Extract some Python code from properties.mako.rs into a separate file.

6 files changed, 330 insertions, 305 deletions

diff --git a/components/style/build.rs b/components/style/build.rs
index f470f5b4079..d5935bc2d81 100644
--- a/components/style/build.rs
+++ b/components/style/build.rs
@@ -35,7 +35,7 @@ fn main() {
     let status = Command::new(python)
         .arg(&script)
         .arg(product)
-        .arg("rust")
+        .arg("style-crate")
         .status()
         .unwrap();
     if !status.success() {
diff --git a/components/style/properties/build.py b/components/style/properties/build.py
index ffc72a678d5..be2e372a240 100644
--- a/components/style/properties/build.py
+++ b/components/style/properties/build.py
@@ -13,21 +13,28 @@ sys.path.insert(0, os.path.join(BASE, "Mako-0.9.1.zip"))
 from mako import exceptions
 from mako.template import Template
 
+import data
+
 
 def main():
-    usage = "Usage: %s [ servo | gecko ] [ rust | html ]" % sys.argv[0]
+    usage = "Usage: %s [ servo | gecko ] [ style-crate | geckolib | html ]" % sys.argv[0]
     if len(sys.argv) < 3:
         abort(usage)
     product = sys.argv[1]
     output = sys.argv[2]
-    if product not in ["servo", "gecko"] or output not in ["rust", "html"]:
+    if product not in ["servo", "gecko"] or output not in ["style-crate", "geckolib", "html"]:
         abort(usage)
 
-    template, rust = render("properties.mako.rs", PRODUCT=product)
-    if output == "rust":
+    properties = data.PropertiesData(product=product)
+    rust = render(os.path.join(BASE, "properties.mako.rs"), product=product, data=properties)
+    if output == "style-crate":
+        write(os.environ["OUT_DIR"], "properties.rs", rust)
+    if output == "geckolib":
+        template = os.path.join(BASE, "..", "..", "..", "ports", "geckolib", "properties.mako.rs")
+        rust = render(template, data=properties)
         write(os.environ["OUT_DIR"], "properties.rs", rust)
     elif output == "html":
-        write_html(template)
+        write_html(properties)
 
 
 def abort(message):
@@ -35,11 +42,18 @@ def abort(message):
     sys.exit(1)
 
 
-def render(name, **context):
+def render(filename, **context):
     try:
-        template = Template(open(os.path.join(BASE, name), "rb").read(), input_encoding="utf8")
-        return template, template.render(**context).encode("utf8")
+        template = Template(open(filename, "rb").read(),
+                            input_encoding="utf8",
+                            strict_undefined=True,
+                            filename=filename)
+        # Uncomment to debug generated Python code:
+        #write("/tmp", "mako_%s.py" % os.path.basename(filename), template.code)
+        return template.render(**context).encode("utf8")
     except:
+        # Uncomment to see a traceback in generated Python code:
+        #raise
         abort(exceptions.text_error_template().render().encode("utf8"))
 
 
@@ -49,19 +63,18 @@ def write(directory, filename, content):
     open(os.path.join(directory, filename), "wb").write(content)
 
 
-def write_html(template):
+def write_html(properties):
     properties = dict(
         (p.name, {
             "flag": p.experimental,
             "shorthand": hasattr(p, "sub_properties")
         })
-        for p in template.module.LONGHANDS + template.module.SHORTHANDS
+        for p in properties.longhands + properties.shorthands
     )
-    _, html = render("properties.html.mako", properties=properties)
-
     doc_servo = os.path.join(BASE, "..", "..", "..", "target", "doc", "servo")
-    write(doc_servo, "css-properties.json", json.dumps(properties, indent=4))
+    html = render(os.path.join(BASE, "properties.html.mako"), properties=properties)
     write(doc_servo, "css-properties.html", html)
+    write(doc_servo, "css-properties.json", json.dumps(properties, indent=4))
 
 
 if __name__ == "__main__":
diff --git a/components/style/properties/data.py b/components/style/properties/data.py
new file mode 100644
index 00000000000..7724114dfe7
--- /dev/null
+++ b/components/style/properties/data.py
@@ -0,0 +1,158 @@
+# 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/.
+
+import re
+
+
+def to_rust_ident(name):
+    name = name.replace("-", "_")
+    if name in ["static", "super", "box", "move"]:  # Rust keywords
+        name += "_"
+    return name
+
+
+def to_camel_case(ident):
+    return re.sub("_([a-z])", lambda m: m.group(1).upper(), ident.strip("_").capitalize())
+
+
+class Keyword(object):
+    def __init__(self, name, values, gecko_constant_prefix=None,
+                 extra_gecko_values=None, extra_servo_values=None):
+        self.name = name
+        self.values = values
+        self.gecko_constant_prefix = gecko_constant_prefix or \
+            "NS_STYLE_" + self.name.upper().replace("-", "_")
+        self.extra_gecko_values = (extra_gecko_values or "").split()
+        self.extra_servo_values = (extra_servo_values or "").split()
+
+    def gecko_values(self):
+        return self.values + self.extra_gecko_values
+
+    def servo_values(self):
+        return self.values + self.extra_servo_values
+
+    def values_for(self, product):
+        if product == "gecko":
+            return self.gecko_values()
+        elif product == "servo":
+            return self.servo_values()
+        else:
+            raise Exception("Bad product: " + product)
+
+    def gecko_constant(self, value):
+        return self.gecko_constant_prefix + "_" + value.upper().replace("-", "_")
+
+
+class Longhand(object):
+    def __init__(self, style_struct, name, derived_from=None, keyword=None,
+                 custom_cascade=False, experimental=False, internal=False,
+                 gecko_ffi_name=None):
+        self.name = name
+        self.keyword = keyword
+        self.ident = to_rust_ident(name)
+        self.camel_case = to_camel_case(self.ident)
+        self.style_struct = style_struct
+        self.experimental = ("layout.%s.enabled" % name) if experimental else None
+        self.custom_cascade = custom_cascade
+        self.internal = internal
+        self.gecko_ffi_name = gecko_ffi_name or "m" + self.camel_case
+        self.derived_from = (derived_from or "").split()
+
+
+class Shorthand(object):
+    def __init__(self, name, sub_properties, experimental=False, internal=False):
+        self.name = name
+        self.ident = to_rust_ident(name)
+        self.camel_case = to_camel_case(self.ident)
+        self.derived_from = None
+        self.experimental = ("layout.%s.enabled" % name) if experimental else None
+        self.sub_properties = sub_properties
+        self.internal = internal
+
+
+class Method(object):
+    def __init__(self, name, return_type=None, arg_types=None, is_mut=False):
+        self.name = name
+        self.return_type = return_type
+        self.arg_types = arg_types or []
+        self.is_mut = is_mut
+
+    def arg_list(self):
+        args = ["_: " + x for x in self.arg_types]
+        args = ["&mut self" if self.is_mut else "&self"] + args
+        return ", ".join(args)
+
+    def signature(self):
+        sig = "fn %s(%s)" % (self.name, self.arg_list())
+        if self.return_type:
+            sig = sig + " -> " + self.return_type
+        return sig
+
+    def declare(self):
+        return self.signature() + ";"
+
+    def stub(self):
+        return self.signature() + "{ unimplemented!() }"
+
+
+class StyleStruct(object):
+    def __init__(self, name, inherited, gecko_ffi_name=None, additional_methods=None):
+        self.servo_struct_name = "Servo" + name
+        self.gecko_struct_name = "Gecko" + name
+        self.trait_name = name
+        self.trait_name_lower = name.lower()
+        self.ident = to_rust_ident(self.trait_name_lower)
+        self.longhands = []
+        self.inherited = inherited
+        self.gecko_ffi_name = gecko_ffi_name
+        self.additional_methods = additional_methods or []
+
+
+class PropertiesData(object):
+    def __init__(self, product):
+        self.product = product
+        self.style_structs = []
+        self.current_style_struct = None
+        self.longhands = []
+        self.longhands_by_name = {}
+        self.derived_longhands = {}
+        self.shorthands = []
+
+    def new_style_struct(self, *args, **kwargs):
+        style_struct = StyleStruct(*args, **kwargs)
+        self.style_structs.append(style_struct)
+        self.current_style_struct = style_struct
+
+
+    def active_style_structs(self):
+        return [s for s in self.style_structs if s.additional_methods or s.longhands]
+
+
+    def switch_to_style_struct(self, name):
+        for style_struct in self.style_structs:
+            if style_struct.trait_name == name:
+                self.current_style_struct = style_struct
+                return
+        raise Exception("Failed to find the struct named " + name)
+
+    def declare_longhand(self, name, products="gecko servo", **kwargs):
+        products = products.split()
+        if not self.product in products:
+            return
+
+        longand = Longhand(self.current_style_struct, name, **kwargs)
+        self.current_style_struct.longhands.append(longand)
+        self.longhands.append(longand)
+        self.longhands_by_name[name] = longand
+
+        for name in longand.derived_from:
+            self.derived_longhands.setdefault(name, []).append(longand)
+
+        return longand
+
+    def declare_shorthand(self, name, sub_properties, *args, **kwargs):
+        sub_properties = [self.longhands_by_name[s] for s in sub_properties]
+        shorthand = Shorthand(name, sub_properties, *args, **kwargs)
+        self.shorthands.append(shorthand)
+        return shorthand
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index b68d47ad1a3..109597119cf 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -37,161 +37,20 @@ use values::specified::BorderStyle;
 use self::property_bit_field::PropertyBitField;
 
 <%!
-
-import re
-
-def to_rust_ident(name):
-    name = name.replace("-", "_")
-    if name in ["static", "super", "box", "move"]:  # Rust keywords
-        name += "_"
-    return name
-
-def to_camel_case(ident):
-    return re.sub("_([a-z])", lambda m: m.group(1).upper(), ident.strip("_").capitalize())
-
-class Keyword(object):
-    def __init__(self, name, values, gecko_constant_prefix=None,
-                 extra_gecko_values=None, extra_servo_values=None, **kwargs):
-        self.name = name
-        self.values = values
-        self.gecko_constant_prefix = gecko_constant_prefix or "NS_STYLE_" + self.name.upper().replace("-", "_")
-        self.extra_gecko_values = (extra_gecko_values or "").split()
-        self.extra_servo_values = (extra_servo_values or "").split()
-    def gecko_values(self):
-        return self.values + self.extra_gecko_values
-    def servo_values(self):
-        return self.values + self.extra_servo_values
-    def values_for(self, product):
-        if product == "gecko":
-            return self.gecko_values()
-        elif product == "servo":
-            return self.servo_values()
-        else:
-            raise Exception("Bad product: " + product)
-    def gecko_constant(self, value):
-        return self.gecko_constant_prefix + "_" + value.upper().replace("-", "_")
-
-class Longhand(object):
-    def __init__(self, name, derived_from=None, keyword=None,
-                 custom_cascade=False, experimental=False, internal=False,
-                 gecko_ffi_name=None, **kwargs):
-        self.name = name
-        self.keyword = keyword
-        self.ident = to_rust_ident(name)
-        self.camel_case = to_camel_case(self.ident)
-        self.style_struct = THIS_STYLE_STRUCT
-        self.experimental = ("layout.%s.enabled" % name) if experimental else None
-        self.custom_cascade = custom_cascade
-        self.internal = internal
-        self.gecko_ffi_name = gecko_ffi_name or "m" + self.camel_case
-        self.derived_from = (derived_from or "").split()
-
-class Shorthand(object):
-    def __init__(self, name, sub_properties, experimental=False, internal=False):
-        self.name = name
-        self.ident = to_rust_ident(name)
-        self.camel_case = to_camel_case(self.ident)
-        self.derived_from = None
-        self.experimental = ("layout.%s.enabled" % name) if experimental else None
-        self.sub_properties = [LONGHANDS_BY_NAME[s] for s in sub_properties]
-        self.internal = internal
-
-class Method(object):
-    def __init__(self, name, return_type=None, arg_types=None, is_mut=False):
-        self.name = name
-        self.return_type = return_type
-        self.arg_types = arg_types or []
-        self.is_mut = is_mut
-    def arg_list(self):
-        args = ["_: " + x for x in self.arg_types]
-        args = ["&mut self" if self.is_mut else "&self"] + args
-        return ", ".join(args)
-    def signature(self):
-        sig = "fn %s(%s)" % (self.name, self.arg_list())
-        if self.return_type:
-            sig = sig + " -> " + self.return_type
-        return sig
-    def declare(self):
-        return self.signature() + ";"
-    def stub(self):
-        return self.signature() + "{ unimplemented!() }"
-
-class StyleStruct(object):
-    def __init__(self, name, inherited, gecko_ffi_name, additional_methods):
-        self.servo_struct_name = "Servo" + name
-        self.gecko_struct_name = "Gecko" + name
-        self.trait_name = name
-        self.trait_name_lower = name.lower()
-        self.ident = to_rust_ident(self.trait_name_lower)
-        self.longhands = []
-        self.inherited = inherited
-        self.gecko_ffi_name = gecko_ffi_name
-        self.additional_methods = additional_methods or []
-
-STYLE_STRUCTS = []
-THIS_STYLE_STRUCT = None
-LONGHANDS = []
-LONGHANDS_BY_NAME = {}
-DERIVED_LONGHANDS = {}
-SHORTHANDS = []
-CONFIG = {}
-
-def set_product(p):
-    global CONFIG
-    CONFIG['product'] = p
-
-def new_style_struct(name, is_inherited, gecko_name=None, additional_methods=None):
-    global THIS_STYLE_STRUCT
-
-    style_struct = StyleStruct(name, is_inherited, gecko_name, additional_methods)
-    STYLE_STRUCTS.append(style_struct)
-    THIS_STYLE_STRUCT = style_struct
-    return ""
-
-def active_style_structs():
-    return filter(lambda s: s.additional_methods or s.longhands, STYLE_STRUCTS)
-
-def switch_to_style_struct(name):
-    global THIS_STYLE_STRUCT
-
-    for style_struct in STYLE_STRUCTS:
-        if style_struct.trait_name == name:
-            THIS_STYLE_STRUCT = style_struct
-            return ""
-    raise Exception("Failed to find the struct named " + name)
+    from data import Method, Keyword, to_rust_ident
 %>
 
-// Work around Mako's really annoying namespacing setup.
-//
-// The above code runs when the template is loaded, rather than when it's
-// rendered, so it can create global variables, doesn't have access to
-// arguments passed to render(). On the flip side, there are various situations,
-// such as code in the body of a def-used-as-tag, where our python code has
-// access to global variables but not to render() arguments. Hack around this
-// by stashing render arguments in a global.
-<% CONFIG['product'] = PRODUCT %>
-
 pub mod longhands {
     use cssparser::Parser;
     use parser::ParserContext;
     use values::specified;
 
-    <%def name="raw_longhand(name, **kwargs)">
-    <%
-        products = kwargs.pop("products", "gecko servo").split()
-        if not CONFIG["product"] in products:
-            return ""
-
-        property = Longhand(name, **kwargs)
-
-        property.style_struct = THIS_STYLE_STRUCT
-        THIS_STYLE_STRUCT.longhands.append(property)
-        LONGHANDS.append(property)
-        LONGHANDS_BY_NAME[name] = property
-
-        for derived in property.derived_from:
-            DERIVED_LONGHANDS.setdefault(derived, []).append(property)
-    %>
+    <%def name="raw_longhand(*args, **kwargs)">
+        <%
+            property = data.declare_longhand(*args, **kwargs)
+            if property is None:
+                return ""
+        %>
         pub mod ${property.ident} {
             #![allow(unused_imports)]
             % if not property.derived_from:
@@ -203,7 +62,7 @@ pub mod longhands {
             use properties::longhands;
             use properties::property_bit_field::PropertyBitField;
             use properties::{ComputedValues, ServoComputedValues, PropertyDeclaration};
-            use properties::style_struct_traits::${THIS_STYLE_STRUCT.trait_name};
+            use properties::style_struct_traits::${data.current_style_struct.trait_name};
             use properties::style_structs;
             use std::boxed::Box as StdBox;
             use std::collections::HashMap;
@@ -237,7 +96,7 @@ pub mod longhands {
                             declared_value, &custom_props, |value| match *value {
                                 DeclaredValue::Value(ref specified_value) => {
                                     let computed = specified_value.to_computed_value(context);
-                                    context.mutate_style().mutate_${THIS_STYLE_STRUCT.trait_name_lower}()
+                                    context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
                                                           .set_${property.ident}(computed);
                                 }
                                 DeclaredValue::WithVariables { .. } => unreachable!(),
@@ -245,8 +104,8 @@ pub mod longhands {
                                     // We assume that it's faster to use copy_*_from rather than
                                     // set_*(get_initial_value());
                                     let initial_struct = C::initial_values()
-                                                          .get_${THIS_STYLE_STRUCT.trait_name_lower}();
-                                    context.mutate_style().mutate_${THIS_STYLE_STRUCT.trait_name_lower}()
+                                                          .get_${data.current_style_struct.trait_name_lower}();
+                                    context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
                                                           .copy_${property.ident}_from(initial_struct);
                                 },
                                 DeclaredValue::Inherit => {
@@ -255,8 +114,8 @@ pub mod longhands {
                                     //
                                     // FIXME: is it still?
                                     *cacheable = false;
-                                    let inherited_struct = inherited_style.get_${THIS_STYLE_STRUCT.trait_name_lower}();
-                                    context.mutate_style().mutate_${THIS_STYLE_STRUCT.trait_name_lower}()
+                                    let inherited_struct = inherited_style.get_${data.current_style_struct.trait_name_lower}();
+                                    context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
                                            .copy_${property.ident}_from(inherited_struct);
                                 }
                             }, error_reporter
@@ -282,7 +141,7 @@ pub mod longhands {
                         Ok(CSSWideKeyword::InheritKeyword) => Ok(DeclaredValue::Inherit),
                         Ok(CSSWideKeyword::InitialKeyword) => Ok(DeclaredValue::Initial),
                         Ok(CSSWideKeyword::UnsetKeyword) => Ok(DeclaredValue::${
-                            "Inherit" if THIS_STYLE_STRUCT.inherited else "Initial"}),
+                            "Inherit" if data.current_style_struct.inherited else "Initial"}),
                         Err(()) => {
                             input.look_for_var_functions();
                             let start = input.position();
@@ -313,7 +172,7 @@ pub mod longhands {
     <%def name="longhand(name, **kwargs)">
         <%call expr="raw_longhand(name, **kwargs)">
             ${caller.body()}
-            % if not LONGHANDS_BY_NAME[name].derived_from:
+            % if not data.longhands_by_name[name].derived_from:
                 pub fn parse_specified(context: &ParserContext, input: &mut Parser)
                                    -> Result<DeclaredValue<SpecifiedValue>, ()> {
                     parse(context, input).map(DeclaredValue::Value)
@@ -323,12 +182,17 @@ pub mod longhands {
     </%def>
 
     <%def name="single_keyword_computed(name, values, **kwargs)">
-        <%call expr="longhand(name, keyword=Keyword(name, values.split(), **kwargs), **kwargs)">
+        <%
+            keyword_kwargs = {a: kwargs.pop(a, None) for a in [
+                'gecko_constant_prefix', 'extra_gecko_values', 'extra_servo_values'
+            ]}
+        %>
+        <%call expr="longhand(name, keyword=Keyword(name, values.split(), **keyword_kwargs), **kwargs)">
             pub use self::computed_value::T as SpecifiedValue;
             ${caller.body()}
             pub mod computed_value {
                 define_css_keyword_enum! { T:
-                    % for value in LONGHANDS_BY_NAME[name].keyword.values_for(CONFIG['product']):
+                    % for value in data.longhands_by_name[name].keyword.values_for(product):
                         "${value}" => ${to_rust_ident(value)},
                     % endfor
                 }
@@ -369,14 +233,14 @@ pub mod longhands {
 
     // CSS 2.1, Section 8 - Box model
 
-    ${new_style_struct("Margin", is_inherited=False, gecko_name="nsStyleMargin")}
+    <% data.new_style_struct("Margin", inherited=False, gecko_ffi_name="nsStyleMargin") %>
 
     % for side in ["top", "right", "bottom", "left"]:
         ${predefined_type("margin-" + side, "LengthOrPercentageOrAuto",
                           "computed::LengthOrPercentageOrAuto::Length(Au(0))")}
     % endfor
 
-    ${new_style_struct("Padding", is_inherited=False, gecko_name="nsStylePadding")}
+    <% data.new_style_struct("Padding", inherited=False, gecko_ffi_name="nsStylePadding") %>
 
     % for side in ["top", "right", "bottom", "left"]:
         ${predefined_type("padding-" + side, "LengthOrPercentage",
@@ -384,9 +248,9 @@ pub mod longhands {
                           "parse_non_negative")}
     % endfor
 
-    ${new_style_struct("Border", is_inherited=False, gecko_name="nsStyleBorder",
+    <% data.new_style_struct("Border", inherited=False, gecko_ffi_name="nsStyleBorder",
                        additional_methods=[Method("border_" + side + "_is_none_or_hidden_and_has_nonzero_width",
-                                                  "bool") for side in ["top", "right", "bottom", "left"]])}
+                                                  "bool") for side in ["top", "right", "bottom", "left"]]) %>
 
     % for side in ["top", "right", "bottom", "left"]:
         ${predefined_type("border-%s-color" % side, "CSSColor", "::cssparser::Color::CurrentColor")}
@@ -441,8 +305,8 @@ pub mod longhands {
                           "parse")}
     % endfor
 
-    ${new_style_struct("Outline", is_inherited=False, gecko_name="nsStyleOutline",
-                       additional_methods=[Method("outline_is_none_or_hidden_and_has_nonzero_width", "bool")])}
+    <% data.new_style_struct("Outline", inherited=False, gecko_ffi_name="nsStyleOutline",
+                       additional_methods=[Method("outline_is_none_or_hidden_and_has_nonzero_width", "bool")]) %>
 
     // TODO(pcwalton): `invert`
     ${predefined_type("outline-color", "CSSColor", "::cssparser::Color::CurrentColor")}
@@ -495,7 +359,7 @@ pub mod longhands {
 
     ${predefined_type("outline-offset", "Length", "Au(0)")}
 
-    ${new_style_struct("Position", is_inherited=False, gecko_name="nsStylePosition")}
+    <% data.new_style_struct("Position", inherited=False, gecko_ffi_name="nsStylePosition") %>
 
     % for side in ["top", "right", "bottom", "left"]:
         ${predefined_type(side, "LengthOrPercentageOrAuto",
@@ -504,7 +368,7 @@ pub mod longhands {
 
     // CSS 2.1, Section 9 - Visual formatting model
 
-    ${new_style_struct("Box", is_inherited=False, gecko_name="nsStyleDisplay",
+    <% data.new_style_struct("Box", inherited=False, gecko_ffi_name="nsStyleDisplay",
                        additional_methods=[Method("clone_display",
                                                   "longhands::display::computed_value::T"),
                                            Method("clone_position",
@@ -512,10 +376,10 @@ pub mod longhands {
                                            Method("is_floated", "bool"),
                                            Method("overflow_x_is_visible", "bool"),
                                            Method("overflow_y_is_visible", "bool"),
-                                           Method("transition_count", "usize")])}
+                                           Method("transition_count", "usize")]) %>
 
     // TODO(SimonSapin): don't parse `inline-table`, since we don't support it
-    <%self:longhand name="display" custom_cascade="${CONFIG['product'] == 'servo'}">
+    <%self:longhand name="display" custom_cascade="${product == 'servo'}">
         <%
             values = """inline block inline-block
                 table inline-table table-row-group table-header-group table-footer-group
@@ -572,7 +436,7 @@ pub mod longhands {
 
         impl ComputedValueAsSpecified for SpecifiedValue {}
 
-        % if CONFIG["product"] == "servo":
+        % if product == "servo":
             fn cascade_property_custom<C: ComputedValues>(
                                        _declaration: &PropertyDeclaration,
                                        _inherited_style: &C,
@@ -626,7 +490,7 @@ pub mod longhands {
 
     </%self:longhand>
 
-    ${switch_to_style_struct("Position")}
+    <% data.switch_to_style_struct("Position") %>
 
     <%self:longhand name="z-index">
         use values::computed::ComputedValueAsSpecified;
@@ -674,19 +538,19 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${new_style_struct("InheritedBox", is_inherited=True, gecko_name="nsStyleVisibility",
+    <% data.new_style_struct("InheritedBox", inherited=True, gecko_ffi_name="nsStyleVisibility",
                        additional_methods=[Method("clone_direction",
                                                   "longhands::direction::computed_value::T"),
                                            Method("clone_writing_mode",
                                                   "longhands::writing_mode::computed_value::T"),
                                            Method("clone_text_orientation",
-                                                  "longhands::text_orientation::computed_value::T")])}
+                                                  "longhands::text_orientation::computed_value::T")]) %>
 
     ${single_keyword("direction", "ltr rtl")}
 
     // CSS 2.1, Section 10 - Visual formatting model details
 
-    ${switch_to_style_struct("Box")}
+    <% data.switch_to_style_struct("Box") %>
 
     ${predefined_type("width", "LengthOrPercentageOrAuto",
                       "computed::LengthOrPercentageOrAuto::Auto",
@@ -696,7 +560,7 @@ pub mod longhands {
                       "computed::LengthOrPercentageOrAuto::Auto",
                       "parse_non_negative")}
 
-    ${switch_to_style_struct("Position")}
+    <% data.switch_to_style_struct("Position") %>
 
     ${predefined_type("min-width", "LengthOrPercentage",
                       "computed::LengthOrPercentage::Length(Au(0))",
@@ -712,10 +576,10 @@ pub mod longhands {
                       "computed::LengthOrPercentageOrNone::None",
                       "parse_non_negative")}
 
-    ${new_style_struct("InheritedText", is_inherited=True, gecko_name="nsStyleText",
+    <% data.new_style_struct("InheritedText", inherited=True, gecko_ffi_name="nsStyleText",
                        additional_methods=([Method("clone__servo_text_decorations_in_effect",
                                                   "longhands::_servo_text_decorations_in_effect::computed_value::T")]
-                                           if CONFIG["product"] == "servo" else []))}
+                                           if product == "servo" else [])) %>
 
     <%self:longhand name="line-height">
         use cssparser::ToCss;
@@ -809,7 +673,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${switch_to_style_struct("Box")}
+    <% data.switch_to_style_struct("Box") %>
 
     <%self:longhand name="vertical-align">
         use cssparser::ToCss;
@@ -962,7 +826,7 @@ pub mod longhands {
     // http://www.w3.org/TR/compositing-1/
     ${single_keyword("isolation", "auto isolate", products="gecko")}
 
-    ${switch_to_style_struct("InheritedBox")}
+    <% data.switch_to_style_struct("InheritedBox") %>
 
     // TODO: collapse. Well, do tables first.
     ${single_keyword("visibility", "visible hidden", extra_gecko_values="collapse",
@@ -970,7 +834,7 @@ pub mod longhands {
 
     // CSS 2.1, Section 12 - Generated content, automatic numbering, and lists
 
-    ${new_style_struct("Counters", is_inherited=False, gecko_name="nsStyleContent")}
+    <% data.new_style_struct("Counters", inherited=False, gecko_ffi_name="nsStyleContent") %>
 
     <%self:longhand name="content">
         use cssparser::Token;
@@ -1135,7 +999,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${new_style_struct("List", is_inherited=True, gecko_name="nsStyleList")}
+    <% data.new_style_struct("List", inherited=True, gecko_ffi_name="nsStyleList") %>
 
     ${single_keyword("list-style-position", "outside inside")}
 
@@ -1283,7 +1147,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${switch_to_style_struct("Counters")}
+    <% data.switch_to_style_struct("Counters") %>
 
     <%self:longhand name="counter-increment">
         use std::fmt;
@@ -1365,7 +1229,7 @@ pub mod longhands {
 
     // CSS 2.1, Section 13 - Paged media
 
-    ${switch_to_style_struct("Box")}
+    <% data.switch_to_style_struct("Box") %>
 
     ${single_keyword("page-break-after", "auto always avoid left right", products="gecko")}
     ${single_keyword("page-break-before", "auto always avoid left right", products="gecko")}
@@ -1374,7 +1238,7 @@ pub mod longhands {
 
     // CSS 2.1, Section 14 - Colors and Backgrounds
 
-    ${new_style_struct("Background", is_inherited=False, gecko_name="nsStyleBackground")}
+    <% data.new_style_struct("Background", inherited=False, gecko_ffi_name="nsStyleBackground") %>
     ${predefined_type(
         "background-color", "CSSColor",
         "::cssparser::Color::RGBA(::cssparser::RGBA { red: 0., green: 0., blue: 0., alpha: 0. }) /* transparent */")}
@@ -1696,9 +1560,9 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${new_style_struct("Color", is_inherited=True, gecko_name="nsStyleColor",
+    <% data.new_style_struct("Color", inherited=True, gecko_ffi_name="nsStyleColor",
                        additional_methods=[Method("clone_color",
-                                                  "longhands::color::computed_value::T")])}
+                                                  "longhands::color::computed_value::T")]) %>
 
     <%self:raw_longhand name="color">
         use cssparser::Color as CSSParserColor;
@@ -1738,12 +1602,12 @@ pub mod longhands {
 
     // CSS 2.1, Section 15 - Fonts
 
-    ${new_style_struct("Font", is_inherited=True, gecko_name="nsStyleFont",
+    <% data.new_style_struct("Font", inherited=True, gecko_ffi_name="nsStyleFont",
                        additional_methods=[Method("clone_font_size",
                                                   "longhands::font_size::computed_value::T"),
                                            Method("clone_font_weight",
                                                   "longhands::font_weight::computed_value::T"),
-                                           Method("compute_font_hash", is_mut=True)])}
+                                           Method("compute_font_hash", is_mut=True)]) %>
 
     <%self:longhand name="font-family">
         use self::computed_value::FontFamily;
@@ -2049,7 +1913,7 @@ pub mod longhands {
 
     // CSS 2.1, Section 16 - Text
 
-    ${switch_to_style_struct("InheritedText")}
+    <% data.switch_to_style_struct("InheritedText") %>
 
     <%self:longhand name="text-align">
         pub use self::computed_value::T as SpecifiedValue;
@@ -2241,16 +2105,16 @@ pub mod longhands {
     // TODO(pcwalton): Support `text-justify: distribute`.
     ${single_keyword("text-justify", "auto none inter-word", products="servo")}
 
-    ${new_style_struct("Text", is_inherited=False, gecko_name="nsStyleTextReset",
+    <% data.new_style_struct("Text", inherited=False, gecko_ffi_name="nsStyleTextReset",
                        additional_methods=[Method("has_underline", "bool"),
                                            Method("has_overline", "bool"),
-                                           Method("has_line_through", "bool")])}
+                                           Method("has_line_through", "bool")]) %>
 
     ${single_keyword("text-overflow", "clip ellipsis")}
 
     ${single_keyword("unicode-bidi", "normal embed isolate bidi-override isolate-override plaintext")}
 
-    <%self:longhand name="text-decoration" custom_cascade="${CONFIG['product'] == 'servo'}">
+    <%self:longhand name="text-decoration" custom_cascade="${product == 'servo'}">
         use cssparser::ToCss;
         use std::fmt;
         use values::computed::ComputedValueAsSpecified;
@@ -2325,7 +2189,7 @@ pub mod longhands {
             if !empty { Ok(result) } else { Err(()) }
         }
 
-        % if CONFIG["product"] == "servo":
+        % if product == "servo":
             fn cascade_property_custom<C: ComputedValues>(
                                        _declaration: &PropertyDeclaration,
                                        _inherited_style: &C,
@@ -2341,7 +2205,7 @@ pub mod longhands {
     ${single_keyword("text-decoration-style", "-moz-none solid double dotted dashed wavy",
                      products="gecko")}
 
-    ${switch_to_style_struct("InheritedText")}
+    <% data.switch_to_style_struct("InheritedText") %>
 
     <%self:longhand name="-servo-text-decorations-in-effect"
                     derived_from="display text-decoration" products="servo">
@@ -2479,11 +2343,11 @@ pub mod longhands {
     ${single_keyword("ruby-position", "over under", products="gecko")}
 
     // CSS 2.1, Section 17 - Tables
-    ${new_style_struct("Table", is_inherited=False, gecko_name="nsStyleTable")}
+    <% data.new_style_struct("Table", inherited=False, gecko_ffi_name="nsStyleTable") %>
 
     ${single_keyword("table-layout", "auto fixed", gecko_ffi_name="mLayoutStrategy")}
 
-    ${new_style_struct("InheritedTable", is_inherited=True, gecko_name="nsStyleTableBorder")}
+    <% data.new_style_struct("InheritedTable", inherited=True, gecko_ffi_name="nsStyleTableBorder") %>
 
     ${single_keyword("border-collapse", "separate collapse", gecko_constant_prefix="NS_STYLE_BORDER")}
 
@@ -2582,13 +2446,13 @@ pub mod longhands {
 
     // CSS Fragmentation Module Level 3
     // https://www.w3.org/TR/css-break-3/
-    ${switch_to_style_struct("Border")}
+    <% data.switch_to_style_struct("Border") %>
 
     ${single_keyword("box-decoration-break", "slice clone", products="gecko")}
 
     // CSS Writing Modes Level 3
     // http://dev.w3.org/csswg/css-writing-modes/
-    ${switch_to_style_struct("InheritedBox")}
+    <% data.switch_to_style_struct("InheritedBox") %>
 
     ${single_keyword("writing-mode", "horizontal-tb vertical-rl vertical-lr", experimental=True)}
 
@@ -2602,15 +2466,15 @@ pub mod longhands {
 
     // CSS Basic User Interface Module Level 3
     // http://dev.w3.org/csswg/css-ui/
-    ${switch_to_style_struct("Box")}
+    <% data.switch_to_style_struct("Box") %>
 
     ${single_keyword("resize", "none both horizontal vertical", products="gecko")}
 
-    ${switch_to_style_struct("Position")}
+    <% data.switch_to_style_struct("Position") %>
 
     ${single_keyword("box-sizing", "content-box border-box")}
 
-    ${new_style_struct("Pointing", is_inherited=True, gecko_name="nsStyleUserInterface")}
+    <% data.new_style_struct("Pointing", inherited=True, gecko_ffi_name="nsStyleUserInterface") %>
 
     <%self:longhand name="cursor">
         pub use self::computed_value::T as SpecifiedValue;
@@ -2662,7 +2526,7 @@ pub mod longhands {
     ${single_keyword("pointer-events", "auto none")}
 
 
-    ${new_style_struct("Column", is_inherited=False, gecko_name="nsStyleColumn")}
+    <% data.new_style_struct("Column", inherited=False, gecko_ffi_name="nsStyleColumn") %>
 
     <%self:longhand name="column-width" experimental="True">
         use cssparser::ToCss;
@@ -2854,7 +2718,7 @@ pub mod longhands {
     </%self:longhand>
 
     // Box-shadow, etc.
-    ${new_style_struct("Effects", is_inherited=False, gecko_name="nsStyleEffects")}
+    <% data.new_style_struct("Effects", inherited=False, gecko_ffi_name="nsStyleEffects") %>
 
     <%self:longhand name="opacity">
         use cssparser::ToCss;
@@ -3258,7 +3122,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${switch_to_style_struct("InheritedText")}
+    <% data.switch_to_style_struct("InheritedText") %>
 
     <%self:longhand name="text-shadow">
         use cssparser::{self, ToCss};
@@ -3438,7 +3302,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${switch_to_style_struct("Effects")}
+    <% data.switch_to_style_struct("Effects") %>
 
     <%self:longhand name="filter">
         //pub use self::computed_value::T as SpecifiedValue;
@@ -4376,11 +4240,11 @@ pub mod longhands {
     // CSS Image Values and Replaced Content Module Level 3
     // https://drafts.csswg.org/css-images-3/
 
-    ${switch_to_style_struct("Position")}
+    <% data.switch_to_style_struct("Position") %>
 
     ${single_keyword("object-fit", "fill contain cover none scale-down", products="gecko")}
 
-    ${switch_to_style_struct("InheritedBox")}
+    <% data.switch_to_style_struct("InheritedBox") %>
 
     <%self:longhand name="image-rendering">
 
@@ -4437,7 +4301,7 @@ pub mod longhands {
         }
     </%self:longhand>
 
-    ${switch_to_style_struct("Box")}
+    <% data.switch_to_style_struct("Box") %>
 
     // TODO(pcwalton): Multiple transitions.
     <%self:longhand name="transition-duration">
@@ -4963,7 +4827,7 @@ pub mod longhands {
     // CSS Flexible Box Layout Module Level 1
     // http://www.w3.org/TR/css3-flexbox/
 
-    ${switch_to_style_struct("Position")}
+    <% data.switch_to_style_struct("Position") %>
 
     // Flex container properties
     ${single_keyword("flex-direction", "row row-reverse column column-reverse", experimental=True)}
@@ -4994,7 +4858,7 @@ pub mod longhands {
 
     // SVG 1.1 (Second Edition)
     // https://www.w3.org/TR/SVG/
-    ${new_style_struct("SVGInherited", is_inherited=True, gecko_name="nsStyleSVG")}
+    <% data.new_style_struct("SVGInherited", inherited=True, gecko_ffi_name="nsStyleSVG") %>
 
     // Section 10 - Text
 
@@ -5019,7 +4883,7 @@ pub mod longhands {
     ${single_keyword("clip-rule", "nonzero evenodd",
                      products="gecko", gecko_constant_prefix="NS_STYLE_FILL_RULE")}
 
-    ${new_style_struct("SVG", is_inherited=False, gecko_name="nsStyleSVGReset")}
+    <% data.new_style_struct("SVG", inherited=False, gecko_ffi_name="nsStyleSVGReset") %>
 
     ${single_keyword("dominant-baseline",
                      """auto use-script no-change reset-size ideographic alphabetic hanging
@@ -5041,8 +4905,7 @@ pub mod shorthands {
 
     <%def name="shorthand(name, sub_properties, experimental=False)">
     <%
-        shorthand = Shorthand(name, sub_properties.split(), experimental=experimental)
-        SHORTHANDS.append(shorthand)
+        shorthand = data.declare_shorthand(name, sub_properties.split(), experimental=experimental)
     %>
         pub mod ${shorthand.ident} {
             use cssparser::Parser;
@@ -5754,13 +5617,13 @@ pub mod shorthands {
 mod property_bit_field {
 
     pub struct PropertyBitField {
-        storage: [u32; (${len(LONGHANDS)} - 1 + 32) / 32]
+        storage: [u32; (${len(data.longhands)} - 1 + 32) / 32]
     }
 
     impl PropertyBitField {
         #[inline]
         pub fn new() -> PropertyBitField {
-            PropertyBitField { storage: [0; (${len(LONGHANDS)} - 1 + 32) / 32] }
+            PropertyBitField { storage: [0; (${len(data.longhands)} - 1 + 32) / 32] }
         }
 
         #[inline]
@@ -5771,7 +5634,7 @@ mod property_bit_field {
         fn set(&mut self, bit: usize) {
             self.storage[bit / 32] |= 1 << (bit % 32)
         }
-        % for i, property in enumerate(LONGHANDS):
+        % for i, property in enumerate(data.longhands):
             % if not property.derived_from:
                 #[allow(non_snake_case)]
                 #[inline]
@@ -5788,7 +5651,7 @@ mod property_bit_field {
     }
 }
 
-% for property in LONGHANDS:
+% for property in data.longhands:
     % if not property.derived_from:
         #[allow(non_snake_case)]
         fn substitute_variables_${property.ident}<F>(
@@ -5838,7 +5701,7 @@ mod property_bit_field {
                             None => {
                                 longhands::${property.ident}::parse_specified(&context, input)
                             }
-                            % for shorthand in SHORTHANDS:
+                            % for shorthand in data.shorthands:
                                 % if property in shorthand.sub_properties:
                                     Some(Shorthand::${shorthand.camel_case}) => {
                                         shorthands::${shorthand.ident}::parse_value(&context, input)
@@ -5958,7 +5821,7 @@ fn deduplicate_property_declarations(declarations: Vec<PropertyDeclaration>)
     let mut seen_custom = Vec::new();
     for declaration in declarations.into_iter().rev() {
         match declaration {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}(..) => {
                     % if not property.derived_from:
                         if seen.get_${property.ident}() {
@@ -6003,7 +5866,7 @@ impl CSSWideKeyword {
 
 #[derive(Clone, Copy, Eq, PartialEq, Debug, HeapSizeOf)]
 pub enum Shorthand {
-    % for property in SHORTHANDS:
+    % for property in data.shorthands:
         ${property.camel_case},
     % endfor
 }
@@ -6011,7 +5874,7 @@ pub enum Shorthand {
 impl Shorthand {
     pub fn from_name(name: &str) -> Option<Shorthand> {
         match_ignore_ascii_case! { name,
-            % for property in SHORTHANDS:
+            % for property in data.shorthands:
                 "${property.name}" => Some(Shorthand::${property.camel_case}),
             % endfor
             _ => None
@@ -6019,7 +5882,7 @@ impl Shorthand {
     }
 
     pub fn longhands(&self) -> &'static [&'static str] {
-        % for property in SHORTHANDS:
+        % for property in data.shorthands:
             static ${property.ident.upper()}: &'static [&'static str] = &[
                 % for sub in property.sub_properties:
                     "${sub.name}",
@@ -6027,7 +5890,7 @@ impl Shorthand {
             ];
         % endfor
         match *self {
-            % for property in SHORTHANDS:
+            % for property in data.shorthands:
                 Shorthand::${property.camel_case} => ${property.ident.upper()},
             % endfor
         }
@@ -6067,7 +5930,7 @@ impl<T: ToCss> ToCss for DeclaredValue<T> {
 
 #[derive(PartialEq, Clone, Debug, HeapSizeOf)]
 pub enum PropertyDeclaration {
-    % for property in LONGHANDS:
+    % for property in data.longhands:
         ${property.camel_case}(DeclaredValue<longhands::${property.ident}::SpecifiedValue>),
     % endfor
     Custom(::custom_properties::Name, DeclaredValue<::custom_properties::SpecifiedValue>),
@@ -6117,7 +5980,7 @@ impl fmt::Display for PropertyDeclarationName {
 impl PropertyDeclaration {
     pub fn name(&self) -> PropertyDeclarationName {
         match *self {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}(..) =>
                 % if not property.derived_from:
                     PropertyDeclarationName::Longhand("${property.name}"),
@@ -6133,7 +5996,7 @@ impl PropertyDeclaration {
 
     pub fn value(&self) -> String {
         match *self {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}
                 % if not property.derived_from:
                     (ref value) => value.to_css_string(),
@@ -6150,7 +6013,7 @@ impl PropertyDeclaration {
     //                                                                          ↓
     pub fn with_variables_from_shorthand(&self, shorthand: Shorthand) -> Option< &str> {
         match *self {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}(ref value) => match *value {
                     DeclaredValue::WithVariables { ref css, from_shorthand: Some(s), .. }
                     if s == shorthand => {
@@ -6167,7 +6030,7 @@ impl PropertyDeclaration {
     /// https://drafts.csswg.org/css-variables/#variables-in-shorthands
     pub fn with_variables(&self) -> bool {
         match *self {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}(ref value) => match *value {
                     DeclaredValue::WithVariables { .. } => true,
                     _ => false,
@@ -6182,7 +6045,7 @@ impl PropertyDeclaration {
 
     pub fn matches(&self, name: &str) -> bool {
         match *self {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 PropertyDeclaration::${property.camel_case}(..) =>
                 % if not property.derived_from:
                     name.eq_ignore_ascii_case("${property.name}"),
@@ -6212,7 +6075,7 @@ impl PropertyDeclaration {
             return PropertyDeclarationParseResult::ValidOrIgnoredDeclaration;
         }
         match_ignore_ascii_case! { name,
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 % if not property.derived_from:
                     "${property.name}" => {
                         % if property.internal:
@@ -6238,7 +6101,7 @@ impl PropertyDeclaration {
                     "${property.name}" => PropertyDeclarationParseResult::UnknownProperty,
                 % endif
             % endfor
-            % for shorthand in SHORTHANDS:
+            % for shorthand in data.shorthands:
                 "${shorthand.name}" => {
                     % if shorthand.internal:
                         if context.stylesheet_origin != Origin::UserAgent {
@@ -6292,7 +6155,7 @@ impl PropertyDeclaration {
 pub mod style_struct_traits {
     use super::longhands;
 
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         pub trait ${style_struct.trait_name}: Clone {
             % for longhand in style_struct.longhands:
                 #[allow(non_snake_case)]
@@ -6313,7 +6176,7 @@ pub mod style_structs {
     use super::longhands;
     use std::hash::{Hash, Hasher};
 
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         % if style_struct.trait_name == "Font":
         #[derive(Clone, HeapSizeOf, Debug)]
         % else:
@@ -6403,7 +6266,7 @@ pub mod style_structs {
                 fn clone_text_orientation(&self) -> longhands::text_orientation::computed_value::T {
                     self.text_orientation.clone()
                 }
-            % elif style_struct.trait_name == "InheritedText" and CONFIG["product"] == "servo":
+            % elif style_struct.trait_name == "InheritedText" and product == "servo":
                 fn clone__servo_text_decorations_in_effect(&self) ->
                     longhands::_servo_text_decorations_in_effect::computed_value::T {
                     self._servo_text_decorations_in_effect.clone()
@@ -6429,7 +6292,7 @@ pub mod style_structs {
 }
 
 pub trait ComputedValues : Clone + Send + Sync + 'static {
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         type Concrete${style_struct.trait_name}: style_struct_traits::${style_struct.trait_name};
     % endfor
 
@@ -6444,7 +6307,7 @@ pub trait ComputedValues : Clone + Send + Sync + 'static {
                shareable: bool,
                writing_mode: WritingMode,
                root_font_size: Au,
-        % for style_struct in active_style_structs():
+        % for style_struct in data.active_style_structs():
                ${style_struct.ident}: Arc<Self::Concrete${style_struct.trait_name}>,
         % endfor
         ) -> Self;
@@ -6453,7 +6316,7 @@ pub trait ComputedValues : Clone + Send + Sync + 'static {
 
         fn do_cascade_property<F: FnOnce(&Vec<Option<CascadePropertyFn<Self>>>)>(f: F);
 
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         fn clone_${style_struct.trait_name_lower}(&self) ->
             Arc<Self::Concrete${style_struct.trait_name}>;
         fn get_${style_struct.trait_name_lower}<'a>(&'a self) ->
@@ -6471,7 +6334,7 @@ pub trait ComputedValues : Clone + Send + Sync + 'static {
 
 #[derive(Clone, HeapSizeOf)]
 pub struct ServoComputedValues {
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         ${style_struct.ident}: Arc<style_structs::${style_struct.servo_struct_name}>,
     % endfor
     custom_properties: Option<Arc<::custom_properties::ComputedValuesMap>>,
@@ -6481,7 +6344,7 @@ pub struct ServoComputedValues {
 }
 
 impl ComputedValues for ServoComputedValues {
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         type Concrete${style_struct.trait_name} = style_structs::${style_struct.servo_struct_name};
     % endfor
 
@@ -6492,7 +6355,7 @@ impl ComputedValues for ServoComputedValues {
                shareable: bool,
                writing_mode: WritingMode,
                root_font_size: Au,
-            % for style_struct in active_style_structs():
+            % for style_struct in data.active_style_structs():
                ${style_struct.ident}: Arc<style_structs::${style_struct.servo_struct_name}>,
             % endfor
         ) -> Self {
@@ -6501,7 +6364,7 @@ impl ComputedValues for ServoComputedValues {
                 shareable: shareable,
                 writing_mode: writing_mode,
                 root_font_size: root_font_size,
-            % for style_struct in active_style_structs():
+            % for style_struct in data.active_style_structs():
                 ${style_struct.ident}: ${style_struct.ident},
             % endfor
             }
@@ -6513,7 +6376,7 @@ impl ComputedValues for ServoComputedValues {
             CASCADE_PROPERTY.with(|x| f(x));
         }
 
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         #[inline]
         fn clone_${style_struct.trait_name_lower}(&self) ->
             Arc<Self::Concrete${style_struct.trait_name}> {
@@ -6715,7 +6578,7 @@ impl ServoComputedValues {
 
     pub fn computed_value_to_string(&self, name: &str) -> Result<String, ()> {
         match name {
-            % for style_struct in active_style_structs():
+            % for style_struct in data.active_style_structs():
                 % for longhand in style_struct.longhands:
                 "${longhand.name}" => Ok(self.${style_struct.ident}.${longhand.ident}.to_css_string()),
                 % endfor
@@ -6769,7 +6632,7 @@ pub fn get_writing_mode<S: style_struct_traits::InheritedBox>(inheritedbox_style
 /// The initial values for all style structs as defined by the specification.
 lazy_static! {
     pub static ref INITIAL_SERVO_VALUES: ServoComputedValues = ServoComputedValues {
-        % for style_struct in active_style_structs():
+        % for style_struct in data.active_style_structs():
             ${style_struct.ident}: Arc::new(style_structs::${style_struct.servo_struct_name} {
                 % for longhand in style_struct.longhands:
                     ${longhand.ident}: longhands::${longhand.ident}::get_initial_value(),
@@ -6807,7 +6670,7 @@ fn cascade_with_cached_declarations<C: ComputedValues>(
             shareable,
             WritingMode::empty(),
             parent_style.root_font_size(),
-            % for style_struct in active_style_structs():
+            % for style_struct in data.active_style_structs():
                 % if style_struct.inherited:
                     parent_style
                 % else:
@@ -6824,7 +6687,7 @@ fn cascade_with_cached_declarations<C: ComputedValues>(
         // Declarations are already stored in reverse order.
         for declaration in sub_list.declarations.iter() {
             match *declaration {
-                % for style_struct in active_style_structs():
+                % for style_struct in data.active_style_structs():
                     % for property in style_struct.longhands:
                         % if not property.derived_from:
                             PropertyDeclaration::${property.camel_case}(ref
@@ -6867,8 +6730,8 @@ fn cascade_with_cached_declarations<C: ComputedValues>(
                                     );
                                 % endif
 
-                                % if property.name in DERIVED_LONGHANDS:
-                                    % for derived in DERIVED_LONGHANDS[property.name]:
+                                % if property.name in data.derived_longhands:
+                                    % for derived in data.derived_longhands[property.name]:
                                             longhands::${derived.ident}
                                                      ::derive_from_${property.ident}(&mut context);
                                     % endfor
@@ -6905,7 +6768,7 @@ pub type CascadePropertyFn<C /*: ComputedValues */> =
 
 pub fn make_cascade_vec<C: ComputedValues>() -> Vec<Option<CascadePropertyFn<C>>> {
     let mut result: Vec<Option<CascadePropertyFn<C>>> = Vec::new();
-    % for style_struct in active_style_structs():
+    % for style_struct in data.active_style_structs():
         % for property in style_struct.longhands:
             let discriminant;
             unsafe {
@@ -7000,7 +6863,7 @@ pub fn cascade<C: ComputedValues>(
             shareable,
             WritingMode::empty(),
             inherited_style.root_font_size(),
-            % for style_struct in active_style_structs():
+            % for style_struct in data.active_style_structs():
             % if style_struct.inherited:
             inherited_style
             % else:
@@ -7090,7 +6953,7 @@ pub fn cascade<C: ComputedValues>(
         if let Some(computed_display) = computed_display {
             let box_ = style.mutate_box();
             box_.set_display(computed_display);
-            % if CONFIG["product"] == "servo":
+            % if product == "servo":
                 box_.set__servo_display_for_hypothetical_box(if is_root_element {
                     computed_display
                 } else {
@@ -7320,7 +7183,7 @@ pub fn modify_style_for_inline_absolute_hypothetical_fragment(style: &mut Arc<Se
 
 pub fn is_supported_property(property: &str) -> bool {
     match_ignore_ascii_case! { property,
-        % for property in SHORTHANDS + LONGHANDS:
+        % for property in data.shorthands + data.longhands:
             "${property.name}" => true,
         % endfor
         _ => property.starts_with("--")
@@ -7331,12 +7194,12 @@ pub fn is_supported_property(property: &str) -> bool {
 macro_rules! css_properties_accessors {
     ($macro_name: ident) => {
         $macro_name! {
-            % for property in SHORTHANDS + LONGHANDS:
+            % for property in data.shorthands + data.longhands:
                 % if not property.derived_from and not property.internal:
                     % if '-' in property.name:
                         [${property.ident.capitalize()}, Set${property.ident.capitalize()}, "${property.name}"],
                     % endif
-                    % if property != LONGHANDS[-1]:
+                    % if property != data.longhands[-1]:
                         [${property.camel_case}, Set${property.camel_case}, "${property.name}"],
                     % else:
                         [${property.camel_case}, Set${property.camel_case}, "${property.name}"]
@@ -7351,7 +7214,7 @@ macro_rules! css_properties_accessors {
 macro_rules! longhand_properties_idents {
     ($macro_name: ident) => {
         $macro_name! {
-            % for property in LONGHANDS:
+            % for property in data.longhands:
                 ${property.ident}
             % endfor
         }
diff --git a/ports/geckolib/build.rs b/ports/geckolib/build.rs
index 9bfe24f8277..17da2b459e4 100644
--- a/ports/geckolib/build.rs
+++ b/ports/geckolib/build.rs
@@ -3,10 +3,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use std::env;
-use std::fs::File;
-use std::io::Write;
 use std::path::Path;
-use std::process::{Command, Stdio, exit};
+use std::process::{Command, exit};
 
 #[cfg(windows)]
 fn find_python() -> String {
@@ -31,36 +29,25 @@ fn find_python() -> String {
 }
 
 fn main() {
-    let python = match env::var("PYTHON") {
-        Ok(python_path) => python_path,
-        Err(_) => find_python(),
-    };
+    let python = env::var("PYTHON").ok().unwrap_or_else(find_python);
 
     // Mako refuses to load templates outside the scope of the current working directory,
     // so we need to run it from the top source directory.
     let geckolib_dir = Path::new(file!()).parent().unwrap();
     let top_dir = geckolib_dir.join("..").join("..");
 
-    let properties_dir = top_dir.join("components").join("style").join("properties");
-    println!("cargo:rerun-if-changed={}", properties_dir.to_str().unwrap());
+    let properties_dir = Path::new("components").join("style").join("properties");
+    println!("cargo:rerun-if-changed={}", top_dir.join(&properties_dir).to_str().unwrap());
     println!("cargo:rerun-if-changed={}", geckolib_dir.join("properties.mako.rs").to_str().unwrap());
 
-    let style_template = Path::new("components/style/properties/properties.mako.rs");
-    let geckolib_template = Path::new("ports/geckolib/properties.mako.rs");
-    let mako = Path::new("components/style/properties/Mako-0.9.1.zip");
-
-    let result = Command::new(python)
-        .current_dir(top_dir)
-        .env("PYTHONPATH", &mako)
-        .env("STYLE_TEMPLATE", &style_template)
-        .env("GECKOLIB_TEMPLATE", &geckolib_template)
-        .arg("ports/geckolib/generate_properties_rs.py")
-        .stderr(Stdio::inherit())
-        .output()
+    let status = Command::new(python)
+        .current_dir(&top_dir)
+        .arg(&properties_dir.join("build.py"))
+        .arg("gecko")
+        .arg("geckolib")
+        .status()
         .unwrap();
-    if !result.status.success() {
+    if !status.success() {
         exit(1)
     }
-    let out = env::var("OUT_DIR").unwrap();
-    File::create(&Path::new(&out).join("properties.rs")).unwrap().write_all(&result.stdout).unwrap();
 }
diff --git a/ports/geckolib/properties.mako.rs b/ports/geckolib/properties.mako.rs
index 77c8b2679c9..422b7116b29 100644
--- a/ports/geckolib/properties.mako.rs
+++ b/ports/geckolib/properties.mako.rs
@@ -2,10 +2,14 @@
  * 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/. */
 
-// STYLE_STRUCTS comes from components/style/properties.mako.rs; see build.rs for more details.
+// `data` comes from components/style/properties.mako.rs; see build.rs for more details.
+
+<%!
+    from data import to_rust_ident
+%>
 
 use app_units::Au;
-% for style_struct in STYLE_STRUCTS:
+% for style_struct in data.style_structs:
 %if style_struct.gecko_ffi_name:
 use gecko_style_structs::${style_struct.gecko_ffi_name};
 use bindings::Gecko_Construct_${style_struct.gecko_ffi_name};
@@ -27,7 +31,7 @@ use style::properties::style_struct_traits::*;
 
 #[derive(Clone)]
 pub struct GeckoComputedValues {
-    % for style_struct in STYLE_STRUCTS:
+    % for style_struct in data.style_structs:
     ${style_struct.ident}: Arc<${style_struct.gecko_struct_name}>,
     % endfor
 
@@ -38,7 +42,7 @@ pub struct GeckoComputedValues {
 }
 
 impl ComputedValues for GeckoComputedValues {
-% for style_struct in STYLE_STRUCTS:
+% for style_struct in data.style_structs:
     type Concrete${style_struct.trait_name} = ${style_struct.gecko_struct_name};
 % endfor
 
@@ -50,7 +54,7 @@ impl ComputedValues for GeckoComputedValues {
            shareable: bool,
            writing_mode: WritingMode,
            root_font_size: Au,
-            % for style_struct in STYLE_STRUCTS:
+            % for style_struct in data.style_structs:
            ${style_struct.ident}: Arc<${style_struct.gecko_struct_name}>,
             % endfor
     ) -> Self {
@@ -59,7 +63,7 @@ impl ComputedValues for GeckoComputedValues {
             shareable: shareable,
             writing_mode: writing_mode,
             root_font_size: root_font_size,
-            % for style_struct in STYLE_STRUCTS:
+            % for style_struct in data.style_structs:
             ${style_struct.ident}: ${style_struct.ident},
             % endfor
         }
@@ -71,7 +75,7 @@ impl ComputedValues for GeckoComputedValues {
         CASCADE_PROPERTY.with(|x| f(x));
     }
 
-    % for style_struct in STYLE_STRUCTS:
+    % for style_struct in data.style_structs:
     #[inline]
     fn clone_${style_struct.trait_name_lower}(&self) -> Arc<Self::Concrete${style_struct.trait_name}> {
         self.${style_struct.ident}.clone()
@@ -237,13 +241,13 @@ impl ${style_struct.trait_name} for ${style_struct.gecko_struct_name} {
 }
 </%def>
 
-<%! MANUAL_STYLE_STRUCTS = [] %>
+<% data.manual_style_structs = [] %>
 <%def name="impl_trait(style_struct_name, skip_longhands=None, skip_additionals=None)">
-<%self:raw_impl_trait style_struct="${next(x for x in STYLE_STRUCTS if x.trait_name == style_struct_name)}"
+<%self:raw_impl_trait style_struct="${next(x for x in data.style_structs if x.trait_name == style_struct_name)}"
                       skip_longhands="${skip_longhands}" skip_additionals="${skip_additionals}">
 ${caller.body()}
 </%self:raw_impl_trait>
-<% MANUAL_STYLE_STRUCTS.append(style_struct_name) %>
+<% data.manual_style_structs.append(style_struct_name) %>
 </%def>
 
 // Proof-of-concept for a style struct with some manually-implemented methods. We add
@@ -270,17 +274,17 @@ ${caller.body()}
     }
 </%self:impl_trait>
 
-% for style_struct in STYLE_STRUCTS:
+% for style_struct in data.style_structs:
 ${declare_style_struct(style_struct)}
 ${impl_style_struct(style_struct)}
-% if not style_struct.trait_name in MANUAL_STYLE_STRUCTS:
+% if not style_struct.trait_name in data.manual_style_structs:
 <%self:raw_impl_trait style_struct="${style_struct}"></%self:raw_impl_trait>
 % endif
 % endfor
 
 lazy_static! {
     pub static ref INITIAL_GECKO_VALUES: GeckoComputedValues = GeckoComputedValues {
-        % for style_struct in STYLE_STRUCTS:
+        % for style_struct in data.style_structs:
            ${style_struct.ident}: ${style_struct.gecko_struct_name}::initial(),
         % endfor
         custom_properties: None,