Split generate_global_constructors.py out of compute_dependencies.py

Source/bindings/scripts/generate_global_constructors.py

+#!/usr/bin/python
+#
+# Copyright 2014 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.
+
+"""Generates interface properties on global objects.
+
+Concretely these are implemented as "constructor attributes", meaning
+"attributes whose name ends with Constructor" (special-cased by code generator),
+hence "global constructors" for short.
+
+For reference on global objects, see:
+http://www.chromium.org/blink/webidl/blink-idl-extended-attributes#TOC-GlobalContext-i-
+
+Design document:
+http://www.chromium.org/developers/design-documents/idl-build
+"""
+
+import optparse
+import os
+import re
+import sys
+
+from utilities import get_file_contents, write_file, get_interface_extended_attributes_from_idl, is_callback_interface_from_idl
+
+global_objects = {}
+
+
+def parse_options():
+    parser = optparse.OptionParser()
+    parser.add_option('--idl-files-list', help='file listing IDL files')
+    parser.add_option('--write-file-only-if-changed', type='int', help='if true, do not write an output file if it would be identical to the existing one, which avoids unnecessary rebuilds in ninja')
+
+    options, args = parser.parse_args()
+
+    if options.idl_files_list is None:
+        parser.error('Must specify a file listing IDL files using --idl-files-list.')
+    if options.write_file_only_if_changed is None:
+        parser.error('Must specify whether output files are only written if changed using --write-file-only-if-changed.')
+    options.write_file_only_if_changed = bool(options.write_file_only_if_changed)
+
+    return options, args
+
+
+def record_global_constructors(idl_filename):
+    interface_name, _ = os.path.splitext(os.path.basename(idl_filename))
+    full_path = os.path.realpath(idl_filename)
+    idl_file_contents = get_file_contents(full_path)
+    extended_attributes = get_interface_extended_attributes_from_idl(idl_file_contents)
+
+    # An interface property is produced for every non-callback interface
+    # that does not have [NoInterfaceObject].
+    # Callback interfaces with constants also have interface properties,
+    # but there are none of these in Blink.
+    # http://heycam.github.io/webidl/#es-interfaces
+    if (is_callback_interface_from_idl(idl_file_contents) or
+        'NoInterfaceObject' in extended_attributes):
+        return
+
+    global_contexts = extended_attributes.get('GlobalContext', 'Window').split('&')
+    new_constructors_list = generate_global_constructors_list(interface_name, extended_attributes)
+    for interface_name in global_contexts:
+        global_objects[interface_name]['constructors'].extend(new_constructors_list)
+
+
+def generate_global_constructors_list(interface_name, extended_attributes):
+    extended_attributes_list = [
+            name + '=' + extended_attributes[name]
+            for name in 'Conditional', 'PerContextEnabled', 'RuntimeEnabled'
+            if name in extended_attributes]
+    if extended_attributes_list:
+        extended_string = '[%s] ' % ', '.join(extended_attributes_list)
+    else:
+        extended_string = ''
+
+    attribute_string = 'attribute {interface_name}Constructor {interface_name}'.format(interface_name=interface_name)
+    attributes_list = [extended_string + attribute_string]
+
+    # In addition to the usual interface property, for every [NamedConstructor]
+    # extended attribute on an interface, a corresponding property MUST exist
+    # on the ECMAScript global object.
+    # http://heycam.github.io/webidl/#NamedConstructor
+    if 'NamedConstructor' in extended_attributes:
+        named_constructor = extended_attributes['NamedConstructor']
+        # Extract function name, namely everything before opening '('
+        constructor_name = re.sub(r'\(.*', '', named_constructor)
+        # Note the reduplicated 'ConstructorConstructor'
+        # FIXME: rename to NamedConsructor
+        attribute_string = 'attribute %sConstructorConstructor %s' % (interface_name, constructor_name)
+        attributes_list.append(extended_string + attribute_string)
+
+    return attributes_list
+
+
+def write_global_constructors_partial_interface(interface_name, destination_filename, constructor_attributes_list, only_if_changed):
+    lines = (['partial interface %s {\n' % interface_name] +
+             ['    %s;\n' % constructor_attribute
+              for constructor_attribute in sorted(constructor_attributes_list)] +
+             ['};\n'])
+    write_file(lines, destination_filename, only_if_changed)
+
+
+################################################################################
+
+def main():
+    options, args = parse_options()
+
+    # Input IDL files are passed in a file, due to OS command line length
+    # limits. This is generated at GYP time, which is ok b/c files are static.
+    with open(options.idl_files_list) as idl_files_list:
+        idl_files = [line.rstrip('\n') for line in idl_files_list]
+
+    # Output IDL files (to generate) are passed at the command line, since
+    # these are in the build directory, which is determined at build time, not
+    # GYP time.
+    # These are passed as pairs of GlobalObjectName, GlobalObject.idl
+    interface_name_filename = [(args[i], args[i + 1])
+                               for i in range(0, len(args), 2)]
+    global_objects.update(
+        (interface_name, {
+            'filename': filename,
+            'constructors': [],
+        })
+        for interface_name, filename in interface_name_filename)
+
+    for idl_filename in idl_files:
+        record_global_constructors(idl_filename)
+
+    for interface_name, global_object in global_objects.iteritems():
+        write_global_constructors_partial_interface(interface_name, global_object['filename'], global_object['constructors'], options.write_file_only_if_changed)
+
+
+if __name__ == '__main__':
+    sys.exit(main())