor, name):
        PropertyDefiner.__init__(self, descriptor, name)
        self.name = name
        self.chrome = [m for m in descriptor.interface.members if m.isConst()]
        self.regular = [m for m in self.chrome if not isChromeOnly(m)]

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def specData(const):
            return (const.identifier.name,
                    convertConstIDLValueToJSVal(const.value))

        def stringDecl(const):
            name = const.identifier.name
            return "static %s_name: [u8, ..%i] = %s;\n" % (name, len(name) + 1,
                                                         str_to_const_array(name))
        
        decls = ''.join([stringDecl(m) for m in array])

        return decls + self.generatePrefableArray(
            array, name,
            '  ConstantSpec { name: &%s_name as *u8 as *libc::c_char, value: %s }',
            '  ConstantSpec { name: 0 as *libc::c_char, value: VoidVal }',
            'ConstantSpec',
            PropertyDefiner.getControllingPref, specData, doIdArrays)

class CGNativePropertyHooks(CGThing):
    """
    Generate a NativePropertyHooks for a given descriptor
    """
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        if self.descriptor.workers:
            return ""
        #return "extern const NativePropertyHooks NativeHooks;\n"
        return ""
    def define(self):
        if self.descriptor.workers:
            return ""
        if self.descriptor.concrete and self.descriptor.proxy:
            resolveOwnProperty = "ResolveOwnProperty"
            enumerateOwnProperties = "EnumerateOwnProperties"
        else:
            enumerateOwnProperties = resolveOwnProperty = "0 as *u8"
        parent = self.descriptor.interface.parent
        parentHooks = ("&" + toBindingNamespace(parent.identifier.name) + "::NativeHooks"
                       if parent else '0 as *NativePropertyHooks')
        return """
static NativeHooks: NativePropertyHooks = NativePropertyHooks { resolve_own_property: /*%s*/ 0 as *u8, resolve_property: ResolveProperty, enumerate_own_properties: /*%s*/ 0 as *u8, enumerate_properties: /*EnumerateProperties*/ 0 as *u8, proto_hooks: /*%s*/ 0 as *NativePropertyHooks };
""" % (resolveOwnProperty, enumerateOwnProperties, parentHooks)

# We'll want to insert the indent at the beginnings of lines, but we
# don't want to indent empty lines.  So only indent lines that have a
# non-newline character on them.
lineStartDetector = re.compile("^(?=[^\n#])", re.MULTILINE)
class CGIndenter(CGThing):
    """
    A class that takes another CGThing and generates code that indents that
    CGThing by some number of spaces.  The default indent is two spaces.
    """
    def __init__(self, child, indentLevel=2, declareOnly=False):
        CGThing.__init__(self)
        self.child = child
        self.indent = " " * indentLevel
        self.declareOnly = declareOnly
    def declare(self):
        decl = self.child.declare()
        if decl is not "":
            return re.sub(lineStartDetector, self.indent, decl)
        else:
            return ""
    def define(self):
        defn = self.child.define()
        if defn is not "" and not self.declareOnly:
            return re.sub(lineStartDetector, self.indent, defn)
        else:
            return defn

class CGWrapper(CGThing):
    """
    Generic CGThing that wraps other CGThings with pre and post text.
    """
    def __init__(self, child, pre="", post="", declarePre=None,
                 declarePost=None, definePre=None, definePost=None,
                 declareOnly=False, defineOnly=False, reindent=False):
        CGThing.__init__(self)
        self.child = child
        self.declarePre = declarePre or pre
        self.declarePost = declarePost or post
        self.definePre = definePre or pre
        self.definePost = definePost or post
        self.declareOnly = declareOnly
        self.defineOnly = defineOnly
        self.reindent = reindent
    def declare(self):
        if self.defineOnly:
            return ''
        decl = self.child.declare()
        if self.reindent:
            # We don't use lineStartDetector because we don't want to
            # insert whitespace at the beginning of our _first_ line.
            decl = stripTrailingWhitespace(
                decl.replace("\n", "\n" + (" " * len(self.declarePre))))
        return self.declarePre + decl + self.declarePost
    def define(self):
        if self.declareOnly:
            return ''
        defn = self.child.define()
        if self.reindent:
            # We don't use lineStartDetector because we don't want to
            # insert whitespace at the beginning of our _first_ line.
            defn = stripTrailingWhitespace(
                defn.replace("\n", "\n" + (" " * len(self.definePre))))
        return self.definePre + defn + self.definePost

class CGImports(CGWrapper):
    """
    Generates the appropriate import/use statements.
    """
    def __init__(self, descriptors, dictionaries, declareImports, defineImports, child):
        """
        Builds a set of imports to cover |descriptors|.

        Also includes the files in |declareIncludes| in the header
        file and the files in |defineIncludes| in the .cpp.
        """

        # TODO imports to cover descriptors, etc.

        def _useString(imports):
            return '#[allow(non_uppercase_statics,unused_imports,unused_variable,unused_unsafe,unused_mut,dead_assignment)];\n' + ''.join(['use %s;\n' % i for i in imports]) + '\n'
        CGWrapper.__init__(self, child,
                           declarePre=_useString(sorted(declareImports)))

    @staticmethod
    def getDeclarationFilename(decl):
        # Use our local version of the header, not the exported one, so that
        # test bindings, which don't export, will work correctly.
        basename = os.path.basename(decl.filename())
        return basename.replace('.webidl', 'Binding.rs')

class CGIfWrapper(CGWrapper):
    def __init__(self, child, condition):
        pre = CGWrapper(CGGeneric(condition), pre="if ", post=" {\n",
                        reindent=True)
        CGWrapper.__init__(self, CGIndenter(child), pre=pre.define(),
                           post="\n}")

class CGNamespace(CGWrapper):
    def __init__(self, namespace, child, declareOnly=False, public=False):
        pre = "%smod %s {\n" % ("pub " if public else "", namespace)
        post = "} // mod %s\n" % namespace
        CGWrapper.__init__(self, child, pre=pre, post=post,
                           declareOnly=declareOnly)
    @staticmethod
    def build(namespaces, child, declareOnly=False, public=False):
        """
        Static helper method to build multiple wrapped namespaces.
        """
        if not namespaces:
            return CGWrapper(child, declareOnly=declareOnly)
        inner = CGNamespace.build(namespaces[1:], child, declareOnly=declareOnly, public=public)
        return CGNamespace(namespaces[0], inner, declareOnly=declareOnly, public=public)

    def declare(self):
        return ""

def DOMClass(descriptor):
        protoList = ['PrototypeList::id::' + proto for proto in descriptor.prototypeChain]
        # Pad out the list to the right length with _ID_Count so we
        # guarantee that all the lists are the same length.  _ID_Count
        # is never the ID of any prototype, so it's safe to use as
        # padding.
        protoList.extend(['PrototypeList::id::_ID_Count'] * (descriptor.config.maxProtoChainLength - len(protoList)))
        prototypeChainString = ', '.join(protoList)
        nativeHooks = "0 as *NativePropertyHooks" if descriptor.workers else "&NativeHooks as *NativePropertyHooks"
        return """DOMClass {
  interface_chain: [ %s ] ,
  unused: %s, native_hooks: %s
}""" % (prototypeChainString, "false", #toStringBool(descriptor.nativeIsISupports),
          nativeHooks)

class CGDOMJSClass(CGThing):
    """
    Generate a DOMJSClass for a given descriptor
    """
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        #return "extern DOMJSClass Class;\n"
        return ""
    def define(self):
        traceHook = "Some(%s)" % TRACE_HOOK_NAME if self.descriptor.customTrace else 'None'
        if self.descriptor.createGlobal:
            flags = "JSCLASS_IS_GLOBAL"
            slots = "JSCLASS_GLOBAL_SLOT_COUNT + 1"
        else:
            flags = "0"
            slots = "1"
        return """
static Class_name: [u8, ..%i] = %s;
static Class: DOMJSClass = DOMJSClass {
  base: JSClass { name: &Class_name as *u8 as *libc::c_char,
    flags: JSCLASS_IS_DOMJSCLASS | %s | (((%s) & JSCLASS_RESERVED_SLOTS_MASK) << JSCLASS_RESERVED_SLOTS_SHIFT), //JSCLASS_HAS_RESERVED_SLOTS(%s),
    addProperty: Some(%s), /* addProperty */
    delProperty: Some(crust::JS_PropertyStub),       /* delProperty */
    getProperty: Some(crust::JS_PropertyStub),       /* getProperty */
    setProperty: Some(crust::JS_StrictPropertyStub), /* setProperty */
    enumerate: Some(crust::JS_EnumerateStub),
    resolve: Some(crust::JS_ResolveStub),
    convert: Some(crust::JS_ConvertStub),
    finalize: Some(%s), /* finalize */
    checkAccess: None,                  /* checkAccess */
    call: None,                  /* call */
    hasInstance: None,                  /* hasInstance */
    construct: None,                  /* construct */
    trace: %s, /* trace */
    reserved: (0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 05
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 10
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 15
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 20
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 25
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 30
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 35
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void)  // 40
  },
  dom_class: %s
};
""" % (len(self.descriptor.interface.identifier.name) + 1,
       str_to_const_array(self.descriptor.interface.identifier.name),
       flags, slots, slots,
       #ADDPROPERTY_HOOK_NAME if self.descriptor.concrete and not self.descriptor.workers and self.descriptor.wrapperCache else 'crust::JS_PropertyStub',
       'crust::JS_PropertyStub',
       FINALIZE_HOOK_NAME, traceHook,
       CGIndenter(CGGeneric(DOMClass(self.descriptor))).define())

def str_to_const_array(s):
    return "[" + (", ".join(map(lambda x: "'" + x + "' as u8", list(s)) + ['0 as u8'])) + "]"

class CGPrototypeJSClass(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        # We're purely for internal consumption
        return ""
    def define(self):
        return """
static PrototypeClassName__: [u8, ..%s] = %s;
static PrototypeClass: JSClass = JSClass {
  name: &PrototypeClassName__ as *u8 as *libc::c_char,
  flags: (1 & JSCLASS_RESERVED_SLOTS_MASK) << JSCLASS_RESERVED_SLOTS_SHIFT, //JSCLASS_HAS_RESERVED_SLOTS(1)
  addProperty: Some(crust::JS_PropertyStub),       /* addProperty */
  delProperty: Some(crust::JS_PropertyStub),       /* delProperty */
  getProperty: Some(crust::JS_PropertyStub),       /* getProperty */
  setProperty: Some(crust::JS_StrictPropertyStub), /* setProperty */
  enumerate: Some(crust::JS_EnumerateStub),
  resolve: Some(crust::JS_ResolveStub),
  convert: Some(crust::JS_ConvertStub),
  finalize: None,                  /* finalize */
  checkAccess: None,                  /* checkAccess */
  call: None,                  /* call */
  hasInstance: None,                  /* hasInstance */
  construct: None,                  /* construct */
  trace: None,                  /* trace */
  reserved: (0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 05
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 10
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 15
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 20
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 25
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 30
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void,  // 35
                    0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void, 0 as *libc::c_void)  // 40
};
""" % (len(self.descriptor.interface.identifier.name + "Prototype") + 1,
       str_to_const_array(self.descriptor.interface.identifier.name + "Prototype"))

class CGInterfaceObjectJSClass(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        # We're purely for internal consumption
        return ""
    def define(self):
        if not self.descriptor.hasInstanceInterface:
            return ""
        ctorname = "0 as *u8" if not self.descriptor.interface.ctor() else CONSTRUCT_HOOK_NAME
        hasinstance = HASINSTANCE_HOOK_NAME
        return """
static InterfaceObjectClass: JSClass = {
  %s, 0,
  crust::JS_PropertyStub,       /* addProperty */
  crust::JS_PropertyStub,       /* delProperty */
  crust::JS_PropertyStub,       /* getProperty */
  crust::JS_StrictPropertyStub, /* setProperty */
  crust::JS_EnumerateStub,
  crust::JS_ResolveStub,
  crust::JS_ConvertStub,
  0 as *u8,                  /* finalize */
  0 as *u8,                  /* checkAccess */
  %s, /* call */
  %s, /* hasInstance */
  %s, /* construct */
  0 as *u8,                  /* trace */
  JSCLASS_NO_INTERNAL_MEMBERS
};
""" % (str_to_const_array("Function"), ctorname, hasinstance, ctorname)

class CGList(CGThing):
    """
    Generate code for a list of GCThings.  Just concatenates them together, with
    an optional joiner string.  "\n" is a common joiner.
    """
    def __init__(self, children, joiner=""):
        CGThing.__init__(self)
        self.children = children
        self.joiner = joiner
    def append(self, child):
        self.children.append(child)
    def prepend(self, child):
        self.children.insert(0, child)
    def join(self, generator):
        return self.joiner.join(filter(lambda s: len(s) > 0, (child for child in generator)))
    def declare(self):
        return self.join(child.declare() for child in self.children if child is not None)
    def define(self):
        return self.join(child.define() for child in self.children if child is not None)

class CGGeneric(CGThing):
    """
    A class that spits out a fixed string into the codegen.  Can spit out a
    separate string for the declaration too.
    """
    def __init__(self, define="", declare=""):
        self.declareText = declare
        self.defineText = define
    def declare(self):
        return self.declareText
    def define(self):
        return self.defineText

class Argument():
    """
    A class for outputting the type and name of an argument
    """
    def __init__(self, argType, name, default=None, mutable=False):
        self.argType = argType
        self.name = name
        self.default = default
        self.mutable = mutable
    def declare(self):
        string = ('mut ' if self.mutable else '') + self.name + ((': ' + self.argType) if self.argType else '')
        #XXXjdm Support default arguments somehow :/
        #if self.default is not None:
        #    string += " = " + self.default
        return string
    def define(self):
        return self.argType + ' ' + self.name

class CGAbstractMethod(CGThing):
    """
    An abstract class for generating code for a method.  Subclasses
    should override definition_body to create the actual code.

    descriptor is the descriptor for the interface the method is associated with

    name is the name of the method as a string

    returnType is the IDLType of the return value

    args is a list of Argument objects

    inline should be True to generate an inline method, whose body is
    part of the declaration.

    alwaysInline should be True to generate an inline method annotated with
    MOZ_ALWAYS_INLINE.

    static should be True to generate a static method, which only has
    a definition.

    If templateArgs is not None it should be a list of strings containing
    template arguments, and the function will be templatized using those
    arguments.
    """
    def __init__(self, descriptor, name, returnType, args, inline=False, alwaysInline=False, static=False, extern=False, pub=False, templateArgs=None, unsafe=True):
        CGThing.__init__(self)
        self.descriptor = descriptor
        self.name = name
        self.returnType = returnType
        self.args = args
        self.inline = inline
        self.alwaysInline = alwaysInline
        self.static = static
        self.extern = extern
        self.templateArgs = templateArgs
        self.pub = pub;
        self.unsafe = unsafe
    def _argstring(self, declare):
        return ', '.join([a.declare() for a in self.args])
    def _template(self):
        if self.templateArgs is None:
            return ''
        return '<%s>\n' % ', '.join(self.templateArgs)
    def _decorators(self):
        decorators = []
        if self.alwaysInline:
            # FIXME Rust #8801 #[inline(always)] and #[fixed_stack_segment] not compatible
            # decorators.append('#[inline(always)]')
            pass
        elif self.inline:
            #decorators.append('inline')
            pass
        if self.extern:
            decorators.append('extern')
        if not self.extern:
            decorators.append('#[fixed_stack_segment]')
        if self.static:
            #decorators.append('static')
            pass
        if self.pub:
            decorators.append('pub')
        if not decorators:
            return ''
        #maybeNewline = " " if self.inline else "\n"
        maybeNewline = " "
        return ' '.join(decorators) + maybeNewline
    def _returnType(self):
        return (" -> %s" % self.returnType) if self.returnType != "void" else ""
    def _unsafe_open(self):
        return "\n  unsafe {" if self.unsafe else ""
    def _unsafe_close(self):
        return "\n  }\n" if self.unsafe else ""
    def declare(self):
        if self.inline:
            return self._define()
        #return "%sfn %s%s(%s)%s;\n" % (self._decorators(), self.name, self._template(),
        #                               self._argstring(), self._returnType())
        return ""

    def _define(self, fromDeclare=False):
        return self.definition_prologue(fromDeclare) + "\n" + self.definition_body() + self.definition_epilogue()
    def define(self):
        return "" if self.inline else self._define()
    def definition_prologue(self, fromDeclare):
        return "%sfn %s%s(%s)%s {%s" % (self._decorators(), self.name, self._template(),
                                        self._argstring(fromDeclare), self._returnType(), self._unsafe_open())
    def definition_epilogue(self):
        return "%s}\n" % self._unsafe_close()
    def definition_body(self):
        assert(False) # Override me!

def CreateBindingJSObject(descriptor, parent=None):
    if descriptor.proxy:
        assert not descriptor.createGlobal
        handler = """
  let page = page_from_context(aCx);
  let handler = (*page).js_info.get_ref().dom_static.proxy_handlers.get(&(PrototypeList::id::%s as uint));
""" % descriptor.name
        create = handler + """  let obj = NewProxyObject(aCx, *handler,
                           ptr::to_unsafe_ptr(&RUST_PRIVATE_TO_JSVAL(squirrel_away(aObject) as *libc::c_void)),
                           proto, %s,
                           ptr::null(), ptr::null());
  if obj.is_null() {
    return ptr::null();
  }

""" % parent
    else:
        if descriptor.createGlobal:
            create = "  let obj = CreateDOMGlobal(aCx, &Class.base);\n"
        else:
            create = "  let obj = JS_NewObject(aCx, &Class.base, proto, %s);\n" % parent
        create += """  if obj.is_null() {
    return ptr::null();
  }

  JS_SetReservedSlot(obj, DOM_OBJECT_SLOT as u32,
                     RUST_PRIVATE_TO_JSVAL(squirrel_away(aObject) as *libc::c_void));
"""
    return create

class CGWrapWithCacheMethod(CGAbstractMethod):
    def __init__(self, descriptor):
        assert descriptor.interface.hasInterfacePrototypeObject()
        args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aScope'),
                Argument('@mut ' + descriptor.concreteType, 'aObject')]
        CGAbstractMethod.__init__(self, descriptor, 'Wrap_', '*JSObject', args)

    def definition_body(self):
        if self.descriptor.workers:
            return """return aObject->GetJSObject();"""

        if not self.descriptor.createGlobal:
            return """
  assert!(aScope.is_not_null());
  assert!(((*JS_GetClass(aScope)).flags & JSCLASS_IS_GLOBAL) != 0);

  //JSAutoCompartment ac(aCx, aScope);
  let proto = GetProtoObject(aCx, aScope, aScope);
  if proto.is_null() {
    return ptr::null();
  }
%s

  //NS_ADDREF(aObject);

  aObject.mut_reflector().set_jsobject(obj);

  return obj;""" % (CreateBindingJSObject(self.descriptor, "aScope"))
        else:
            return """
  assert!(aScope.is_null());
%s
  let proto = GetProtoObject(aCx, obj, obj);
  JS_SetPrototype(aCx, obj, proto);
  aObject.mut_reflector().set_jsobject(obj);
  return obj;""" % CreateBindingJSObject(self.descriptor)

class CGWrapMethod(CGAbstractMethod):
    def __init__(self, descriptor):
        # XXX can we wrap if we don't have an interface prototype object?
        assert descriptor.interface.hasInterfacePrototypeObject()
        args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aScope'),
                Argument('@mut ' + descriptor.concreteType, 'aObject')]
        CGAbstractMethod.__init__(self, descriptor, 'Wrap', '*JSObject', args, inline=True, pub=True)

    def definition_body(self):
        return "return Wrap_(aCx, aScope, aObject);"

class CGWrapNonWrapperCacheMethod(CGAbstractMethod):
    def __init__(self, descriptor):
        # XXX can we wrap if we don't have an interface prototype object?
        assert descriptor.interface.hasInterfacePrototypeObject()
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aScope'),
                Argument('@' + descriptor.nativeType, 'aObject')]
        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'JSObject*', args)

    def definition_body(self):
        return """
  JSObject* global = JS_GetGlobalForObject(aCx, aScope);
  JSObject* proto = GetProtoObject(aCx, global, global);
  if (!proto) {
    return NULL;
  }

%s
  NS_ADDREF(aObject);

  return obj;""" % CreateBindingJSObject(self.descriptor, "global")

class CGAbstractExternMethod(CGAbstractMethod):
    """
    Abstract base class for codegen of implementation-only (no
    declaration) static methods.
    """
    def __init__(self, descriptor, name, returnType, args):
        CGAbstractMethod.__init__(self, descriptor, name, returnType, args,
                                  inline=False, extern=True)
    def declare(self):
        # We only have implementation
        return ""

class PropertyArrays():
    def __init__(self, descriptor):
        self.staticMethods = MethodDefiner(descriptor, "StaticMethods", True)
        self.methods = MethodDefiner(descriptor, "Methods", False)
        self.attrs = AttrDefiner(descriptor, "Attributes")
        self.consts = ConstDefiner(descriptor, "Constants")
        pass

    @staticmethod
    def arrayNames():
        return [ "staticMethods", "methods", "attrs", "consts" ]

    @staticmethod
    def xrayRelevantArrayNames():
        return [ "methods", "attrs", "consts" ]

    def hasChromeOnly(self):
        return reduce(lambda b, a: b or getattr(self, a).hasChromeOnly(),
                      self.arrayNames(), False)
    def variableNames(self, chrome):
        names = {}
        for array in self.arrayNames():
            names[array] = getattr(self, array).variableName(chrome)
        return names
    def __str__(self):
        define = ""
        for array in self.arrayNames():
            define += str(getattr(self, array))
        return define

class CGCreateInterfaceObjectsMethod(CGAbstractMethod):
    """
    Generate the CreateInterfaceObjects method for an interface descriptor.

    properties should be a PropertyArrays instance.
    """
    def __init__(self, descriptor, properties):
        args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aGlobal'),
                Argument('*JSObject', 'aReceiver')]
        CGAbstractMethod.__init__(self, descriptor, 'CreateInterfaceObjects', '*JSObject', args)
        self.properties = properties
    def definition_body(self):
        protoChain = self.descriptor.prototypeChain
        if len(protoChain) == 1:
            getParentProto = "JS_GetObjectPrototype(aCx, aGlobal)"
        else:
            parentProtoName = self.descriptor.prototypeChain[-2]
            getParentProto = ("%s::GetProtoObject(aCx, aGlobal, aReceiver)" %
                              toBindingNamespace(parentProtoName))

        needInterfaceObject = self.descriptor.interface.hasInterfaceObject()
        needInterfacePrototypeObject = self.descriptor.interface.hasInterfacePrototypeObject()

        # if we don't need to create anything, why are we generating this?
        assert needInterfaceObject or needInterfacePrototypeObject

        idsToInit = []
        # There is no need to init any IDs in workers, because worker bindings
        # don't have Xrays.
        if False and not self.descriptor.workers: #XXXjdm don't need xray stuff yet
            for var in self.properties.xrayRelevantArrayNames():
                props = getattr(self.properties, var)
                # We only have non-chrome ids to init if we have no chrome ids.
                if props.hasChromeOnly():
                    idsToInit.append(props.variableName(True))
                elif props.hasNonChromeOnly():
                    idsToInit.append(props.variableName(False))
        if len(idsToInit) > 0:
            setup = CGList([CGGeneric("let page = page_from_context(aCx);"),
                            CGList([CGGeneric("let %s_ids_mut = (*page).js_info.get_ref().dom_static.attribute_ids.get(&(PrototypeList::id::%s as uint));" % (varname, self.descriptor.name)) for varname in idsToInit], '\n')], '\n')
            initIds = CGList(
                [CGGeneric("!InitIds(aCx, %s, *%s_ids_mut)" % (varname, varname)) for
                 varname in idsToInit], ' ||\n')
            if len(idsToInit) > 1:
                initIds = CGWrapper(initIds, pre="(", post=")", reindent=True)
            initIds = CGList(
                [CGGeneric("%s_ids_mut[0] == JSID_VOID &&" % idsToInit[0]), initIds],
                "\n")
            initIds = CGWrapper(initIds, pre="if ", post=" {", reindent=True)
            initIds = CGList(
                [setup,
                 initIds,
                 CGGeneric(("  %s_ids_mut[0] = JSID_VOID;\n"
                            "  return ptr::null();") % idsToInit[0]),
                 CGGeneric("}")],
                "\n")
        else:
            initIds = None

        prefCacheData = []
        for var in self.properties.arrayNames():
            props = getattr(self.properties, var)
            prefCacheData.extend(props.prefCacheData)
        if len(prefCacheData) is not 0:
            prefCacheData = [
                CGGeneric('Preferences::AddBoolVarCache(%s, "%s");' % (ptr, pref)) for
                (pref, ptr) in prefCacheData]
            prefCache = CGWrapper(CGIndenter(CGList(prefCacheData, "\n")),
                                  pre=("static bool sPrefCachesInited = false;\n"
                                       "if (!sPrefCachesInited) {\n"
                                       "  sPrefCachesInited = true;\n"),
                                  post="\n}")
        else:
            prefCache = None
            
        getParentProto = ("let parentProto: *JSObject = %s;\n" +
                          "if parentProto.is_null() {\n" +
                          "  return ptr::null();\n" +
                          "}\n") % getParentProto

        needInterfaceObjectClass = (needInterfaceObject and
                                    self.descriptor.hasInstanceInterface)
        needConstructor = (needInterfaceObject and
                           not self.descriptor.hasInstanceInterface)
        if self.descriptor.interface.ctor():
            constructHook = CONSTRUCT_HOOK_NAME
            constructArgs = methodLength(self.descriptor.interface.ctor())
        else:
            constructHook = "ThrowingConstructor"
            constructArgs = 0

        if self.descriptor.concrete:
            if self.descriptor.proxy:
                domClass = "&Class"
            else:
                domClass = "&Class.dom_class"
        else:
            domClass = "ptr::null()"

        def arrayPtr(name):
            val = ('%(' + name + ')s') % self.properties.variableNames(False)
            if val == "ptr::null()":
                return val
            return "ptr::to_unsafe_ptr(&%s[0])" % val

        call = """return CreateInterfaceObjects2(aCx, aGlobal, aReceiver, parentProto,
                               %s, %s, %s, %d,
                               %s,
                               %s,
                               %s,
                               %s,
                               %s,
                               %s);""" % (
            "&PrototypeClass" if needInterfacePrototypeObject else "ptr::null()",
            "&InterfaceObjectClass" if needInterfaceObjectClass else "ptr::null()",
            "Some(%s)" % constructHook if needConstructor else "None",
            constructArgs,
            domClass,
            arrayPtr("methods"), arrayPtr("attrs"),
            arrayPtr("consts"), arrayPtr("staticMethods"),
            '"' + self.descriptor.interface.identifier.name + '"' if needInterfaceObject else "ptr::null()")
        if self.properties.hasChromeOnly():
            if self.descriptor.workers:
                accessCheck = "mozilla::dom::workers::GetWorkerPrivateFromContext(aCx)->IsChromeWorker()"
            else:
                accessCheck = "xpc::AccessCheck::isChrome(js::GetObjectCompartment(aGlobal))"
            chrome = CGIfWrapper(CGGeneric(call % self.properties.variableNames(True)),
                                 accessCheck)
            chrome = CGWrapper(chrome, pre="\n\n")
        else:
            chrome = None

        functionBody = CGList(
            [CGGeneric(getParentProto), initIds, prefCache, chrome,
             CGGeneric(call % self.properties.variableNames(False))],
            "\n\n")
        #return CGIndenter(CGWrapper(functionBody, pre="/*", post="*/return ptr::null()")).define()
        return CGIndenter(functionBody).define()

class CGGetPerInterfaceObject(CGAbstractMethod):
    """
    A method for getting a per-interface object (a prototype object or interface
    constructor object).
    """
    def __init__(self, descriptor, name, idPrefix="", pub=False):
        args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aGlobal'),
                Argument('*JSObject', 'aReceiver')]
        CGAbstractMethod.__init__(self, descriptor, name,
                                  '*JSObject', args, inline=True, pub=pub)
        self.id = idPrefix + "id::" + self.descriptor.name
    def definition_body(self):
        return """

  /* aGlobal and aReceiver are usually the same, but they can be different
     too. For example a sandbox often has an xray wrapper for a window as the
     prototype of the sandbox's global. In that case aReceiver is the xray
     wrapper and aGlobal is the sandbox's global.
   */

  /* Make sure our global is sane.  Hopefully we can remove this sometime */
  /*if ((*JS_GetClass(aGlobal)).flags & JSCLASS_DOM_GLOBAL) == 0 {
    return ptr::null();
  }*/
  /* Check to see whether the interface objects are already installed */
  let protoOrIfaceArray: *mut *JSObject = cast::transmute(GetProtoOrIfaceArray(aGlobal));
  let cachedObject: *JSObject = *protoOrIfaceArray.offset(%s as int);
  if cachedObject.is_null() {
    let tmp: *JSObject = CreateInterfaceObjects(aCx, aGlobal, aReceiver);
    *protoOrIfaceArray.offset(%s as int) = tmp;
    tmp
  } else {
    cachedObject
  }""" % (self.id, self.id)

class CGGetProtoObjectMethod(CGGetPerInterfaceObject):
    """
    A method for getting the interface prototype object.
    """
    def __init__(self, descriptor):
        CGGetPerInterfaceObject.__init__(self, descriptor, "GetProtoObject",
                                         "PrototypeList::", pub=True)
    def definition_body(self):
        return """
  /* Get the interface prototype object for this class.  This will create the
     object as needed. */""" + CGGetPerInterfaceObject.definition_body(self)

class CGGetConstructorObjectMethod(CGGetPerInterfaceObject):
    """
    A method for getting the interface constructor object.
    """
    def __init__(self, descriptor):
        CGGetPerInterfaceObject.__init__(self, descriptor, "GetConstructorObject",
                                         "constructors::")
    def definition_body(self):
        return """
  /* Get the interface object for this class.  This will create the object as
     needed. */""" + CGGetPerInterfaceObject.definition_body(self)

class CGDefineDOMInterfaceMethod(CGAbstractMethod):
    """
    A method for resolve hooks to try to lazily define the interface object for
    a given interface.
    """
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aReceiver'),
                Argument('*mut bool', 'aEnabled')]
        CGAbstractMethod.__init__(self, descriptor, 'DefineDOMInterface', 'bool', args, pub=True)

    def declare(self):
        if self.descriptor.workers:
            return ''
        #return CGAbstractMethod.declare(self)
        return ""

    def define(self):
        if self.descriptor.workers:
            return ''
        return CGAbstractMethod.define(self)

    def definition_body(self):
        if self.descriptor.interface.hasInterfacePrototypeObject():
            # We depend on GetProtoObject defining an interface constructor
            # object as needed.
            getter = "GetProtoObject"
        else:
            getter = "GetConstructorObject"

        body = "let page = page_from_context(aCx);"
        #XXXjdm This self.descriptor.concrete check shouldn't be necessary
        if not self.descriptor.concrete or self.descriptor.proxy:
            body += """  let traps = ProxyTraps {
    getPropertyDescriptor: getPropertyDescriptor,
    getOwnPropertyDescriptor: getOwnPropertyDescriptor,
    defineProperty: defineProperty,
    getOwnPropertyNames: ptr::null(),
    delete_: ptr::null(),
    enumerate: ptr::null(),

    has: ptr::null(),
    hasOwn: hasOwn,
    get: get,
    set: ptr::null(),
    keys: ptr::null(),
    iterate: ptr::null(),

    call: ptr::null(),
    construct: ptr::null(),
    nativeCall: ptr::null(),
    hasInstance: ptr::null(),
    typeOf: ptr::null(),
    objectClassIs: ptr::null(),
    obj_toString: obj_toString,
    fun_toString: ptr::null(),
    //regexp_toShared: ptr::null(),
    defaultValue: ptr::null(),
    iteratorNext: ptr::null(),
    finalize: %s,
    getElementIfPresent: ptr::null(),
    getPrototypeOf: ptr::null(),
    trace: %s
  };
  (*page).js_info.get_mut_ref().dom_static.proxy_handlers.insert(PrototypeList::id::%s as uint,
                                              CreateProxyHandler(ptr::to_unsafe_ptr(&traps), ptr::to_unsafe_ptr(&Class) as *libc::c_void));

""" % (FINALIZE_HOOK_NAME,
       ('Some(%s)' % TRACE_HOOK_NAME) if self.descriptor.customTrace else 'None',
       self.descriptor.name)
        else:
            body += """  (*page).js_info.get_ref().dom_static.attribute_ids.insert(PrototypeList::id::%s as uint,
                                             vec::cast_to_mut(vec::from_slice(sAttributes_ids)));
""" % self.descriptor.name
            body = "" #XXXjdm xray stuff isn't necessary yet

        return (body + "  let global: *JSObject = JS_GetGlobalForObject(aCx, aReceiver);\n" +
                """
  *aEnabled = true;
  return %s(aCx, global, aReceiver).is_not_null();""" % (getter))

def isResultAlreadyAddRefed(extendedAttributes):
    return not 'resultNotAddRefed' in extendedAttributes

def needCx(returnType, arguments, extendedAttributes, considerTypes):
    return (considerTypes and
            (typeNeedsCx(returnType, True) or
             any(typeNeedsCx(a.type) for a in arguments)) or
            'implicitJSContext' in extendedAttributes)

def needScopeObject(returnType, arguments, extendedAttributes,
                    isWrapperCached, considerTypes):
    return (considerTypes and not isWrapperCached and
            (typeNeedsScopeObject(returnType, True) or
             any(typeNeedsScopeObject(a.type) for a in arguments)))

class CGCallGenerator(CGThing):
    """
    A class to generate an actual call to a C++ object.  Assumes that the C++
    object is stored in a variable whose name is given by the |object| argument.

    errorReport should be a CGThing for an error report or None if no
    error reporting is needed.
    """
    def __init__(self, errorReport, arguments, argsPre, returnType,
                 extendedAttributes, descriptorProvider, nativeMethodName,
                 static, object="this", declareResult=True):
        CGThing.__init__(self)

        assert errorReport is None or isinstance(errorReport, CGThing)

        isFallible = errorReport is not None

        #resultAlreadyAddRefed = isResultAlreadyAddRefed(descriptorProvider,
        #                                                extendedAttributes)
        resultAlreadyAddRefed = True
        (result, resultOutParam) = getRetvalDeclarationForType(returnType,
                                                               descriptorProvider,
                                                               resultAlreadyAddRefed)

        args = CGList([CGGeneric(arg) for arg in argsPre], ", ")
        for (a, name) in arguments:
            # This is a workaround for a bug in Apple's clang.
            if a.type.isObject() and not a.type.nullable() and not a.optional:
                name = "(JSObject&)" + name
            #XXXjdm Perhaps we should pass all nontrivial types by borrowed pointer
            # Aoid passing Option<Option<DOMString>> by reference. If only one of optional or
            # defaultValue are truthy we pass an Option, otherwise it's a concrete Option<DOMString>.
            if a.type.isDictionary() or (a.type.isString() and not (bool(a.defaultValue) ^ a.optional)):
                name = "&" + name
            args.append(CGGeneric(name))

        # Return values that go in outparams go here
        if resultOutParam:
            args.append(CGGeneric("result"))

        needsCx = (typeNeedsCx(returnType, True) or
                   any(typeNeedsCx(a.type) for (a, _) in arguments) or
                   'implicitJSContext' in extendedAttributes)

        if not "cx" in argsPre and needsCx:
            args.prepend(CGGeneric("cx"))

        # Build up our actual call
        self.cgRoot = CGList([], "\n")

        call = CGGeneric(nativeMethodName)
        if static:
            call = CGWrapper(call, pre="%s::" % descriptorProvider.interface.identifier.name)
        else: 
            call = CGWrapper(call, pre="(*%s)." % object)
        call = CGList([call, CGWrapper(args, pre="(", post=");")])

        if isFallible:
            self.cgRoot.prepend(CGWrapper(result if result is not None else CGGeneric("()"),
                pre="let mut result_fallible: Result<", post=",Error>;"))

        if result is not None and declareResult:
            result = CGWrapper(result, pre="let mut result: ", post=";")
            self.cgRoot.prepend(result)

        if isFallible:
            call = CGWrapper(call, pre="result_fallible = ")
        elif result is not None and not resultOutParam:
            call = CGWrapper(call, pre="result = ")

        call = CGWrapper(call)
        self.cgRoot.append(call)

        if isFallible:
            self.cgRoot.append(CGGeneric("if (result_fallible.is_err()) {"))
            self.cgRoot.append(CGIndenter(errorReport))
            self.cgRoot.append(CGGeneric("}"))
            if result is not None and not resultOutParam:
                self.cgRoot.append(CGGeneric("result = result_fallible.unwrap();"))

    def define(self):
        return self.cgRoot.define()

class MethodNotCreatorError(Exception):
    def __init__(self, typename):
        self.typename = typename

class CGPerSignatureCall(CGThing):
    """
    This class handles the guts of generating code for a particular
    call signature.  A call signature consists of four things:

    1) A return type, which can be None to indicate that there is no
       actual return value (e.g. this is an attribute setter) or an
       IDLType if there's an IDL type involved (including |void|).
    2) An argument list, which is allowed to be empty.
    3) A name of a native method to call.
    4) Whether or not this method is static.

    We also need to know whether this is a method or a getter/setter
    to do error reporting correctly.

    The idlNode parameter can be either a method or an attr. We can query
    |idlNode.identifier| in both cases, so we can be agnostic between the two.
    """
    # XXXbz For now each entry in the argument list is either an
    # IDLArgument or a FakeArgument, but longer-term we may want to
    # have ways of flagging things like JSContext* or optional_argc in
    # there.

    def __init__(self, returnType, argsPre, arguments, nativeMethodName, static,
                 descriptor, idlNode, argConversionStartsAt=0,
                 getter=False, setter=False):
        CGThing.__init__(self)
        self.returnType = returnType
        self.descriptor = descriptor
        self.idlNode = idlNode
        self.extendedAttributes = descriptor.getExtendedAttributes(idlNode,
                                                                   getter=getter,
                                                                   setter=setter)
        self.argsPre = argsPre
        self.arguments = arguments
        self.argCount = len(arguments)
        if self.argCount > argConversionStartsAt:
            # Insert our argv in there
            cgThings = [CGGeneric(self.getArgvDecl())]
        else:
            cgThings = []
        cgThings.extend([CGArgumentConverter(arguments[i], i, self.getArgv(),
                                             self.getArgc(), self.descriptor,
                                             invalidEnumValueFatal=not setter) for
                         i in range(argConversionStartsAt, self.argCount)])

        cgThings.append(CGCallGenerator(
                    self.getErrorReport() if self.isFallible() else None,
                    self.getArguments(), self.argsPre, returnType,
                    self.extendedAttributes, descriptor, nativeMethodName,
                    static))
        self.cgRoot = CGList(cgThings, "\n")

    def getArgv(self):
        return "argv" if self.argCount > 0 else ""
    def getArgvDecl(self):
        return "\nlet argv = JS_ARGV(cx, cast::transmute(vp));\n"
    def getArgc(self):
        return "argc"
    def getArguments(self):
        return [(a, "arg" + str(i)) for (i, a) in enumerate(self.arguments)]

    def isFallible(self):
        return not 'infallible' in self.extendedAttributes

    def wrap_return_value(self):
        isCreator = memberIsCreator(self.idlNode)
        if isCreator:
            # We better be returning addrefed things!
            #assert(isResultAlreadyAddRefed(self.descriptor,
            #                               self.extendedAttributes) or
                   # Workers use raw pointers for new-object return
                   # values or something
            #       self.descriptor.workers)
            pass

        resultTemplateValues = { 'jsvalRef': '*vp', 'jsvalPtr': 'vp',
                                 'isCreator': isCreator}
        try:
            return wrapForType(self.returnType, self.descriptor,
                               resultTemplateValues)
        except MethodNotCreatorError, err:
            assert not isCreator
            raise TypeError("%s being returned from non-creator method or property %s.%s" %
                            (err.typename,
                             self.descriptor.interface.identifier.name,
                             self.idlNode.identifier.name))

    def getErrorReport(self):
        #return CGGeneric('return ThrowMethodFailedWithDetails<%s>(cx, rv, "%s", "%s");'
        #                 % (toStringBool(not self.descriptor.workers),
        #                    self.descriptor.interface.identifier.name,
        #                    self.idlNode.identifier.name))
        return CGGeneric('return 0'); #XXXjdm

    def define(self):
        return (self.cgRoot.define() + "\n" + self.wrap_return_value())

class CGSwitch(CGList):
    """
    A class to generate code for a switch statement.

    Takes three constructor arguments: an expression, a list of cases,
    and an optional default.

    Each case is a CGCase.  The default is a CGThing for the body of
    the default case, if any.
    """
    def __init__(self, expression, cases, default=None):
        CGList.__init__(self, [CGIndenter(c) for c in cases], "\n")
        self.prepend(CGWrapper(CGGeneric(expression),
                               pre="match ", post=" {"));
        if default is not None:
            self.append(
                CGIndenter(
                    CGWrapper(
                        CGIndenter(default),
                        pre="_ => {\n",
                        post="\n}"
                        )
                    )
                )

        self.append(CGGeneric("}"))

class CGCase(CGList):
    """
    A class to generate code for a case statement.

    Takes three constructor arguments: an expression, a CGThing for
    the body (allowed to be None if there is no body), and an optional
    argument (defaulting to False) for whether to fall through.
    """
    def __init__(self, expression, body, fallThrough=False):
        CGList.__init__(self, [], "\n")
        self.append(CGWrapper(CGGeneric(expression), post=" => {"))
        bodyList = CGList([body], "\n")
        if fallThrough:
            raise TypeError("fall through required but unsupported")
            #bodyList.append(CGGeneric('fail!("fall through unsupported"); /* Fall through */'))
        self.append(CGIndenter(bodyList));
        self.append(CGGeneric("}"))

class CGGetterCall(CGPerSignatureCall):
    """
    A class to generate a native object getter call for a particular IDL
    getter.
    """
    def __init__(self, argsPre, returnType, nativeMethodName, descriptor, attr):
        CGPerSignatureCall.__init__(self, returnType, argsPre, [],
                                    nativeMethodName, False, descriptor,
                                    attr, getter=True)

class FakeArgument():
    """
    A class that quacks like an IDLArgument.  This is used to make
    setters look like method calls or for special operations.
    """
    def __init__(self, type, interfaceMember):
        self.type = type
        self.optional = False
        self.variadic = False
        self.defaultValue = None
        self.treatNullAs = interfaceMember.treatNullAs
        self.enforceRange = False
        self.clamp = False

class CGSetterCall(CGPerSignatureCall):
    """
    A class to generate a native object setter call for a particular IDL
    setter.
    """
    def __init__(self, argsPre, argType, nativeMethodName, descriptor, attr):
        CGPerSignatureCall.__init__(self, None, argsPre,
                                    [FakeArgument(argType, attr)],
                                    nativeMethodName, False, descriptor, attr,
                                    setter=True)
    def wrap_return_value(self):
        # We have no return value
        return "\nreturn 1;"
    def getArgc(self):
        return "1"
    def getArgvDecl(self):
        # We just get our stuff from our last arg no matter what
        return ""

class CGAbstractBindingMethod(CGAbstractExternMethod):
    """
    Common class to generate the JSNatives for all our methods, getters, and
    setters.  This will generate the function declaration and unwrap the
    |this| object.  Subclasses are expected to override the generate_code
    function to do the rest of the work.  This function should return a
    CGThing which is already properly indented.
    """
    def __init__(self, descriptor, name, args, unwrapFailureCode=None):
        CGAbstractExternMethod.__init__(self, descriptor, name, "JSBool", args)

        if unwrapFailureCode is None:
            self.unwrapFailureCode = ("return 0; //XXXjdm return Throw<%s>(cx, rv);" %
                                      toStringBool(not descriptor.workers))
        else:
            self.unwrapFailureCode = unwrapFailureCode

    def definition_body(self):
        # Our descriptor might claim that we're not castable, simply because
        # we're someone's consequential interface.  But for this-unwrapping, we
        # know that we're the real deal.  So fake a descriptor here for
        # consumption by FailureFatalCastableObjectUnwrapper.
        unwrapThis = CGIndenter(CGGeneric(
            str(CastableObjectUnwrapper(
                        FakeCastableDescriptor(self.descriptor),
                        "obj", "this", self.unwrapFailureCode))))
        return CGList([ self.getThis(), unwrapThis,
                        self.generate_code() ], "\n").define()

    def getThis(self):
        return CGIndenter(
            CGGeneric("let obj: *JSObject = JS_THIS_OBJECT(cx, cast::transmute(vp));\n"
                      "if obj.is_null() {\n"
                      "  return false as JSBool;\n"
                      "}\n"
                      "\n"
                      "let this: *Box<%s>;" % self.descriptor.concreteType))

    def generate_code(self):
        assert(False) # Override me

class CGGenericMethod(CGAbstractBindingMethod):
    """
    A class for generating the C++ code for an IDL method..
    """
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('libc::c_uint', 'argc'),
                Argument('*mut JSVal', 'vp')]
        CGAbstractBindingMethod.__init__(self, descriptor, 'genericMethod', args)

    def generate_code(self):
        return CGIndenter(CGGeneric(
            "let _info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, &*vp));\n"
            "return CallJitMethodOp(_info, cx, obj, this as *libc::c_void, argc, &*vp);"))

class CGAbstractStaticMethod(CGAbstractMethod):
    """
    Abstract base class for codegen of implementation-only (no
    declaration) static methods.
    """
    def __init__(self, descriptor, name, returnType, args):
        CGAbstractMethod.__init__(self, descriptor, name, returnType, args,
                                  inline=False, static=True)
    def declare(self):
        # We only have implementation
        return ""

class CGSpecializedMethod(CGAbstractExternMethod):
    """
    A class for generating the C++ code for a specialized method that the JIT
    can call with lower overhead.
    """
    def __init__(self, descriptor, method):
        self.method = method
        name = method.identifier.name
        args = [Argument('*JSContext', 'cx'), Argument('JSHandleObject', 'obj'),
                Argument('*mut Box<%s>' % descriptor.concreteType, 'this'),
                Argument('libc::c_uint', 'argc'), Argument('*mut JSVal', 'vp')]
        CGAbstractExternMethod.__init__(self, descriptor, name, 'JSBool', args)

    def definition_body(self):
        name = self.method.identifier.name
        nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
        extraPre = ''
        argsPre = []
        if name in self.descriptor.needsAbstract:
            abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
            argsPre = ['abstract_this']
        return CGWrapper(CGMethodCall(argsPre, nativeName, self.method.isStatic(),
                                      self.descriptor, self.method),
                         pre=extraPre +
                             "  let obj = (*obj.unnamed);\n" +
                             "  let this = &mut (*this).data;\n").define()

class CGGenericGetter(CGAbstractBindingMethod):
    """
    A class for generating the C++ code for an IDL attribute getter.
    """
    def __init__(self, descriptor, lenientThis=False):
        args = [Argument('*JSContext', 'cx'), Argument('libc::c_uint', 'argc'),
                Argument('*mut JSVal', 'vp')]
        if lenientThis:
            name = "genericLenientGetter"
            unwrapFailureCode = (
                "MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"
                "JS_SET_RVAL(cx, vp, JS::UndefinedValue());\n"
                "return true;")
        else:
            name = "genericGetter"
            unwrapFailureCode = None
        CGAbstractBindingMethod.__init__(self, descriptor, name, args,
                                         unwrapFailureCode)

    def generate_code(self):
        return CGIndenter(CGGeneric(
            "let info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, &*vp));\n"
            "return CallJitPropertyOp(info, cx, obj, this as *libc::c_void, &*vp);"))

class CGSpecializedGetter(CGAbstractExternMethod):
    """
    A class for generating the code for a specialized attribute getter
    that the JIT can call with lower overhead.
    """
    def __init__(self, descriptor, attr):
        self.attr = attr
        name = 'get_' + attr.identifier.name
        args = [ Argument('*JSContext', 'cx'),
                 Argument('JSHandleObject', 'obj'),
                 Argument('*mut Box<%s>' % descriptor.concreteType, 'this'),
                 Argument('*mut JSVal', 'vp') ]
        CGAbstractExternMethod.__init__(self, descriptor, name, "JSBool", args)

    def definition_body(self):
        name = self.attr.identifier.name
        nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
        extraPre = ''
        argsPre = []
        # resultOutParam does not depend on whether resultAlreadyAddRefed is set
        (_, resultOutParam) = getRetvalDeclarationForType(self.attr.type,
                                                          self.descriptor,
                                                          False)
        infallible = ('infallible' in
                      self.descriptor.getExtendedAttributes(self.attr,
                                                            getter=True))
        if name in self.descriptor.needsAbstract:
            abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
            argsPre = ['abstract_this']
        if resultOutParam or self.attr.type.nullable() or not infallible:
            nativeName = "Get" + nativeName
        return CGWrapper(CGIndenter(CGGetterCall(argsPre, self.attr.type, nativeName,
                                                 self.descriptor, self.attr)),
                         pre=extraPre +
                             "  let obj = (*obj.unnamed);\n" +
                             "  let this = &mut (*this).data;\n").define()

class CGGenericSetter(CGAbstractBindingMethod):
    """
    A class for generating the Rust code for an IDL attribute setter.
    """
    def __init__(self, descriptor, lenientThis=False):
        args = [Argument('*JSContext', 'cx'), Argument('libc::c_uint', 'argc'),
                Argument('*mut JSVal', 'vp')]
        if lenientThis:
            name = "genericLenientSetter"
            unwrapFailureCode = (
                "MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"
                "return true;")
        else:
            name = "genericSetter"
            unwrapFailureCode = None
        CGAbstractBindingMethod.__init__(self, descriptor, name, args,
                                         unwrapFailureCode)

    def generate_code(self):
        return CGIndenter(CGGeneric(
                "let undef = JSVAL_VOID;\n"
                "let argv: *JSVal = if argc != 0 { JS_ARGV(cx, cast::transmute(vp)) } else { &undef as *JSVal };\n"
                "let info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, cast::transmute(vp)));\n"
                "if CallJitPropertyOp(info, cx, obj, this as *libc::c_void, argv) == 0 {"
                "  return 0;\n"
                "}\n"
                "*vp = JSVAL_VOID;\n"
                "return 1;"))

class CGSpecializedSetter(CGAbstractExternMethod):
    """
    A class for generating the code for a specialized attribute setter
    that the JIT can call with lower overhead.
    """
    def __init__(self, descriptor, attr):
        self.attr = attr
        name = 'set_' + attr.identifier.name
        args = [ Argument('*JSContext', 'cx'),
                 Argument('JSHandleObject', 'obj'),
                 Argument('*mut Box<%s>' % descriptor.concreteType, 'this'),
                 Argument('*mut JSVal', 'argv')]
        CGAbstractExternMethod.__init__(self, descriptor, name, "JSBool", args)

    def definition_body(self):
        name = self.attr.identifier.name
        nativeName = "Set" + MakeNativeName(self.descriptor.binaryNames.get(name, name))
        argsPre = []
        extraPre = ''
        if name in self.descriptor.needsAbstract:
            abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
            argsPre = ['abstract_this']
        return CGWrapper(CGIndenter(CGSetterCall(argsPre, self.attr.type, nativeName,
                                                 self.descriptor, self.attr)),
                         pre=extraPre +
                             "  let obj = (*obj.unnamed);\n" +
                             "  let this = &mut (*this).data;\n").define()

def infallibleForMember(member, type, descriptorProvider):
    """
    Determine the fallibility of changing a C++ value of IDL type "type" into
    JS for the given attribute. Apart from isCreator, all the defaults are used,
    since the fallbility does not change based on the boolean values,
    and the template will be discarded.

    CURRENT ASSUMPTIONS:
        We assume that successCode for wrapping up return values cannot contain
        failure conditions.
    """
    return getWrapTemplateForType(type, descriptorProvider, 'result', None,\
                                  memberIsCreator(member), "return false;",)[1]

class CGMemberJITInfo(CGThing):
    """
    A class for generating the JITInfo for a property that points to
    our specialized getter and setter.
    """
    def __init__(self, descriptor, member):
        self.member = member
        self.descriptor = descriptor

    def declare(self):
        return ""

    def defineJitInfo(self, infoName, opName, infallible):
        protoID =  "PrototypeList::id::%s as u32" % self.descriptor.name
        depth = self.descriptor.interface.inheritanceDepth()
        failstr = "true" if infallible else "false"
        return ("\n"
                "static %s: JSJitInfo = JSJitInfo {\n"
                "  op: %s as *u8,\n"
                "  protoID: %s,\n"
                "  depth: %s,\n"
                "  isInfallible: %s,  /* False in setters. */\n"
                "  isConstant: false  /* Only relevant for getters. */\n"
                "};\n" % (infoName, opName, protoID, depth, failstr))

    def define(self):
        if self.member.isAttr():
            getterinfo = ("%s_getterinfo" % self.member.identifier.name)
            getter = ("get_%s" % self.member.identifier.name)
            getterinfal = "infallible" in self.descriptor.getExtendedAttributes(self.member, getter=True)
            getterinfal = getterinfal and infallibleForMember(self.member, self.member.type, self.descriptor)
            result = self.defineJitInfo(getterinfo, getter, getterinfal)
            if not self.member.readonly:
                setterinfo = ("%s_setterinfo" % self.member.identifier.name)
                setter = ("set_%s" % self.member.identifier.name)
                # Setters are always fallible, since they have to do a typed unwrap.
                result += self.defineJitInfo(setterinfo, setter, False)
            return result
        if self.member.isMethod():
            methodinfo = ("%s_methodinfo" % self.member.identifier.name)
            # Actually a JSJitMethodOp, but JSJitPropertyOp by struct definition.
            method = ("%s" % self.member.identifier.name)

            # Methods are infallible if they are infallible, have no arguments
            # to unwrap, and have a return type that's infallible to wrap up for
            # return.
            methodInfal = False
            sigs = self.member.signatures()
            if len(sigs) == 1:
                # Don't handle overloading. If there's more than one signature,
                # one of them must take arguments.
                sig = sigs[0]
                if len(sig[1]) == 0 and infallibleForMember(self.member, sig[0], self.descriptor):
                    # No arguments and infallible return boxing
                    methodInfal = True

            result = self.defineJitInfo(methodinfo, method, methodInfal)
            return result
        raise TypeError("Illegal member type to CGPropertyJITInfo")

def getEnumValueName(value):
    # Some enum values can be empty strings.  Others might have weird
    # characters in them.  Deal with the former by returning "_empty",
    # deal with possible name collisions from that by throwing if the
    # enum value is actually "_empty", and throw on any value
    # containing non-ASCII chars for now. Replace all chars other than
    # [0-9A-Za-z_] with '_'.
    if re.match("[^\x20-\x7E]", value):
        raise SyntaxError('Enum value "' + value + '" contains non-ASCII characters')
    if re.match("^[0-9]", value):
        raise SyntaxError('Enum value "' + value + '" starts with a digit')
    value = re.sub(r'[^0-9A-Za-z_]', '_', value)
    if re.match("^_[A-Z]|__", value):
        raise SyntaxError('Enum value "' + value + '" is reserved by the C++ spec')
    if value == "_empty":
        raise SyntaxError('"_empty" is not an IDL enum value we support yet')
    if value == "":
        return "_empty"
    return MakeNativeName(value)

class CGEnum(CGThing):
    def __init__(self, enum):
        CGThing.__init__(self)
        self.enum = enum

    def declare(self):
        return ""

    def define(self):
        return """
  pub enum valuelist {
    %s
  }

  pub static strings: &'static [EnumEntry] = &[
    %s,
  ];
""" % (",\n    ".join(map(getEnumValueName, self.enum.values())),
       ",\n    ".join(['EnumEntry {value: &"' + val + '", length: ' + str(len(val)) + '}' for val in self.enum.values()]))

class ClassItem:
    """ Use with CGClass """
    def __init__(self, name, visibility):
        self.name = name
        self.visibility = visibility
    def declare(self, cgClass):
        assert False
    def define(self, cgClass):
        assert False

class ClassBase(ClassItem):
    def __init__(self, name, visibility='pub'):
        ClassItem.__init__(self, name, visibility)
    def declare(self, cgClass):
        return '%s %s' % (self.visibility, self.name)
    def define(self, cgClass):
        # Only in the header
        return ''

class ClassMethod(ClassItem):
    def __init__(self, name, returnType, args, inline=False, static=False,
                 virtual=False, const=False, bodyInHeader=False,
                 templateArgs=None, visibility='public', body=None,
                 breakAfterReturnDecl="\n",
                 breakAfterSelf="\n", override=False):
        """
        override indicates whether to flag the method as MOZ_OVERRIDE
        """
        assert not override or virtual
        self.returnType = returnType
        self.args = args
        self.inline = False
        self.static = static
        self.virtual = virtual
        self.const = const
        self.bodyInHeader = True
        self.templateArgs = templateArgs
        self.body = body
        self.breakAfterReturnDecl = breakAfterReturnDecl
        self.breakAfterSelf = breakAfterSelf
        self.override = override
        ClassItem.__init__(self, name, visibility)

    def getDecorators(self, declaring):
        decorators = ['#[fixed_stack_segment]']
        if self.inline:
            decorators.append('inline')
        if declaring:
            if self.static:
                decorators.append('static')
            if self.virtual:
                decorators.append('virtual')
        if decorators:
            return ' '.join(decorators) + ' '
        return ''

    def getBody(self):
        # Override me or pass a string to constructor
        assert self.body is not None
        return self.body

    def declare(self, cgClass):
        templateClause = '<%s>' % ', '.join(self.templateArgs) \
                         if self.bodyInHeader and self.templateArgs else ''
        args = ', '.join([a.declare() for a in self.args])
        if self.bodyInHeader:
            body = CGIndenter(CGGeneric(self.getBody())).define()
            body = ' {\n' + body + '\n}'
        else:
           body = ';'

        return string.Template("${decorators}%s"
                               "${visibility}fn ${name}${templateClause}(${args})${returnType}${const}${override}${body}%s" %
                               (self.breakAfterReturnDecl, self.breakAfterSelf)
                               ).substitute({
                'templateClause': templateClause,
                'decorators': self.getDecorators(True),
                'returnType': (" -> %s" % self.returnType) if self.returnType else "",
                'name': self.name,
                'const': ' const' if self.const else '',
                'override': ' MOZ_OVERRIDE' if self.override else '',
                'args': args,
                'body': body,
                'visibility': self.visibility + ' ' if self.visibility is not 'priv' else ''
                })

    def define(self, cgClass):
        pass

class ClassUsingDeclaration(ClassItem):
    """"
    Used for importing a name from a base class into a CGClass

    baseClass is the name of the base class to import the name from

    name is the name to import

    visibility determines the visibility of the name (public,
    protected, private), defaults to public.
    """
    def __init__(self, baseClass, name, visibility='public'):
        self.baseClass = baseClass
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        return string.Template("""using ${baseClass}::${name};
""").substitute({ 'baseClass': self.baseClass,
                  'name': self.name })

    def define(self, cgClass):
        return ''

class ClassConstructor(ClassItem):
    """
    Used for adding a constructor to a CGClass.

    args is a list of Argument objects that are the arguments taken by the
    constructor.

    inline should be True if the constructor should be marked inline.

    bodyInHeader should be True if the body should be placed in the class
    declaration in the header.

    visibility determines the visibility of the constructor (public,
    protected, private), defaults to private.

    explicit should be True if the constructor should be marked explicit.

    baseConstructors is a list of strings containing calls to base constructors,
    defaults to None.

    body contains a string with the code for the constructor, defaults to empty.
    """
    def __init__(self, args, inline=False, bodyInHeader=False,
                 visibility="priv", explicit=False, baseConstructors=None,
                 body=""):
        self.args = args
        self.inline = False
        self.bodyInHeader = bodyInHeader
        self.explicit = explicit
        self.baseConstructors = baseConstructors or []
        self.body = body
        ClassItem.__init__(self, None, visibility)

    def getDecorators(self, declaring):
        decorators = []
        if self.explicit:
            decorators.append('explicit')
        if self.inline and declaring:
            decorators.append('inline')
        if decorators:
            return ' '.join(decorators) + ' '
        return ''

    def getInitializationList(self, cgClass):
        items = [str(c) for c in self.baseConstructors]
        for m in cgClass.members:
            if not m.static:
                initialize = m.body
                if initialize:
                    items.append(m.name + "(" + initialize + ")")

        if len(items) > 0:
            return '\n  : ' + ',\n    '.join(items)
        return ''

    def getBody(self, cgClass):
        initializers = ["  parent: %s" % str(self.baseConstructors[0])]
        return (self.body + (
                "%s {\n"
                "%s\n"
                "}") % (cgClass.name, '\n'.join(initializers)))

    def declare(self, cgClass):
        args = ', '.join([a.declare() for a in self.args])
        body = '  ' + self.getBody(cgClass);
        body = stripTrailingWhitespace(body.replace('\n', '\n  '))
        if len(body) > 0:
            body += '\n'
        body = ' {\n' + body + '}'

        return string.Template("""pub fn ${decorators}new(${args}) -> ${className}${body}
""").substitute({ 'decorators': self.getDecorators(True),
                  'className': cgClass.getNameString(),
                  'args': args,
                  'body': body })

    def define(self, cgClass):
        if self.bodyInHeader:
            return ''

        args = ', '.join([a.define() for a in self.args])

        body = '  ' + self.getBody()
        body = '\n' + stripTrailingWhitespace(body.replace('\n', '\n  '))
        if len(body) > 0:
            body += '\n'

        return string.Template("""${decorators}
${className}::${className}(${args})${initializationList}
{${body}}
""").substitute({ 'decorators': self.getDecorators(False),
                  'className': cgClass.getNameString(),
                  'args': args,
                  'initializationList': self.getInitializationList(cgClass),
                  'body': body })

class ClassDestructor(ClassItem):
    """
    Used for adding a destructor to a CGClass.

    inline should be True if the destructor should be marked inline.

    bodyInHeader should be True if the body should be placed in the class
    declaration in the header.

    visibility determines the visibility of the destructor (public,
    protected, private), defaults to private.

    body contains a string with the code for the destructor, defaults to empty.

    virtual determines whether the destructor is virtual, defaults to False.
    """
    def __init__(self, inline=False, bodyInHeader=False,
                 visibility="private", body='', virtual=False):
        self.inline = inline or bodyInHeader
        self.bodyInHeader = bodyInHeader
        self.body = body
        self.virtual = virtual
        ClassItem.__init__(self, None, visibility)

    def getDecorators(self, declaring):
        decorators = []
        if self.virtual and declaring:
            decorators.append('virtual')
        if self.inline and declaring:
            decorators.append('inline')
        if decorators:
            return ' '.join(decorators) + ' '
        return ''

    def getBody(self):
        return self.body

    def declare(self, cgClass):
        if self.bodyInHeader:
            body = '  ' + self.getBody();
            body = stripTrailingWhitespace(body.replace('\n', '\n  '))
            if len(body) > 0:
                body += '\n'
            body = '\n{\n' + body + '}'
        else:
            body = ';'

        return string.Template("""${decorators}~${className}()${body}
""").substitute({ 'decorators': self.getDecorators(True),
                  'className': cgClass.getNameString(),
                  'body': body })

    def define(self, cgClass):
        if self.bodyInHeader:
            return ''

        body = '  ' + self.getBody()
        body = '\n' + stripTrailingWhitespace(body.replace('\n', '\n  '))
        if len(body) > 0:
            body += '\n'

        return string.Template("""${decorators}
${className}::~${className}()
{${body}}
""").substitute({ 'decorators': self.getDecorators(False),
                  'className': cgClass.getNameString(),
                  'body': body })

class ClassMember(ClassItem):
    def __init__(self, name, type, visibility="priv", static=False,
                 body=None):
        self.type = type;
        self.static = static
        self.body = body
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        return '%s: %s,\n' % (self.name, self.type)

    def define(self, cgClass):
        if not self.static:
            return ''
        if self.body:
            body = " = " + self.body
        else:
            body = ""
        return '%s %s::%s%s;\n' % (self.type, cgClass.getNameString(),
                                      self.name, body)

class ClassTypedef(ClassItem):
    def __init__(self, name, type, visibility="public"):
        self.type = type
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        return 'typedef %s %s;\n' % (self.type, self.name)

    def define(self, cgClass):
        # Only goes in the header
        return ''

class ClassEnum(ClassItem):
    def __init__(self, name, entries, values=None, visibility="public"):
        self.entries = entries
        self.values = values
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        entries = []
        for i in range(0, len(self.entries)):
            if not self.values or i >= len(self.values):
                entry = '%s' % self.entries[i]
            else:
                entry = '%s = %s' % (self.entries[i], self.values[i])
            entries.append(entry)
        name = '' if not self.name else ' ' + self.name
        return 'enum%s\n{\n  %s\n};\n' % (name, ',\n  '.join(entries))

    def define(self, cgClass):
        # Only goes in the header
        return ''

class ClassUnion(ClassItem):
    def __init__(self, name, entries, visibility="public"):
        self.entries = [entry + ";" for entry in entries]
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        return 'union %s\n{\n  %s\n};\n' % (self.name, '\n  '.join(self.entries))

    def define(self, cgClass):
        # Only goes in the header
        return ''

class CGClass(CGThing):
    def __init__(self, name, bases=[], members=[], constructors=[],
                 destructor=None, methods=[],
                 typedefs = [], enums=[], unions=[], templateArgs=[],
                 templateSpecialization=[], isStruct=False,
                 disallowCopyConstruction=False, indent='',
                 decorators='',
                 extradeclarations='',
                 extradefinitions=''):
        CGThing.__init__(self)
        self.name = name
        self.bases = bases
        self.members = members
        self.constructors = constructors
        # We store our single destructor in a list, since all of our
        # code wants lists of members.
        self.destructors = [destructor] if destructor else []
        self.methods = methods
        self.typedefs = typedefs
        self.enums = enums
        self.unions = unions
        self.templateArgs = templateArgs
        self.templateSpecialization = templateSpecialization
        self.isStruct = isStruct
        self.disallowCopyConstruction = disallowCopyConstruction
        self.indent = indent
        self.defaultVisibility ='pub' if isStruct else 'priv'
        self.decorators = decorators
        self.extradeclarations = extradeclarations
        self.extradefinitions = extradefinitions

    def getNameString(self):
        className = self.name
        if self.templateSpecialization:
            className = className + \
                '<%s>' % ', '.join([str(a) for a
                                    in self.templateSpecialization])
        return className

    def declare(self):
        result = ''
        if self.templateArgs:
            templateArgs = [a.declare() for a in self.templateArgs]
            templateArgs = templateArgs[len(self.templateSpecialization):]
            result = result + self.indent + 'template <%s>\n' \
                     % ','.join([str(a) for a in templateArgs])

        if self.templateSpecialization:
            specialization = \
                '<%s>' % ', '.join([str(a) for a in self.templateSpecialization])
        else:
            specialization = ''

        myself = ''
        if self.decorators != '':
            myself += self.decorators + '\n'
        myself += '%spub struct %s%s' % (self.indent, self.name, specialization)
        result += myself

        assert len(self.bases) == 1 #XXjdm Can we support multiple inheritance?

        result += '{\n%s\n' % self.indent

        if self.bases:
            self.members = [ClassMember("parent", self.bases[0].name, "pub")] + self.members

        result += CGIndenter(CGGeneric(self.extradeclarations),
                             len(self.indent)).define()

        def declareMembers(cgClass, memberList):
            result = ''

            for member in memberList:
                declaration = member.declare(cgClass)
                declaration = CGIndenter(CGGeneric(declaration)).define()
                result = result + declaration
            return result

        if self.disallowCopyConstruction:
            class DisallowedCopyConstructor(object):
                def __init__(self):
                    self.visibility = "private"
                def declare(self, cgClass):
                    name = cgClass.getNameString()
                    return ("%s(const %s&) MOZ_DELETE;\n"
                            "void operator=(const %s) MOZ_DELETE;\n" % (name, name, name))
            disallowedCopyConstructors = [DisallowedCopyConstructor()]
        else:
            disallowedCopyConstructors = []

        order = [(self.enums, ''), (self.unions, ''),
                 (self.typedefs, ''), (self.members, '')]

        for (memberList, separator) in order:
            memberString = declareMembers(self, memberList)
            if self.indent:
                memberString = CGIndenter(CGGeneric(memberString),
                                          len(self.indent)).define()
            result = result + memberString

        result += self.indent + '}\n\n'
        result += 'impl %s {\n' % self.name

        order = [(self.constructors + disallowedCopyConstructors, '\n'),
                 (self.destructors, '\n'), (self.methods, '\n)')]
        for (memberList, separator) in order:
            memberString = declareMembers(self, memberList)
            if self.indent:
                memberString = CGIndenter(CGGeneric(memberString),
                                          len(self.indent)).define()
            result = result + memberString

        result += "}"
        return result

    def define(self):
        return ''

class CGXrayHelper(CGAbstractExternMethod):
    def __init__(self, descriptor, name, args, properties):
        CGAbstractExternMethod.__init__(self, descriptor, name, "bool", args)
        self.properties = properties

    def definition_body(self):
        varNames = self.properties.variableNames(True)

        setup = "let page = page_from_context(cx);\n"

        methods = self.properties.methods
        if methods.hasNonChromeOnly() or methods.hasChromeOnly():
            methodArgs = "Some(zip_copies(%(methods)s, *method_ids))" % varNames
            setup += "let method_ids = (*page).js_info.get_ref().dom_static.method_ids.get(&(PrototypeList::id::ClientRect as uint));\n"
        else:
            methodArgs = "None"
        methodArgs = CGGeneric(methodArgs)

        attrs = self.properties.attrs
        if attrs.hasNonChromeOnly() or attrs.hasChromeOnly():
            attrArgs = "Some(zip_copies(%(attrs)s, *attr_ids))" % varNames
            setup += "let attr_ids = (*page).js_info.get_ref().dom_static.attribute_ids.get(&(PrototypeList::id::ClientRect as uint));\n"
        else:
            attrArgs = "None"
        attrArgs = CGGeneric(attrArgs)

        consts = self.properties.consts
        if consts.hasNonChromeOnly() or consts.hasChromeOnly():
            constArgs = "Some(zip_copies(%(consts)s, *const_ids))" % varNames
            setup += "let const_ids = (*page).js_info.get_ref().dom_static.constant_ids.get(&(PrototypeList::id::ClientRect as uint));\n"
        else:
            constArgs = "None"
        constArgs = CGGeneric(constArgs)

        prefixArgs = CGGeneric(self.getPrefixArgs())

        return CGIndenter(
            CGWrapper(CGList([prefixArgs, methodArgs, attrArgs, constArgs], ", "),
                      pre=(setup + "return Xray%s(" % self.name),
                      post=");",
                      reindent=True)).define()

class CGResolveProperty(CGXrayHelper):
    def __init__(self, descriptor, properties):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'wrapper'),
                Argument('jsid', 'id'), Argument('bool', 'set'),
                Argument('*mut JSPropertyDescriptor', 'desc')]
        CGXrayHelper.__init__(self, descriptor, "ResolveProperty", args,
                              properties)

    def getPrefixArgs(self):
        return "cx, wrapper, id, desc"


class CGEnumerateProperties(CGXrayHelper):
    def __init__(self, descriptor, properties):
        args = [Argument('JSContext*', 'cx'), Argument('JSObject*', 'wrapper'),
                Argument('JS::AutoIdVector&', 'props')]
        CGXrayHelper.__init__(self, descriptor, "EnumerateProperties", args,
                              properties)

    def getPrefixArgs(self):
        return "props"

class CGProxySpecialOperation(CGPerSignatureCall):
    """
    Base class for classes for calling an indexed or named special operation
    (don't use this directly, use the derived classes below).
    """
    def __init__(self, descriptor, operation):
        nativeName = MakeNativeName(descriptor.binaryNames.get(operation, operation))
        operation = descriptor.operations[operation]
        assert len(operation.signatures()) == 1
        signature = operation.signatures()[0]
        extendedAttributes = descriptor.getExtendedAttributes(operation)

        (returnType, arguments) = signature

        # We pass len(arguments) as the final argument so that the
        # CGPerSignatureCall won't do any argument conversion of its own.
        CGPerSignatureCall.__init__(self, returnType, "", arguments, nativeName,
                                    False, descriptor, operation,
                                    len(arguments))

        if operation.isSetter() or operation.isCreator():
            # arguments[0] is the index or name of the item that we're setting.
            argument = arguments[1]
            template = getJSToNativeConversionTemplate(argument.type, descriptor,
                                                       treatNullAs=argument.treatNullAs)
            templateValues = {
                "declName": argument.identifier.name,
                "holderName": argument.identifier.name + "_holder",
                "val": "(*desc).value",
                "valPtr": "&(*desc).value"
            }
            self.cgRoot.prepend(instantiateJSToNativeConversionTemplate(template, templateValues))
        elif operation.isGetter():
            self.cgRoot.prepend(CGGeneric("let mut found = false;"))

    def getArguments(self):
        args = [(a, a.identifier.name) for a in self.arguments]
        if self.idlNode.isGetter():
            args.append((FakeArgument(BuiltinTypes[IDLBuiltinType.Types.boolean],
                                      self.idlNode),
                         "&mut found"))
        return args

    def wrap_return_value(self):
        if not self.idlNode.isGetter() or self.templateValues is None:
            return ""

        wrap = CGGeneric(wrapForType(self.returnType, self.descriptor, self.templateValues))
        wrap = CGIfWrapper(wrap, "found")
        return "\n" + wrap.define()

class CGProxyIndexedGetter(CGProxySpecialOperation):
    """
    Class to generate a call to an indexed getter. If templateValues is not None
    the returned value will be wrapped with wrapForType using templateValues.
    """
    def __init__(self, descriptor, templateValues=None):
        self.templateValues = templateValues
        CGProxySpecialOperation.__init__(self, descriptor, 'IndexedGetter')

class CGProxyIndexedSetter(CGProxySpecialOperation):
    """
    Class to generate a call to an indexed setter.
    """
    def __init__(self, descriptor):
        CGProxySpecialOperation.__init__(self, descriptor, 'IndexedSetter')

class CGProxyNamedGetter(CGProxySpecialOperation):
    """
    Class to generate a call to an named getter. If templateValues is not None
    the returned value will be wrapped with wrapForType using templateValues.
    """
    def __init__(self, descriptor, templateValues=None):
        self.templateValues = templateValues
        CGProxySpecialOperation.__init__(self, descriptor, 'NamedGetter')

class CGProxyNamedSetter(CGProxySpecialOperation):
    """
    Class to generate a call to a named setter.
    """
    def __init__(self, descriptor):
        CGProxySpecialOperation.__init__(self, descriptor, 'NamedSetter')

class CGProxyUnwrap(CGAbstractMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSObject', 'obj')]
        CGAbstractMethod.__init__(self, descriptor, "UnwrapProxy", '*' + descriptor.concreteType, args, alwaysInline=True)
    def declare(self):
        return ""
    def definition_body(self):
        return """  /*if (xpc::WrapperFactory::IsXrayWrapper(obj)) {
    obj = js::UnwrapObject(obj);
  }*/
  //MOZ_ASSERT(IsProxy(obj));
  let box: *Box<%s> = cast::transmute(RUST_JSVAL_TO_PRIVATE(GetProxyPrivate(obj)));
  return ptr::to_unsafe_ptr(&(*box).data);""" % (self.descriptor.concreteType)

class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'proxy'),
                Argument('jsid', 'id'), Argument('JSBool', 'set'),
                Argument('*mut JSPropertyDescriptor', 'desc')]
        CGAbstractExternMethod.__init__(self, descriptor, "getOwnPropertyDescriptor",
                                        "JSBool", args)
        self.descriptor = descriptor
    def getBody(self):
        indexedGetter = self.descriptor.operations['IndexedGetter']
        indexedSetter = self.descriptor.operations['IndexedSetter']

        setOrIndexedGet = ""
        if indexedGetter or indexedSetter:
            setOrIndexedGet += "let index = GetArrayIndexFromId(cx, id);\n"

        if indexedGetter:
            readonly = toStringBool(self.descriptor.operations['IndexedSetter'] is None)
            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn 1;" % readonly
            templateValues = {'jsvalRef': '(*desc).value', 'jsvalPtr': 'ptr::to_mut_unsafe_ptr(&mut (*desc).value)',
                              'obj': 'proxy', 'successCode': fillDescriptor}
            get = ("if index.is_some() {\n" +
                   "  let index = index.unwrap();\n" +
                   "  let this: *%s = UnwrapProxy(proxy);\n" +
                   CGIndenter(CGProxyIndexedGetter(self.descriptor, templateValues)).define() + "\n" +
                   "}\n") % (self.descriptor.concreteType)

        if indexedSetter or self.descriptor.operations['NamedSetter']:
            setOrIndexedGet += "if set != 0 {\n"
            if indexedSetter:
                setOrIndexedGet += ("  if index.is_some() {\n" +
                                    "    let index = index.unwrap();\n")
                if not 'IndexedCreator' in self.descriptor.operations:
                    # FIXME need to check that this is a 'supported property index'
                    assert False
                setOrIndexedGet += ("    FillPropertyDescriptor(&mut *desc, proxy, false);\n" +
                                    "    return 1;\n" +
                                    "  }\n")
            if self.descriptor.operations['NamedSetter']:
                setOrIndexedGet += "  if RUST_JSID_IS_STRING(id) {\n"
                if not 'NamedCreator' in self.descriptor.operations:
                    # FIXME need to check that this is a 'supported property name'
                    assert False
                setOrIndexedGet += ("    FillPropertyDescriptor(&mut *desc, proxy, false);\n" +
                                    "    return 1;\n" +
                                    "  }\n")
            setOrIndexedGet += "}"
            if indexedGetter:
                setOrIndexedGet += (" else {\n" +
                                    CGIndenter(CGGeneric(get)).define() +
                                    "}")
            setOrIndexedGet += "\n\n"
        elif indexedGetter:
            setOrIndexedGet += ("if set == 0 {\n" +
                                CGIndenter(CGGeneric(get)).define() +
                                "}\n\n")

        namedGetter = self.descriptor.operations['NamedGetter']
        if namedGetter:
            readonly = toStringBool(self.descriptor.operations['NamedSetter'] is None)
            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn 1;" % readonly
            templateValues = {'jsvalRef': '(*desc).value', 'jsvalPtr': 'ptr::to_unsafe_ptr(&(*desc).value)',
                              'obj': 'proxy', 'successCode': fillDescriptor}
            # Once we start supporting OverrideBuiltins we need to make
            # ResolveOwnProperty or EnumerateOwnProperties filter out named
            # properties that shadow prototype properties.
            namedGet = ("\n" +
                        "if set == 0 && RUST_JSID_IS_STRING(id) != 0 && !HasPropertyOnPrototype(cx, proxy, id) {\n" +
                        "  let name = Some(jsid_to_str(cx, id));\n" +
                        "  let this: *%s = UnwrapProxy(proxy);\n" +
                        CGIndenter(CGProxyNamedGetter(self.descriptor, templateValues)).define() + "\n" +
                        "}\n") % (self.descriptor.concreteType)
        else:
            namedGet = ""

        return setOrIndexedGet + """let expando: *JSObject = GetExpandoObject(proxy);
//if (!xpc::WrapperFactory::IsXrayWrapper(proxy) && (expando = GetExpandoObject(proxy))) {
if expando.is_not_null() {
  let flags = if set != 0 { JSRESOLVE_ASSIGNING } else { 0 } | JSRESOLVE_QUALIFIED;
  if JS_GetPropertyDescriptorById(cx, expando, id, flags, desc as *JSPropertyDescriptor) == 0 {
    return 0;
  }
  if (*desc).obj.is_not_null() {
    // Pretend the property lives on the wrapper.
    (*desc).obj = proxy;
    return 1;
  }
}
""" + namedGet + """
(*desc).obj = ptr::null();
return 1;"""

    def definition_body(self):
        return self.getBody()

class CGDOMJSProxyHandler_defineProperty(CGAbstractExternMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'proxy'),
                Argument('jsid', 'id'),
                Argument('*JSPropertyDescriptor', 'desc')]
        CGAbstractExternMethod.__init__(self, descriptor, "defineProperty", "JSBool", args)
        self.descriptor = descriptor
    def getBody(self):
        set = ""

        indexedSetter = self.descriptor.operations['IndexedSetter']
        if indexedSetter:
            if not (self.descriptor.operations['IndexedCreator'] is indexedSetter):
                raise TypeError("Can't handle creator that's different from the setter")
            set += ("let index = GetArrayIndexFromId(cx, id);\n" +
                    "if index.is_some() {\n" +
                    "  let index = index.unwrap();\n" +
                    "  let this: *mut %s = UnwrapProxy(proxy) as *mut %s;\n" +
                    CGIndenter(CGProxyIndexedSetter(self.descriptor)).define() +
                    "  return 1;\n" +
                    "}\n") % (self.descriptor.concreteType, self.descriptor.concreteType)
        elif self.descriptor.operations['IndexedGetter']:
            set += ("if GetArrayIndexFromId(cx, id).is_some() {\n" +
                    "  return 0;\n" +
                    "  //return ThrowErrorMessage(cx, MSG_NO_PROPERTY_SETTER, \"%s\");\n" +
                    "}\n") % self.descriptor.name

        namedSetter = self.descriptor.operations['NamedSetter']
        if namedSetter:
            if not self.descriptor.operations['NamedCreator'] is namedSetter:
                raise TypeError("Can't handle creator that's different from the setter")
            set += ("if RUST_JSID_IS_STRING(id) != 0 {\n" +
                    "  let name = Some(jsid_to_str(cx, id));\n" +
                    "  let this: *%s = UnwrapProxy(proxy);\n" +
                    CGIndenter(CGProxyNamedSetter(self.descriptor)).define() + "\n" +
                    "}\n") % (self.descriptor.concreteType)
        elif self.descriptor.operations['NamedGetter']:
            set += ("if RUST_JSID_IS_STRING(id) {\n" +
                    "  let name = Some(jsid_to_str(cx, id));\n" +
                    "  let this: %%s = UnwrapProxy(proxy);\n" +
                    CGIndenter(CGProxyNamedGetter(self.descriptor)).define() +
                    "  if (found) {\n"
                    "    return 0;\n" +
                    "    //return ThrowErrorMessage(cx, MSG_NO_PROPERTY_SETTER, \"%s\");\n" +
                    "  }\n" +
                    "  return 1;\n"
                    "}\n") % (self.descriptor.concreteType, self.descriptor.name)
        return set + """return proxyhandler::defineProperty_(%s);""" % ", ".join(a.name for a in self.args)

    def definition_body(self):
        return self.getBody()

class CGDOMJSProxyHandler_hasOwn(CGAbstractExternMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'proxy'),
                Argument('jsid', 'id'), Argument('*mut JSBool', 'bp')]
        CGAbstractExternMethod.__init__(self, descriptor, "hasOwn", "JSBool", args)
        self.descriptor = descriptor
    def getBody(self):
        indexedGetter = self.descriptor.operations['IndexedGetter']
        if indexedGetter:
            indexed = ("let index = GetArrayIndexFromId(cx, id);\n" +
                       "if index.is_some() {\n" +
                       "  let index = index.unwrap();\n" +
                       "  let this: *%s = UnwrapProxy(proxy);\n" +
                       CGIndenter(CGProxyIndexedGetter(self.descriptor)).define() + "\n" +
                       "  *bp = found as JSBool;\n" +
                       "  return 1;\n" +
                       "}\n\n") % (self.descriptor.concreteType)
        else:
            indexed = ""

        namedGetter = self.descriptor.operations['NamedGetter']
        if namedGetter:
            named = ("if RUST_JSID_IS_STRING(id) != 0 && !HasPropertyOnPrototype(cx, proxy, id) {\n" +
                     "  let name = Some(jsid_to_str(cx, id));\n" +
                     "  let this: *%s = UnwrapProxy(proxy);\n" +
                     CGIndenter(CGProxyNamedGetter(self.descriptor)).define() + "\n" +
                     "  *bp = found as JSBool;\n"
                     "  return 1;\n"
                     "}\n" +
                     "\n") % (self.descriptor.concreteType)
        else:
            named = ""

        return indexed + """let expando: *JSObject = GetExpandoObject(proxy);
if expando.is_not_null() {
  let b: JSBool = 1;
  let ok: JSBool = JS_HasPropertyById(cx, expando, id, &b);
  *bp = !!b;
  if ok == 0 || *bp != 0 {
    return ok;
  }
}

""" + named + """*bp = 0;
return 1;"""

    def definition_body(self):
        return self.getBody()

class CGDOMJSProxyHandler_get(CGAbstractExternMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'proxy'),
                Argument('*JSObject', 'receiver'), Argument('jsid', 'id'),
                Argument('*mut JSVal', 'vp')]
        CGAbstractExternMethod.__init__(self, descriptor, "get", "JSBool", args)
        self.descriptor = descriptor
    def getBody(self):
        getFromExpando = """let expando = GetExpandoObject(proxy);
if expando.is_not_null() {
  let hasProp = 0;
  if JS_HasPropertyById(cx, expando, id, ptr::to_unsafe_ptr(&hasProp)) == 0 {
    return 0;
  }

  if hasProp != 0 {
    return JS_GetPropertyById(cx, expando, id, cast::transmute(vp));
  }
}"""

        templateValues = {'jsvalRef': '*vp', 'jsvalPtr': 'vp', 'obj': 'proxy'}

        indexedGetter = self.descriptor.operations['IndexedGetter']
        if indexedGetter:
            getIndexedOrExpando = ("let index = GetArrayIndexFromId(cx, id);\n" +
                                   "if index.is_some() {\n" +
                                   "  let index = index.unwrap();\n" +
                                   "  let this = UnwrapProxy(proxy);\n" +
                                   CGIndenter(CGProxyIndexedGetter(self.descriptor, templateValues)).define())
            getIndexedOrExpando += """
  // Even if we don't have this index, we don't forward the
  // get on to our expando object.
} else {
  %s
}
""" % (stripTrailingWhitespace(getFromExpando.replace('\n', '\n  ')))
        else:
            getIndexedOrExpando = getFromExpando + "\n"

        namedGetter = self.descriptor.operations['NamedGetter']
        if namedGetter and False: #XXXjdm unfinished
            getNamed = ("if (JSID_IS_STRING(id)) {\n" +
                        "  let name = Some(jsid_to_str(cx, id));\n" +
                        "  let this = UnwrapProxy(proxy);\n" +
                        CGIndenter(CGProxyNamedGetter(self.descriptor, templateValues)).define() +
                        "}\n") % (self.descriptor.concreteType)
        else:
            getNamed = ""

        return """//MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
            //"Should not have a XrayWrapper here");

%s
let mut found = false;
if !GetPropertyOnPrototype(cx, proxy, id, &mut found, cast::transmute(vp)) {
  return 0;
}

if found {
  return 1;
}
%s
*vp = JSVAL_VOID;
return 1;""" % (getIndexedOrExpando, getNamed)

    def definition_body(self):
        return self.getBody()

class CGDOMJSProxyHandler_obj_toString(CGAbstractExternMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('*JSObject', 'proxy')]
        CGAbstractExternMethod.__init__(self, descriptor, "obj_toString", "*JSString", args)
        self.descriptor = descriptor
    def getBody(self):
        stringifier = self.descriptor.operations['Stringifier']
        if stringifier:
            name = stringifier.identifier.name
            nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
            signature = stringifier.signatures()[0]
            returnType = signature[0]
            extendedAttributes = self.descriptor.getExtendedAttributes(stringifier)
            infallible = 'infallible' in extendedAttributes
            if not infallible:
                error = CGGeneric(
                    ('ThrowMethodFailedWithDetails(cx, rv, "%s", "toString");\n' +
                     "return NULL;") % self.descriptor.interface.identifier.name)
            else:
                error = None
            call = CGCallGenerator(error, [], "", returnType, extendedAttributes, self.descriptor, nativeName, False, object="UnwrapProxy(proxy)")
            return call.define() + """

JSString* jsresult;
return xpc_qsStringToJsstring(cx, result, &jsresult) ? jsresult : NULL;""" 

        return """    do "%s".to_c_str().with_ref |s| {
      _obj_toString(cx, s)
    }""" % self.descriptor.name

    def definition_body(self):
        return self.getBody()

class CGAbstractClassHook(CGAbstractExternMethod):
    """
    Meant for implementing JSClass hooks, like Finalize or Trace. Does very raw
    'this' unwrapping as it assumes that the unwrapped type is always known.
    """
    def __init__(self, descriptor, name, returnType, args):
        CGAbstractExternMethod.__init__(self, descriptor, name, returnType,
                                        args)

    def definition_body_prologue(self):
        return """
  let this: *%s = &(*unwrap::<*Box<%s>>(obj)).data;
""" % (self.descriptor.concreteType, self.descriptor.concreteType)

    def definition_body(self):
        return self.definition_body_prologue() + self.generate_code()

    def generate_code(self):
        # Override me
        assert(False)

def finalizeHook(descriptor, hookName, context):
    if descriptor.customFinalize:
        return """if (this) {
  this->%s(%s);
}""" % (hookName, context)
    #clearWrapper = "ClearWrapper(self, self);\n" if descriptor.wrapperCache else ""
    if descriptor.workers:
        #release = "self->Release();"
        pass
    else:
        assert descriptor.nativeIsISupports
        release = """let val = JS_GetReservedSlot(obj, dom_object_slot(obj));
let _: @mut %s = cast::transmute(RUST_JSVAL_TO_PRIVATE(val));
debug!("%s finalize: {:p}", this);
""" % (descriptor.concreteType, descriptor.concreteType)
    #return clearWrapper + release
    return release

class CGClassTraceHook(CGAbstractClassHook):
    """
    A hook to trace through our native object; used for GC and CC
    """
    def __init__(self, descriptor):
        args = [Argument('*mut JSTracer', 'trc'), Argument('*JSObject', 'obj')]
        CGAbstractClassHook.__init__(self, descriptor, TRACE_HOOK_NAME, 'void',
                                     args)

    def generate_code(self):
        return "  (*this).trace(%s);" % self.args[0].name

class CGClassConstructHook(CGAbstractExternMethod):
    """
    JS-visible constructor for our objects
    """
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('u32', 'argc'), Argument('*mut JSVal', 'vp')]
        CGAbstractExternMethod.__init__(self, descriptor, CONSTRUCT_HOOK_NAME,
                                        'JSBool', args)
        self._ctor = self.descriptor.interface.ctor()

    def define(self):
        if not self._ctor:
            return ""
        return CGAbstractExternMethod.define(self)

    def definition_body(self):
        return self.generate_code()

    def generate_code(self):
        preamble = """
  //JSObject* obj = JS_GetGlobalForObject(cx, JSVAL_TO_OBJECT(JS_CALLEE(cx, vp)));
"""
        if self.descriptor.workers:
            preArgs = ["cx", "obj"]
        else:
            preamble += """
  //XXXjdm Gecko obtains a GlobalObject from the global (maybe from the private value,
  //       or through unwrapping a slot or something). We'll punt and get the Window
  //       from the context for now. 
  let page = page_from_context(cx);
  let global = (*page).frame.get_ref().window;
  let obj = global.reflector().get_jsobject();
"""
            preArgs = ["global"]

        name = self._ctor.identifier.name
        nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
        callGenerator = CGMethodCall(preArgs, nativeName, True,
                                     self.descriptor, self._ctor)
        return preamble + callGenerator.define();

class CGClassHasInstanceHook(CGAbstractStaticMethod):
    def __init__(self, descriptor):
        args = [Argument('*JSContext', 'cx'), Argument('JSHandleObject', 'obj'),
                Argument('JSMutableHandleValue', 'vp'), Argument('*JSBool', 'bp')]
        CGAbstractStaticMethod.__init__(self, descriptor, HASINSTANCE_HOOK_NAME,
                                        'JSBool', args)

    def define(self):
        if not self.descriptor.hasInstanceInterface:
            return ""
        return CGAbstractStaticMethod.define(self)

    def definition_body(self):
        return self.generate_code()

    def generate_code(self):
        return """  if (!vp.isObject()) {
    *bp = 0;
    return 1;
  }

  jsval protov;
  if (!JS_GetProperty(cx, obj, "prototype", &protov))
    return false;
  if (!protov.isObject()) {
    JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_BAD_PROTOTYPE,
                         "%s");
    return false;
  }
  JSObject *objProto = &protov.toObject();

  JSObject* instance = &vp.toObject();
  JSObject* proto;
  if (!JS_GetPrototype(cx, instance, &proto))
    return false;
  while (proto) {
    if (proto == objProto) {
      *bp = true;
      return true;
    }
    if (!JS_GetPrototype(cx, proto, &proto))
      return false;
  }

  nsISupports* native =
    nsContentUtils::XPConnect()->GetNativeOfWrapper(cx, instance);
  nsCOMPtr<%s> qiResult = do_QueryInterface(native);
  *bp = !!qiResult;
  return true;
""" % (self.descriptor.name, self.descriptor.hasInstanceInterface)

class CGClassFinalizeHook(CGAbstractClassHook):
    """
    A hook for finalize, used to release our native object.
    """
    def __init__(self, descriptor):
        args = [Argument('*JSFreeOp', 'fop'), Argument('*JSObject', 'obj')]
        CGAbstractClassHook.__init__(self, descriptor, FINALIZE_HOOK_NAME,
                                     'void', args)

    def generate_code(self):
        return CGIndenter(CGGeneric(finalizeHook(self.descriptor, self.name, self.args[0].name))).define()

class CGDOMJSProxyHandlerDOMClass(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        #return "extern const DOMClass Class;\n"
        return ""
    def define(self):
        return """
static Class: DOMClass = """ + DOMClass(self.descriptor) + """;

"""

class CGDescriptor(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)

        assert not descriptor.concrete or descriptor.interface.hasInterfacePrototypeObject()

        cgThings = []
        if descriptor.interface.hasInterfacePrototypeObject():
            (hasMethod, hasGetter, hasLenientGetter,
             hasSetter, hasLenientSetter) = False, False, False, False, False
            for m in descriptor.interface.members:
                if m.isMethod() and not m.isStatic() and not m.isIdentifierLess():
                    cgThings.append(CGSpecializedMethod(descriptor, m))
                    cgThings.append(CGMemberJITInfo(descriptor, m))
                    hasMethod = True
                elif m.isAttr():
                    cgThings.append(CGSpecializedGetter(descriptor, m))
                    if m.hasLenientThis():
                        hasLenientGetter = True
                    else:
                        hasGetter = True
                    if not m.readonly:
                        cgThings.append(CGSpecializedSetter(descriptor, m))
                        if m.hasLenientThis():
                            hasLenientSetter = True
                        else:
                            hasSetter = True
                    cgThings.append(CGMemberJITInfo(descriptor, m))
            if hasMethod: cgThings.append(CGGenericMethod(descriptor))
            if hasGetter: cgThings.append(CGGenericGetter(descriptor))
            #if hasLenientGetter: cgThings.append(CGGenericGetter(descriptor,
            #                                                     lenientThis=True))
            if hasSetter: cgThings.append(CGGenericSetter(descriptor))
            #if hasLenientSetter: cgThings.append(CGGenericSetter(descriptor,
            #                                                     lenientThis=True))

        if descriptor.concrete:
            if not descriptor.workers and descriptor.wrapperCache:
                #cgThings.append(CGAddPropertyHook(descriptor))
                pass

            # Always have a finalize hook, regardless of whether the class wants a
            # custom hook.
            cgThings.append(CGClassFinalizeHook(descriptor))

            # Only generate a trace hook if the class wants a custom hook.
            if (descriptor.customTrace):
                cgThings.append(CGClassTraceHook(descriptor))

        if descriptor.interface.hasInterfaceObject():
            cgThings.append(CGClassConstructHook(descriptor))
            cgThings.append(CGClassHasInstanceHook(descriptor))
            cgThings.append(CGInterfaceObjectJSClass(descriptor))
            pass

        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGPrototypeJSClass(descriptor))
            pass

        properties = PropertyArrays(descriptor)
        cgThings.append(CGGeneric(define=str(properties)))
        cgThings.append(CGCreateInterfaceObjectsMethod(descriptor, properties))
        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGGetProtoObjectMethod(descriptor))
            pass
        else:
            cgThings.append(CGGetConstructorObjectMethod(descriptor))
            pass

        # Set up our Xray callbacks as needed.  Note that we don't need to do
        # it in workers.
        if (descriptor.interface.hasInterfacePrototypeObject() and
            not descriptor.workers):
            if descriptor.concrete and descriptor.proxy:
                #cgThings.append(CGResolveOwnProperty(descriptor))
                #cgThings.append(CGEnumerateOwnProperties(descriptor))
                pass
            cgThings.append(CGResolveProperty(descriptor, properties))
            #cgThings.append(CGEnumerateProperties(descriptor, properties))

        if descriptor.interface.hasInterfaceObject():
            cgThings.append(CGDefineDOMInterfaceMethod(descriptor))
            if (not descriptor.interface.isExternal() and
                # Workers stuff is never pref-controlled
                not descriptor.workers and
                descriptor.interface.getExtendedAttribute("PrefControlled") is not None):
                #cgThings.append(CGPrefEnabled(descriptor))
                pass

        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGNativePropertyHooks(descriptor))
            pass

        if descriptor.concrete:
            if descriptor.proxy:
                #cgThings.append(CGProxyIsProxy(descriptor))
                cgThings.append(CGProxyUnwrap(descriptor))
                cgThings.append(CGDOMJSProxyHandlerDOMClass(descriptor))
                cgThings.append(CGDOMJSProxyHandler_getOwnPropertyDescriptor(descriptor))
                cgThings.append(CGDOMJSProxyHandler_obj_toString(descriptor))
                cgThings.append(CGDOMJSProxyHandler_get(descriptor))
                cgThings.append(CGDOMJSProxyHandler_hasOwn(descriptor))
                if descriptor.operations['IndexedSetter'] or descriptor.operations['NamedSetter']:
                    cgThings.append(CGDOMJSProxyHandler_defineProperty(descriptor))

                #cgThings.append(CGDOMJSProxyHandler(descriptor))
                #cgThings.append(CGIsMethod(descriptor))
                pass
            else:
                cgThings.append(CGDOMJSClass(descriptor))
                pass

            if descriptor.wrapperCache:
                cgThings.append(CGWrapWithCacheMethod(descriptor))
                cgThings.append(CGWrapMethod(descriptor))
                pass
            else:
                cgThings.append(CGWrapNonWrapperCacheMethod(descriptor))
                pass

        cgThings = CGList((CGIndenter(t, declareOnly=True) for t in cgThings), "\n")
        cgThings = CGWrapper(cgThings, pre='\n', post='\n')
        #self.cgRoot = CGWrapper(CGNamespace(toBindingNamespace(descriptor.name),
        #                                    cgThings),
        #                        post='\n')
        self.cgRoot = cgThings

    def declare(self):
        return self.cgRoot.declare()
    def define(self):
        return self.cgRoot.define()

class CGNamespacedEnum(CGThing):
    def __init__(self, namespace, enumName, names, values, comment="", deriving=""):

        if not values:
            values = []

        # Account for explicit enum values.
        entries = []
        for i in range(0, len(names)):
            if len(values) > i and values[i] is not None:
                entry = "%s = %s" % (names[i], values[i])
            else:
                entry = names[i]
            entries.append(entry)

        # Append a Count.
        entries.append('_' + enumName + '_Count = ' + str(len(entries)))

        # Indent.
        entries = ['  ' + e for e in entries]

        # Build the enum body.
        enumstr = comment + 'pub enum %s {\n%s\n}\n' % (enumName, ',\n'.join(entries))
        if deriving:
            enumstr = ('#[deriving(%s)]\n' % deriving) + enumstr
        curr = CGGeneric(enumstr)

        # Add some whitespace padding.
        curr = CGWrapper(curr, pre='\n',post='\n')

        # Add the namespace.
        curr = CGNamespace(namespace, curr, public=True)

        # Add the typedef
        #typedef = '\ntypedef %s::%s %s;\n\n' % (namespace, enumName, enumName)
        #curr = CGList([curr, CGGeneric(typedef)])

        # Save the result.
        self.node = curr

    def declare(self):
        return self.node.declare()
    def define(self):
        return self.node.define()

class CGDictionary(CGThing):
    def __init__(self, dictionary, descriptorProvider):
        self.dictionary = dictionary;
        self.workers = descriptorProvider.workers
        if all(CGDictionary(d, descriptorProvider).generatable for
               d in CGDictionary.getDictionaryDependencies(dictionary)):
            self.generatable = True
        else:
            self.generatable = False
            # Nothing else to do here
            return
        # Getting a conversion template for interface types can fail
        # if we don't have a relevant descriptor when self.workers is True.
        # If that happens, just mark ourselves as not being
        # generatable and move on.
        try:
            self.memberInfo = [
                (member,
                 getJSToNativeConversionTemplate(member.type,
                                                 descriptorProvider,
                                                 isMember=True,
                                                 isOptional=(not member.defaultValue),
                                                 defaultValue=member.defaultValue))
                for member in dictionary.members ]
        except NoSuchDescriptorError, err:
            if not self.workers:
                raise err
            self.generatable = False

    def declare(self):
        if not self.generatable:
            return ""
        d = self.dictionary
        if d.parent:
            inheritance = "  parent: %s::%s,\n" % (self.makeModuleName(d.parent),
                                                   self.makeClassName(d.parent))
        else:
            inheritance = ""
        memberDecls = ["  %s: %s," %
                       (m[0].identifier.name, self.getMemberType(m))
                       for m in self.memberInfo]

        return (string.Template(
                "pub struct ${selfName} {\n" +
                "${inheritance}" +
                "\n".join(memberDecls) + "\n" +
                # NOTE: jsids are per-runtime, so don't use them in workers
                "\n".join("  //static jsid " +
                          self.makeIdName(m.identifier.name) + ";" for
                          m in d.members) + "\n"
                "}").substitute( { "selfName": self.makeClassName(d),
                                    "inheritance": inheritance }))

    def define(self):
        if not self.generatable:
            return ""
        d = self.dictionary
        if d.parent:
            initParent = ("// Per spec, we init the parent's members first\n"
                          "if self.parent.Init(cx, val) == 0 {\n"
                          "  return 0;\n"
                          "}\n")
        else:
            initParent = ""

        memberInits = [CGIndenter(self.getMemberConversion(m), indentLevel=6).define()
                       for m in self.memberInfo]
        idinit = [CGGeneric('!InternJSString(cx, %s, "%s")' %
                            (m.identifier.name + "_id", m.identifier.name))
                  for m in d.members]
        idinit = CGList(idinit, " ||\n")
        idinit = CGWrapper(idinit, pre="if (",
                           post=(") {\n"
                                 "  return false;\n"
                                 "}"),
                           reindent=True)

        def defaultValue(ty):
            if ty is "bool":
                return "false"
            elif ty in ["i32", "u32", "i16", "u16"]:
                return "0"
            elif ty is "nsString":
                return "\"\""
            elif ty.startswith("Option"):
                return "None"
            else:
                return "/* uh oh: %s */" % ty

        return string.Template(
            # NOTE: jsids are per-runtime, so don't use them in workers
            ("static initedIds: bool = false;\n" +
             "\n".join("static %s: jsid = JSID_VOID;" %
                       self.makeIdName(m.identifier.name)
                       for m in d.members) + "\n"
             "\n"
             "impl ${selfName} {\n"
             "  pub fn new() -> ${selfName} {\n"
             "    ${selfName} {\n" +
             (("      parent: %s::%s::new(),\n" % (self.makeModuleName(d.parent),
                                                   self.makeClassName(d.parent))) if d.parent else "") +
             "\n".join("      %s: %s," % (m[0].identifier.name, defaultValue(self.getMemberType(m))) for m in self.memberInfo) + "\n"
             "    }\n"
             "  }\n"
             "\n"
             "  pub fn InitIds(&mut self, cx: *JSContext) -> bool {\n"
             "    //MOZ_ASSERT(!initedIds);\n"
             "  /*${idInit}\n"
             "    initedIds = true;*/ //XXXjdm\n"
             "    return true;\n"
             "  }\n"
             "\n" if not self.workers else "") +
            "  #[fixed_stack_segment]\n" +
            "  pub fn Init(&mut self, cx: *JSContext, val: JSVal) -> JSBool {\n"
            "    unsafe {\n" +
            # NOTE: jsids are per-runtime, so don't use them in workers
            ("      if (!initedIds && !self.InitIds(cx)) {\n"
             "        return 0;\n"
             "      }\n" if not self.workers else "") +
            "${initParent}"
            "      let mut found: JSBool = 0;\n"
            "      let temp: JSVal = JSVAL_NULL;\n"
            "      let isNull = RUST_JSVAL_IS_NULL(val) != 0 || RUST_JSVAL_IS_VOID(val) != 0;\n"
            "      if !isNull && RUST_JSVAL_IS_PRIMITIVE(val) != 0 {\n"
            "        return 0; //XXXjdm throw properly here\n"
            "        //return Throw<${isMainThread}>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);\n"
            "      }\n"
            "\n"
            "${initMembers}\n"
            "      return 1;\n"
            "    }\n"
            "  }\n"
            "}").substitute({
                "selfName": self.makeClassName(d),
                "initParent": CGIndenter(CGGeneric(initParent), indentLevel=6).define(),
                "initMembers": "\n\n".join(memberInits),
                "idInit": CGIndenter(idinit).define(),
                "isMainThread": toStringBool(not self.workers)
                })

    @staticmethod
    def makeDictionaryName(dictionary, workers):
        suffix = "Workers" if workers else ""
        return dictionary.identifier.name + suffix

    def makeClassName(self, dictionary):
        return self.makeDictionaryName(dictionary, self.workers)

    @staticmethod
    def makeModuleName(dictionary):
        name = dictionary.identifier.name
        if name.endswith('Init'):
            return toBindingNamespace(name.replace('Init', ''))
        #XXXjdm This breaks on the test webidl files, sigh.
        #raise TypeError("No idea how to find this dictionary's definition: " + name)
        return "/* uh oh */ %s" % name

    def getMemberType(self, memberInfo):
        (member, (templateBody, declType,
                  holderType, dealWithOptional, initialValue)) = memberInfo
        # We can't handle having a holderType here
        assert holderType is None
        if dealWithOptional:
            declType = CGWrapper(declType, pre="Optional< ", post=" >")
        return declType.define()

    def getMemberConversion(self, memberInfo):
        (member, (templateBody, declType,
                  holderType, dealWithOptional, initialValue)) = memberInfo
        replacements = { "val": "temp",
                         "valPtr": "&temp",
                         "declName": ("self.%s" % member.identifier.name),
                         # We need a holder name for external interfaces, but
                         # it's scoped down to the conversion so we can just use
                         # anything we want.
                         "holderName": "holder"}
        # We can't handle having a holderType here
        assert holderType is None
        if dealWithOptional:
            replacements["declName"] = "(" + replacements["declName"] + ".Value())"
        if member.defaultValue:
            replacements["haveValue"] = "found != 0"

        # NOTE: jsids are per-runtime, so don't use them in workers
        if True or self.workers: #XXXjdm hack until 'static mut' exists for global jsids
            propName = member.identifier.name
            propCheck = ('"%s".to_c_str().with_ref(|s| { JS_HasProperty(cx, RUST_JSVAL_TO_OBJECT(val), s, ptr::to_unsafe_ptr(&found)) })' %
                         propName)
            propGet = ('"%s".to_c_str().with_ref(|s| { JS_GetProperty(cx, RUST_JSVAL_TO_OBJECT(val), s, ptr::to_unsafe_ptr(&temp)) })' %
                       propName)
        else:
            propId = self.makeIdName(member.identifier.name);
            propCheck = ("JS_HasPropertyById(cx, RUST_JSVAL_TO_OBJECT(val), %s, ptr::to_unsafe_ptr(&found))" %
                         propId)
            propGet = ("JS_GetPropertyById(cx, RUST_JSVAL_TO_OBJECT(val), %s, ptr::to_unsafe_ptr(&temp))" %
                       propId)

        conversionReplacements = {
            "prop": "(this->%s)" % member.identifier.name,
            "convert": string.Template(templateBody).substitute(replacements),
            "propCheck": propCheck,
            "propGet": propGet
            }
        conversion = ("if isNull {\n"
                      "  found = 0;\n"
                      "} else if ${propCheck} == 0 {\n"
                      "  return 0;\n"
                      "}\n")
        if member.defaultValue:
            conversion += (
                "if found != 0 {\n"
                "  if ${propGet} == 0 {\n"
                "    return 0;\n"
                "  }\n"
                "}\n"
                "${convert}")
        else:
            conversion += (
                "if found != 0 {\n"
                "  ${prop}.Construct();\n"
                "  if ${propGet} == 0 {\n"
                "    return 0;\n"
                "  }\n"
                "${convert}\n"
                "}")
            conversionReplacements["convert"] = CGIndenter(
                CGGeneric(conversionReplacements["convert"])).define()
        
        return CGGeneric(
            string.Template(conversion).substitute(conversionReplacements)
            )

    @staticmethod
    def makeIdName(name):
        return name + "_id"

    @staticmethod
    def getDictionaryDependencies(dictionary):
        deps = set();
        if dictionary.parent:
            deps.add(dictionary.parent)
        for member in dictionary.members:
            if member.type.isDictionary():
                deps.add(member.type.unroll().inner)
        return deps

class CGRegisterProtos(CGAbstractMethod):
    def __init__(self, config):
        CGAbstractMethod.__init__(self, None, 'Register', 'void',
                                  [Argument('@mut Compartment', 'compartment')],
                                  unsafe=False, pub=True)
        self.config = config

    def _registerProtos(self):
        lines = ["  assert!(codegen::%sBinding::DefineDOMInterface(\n"
                 "      compartment.cx.ptr,\n"
                 "      compartment.global_obj.ptr,\n"
                 "      &mut unused));" % (desc.name)
                 for desc in self.config.getDescriptors(hasInterfaceObject=True,
                                                        isExternal=False,
                                                        workers=False,
                                                        register=True)]
        return '\n'.join(lines) + '\n'
    def definition_body(self):
        return "  let mut unused = false;\n" + self._registerProtos()

class CGBindingRoot(CGThing):
    """
    Root codegen class for binding generation. Instantiate the class, and call
    declare or define to generate header or cpp code (respectively).
    """
    def __init__(self, config, prefix, webIDLFile):
        descriptors = config.getDescriptors(webIDLFile=webIDLFile,
                                            hasInterfaceOrInterfacePrototypeObject=True)
        dictionaries = config.getDictionaries(webIDLFile=webIDLFile)

        cgthings = []

        mainCallbacks = config.getCallbacks(webIDLFile=webIDLFile,
                                            workers=False)
        callbackDescriptors = config.getDescriptors(webIDLFile=webIDLFile,
                                                    isCallback=True)

        # Do codegen for all the enums
        def makeEnum(e):
            return CGNamespace.build([e.identifier.name + "Values"],
                                     CGList([CGGeneric("  use dom::bindings::utils::EnumEntry;"),
                                             CGEnum(e)]), public=True)
        def makeEnumTypedef(e):
            return CGGeneric(declare=("pub type %s = self::%sValues::valuelist;\n" %
                                      (e.identifier.name, e.identifier.name)))
        cgthings = [ fun(e) for e in config.getEnums(webIDLFile)
                     for fun in [makeEnum, makeEnumTypedef] ]

        # Do codegen for all the dictionaries.  We have to be a bit careful
        # here, because we have to generate these in order from least derived
        # to most derived so that class inheritance works out.  We also have to
        # generate members before the dictionary that contains them.
        #
        # XXXbz this will fail if we have two webidl files A and B such that A
        # declares a dictionary which inherits from a dictionary in B and B
        # declares a dictionary (possibly a different one!) that inherits from a
        # dictionary in A.  The good news is that I expect this to never happen.
        reSortedDictionaries = []
        dictionaries = set(dictionaries)
        while len(dictionaries) != 0:
            # Find the dictionaries that don't depend on anything else anymore
            # and move them over.
            toMove = [d for d in dictionaries if
                      len(CGDictionary.getDictionaryDependencies(d) &
                          dictionaries) == 0]
            if len(toMove) == 0:
                raise TypeError("Loop in dictionary dependency graph")
            dictionaries = dictionaries - set(toMove)
            reSortedDictionaries.extend(toMove)

        dictionaries = reSortedDictionaries
        #XXXjdm No codegen for workers right now.
        #cgthings.extend([CGDictionary(d, config.getDescriptorProvider(True))
        #                 for d in dictionaries])
        cgthings.extend([CGDictionary(d, config.getDescriptorProvider(False))
                         for d in dictionaries])

        # Do codegen for all the callbacks.
        cgthings.extend(CGCallbackFunction(c, config.getDescriptorProvider(False))
                        for c in mainCallbacks)

        # Do codegen for all the descriptors
        cgthings.extend([CGDescriptor(x) for x in descriptors])

        # Do codegen for all the callback interfaces.  Skip worker callbacks.
        cgthings.extend([CGCallbackInterface(x) for x in callbackDescriptors if
                         not x.workers])

        # And make sure we have the right number of newlines at the end
        curr = CGWrapper(CGList(cgthings, "\n\n"), post="\n\n")

        # Wrap all of that in our namespaces.
        #curr = CGNamespace.build(['dom'],
        #                         CGWrapper(curr, pre="\n"))

        # Add imports
        #XXXjdm This should only import the namespace for the current binding,
        #       not every binding ever.
        curr = CGImports(descriptors,
                         dictionaries,
                         ['js::*',
                          'js::jsapi::*',
                          'js::jsfriendapi::bindgen::*',
                          'js::glue::*',
                          'dom::types::*',
                          'dom::bindings::utils::*',
                          'dom::bindings::callback::*',
                          'dom::bindings::conversions::*',
                          'dom::bindings::codegen::*', #XXXjdm
                          'script_task::{JSPageInfo, page_from_context}',
                          'dom::bindings::proxyhandler',
                          'dom::bindings::proxyhandler::*',
                          'dom::document::AbstractDocument',
                          'dom::node::{AbstractNode, ScriptView}',
                          'dom::eventtarget::AbstractEventTarget',
                          'dom::event::AbstractEvent',
                          'servo_util::vec::zip_copies',
                          'std::cast',
                          'std::libc',
                          'std::ptr',
                          'std::vec',
                          'std::str',
                          'std::num',
                          'std::unstable::raw::Box',
                         ], 
                         [],
                         curr)

        # Add the auto-generated comment.
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)

        # Store the final result.
        self.root = curr
    def declare(self):
        return stripTrailingWhitespace(self.root.declare())
    def define(self):
        return stripTrailingWhitespace(self.root.define())

class CGNativeMember(ClassMethod):
    def __init__(self, descriptorProvider, member, name, signature, extendedAttrs,
                 breakAfter=True, passJSBitsAsNeeded=True, visibility="public",
                 jsObjectsArePtr=False, variadicIsSequence=False):
        """
        If jsObjectsArePtr is true, typed arrays and "object" will be
        passed as JSObject*.

        If passJSBitsAsNeeded is false, we don't automatically pass in a
        JSContext* or a JSObject* based on the return and argument types.  We
        can still pass it based on 'implicitJSContext' annotations.
        """
        self.descriptorProvider = descriptorProvider
        self.member = member
        self.extendedAttrs = extendedAttrs
        self.resultAlreadyAddRefed = isResultAlreadyAddRefed(self.extendedAttrs)
        self.passJSBitsAsNeeded = passJSBitsAsNeeded
        self.jsObjectsArePtr = jsObjectsArePtr
        self.variadicIsSequence = variadicIsSequence
        breakAfterSelf = "\n" if breakAfter else ""
        ClassMethod.__init__(self, name,
                             self.getReturnType(signature[0], False),
                             self.getArgs(signature[0], signature[1]),
                             static=member.isStatic(),
                             # Mark our getters, which are attrs that
                             # have a non-void return type, as const.
                             const=(not member.isStatic() and member.isAttr() and
                                    not signature[0].isVoid()),
                             breakAfterReturnDecl=" ",
                             breakAfterSelf=breakAfterSelf,
                             visibility=visibility)

    def getReturnType(self, type, isMember):
        return self.getRetvalInfo(type, isMember)[0]

    def getRetvalInfo(self, type, isMember):
        """
        Returns a tuple:

        The first element is the type declaration for the retval

        The second element is a default value that can be used on error returns.
        For cases whose behavior depends on isMember, the second element will be
        None if isMember is true.

        The third element is a template for actually returning a value stored in
        "${declName}" and "${holderName}".  This means actually returning it if
        we're not outparam, else assigning to the "retval" outparam.  If
        isMember is true, this can be None, since in that case the caller will
        never examine this value.
        """
        if type.isVoid():
            typeDecl, errorDefault, template = "", "", ""
        elif type.isPrimitive() and type.tag() in builtinNames:
            result = CGGeneric(builtinNames[type.tag()])
            defaultReturnArg = "0"
            if type.nullable():
                result = CGTemplatedType("Nullable", result)
                defaultReturnArg = ""
            typeDecl, errorDefault, template = \
                (result.define(),
                 "%s(%s)" % (result.define(), defaultReturnArg),
                 "return ${declName};")
        elif type.isDOMString():
            if isMember:
                # No need for a third element in the isMember case
                typeDecl, errorDefault, template = "nsString", None, None
            # Outparam
            else:
                typeDecl, errorDefault, template = "void", "", "retval = ${declName};"
        elif type.isByteString():
            if isMember:
                # No need for a third element in the isMember case
                typeDecl, errorDefault, template = "nsCString", None, None
            # Outparam
            typeDecl, errorDefault, template = "void", "", "retval = ${declName};"
        elif type.isEnum():
            enumName = type.unroll().inner.identifier.name
            if type.nullable():
                enumName = CGTemplatedType("Nullable",
                                           CGGeneric(enumName)).define()
                defaultValue = "%s()" % enumName
            else:
                defaultValue = "%s(0)" % enumName
            typeDecl, errorDefault, template = enumName, defaultValue, "return ${declName};"
        elif type.isGeckoInterface():
            iface = type.unroll().inner;
            nativeType = self.descriptorProvider.getDescriptor(
                iface.identifier.name).nativeType
            # Now trim off unnecessary namespaces
            nativeType = nativeType.split("::")
            if nativeType[0] == "mozilla":
                nativeType.pop(0)
                if nativeType[0] == "dom":
                    nativeType.pop(0)
            result = CGGeneric("::".join(nativeType))
            if self.resultAlreadyAddRefed:
                if isMember:
                    holder = "nsRefPtr"
                else:
                    holder = "already_AddRefed"
                if memberReturnsNewObject(self.member):
                    warning = ""
                else:
                    warning = "// Mark this as resultNotAddRefed to return raw pointers\n"
                result = CGWrapper(result,
                                   pre=("%s%s<" % (warning, holder)),
                                   post=">")
            else:
                result = CGWrapper(result, post="*")
            # Since we always force an owning type for callback return values,
            # our ${declName} is an OwningNonNull or nsRefPtr.  So we can just
            # .forget() to get our already_AddRefed.
            typeDecl, errorDefault, template = \
                result.define(), "nullptr", "return ${declName}.forget();"
        elif type.isCallback():
            typeDecl, errorDefault, template = \
                ("already_AddRefed<%s>" % type.unroll().identifier.name,
                 "nullptr", "return ${declName}.forget();")
        elif type.isAny():
            typeDecl, errorDefault, template = \
                "JS::Value", "JS::UndefinedValue()", "return ${declName};"
        elif type.isObject():
            typeDecl, errorDefault, template = \
                "JSObject*", "nullptr", "return ${declName};"
        elif type.isSpiderMonkeyInterface():
            if type.nullable():
                returnCode = "return ${declName}.IsNull() ? nullptr : ${declName}.Value().Obj();"
            else:
                returnCode = "return ${declName}.Obj();"
            typeDecl, errorDefault, template = "JSObject*", "nullptr", returnCode
        elif type.isSequence():
            # If we want to handle sequence-of-sequences return values, we're
            # going to need to fix example codegen to not produce nsTArray<void>
            # for the relevant argument...
            assert not isMember
            # Outparam.
            if type.nullable():
                returnCode = ("if (${declName}.IsNull()) {\n"
                              "  retval.SetNull();\n"
                              "} else {\n"
                              "  retval.SetValue().SwapElements(${declName}.Value());\n"
                              "}")
            else:
                returnCode = "retval.SwapElements(${declName});"
            typeDecl, errorDefault, template = "void", "", returnCode
        elif type.isDate():
            result = CGGeneric("Date")
            if type.nullable():
                result = CGTemplatedType("Nullable", result)
            typeDecl, errorDefault, template = \
                (result.define(), "%s()" % result.define(), "return ${declName};")
        else:
            raise TypeError("Don't know how to declare return value for %s" % type)

        if not 'infallible' in self.extendedAttrs:
            if typeDecl:
                typeDecl = "Fallible<%s>" % typeDecl
            else:
                typeDecl = "ErrorResult"
            if not errorDefault:
                errorDefault = "Err(FailureUnknown)"
            if not template:
                template = "return Ok(());"
        return typeDecl, errorDefault, template

    def getArgs(self, returnType, argList):
        args = [self.getArg(arg) for arg in argList]
        # Now the outparams
        if returnType.isDOMString():
            args.append(Argument("nsString&", "retval"))
        if returnType.isByteString():
            args.append(Argument("nsCString&", "retval"))
        elif returnType.isSequence():
            nullable = returnType.nullable()
            if nullable:
                returnType = returnType.inner
            # And now the actual underlying type
            elementDecl = self.getReturnType(returnType.inner, True)
            type = CGTemplatedType("nsTArray", CGGeneric(elementDecl))
            if nullable:
                type = CGTemplatedType("Nullable", type)
            args.append(Argument("%s&" % type.define(), "retval"))
        # The legacycaller thisval
        if self.member.isMethod() and self.member.isLegacycaller():
            # If it has an identifier, we can't deal with it yet
            assert self.member.isIdentifierLess()
            args.insert(0, Argument("JS::Value", "aThisVal"))
        # And jscontext bits.
        if needCx(returnType, argList, self.extendedAttrs,
                  self.passJSBitsAsNeeded):
            args.insert(0, Argument("JSContext*", "cx"))
            if needScopeObject(returnType, argList, self.extendedAttrs,
                               self.descriptorProvider,
                               self.passJSBitsAsNeeded):
                args.insert(1, Argument("JS::Handle<JSObject*>", "obj"))
        # And if we're static, a global
        if self.member.isStatic():
            args.insert(0, Argument("const GlobalObject&", "global"))
        return args

    def doGetArgType(self, type, optional, isMember):
        """
        The main work of getArgType.  Returns a string type decl, whether this
        is a const ref, as well as whether the type should be wrapped in
        Nullable as needed.

        isMember can be false or one of the strings "Sequence" or "Variadic"
        """
        if type.isArray():
            raise TypeError("Can't handle array arguments yet")

        if type.isSequence():
            nullable = type.nullable()
            if nullable:
                type = type.inner
            elementType = type.inner
            argType = self.getArgType(elementType, False, "Sequence")[0]
            decl = CGTemplatedType("Sequence", argType)
            return decl.define(), True, True

        if type.isUnion():
            if type.nullable():
                type = type.inner
            return str(type), True, True

        if type.isGeckoInterface() and not type.isCallbackInterface():
            iface = type.unroll().inner
            argIsPointer = type.nullable() or iface.isExternal()
            forceOwningType = iface.isCallback() or isMember
            if argIsPointer:
                if (optional or isMember) and forceOwningType:
                    typeDecl = "nsRefPtr<%s>"
                else:
                    typeDecl = "*%s"
            else:
                if optional or isMember:
                    if forceOwningType:
                        typeDecl = "OwningNonNull<%s>"
                    else:
                        typeDecl = "NonNull<%s>"
                else:
                    typeDecl = "%s%s"
            descriptor = self.descriptorProvider.getDescriptor(iface.identifier.name)
            return (typeDecl % (descriptor.pointerType, descriptor.nativeType),
                    False, False)

        if type.isSpiderMonkeyInterface():
            if self.jsObjectsArePtr:
                return "JSObject*", False, False

            return type.name, True, True

        if type.isDOMString():
            if isMember:
                declType = "nsString"
            else:
                declType = "nsAString"
            return declType, True, False

        if type.isByteString():
            declType = "nsCString"
            return declType, True, False

        if type.isEnum():
            return type.unroll().inner.identifier.name, False, True

        if type.isCallback() or type.isCallbackInterface():
            forceOwningType = optional or isMember
            if type.nullable():
                if forceOwningType:
                    declType = "nsRefPtr<%s>"
                else:
                    declType = "%s*"
            else:
                if forceOwningType:
                    declType = "OwningNonNull<%s>"
                else:
                    declType = "%s&"
            if type.isCallback():
                name = type.unroll().identifier.name
            else:
                name = type.unroll().inner.identifier.name
            return declType % name, False, False

        if type.isAny():
            # Don't do the rooting stuff for variadics for now
            if isMember:
                declType = "JS::Value"
            else:
                declType = "JS::Handle<JS::Value>"
            return declType, False, False

        if type.isObject():
            if isMember:
                declType = "JSObject*"
            else:
                declType = "JS::Handle<JSObject*>"
            return declType, False, False

        if type.isDictionary():
            typeName = CGDictionary.makeDictionaryName(type.inner)
            return typeName, True, True

        if type.isDate():
            return "Date", False, True

        assert type.isPrimitive()

        return builtinNames[type.tag()], False, True

    def getArgType(self, type, optional, isMember):
        """
        Get the type of an argument declaration.  Returns the type CGThing, and
        whether this should be a const ref.

        isMember can be False, "Sequence", or "Variadic"
        """
        (decl, ref, handleNullable) = self.doGetArgType(type, optional,
                                                        isMember)
        decl = CGGeneric(decl)
        if handleNullable and type.nullable():
            decl = CGTemplatedType("Nullable", decl)
            ref = True
        if isMember == "Variadic":
            arrayType = "Sequence" if self.variadicIsSequence else "nsTArray"
            decl = CGTemplatedType(arrayType, decl)
            ref = True
        elif optional:
            # Note: All variadic args claim to be optional, but we can just use
            # empty arrays to represent them not being present.
            decl = CGTemplatedType("Optional", decl)
            ref = True
        return (decl, ref)

    def getArg(self, arg):
        """
        Get the full argument declaration for an argument
        """
        (decl, ref) = self.getArgType(arg.type,
                                      arg.optional and not arg.defaultValue,
                                      "Variadic" if arg.variadic else False)
        if ref:
            decl = CGWrapper(decl, pre="const ", post="&")

        return Argument(decl.define(), arg.identifier.name)

def isJSImplementedDescriptor(descriptorProvider):
    return (isinstance(descriptorProvider, Descriptor) and
            descriptorProvider.interface.isJSImplemented())

class CGCallback(CGClass):
    def __init__(self, idlObject, descriptorProvider, baseName, methods,
                 getters=[], setters=[]):
        self.baseName = baseName
        self._deps = idlObject.getDeps()
        name = idlObject.identifier.name
        if isJSImplementedDescriptor(descriptorProvider):
            name = jsImplName(name)
        # For our public methods that needThisHandling we want most of the
        # same args and the same return type as what CallbackMember
        # generates.  So we want to take advantage of all its
        # CGNativeMember infrastructure, but that infrastructure can't deal
        # with templates and most especially template arguments.  So just
        # cheat and have CallbackMember compute all those things for us.
        realMethods = []
        for method in methods:
            if not method.needThisHandling:
                realMethods.append(method)
            else:
                realMethods.extend(self.getMethodImpls(method))
        CGClass.__init__(self, name,
                         bases=[ClassBase(baseName)],
                         constructors=self.getConstructors(),
                         methods=realMethods+getters+setters,
                         decorators="#[deriving(Eq,Clone)]")

    def getConstructors(self):
        return [ClassConstructor(
            [Argument("*JSObject", "aCallback")],
            bodyInHeader=True,
            visibility="pub",
            explicit=False,
            baseConstructors=[
                "%s::new(aCallback)" % self.baseName
                ])]

    def getMethodImpls(self, method):
        assert method.needThisHandling
        args = list(method.args)
        # Strip out the JSContext*/JSObject* args
        # that got added.
        assert args[0].name == "cx" and args[0].argType == "*JSContext"
        assert args[1].name == "aThisObj" and args[1].argType == "*JSObject"
        args = args[2:]
        # Record the names of all the arguments, so we can use them when we call
        # the private method.
        argnames = [arg.name for arg in args]
        argnamesWithThis = ["s.GetContext()", "thisObjJS"] + argnames
        argnamesWithoutThis = ["s.GetContext()", "JSVAL_TO_OBJECT(JSVAL_NULL)"] + argnames
        # Now that we've recorded the argnames for our call to our private
        # method, insert our optional argument for deciding whether the
        # CallSetup should re-throw exceptions on aRv.
        args.append(Argument("ExceptionHandling", "aExceptionHandling",
                             "eReportExceptions"))

        # Ensure the first argument is mutable
        args[0] = Argument(args[0].argType, args[0].name, args[0].default, mutable=True)
        method.args[2] = args[0]

        # And now insert our template argument.
        argsWithoutThis = list(args)
        args.insert(0, Argument("@mut T",  "thisObj"))

        # And the self argument
        method.args.insert(0, Argument(None, "&self"))
        args.insert(0, Argument(None, "&self"))
        argsWithoutThis.insert(0, Argument(None, "&self"))

        setupCall = ("let s = CallSetup::new(cx_for_dom_object(&mut ${cxProvider}), aExceptionHandling);\n"
                     "if s.GetContext().is_null() {\n"
                     "  return${errorReturn};\n"
                     "}\n")

        bodyWithThis = string.Template(
            setupCall+
            "let thisObjJS = WrapCallThisObject(s.GetContext(), ptr::null() /*XXXjdm proper scope*/, thisObj);\n"
            "if thisObjJS.is_null() {\n"
            "  return${errorReturn};\n"
            "}\n"
            "return ${methodName}(${callArgs});").substitute({
                "errorReturn" : method.getDefaultRetval(),
                "callArgs" : ", ".join(argnamesWithThis),
                "methodName": 'self.' + method.name,
                "cxProvider": '*thisObj'
                })
        bodyWithoutThis = string.Template(
            setupCall +
            "return ${methodName}(${callArgs});").substitute({
                "errorReturn" : method.getDefaultRetval(),
                "callArgs" : ", ".join(argnamesWithoutThis),
                "methodName": 'self.' + method.name,
                "cxProvider": args[2].name #XXXjdm There's no guarantee that this is a DOM object
                })
        return [ClassMethod(method.name+'_', method.returnType, args,
                            bodyInHeader=True,
                            templateArgs=["T: 'static+CallbackContainer+Reflectable"],
                            body=bodyWithThis,
                            visibility='pub'),
                ClassMethod(method.name+'__', method.returnType, argsWithoutThis,
                            bodyInHeader=True,
                            body=bodyWithoutThis,
                            visibility='pub'),
                method]

    def deps(self):
        return self._deps

# We're always fallible
def callbackGetterName(attr):
    return "Get" + MakeNativeName(attr.identifier.name)

def callbackSetterName(attr):
    return "Set" + MakeNativeName(attr.identifier.name)

class CGCallbackFunction(CGCallback):
    def __init__(self, callback, descriptorProvider):
        CGCallback.__init__(self, callback, descriptorProvider,
                            "CallbackFunction",
                            methods=[CallCallback(callback, descriptorProvider)])

    def getConstructors(self):
        return CGCallback.getConstructors(self) + [
            ClassConstructor(
            [Argument("CallbackFunction*", "aOther")],
            bodyInHeader=True,
            visibility="pub",
            explicit=True,
            baseConstructors=[
                "CallbackFunction(aOther)"
                ])]

class CGCallbackInterface(CGCallback):
    def __init__(self, descriptor):
        iface = descriptor.interface
        attrs = [m for m in iface.members if m.isAttr() and not m.isStatic()]
        getters = [CallbackGetter(a, descriptor) for a in attrs]
        setters = [CallbackSetter(a, descriptor) for a in attrs
                   if not a.readonly]
        methods = [m for m in iface.members
                   if m.isMethod() and not m.isStatic() and not m.isIdentifierLess()]
        methods = [CallbackOperation(m, sig, descriptor) for m in methods
                   for sig in m.signatures()]
        if iface.isJSImplemented() and iface.ctor():
            sigs = descriptor.interface.ctor().signatures()
            if len(sigs) != 1:
                raise TypeError("We only handle one constructor.  See bug 869268.")
            methods.append(CGJSImplInitOperation(sigs[0], descriptor))
        CGCallback.__init__(self, iface, descriptor, "CallbackInterface",
                            methods, getters=getters, setters=setters)

class FakeMember():
    def __init__(self):
        self.treatNullAs = "Default"
    def isStatic(self):
        return False
    def isAttr(self):
        return False
    def isMethod(self):
        return False
    def getExtendedAttribute(self, name):
        # Claim to be a [NewObject] so we can avoid the "mark this
        # resultNotAddRefed" comments CGNativeMember codegen would
        # otherwise stick in.
        if name == "NewObject":
            return True
        return None

class CallbackMember(CGNativeMember):
    def __init__(self, sig, name, descriptorProvider, needThisHandling, rethrowContentException=False):
        """
        needThisHandling is True if we need to be able to accept a specified
        thisObj, False otherwise.
        """
        assert not rethrowContentException or not needThisHandling

        self.retvalType = sig[0]
        self.originalSig = sig
        args = sig[1]
        self.argCount = len(args)
        if self.argCount > 0:
            # Check for variadic arguments
            lastArg = args[self.argCount-1]
            if lastArg.variadic:
                self.argCountStr = (
                    "(%d - 1) + %s.Length()" % (self.argCount,
                                                lastArg.identifier.name))
            else:
                self.argCountStr = "%d" % self.argCount
        self.needThisHandling = needThisHandling
        # If needThisHandling, we generate ourselves as private and the caller
        # will handle generating public versions that handle the "this" stuff.
        visibility = "priv" if needThisHandling else "pub"
        self.rethrowContentException = rethrowContentException
        # We don't care, for callback codegen, whether our original member was
        # a method or attribute or whatnot.  Just always pass FakeMember()
        # here.
        CGNativeMember.__init__(self, descriptorProvider, FakeMember(),
                                name, (self.retvalType, args),
                                extendedAttrs={},
                                passJSBitsAsNeeded=False,
                                visibility=visibility,
                                jsObjectsArePtr=True)
        # We have to do all the generation of our body now, because
        # the caller relies on us throwing if we can't manage it.
        self.exceptionCode= "return Err(FailureUnknown);\n"
        self.body = self.getImpl()

    def getImpl(self):
        replacements = {
            "declRval": self.getRvalDecl(),
            "errorReturn" : self.getDefaultRetval(),
            "returnResult": self.getResultConversion(),
            "convertArgs": self.getArgConversions(),
            "doCall": self.getCall(),
            "setupCall": self.getCallSetup(),
            }
        if self.argCount > 0:
            replacements["argCount"] = self.argCountStr
            replacements["argvDecl"] = string.Template(
                "let mut argv = vec::from_elem(${argCount}, JSVAL_VOID);\n"
                ).substitute(replacements)
        else:
            # Avoid weird 0-sized arrays
            replacements["argvDecl"] = ""

        return string.Template(
            # Newlines and semicolons are in the values
            "${setupCall}"
            "${declRval}"
            "${argvDecl}"
            "${convertArgs}"
            "${doCall}"
            "${returnResult}").substitute(replacements)

    def getResultConversion(self):
        replacements = {
            "val": "rval",
            "mutableVal": "&rval",
            "holderName" : "rvalHolder",
            "declName" : "rvalDecl",
            # We actually want to pass in a null scope object here, because
            # wrapping things into our current compartment (that of mCallback)
            # is what we want.
            "obj": "nullptr"
            }

        if isJSImplementedDescriptor(self.descriptorProvider):
            isCallbackReturnValue = "JSImpl"
        else:
            isCallbackReturnValue = "Callback"
        convertType = instantiateJSToNativeConversionTemplate(
            getJSToNativeConversionTemplate(self.retvalType,
                                            self.descriptorProvider,
                                            exceptionCode=self.exceptionCode,
                                            isCallbackReturnValue=isCallbackReturnValue,
                                            # XXXbz we should try to do better here
                                            sourceDescription="return value"),
            replacements)
        assignRetval = string.Template(
            self.getRetvalInfo(self.retvalType,
                               False)[2]).substitute(replacements)
        return convertType.define() + "\n" + assignRetval

    def getArgConversions(self):
        # Just reget the arglist from self.originalSig, because our superclasses
        # just have way to many members they like to clobber, so I can't find a
        # safe member name to store it in.
        argConversions = [self.getArgConversion(i, arg) for (i, arg)
                          in enumerate(self.originalSig[1])]
        # Do them back to front, so our argc modifications will work
        # correctly, because we examine trailing arguments first.
        argConversions.reverse();
        # Wrap each one in a scope so that any locals it has don't leak out, and
        # also so that we can just "break;" for our successCode.
        argConversions = [CGWrapper(CGIndenter(CGGeneric(c)),
                                    pre="loop {\n",
                                    post="\nbreak;}\n")
                          for c in argConversions]
        if self.argCount > 0:
            argConversions.insert(0, self.getArgcDecl())
        # And slap them together.
        return CGList(argConversions, "\n\n").define() + "\n\n"

    def getArgConversion(self, i, arg):
        argval = arg.identifier.name

        if arg.variadic:
            argval = argval + "[idx]"
            jsvalIndex = "%d + idx" % i
        else:
            jsvalIndex = "%d" % i
            if arg.optional and not arg.defaultValue:
                argval += ".Value()"
        if arg.type.isDOMString():
            # XPConnect string-to-JS conversion wants to mutate the string.  So
            # let's give it a string it can mutate
            # XXXbz if we try to do a sequence of strings, this will kinda fail.
            result = "mutableStr"
            prepend = "nsString mutableStr(%s);\n" % argval
        else:
            result = argval
            prepend = ""

        conversion = prepend + wrapForType(
            arg.type, self.descriptorProvider,
            {
                'result' : result,
                'successCode' : "continue;" if arg.variadic else "break;",
                'jsvalRef' : "argv.handleAt(%s)" % jsvalIndex,
                'jsvalHandle' : "argv.handleAt(%s)" % jsvalIndex,
                'jsvalPtr': "&mut argv[%s]" % jsvalIndex,
                # XXXbz we don't have anything better to use for 'obj',
                # really...  It's OK to use CallbackPreserveColor because
                # CallSetup already handled the unmark-gray bits for us.
                'obj' : 'ptr::null() /*XXXjdm proper scope*/', #XXXjdm 'CallbackPreserveColor()',
                'returnsNewObject': False,
                'exceptionCode' : self.exceptionCode
                })
        if arg.variadic:
            conversion = string.Template(
                "for (uint32_t idx = 0; idx < ${arg}.Length(); ++idx) {\n" +
                CGIndenter(CGGeneric(conversion)).define() + "\n"
                "}\n"
                "break;").substitute({ "arg": arg.identifier.name })
        elif arg.optional and not arg.defaultValue:
            conversion = (
                CGIfWrapper(CGGeneric(conversion),
                            "%s.WasPassed()" % arg.identifier.name).define() +
                " else if (argc == %d) {\n"
                "  // This is our current trailing argument; reduce argc\n"
                "  --argc;\n"
                "} else {\n"
                "  argv[%d] = JS::UndefinedValue();\n"
                "}" % (i+1, i))
        return conversion

    def getDefaultRetval(self):
        default = self.getRetvalInfo(self.retvalType, False)[1]
        if len(default) != 0:
            default = " " + default
        return default

    def getArgs(self, returnType, argList):
        args = CGNativeMember.getArgs(self, returnType, argList)
        if not self.needThisHandling:
            # Since we don't need this handling, we're the actual method that
            # will be called, so we need an aRethrowExceptions argument.
            if self.rethrowContentException:
                args.append(Argument("JSCompartment*", "aCompartment", "nullptr"))
            else:
                args.append(Argument("ExceptionHandling", "aExceptionHandling",
                                     "eReportExceptions"))
            return args
        # We want to allow the caller to pass in a "this" object, as
        # well as a JSContext.
        return [Argument("*JSContext", "cx"),
                Argument("*JSObject", "aThisObj")] + args

    def getCallSetup(self):
        if self.needThisHandling:
            # It's been done for us already
            return ""
        callSetup = "CallSetup s(CallbackPreserveColor(), aRv"
        if self.rethrowContentException:
            # getArgs doesn't add the aExceptionHandling argument but does add
            # aCompartment for us.
            callSetup += ", eRethrowContentExceptions, aCompartment"
        else:
            callSetup += ", aExceptionHandling"
        callSetup += ");"
        return string.Template(
            "${callSetup}\n"
            "JSContext* cx = s.GetContext();\n"
            "if (!cx) {\n"
            "  return${errorReturn};\n"
            "}\n").substitute({
                "callSetup": callSetup,
                "errorReturn" : self.getDefaultRetval(),
                })

    def getArgcDecl(self):
        return CGGeneric("let argc = %su32;" % self.argCountStr);

    @staticmethod
    def ensureASCIIName(idlObject):
        type = "attribute" if idlObject.isAttr() else "operation"
        if re.match("[^\x20-\x7E]", idlObject.identifier.name):
            raise SyntaxError('Callback %s name "%s" contains non-ASCII '
                              "characters.  We can't handle that.  %s" %
                              (type, idlObject.identifier.name,
                               idlObject.location))
        if re.match('"', idlObject.identifier.name):
            raise SyntaxError("Callback %s name '%s' contains "
                              "double-quote character.  We can't handle "
                              "that.  %s" %
                              (type, idlObject.identifier.name,
                               idlObject.location))

class CallbackMethod(CallbackMember):
    def __init__(self, sig, name, descriptorProvider, needThisHandling, rethrowContentException=False):
        CallbackMember.__init__(self, sig, name, descriptorProvider,
                                needThisHandling, rethrowContentException)
    def getRvalDecl(self):
        return "let mut rval = JSVAL_VOID;\n"

    def getCall(self):
        replacements = {
            "errorReturn" : self.getDefaultRetval(),
            "thisObj": self.getThisObj(),
            "getCallable": self.getCallableDecl()
            }
        if self.argCount > 0:
            replacements["argv"] = "&argv[0]"
            replacements["argc"] = "argc"
        else:
            replacements["argv"] = "nullptr"
            replacements["argc"] = "0"
        return string.Template("${getCallable}"
                "if unsafe { JS_CallFunctionValue(cx, ${thisObj}, callable,\n"
                "                        ${argc}, ${argv}, &rval) == 0 } {\n"
                "  return${errorReturn};\n"
                "}\n").substitute(replacements)

class CallCallback(CallbackMethod):
    def __init__(self, callback, descriptorProvider):
        CallbackMethod.__init__(self, callback.signatures()[0], "Call",
                                descriptorProvider, needThisHandling=True)

    def getThisObj(self):
        return "aThisObj"

    def getCallableDecl(self):
        return "JS::Rooted<JS::Value> callable(cx, JS::ObjectValue(*mCallback));\n"

class CallbackOperationBase(CallbackMethod):
    """
    Common class for implementing various callback operations.
    """
    def __init__(self, signature, jsName, nativeName, descriptor, singleOperation, rethrowContentException=False):
        self.singleOperation = singleOperation
        self.methodName = jsName
        CallbackMethod.__init__(self, signature, nativeName, descriptor, singleOperation, rethrowContentException)

    def getThisObj(self):
        if not self.singleOperation:
            return "self.parent.callback"
        # This relies on getCallableDecl declaring a boolean
        # isCallable in the case when we're a single-operation
        # interface.
        return "if isCallable { aThisObj } else { self.parent.callback }"

    def getCallableDecl(self):
        replacements = {
            "errorReturn" : self.getDefaultRetval(),
            "methodName": self.methodName
            }
        getCallableFromProp = string.Template(
                'if "${methodName}".to_c_str().with_ref(|name| !self.parent.GetCallableProperty(cx, name, &mut callable)) {\n'
                '  return${errorReturn};\n'
                '}\n').substitute(replacements)
        if not self.singleOperation:
            return 'JS::Rooted<JS::Value> callable(cx);\n' + getCallableFromProp
        return (
            'let isCallable = unsafe { JS_ObjectIsCallable(cx, self.parent.callback) != 0 };\n'
            'let mut callable = JSVAL_VOID;\n'
            'if isCallable {\n'
            '  callable = unsafe { RUST_OBJECT_TO_JSVAL(self.parent.callback) };\n'
            '} else {\n'
            '%s'
            '}\n' % CGIndenter(CGGeneric(getCallableFromProp)).define())

class CallbackOperation(CallbackOperationBase):
    """
    Codegen actual WebIDL operations on callback interfaces.
    """
    def __init__(self, method, signature, descriptor):
        self.ensureASCIIName(method)
        jsName = method.identifier.name
        CallbackOperationBase.__init__(self, signature,
                                       jsName, MakeNativeName(jsName),
                                       descriptor, descriptor.interface.isSingleOperationInterface(),
                                       rethrowContentException=descriptor.interface.isJSImplemented())

class CallbackGetter(CallbackMember):
    def __init__(self, attr, descriptor):
        self.ensureASCIIName(attr)
        self.attrName = attr.identifier.name
        CallbackMember.__init__(self,
                                (attr.type, []),
                                callbackGetterName(attr),
                                descriptor,
                                needThisHandling=False,
                                rethrowContentException=descriptor.interface.isJSImplemented())

    def getRvalDecl(self):
        return "JS::Rooted<JS::Value> rval(cx, JS::UndefinedValue());\n"

    def getCall(self):
        replacements = {
            "errorReturn" : self.getDefaultRetval(),
            "attrName": self.attrName
            }
        return string.Template(
            'if (!JS_GetProperty(cx, mCallback, "${attrName}", &rval)) {\n'
            '  aRv.Throw(NS_ERROR_UNEXPECTED);\n'
            '  return${errorReturn};\n'
            '}\n').substitute(replacements);

class CallbackSetter(CallbackMember):
    def __init__(self, attr, descriptor):
        self.ensureASCIIName(attr)
        self.attrName = attr.identifier.name
        CallbackMember.__init__(self,
                                (BuiltinTypes[IDLBuiltinType.Types.void],
                                 [FakeArgument(attr.type, attr)]),
                                callbackSetterName(attr),
                                descriptor,
                                needThisHandling=False,
                                rethrowContentException=descriptor.interface.isJSImplemented())

    def getRvalDecl(self):
        # We don't need an rval
        return ""

    def getCall(self):
        replacements = {
            "errorReturn" : self.getDefaultRetval(),
            "attrName": self.attrName,
            "argv": "argv.handleAt(0)",
            }
        return string.Template(
            'MOZ_ASSERT(argv.length() == 1);\n'
            'if (!JS_SetProperty(cx, mCallback, "${attrName}", ${argv})) {\n'
            '  aRv.Throw(NS_ERROR_UNEXPECTED);\n'
            '  return${errorReturn};\n'
            '}\n').substitute(replacements)

    def getArgcDecl(self):
        return None

class GlobalGenRoots():
    """
    Roots for global codegen.

    To generate code, call the method associated with the target, and then
    call the appropriate define/declare method.
    """

    @staticmethod
    def PrototypeList(config):

        # Prototype ID enum.
        protos = [d.name for d in config.getDescriptors(hasInterfacePrototypeObject=True)]

        idEnum = CGNamespacedEnum('id', 'ID', protos, [0], deriving="Eq")
        idEnum = CGList([idEnum])
        idEnum.append(CGGeneric(declare="pub static MAX_PROTO_CHAIN_LENGTH: uint = " +
                                str(config.maxProtoChainLength) + ";\n\n"))

        # Wrap all of that in our namespaces.
        #idEnum = CGNamespace.build(['mozilla', 'dom', 'prototypes'],
        #                           CGWrapper(idEnum, pre='\n'))
        #idEnum = CGWrapper(idEnum, post='\n')

        curr = CGList([idEnum])

        # Constructor ID enum.
        constructors = [d.name for d in config.getDescriptors(hasInterfaceObject=True,
                                                              hasInterfacePrototypeObject=False)]
        idEnum = CGNamespacedEnum('id', 'ID', constructors, [0])

        # Wrap all of that in our namespaces.
        idEnum = CGNamespace.build(['mozilla', 'dom', 'constructors'],
                                   CGWrapper(idEnum, pre='\n'))
        idEnum = CGWrapper(idEnum, post='\n')

        #XXXjdm Not sure what to do with the constructors right now
        #curr.append(idEnum)

        #traitsDecl = CGGeneric(declare="""
#template <prototypes::ID PrototypeID>
#struct PrototypeTraits;
#
#template <class ConcreteClass>
#struct PrototypeIDMap;
#""")

        #traitsDecl = CGNamespace.build(['mozilla', 'dom'],
        #                                CGWrapper(traitsDecl, post='\n'))

        #curr.append(traitsDecl)

        # Add the auto-generated comment.
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)

        # Done.
        return curr

    @staticmethod
    def RegisterBindings(config):

        # TODO - Generate the methods we want
        curr = CGRegisterProtos(config)

        # Wrap all of that in our namespaces.
        #curr = CGNamespace.build(['mozilla', 'dom'],
        #                         CGWrapper(curr, post='\n'))
        #curr = CGWrapper(curr, post='\n')

        # Add the includes
        defineIncludes = [CGImports.getDeclarationFilename(desc.interface)
                          for desc in config.getDescriptors(hasInterfaceObject=True,
                                                            workers=False,
                                                            register=True)]
        curr = CGImports([], [], ['dom::bindings::codegen',
                                  'js::rust::Compartment'], defineIncludes, curr)

        # Done.
        return curr

    @staticmethod
    def InterfaceTypes(config):

        def pathToType(descriptor):
            if descriptor.interface.isCallback():
                return "dom::bindings::codegen::%sBinding" % descriptor.name
            return "dom::%s" % descriptor.name.lower()

        descriptors = [d.name for d in config.getDescriptors(register=True, hasInterfaceObject=True)]
        curr = CGList([CGGeneric(declare="pub use dom::%s::%s;\n" % (name.lower(), name)) for name in descriptors])
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
        return curr

    @staticmethod
    def BindingDeclarations(config):

        descriptors = [d.name for d in config.getDescriptors(register=True)]
        curr = CGList([CGGeneric(declare="pub mod %sBinding;\n" % name) for name in descriptors])
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
        return curr