Add a generated ComputedStyleBase class that ComputedStyle extends

third_party/WebKit/Source/build/scripts/make_computed_style_base.py

Index: third_party/WebKit/Source/build/scripts/make_computed_style_base.py
diff --git a/third_party/WebKit/Source/build/scripts/make_computed_style_base.py b/third_party/WebKit/Source/build/scripts/make_computed_style_base.py
new file mode 100755
index 0000000000000000000000000000000000000000..06db1ccf8955b601cf9bc14ab90506d0584a2b95
--- /dev/null
+++ b/third_party/WebKit/Source/build/scripts/make_computed_style_base.py
@@ -0,0 +1,88 @@
+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from collections import namedtuple
+import math
+import sys
+
+import in_generator
+import template_expander
+import make_style_builder
+
+
+class ComputedStyleBaseWriter(make_style_builder.StyleBuilderWriter):
+    def __init__(self, in_file_path):
+        super(ComputedStyleBaseWriter, self).__init__(in_file_path)
+        self._outputs = {
+            'ComputedStyleBase.h': self.generate_base_computed_style_h,
+            'ComputedStyleBase.cpp': self.generate_base_computed_style_cpp,
+            'ComputedStyleBaseConstants.h': self.generate_base_computed_style_constants,
+        }
+
+        # A map of enum name -> list of enum values
+        self._computed_enums = {}
+        for property in self._properties.values():
+            if property['keyword_only']:
+                enum_name = property['type_name']
+                # From the Blink style guide: Enum members should use InterCaps with an initial capital letter. [names-enum-members]
+                enum_values = [k.title() for k in property['keywords']]
+                self._computed_enums[enum_name] = enum_values
+
+        # A list of fields
+        Field = namedtuple('Field', [
+            # Name of field member variable
+            'name',
+            # Property field is for
+            'property',
+            # Field storage type
+            'type',
+            # Bits needed for storage
+            'size',
+            # Default value for field
+            'default_value',
+        ])
+        self._fields = []
+        for property in self._properties.values():
+            if property['keyword_only']:
+                # From the Blink style guide: Other data members should be prefixed by "m_". [names-data-members]
+                field_name = 'm_' + property['lower_camel_name']
+                bits_needed = math.log(len(property['keywords']), 2)
+                type_name = property['type_name']
+                # For now, assume the default value is the first enum value.
+                default_value = type_name + '::' + self._computed_enums[type_name][0]
+                self._fields.append(Field(
+                    name=field_name,
+                    property=property,
+                    type=type_name,
+                    size=int(math.ceil(bits_needed)),
+                    default_value=default_value,
+                ))
+
+    @template_expander.use_jinja('ComputedStyleBase.h.tmpl')
+    def generate_base_computed_style_h(self):
+        return {
+            'properties': self._properties,
+            'enums': self._computed_enums,
+            'fields': self._fields,
+        }
+
+    @template_expander.use_jinja('ComputedStyleBase.cpp.tmpl')
+    def generate_base_computed_style_cpp(self):
+        return {
+            'properties': self._properties,
+            'enums': self._computed_enums,
+            'fields': self._fields,
+        }
+
+    @template_expander.use_jinja('ComputedStyleBaseConstants.h.tmpl')
+    def generate_base_computed_style_constants(self):
+        return {
+            'properties': self._properties,
+            'enums': self._computed_enums,
+            'fields': self._fields,
+        }
+
+if __name__ == '__main__':
+    in_generator.Maker(ComputedStyleBaseWriter).main(sys.argv)