WebIDL codegen: Replace cmake with a single Python script

When playing around with Cargo’s new timing visualization:
https://internals.rust-lang.org/t/exploring-crate-graph-build-times-with-cargo-build-ztimings/10975/21

… I was surprised to see the `script` crate’s build script take 76 seconds.
I did not expect WebIDL bindings generation to be *that* computationally
intensive.

It turns out almost all of this time is overhead. The build script uses CMake
to generate bindings for each WebIDL file in parallel, but that causes a lot
of work to be repeated 366 times:

* Starting up a Python VM
* Importing (parts of) the Python standard library
* Importing ~16k lines of our Python code
* Recompiling the latter to bytecode, since we used `python -B` to disable
  writing `.pyc` file
* Deserializing with `cPickle` and recreating in memory the results
  of parsing all WebIDL files

----

This commit remove the use of CMake and cPickle for the `script` crate.
Instead, all WebIDL bindings generation is done sequentially
in a single Python process. This takes 2 to 3 seconds.

1 files changed, 0 insertions, 143 deletions

diff --git a/components/script/dom/bindings/codegen/GlobalGen.py b/components/script/dom/bindings/codegen/GlobalGen.py
deleted file mode 100644
index 1850a41d5f3..00000000000
--- a/components/script/dom/bindings/codegen/GlobalGen.py
+++ /dev/null
@@ -1,143 +0,0 @@
-# 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 https://mozilla.org/MPL/2.0/.
-
-# We do one global pass over all the WebIDL to generate our prototype enum
-# and generate information for subsequent phases.
-
-import sys
-import os
-import json
-sys.path.append(os.path.join(".", "parser"))
-sys.path.append(os.path.join(".", "ply"))
-import WebIDL
-import cPickle
-from Configuration import Configuration
-from CodegenRust import GlobalGenRoots, replaceFileIfChanged
-
-
-def generate_file(config, name, filename):
-    root = getattr(GlobalGenRoots, name)(config)
-    code = root.define()
-
-    if replaceFileIfChanged(filename, code):
-        print "Generating %s" % (filename)
-    else:
-        print "%s hasn't changed - not touching it" % (filename)
-
-
-def main():
-    # Parse arguments.
-    from optparse import OptionParser
-    usageString = "usage: %prog [options] configFile outputdir webidldir cssProperties.json docServoDir [files]"
-    o = OptionParser(usage=usageString)
-    o.add_option("--cachedir", dest='cachedir', default=None,
-                 help="Directory in which to cache lex/parse tables.")
-    o.add_option("--filelist", dest='filelist', default=None,
-                 help="A file containing the list (one per line) of webidl files to process.")
-    (options, args) = o.parse_args()
-
-    if len(args) < 2:
-        o.error(usageString)
-
-    configFile = args[0]
-    outputdir = args[1]
-    baseDir = args[2]
-    css_properties_json = args[3]
-    doc_servo = args[4]
-    if options.filelist is not None:
-        fileList = [l.strip() for l in open(options.filelist).xreadlines()]
-    else:
-        fileList = args[3:]
-
-    # Parse the WebIDL.
-    parser = WebIDL.Parser(options.cachedir)
-    for filename in fileList:
-        fullPath = os.path.normpath(os.path.join(baseDir, filename))
-        with open(fullPath, 'rb') as f:
-            lines = f.readlines()
-        parser.parse(''.join(lines), fullPath)
-
-    add_css_properties_attributes(fileList, css_properties_json, parser)
-
-    parserResults = parser.finish()
-
-    # Write the parser results out to a pickle.
-    resultsPath = os.path.join(outputdir, 'ParserResults.pkl')
-    with open(resultsPath, 'wb') as resultsFile:
-        cPickle.dump(parserResults, resultsFile, -1)
-
-    # Load the configuration.
-    config = Configuration(configFile, parserResults)
-
-    to_generate = [
-        ('PrototypeList', 'PrototypeList.rs'),
-        ('RegisterBindings', 'RegisterBindings.rs'),
-        ('InterfaceObjectMap', 'InterfaceObjectMap.rs'),
-        ('InterfaceObjectMapData', 'InterfaceObjectMapData.json'),
-        ('InterfaceTypes', 'InterfaceTypes.rs'),
-        ('InheritTypes', 'InheritTypes.rs'),
-        ('Bindings', os.path.join('Bindings', 'mod.rs')),
-        ('UnionTypes', 'UnionTypes.rs'),
-    ]
-
-    for name, filename in to_generate:
-        generate_file(config, name, os.path.join(outputdir, filename))
-
-    generate_file(config, 'SupportedDomApis', os.path.join(doc_servo, 'apis.html'))
-
-
-def add_css_properties_attributes(webidl_files, css_properties_json, parser):
-    for filename in webidl_files:
-        if os.path.basename(filename) == "CSSStyleDeclaration.webidl":
-            break
-    else:
-        return
-
-    css_properties = json.load(open(css_properties_json, "rb"))
-    idl = "partial interface CSSStyleDeclaration {\n%s\n};\n" % "\n".join(
-        "  [%sCEReactions, SetterThrows] attribute [TreatNullAs=EmptyString] DOMString %s;" % (
-            ('Pref="%s", ' % data["pref"] if data["pref"] else ""),
-            attribute_name
-        )
-        for (kind, properties_list) in sorted(css_properties.items())
-        for (property_name, data) in sorted(properties_list.items())
-        for attribute_name in attribute_names(property_name)
-    )
-    parser.parse(idl.encode("utf-8"), "CSSStyleDeclaration_generated.webidl")
-
-
-def attribute_names(property_name):
-    # https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-dashed-attribute
-    if property_name != "float":
-        yield property_name
-    else:
-        yield "_float"
-
-    # https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-camel-cased-attribute
-    if "-" in property_name:
-        yield "".join(camel_case(property_name))
-
-    # https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-webkit-cased-attribute
-    if property_name.startswith("-webkit-"):
-        yield "".join(camel_case(property_name), True)
-
-
-# https://drafts.csswg.org/cssom/#css-property-to-idl-attribute
-def camel_case(chars, webkit_prefixed=False):
-    if webkit_prefixed:
-        chars = chars[1:]
-    next_is_uppercase = False
-    for c in chars:
-        if c == '-':
-            next_is_uppercase = True
-        elif next_is_uppercase:
-            next_is_uppercase = False
-            # Should be ASCII-uppercase, but all non-custom CSS property names are within ASCII
-            yield c.upper()
-        else:
-            yield c
-
-
-if __name__ == '__main__':
-    main()