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1# Copyright (C) 2013 Google Inc. All rights reserved.
2#
3# Redistribution and use in source and binary forms, with or without
4# modification, are permitted provided that the following conditions are
5# met:
6#
7#     * Redistributions of source code must retain the above copyright
8# notice, this list of conditions and the following disclaimer.
9#     * Redistributions in binary form must reproduce the above
10# copyright notice, this list of conditions and the following disclaimer
11# in the documentation and/or other materials provided with the
12# distribution.
13#     * Neither the name of Google Inc. nor the names of its
14# contributors may be used to endorse or promote products derived from
15# this software without specific prior written permission.
16#
17# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29"""Resolve interface dependencies, producing a merged IdlDefinitions object.
30
31This library computes interface dependencies (partial interfaces and
32implements), reads the dependency files, and merges them to the IdlDefinitions
33for the main IDL file, producing an IdlDefinitions object representing the
34entire interface.
35
36Design doc: http://www.chromium.org/developers/design-documents/idl-compiler#TOC-Dependency-resolution
37"""
38
39import os.path
40
41# The following extended attributes can be applied to a dependency interface,
42# and are then applied to the individual members when merging.
43# Note that this moves the extended attribute from the interface to the member,
44# which changes the semantics and yields different code than the same extended
45# attribute on the main interface.
46DEPENDENCY_EXTENDED_ATTRIBUTES = set([
47    'Conditional',
48    'PerContextEnabled',
49    'RuntimeEnabled',
50])
51
52
53class InterfaceDependencyResolver(object):
54    def __init__(self, interfaces_info, reader):
55        """Initialize dependency resolver.
56
57        Args:
58            interfaces_info:
59                dict of interfaces information, from compute_dependencies.py
60            reader:
61                IdlReader, used for reading dependency files
62        """
63        self.interfaces_info = interfaces_info
64        self.reader = reader
65
66    def resolve_dependencies(self, definitions):
67        """Resolve dependencies, merging them into IDL definitions of main file.
68
69        Dependencies consist of 'partial interface' for the same interface as
70        in the main file, and other interfaces that this interface 'implements'.
71        These are merged into the main IdlInterface, as the main IdlInterface
72        implements all these members.
73
74        Referenced interfaces are added to IdlDefinitions, but not merged into
75        the main IdlInterface, as these are only referenced (their members are
76        introspected, but not implemented in this interface).
77
78        Inherited extended attributes are also added to the main IdlInterface.
79
80        Modifies definitions in place by adding parsed dependencies.
81
82        Args:
83            definitions: IdlDefinitions object, modified in place
84        """
85        target_interface = next(definitions.interfaces.itervalues())
86        interface_name = target_interface.name
87        interface_info = self.interfaces_info[interface_name]
88
89        if 'inherited_extended_attributes' in interface_info:
90            target_interface.extended_attributes.update(
91                interface_info['inherited_extended_attributes'])
92
93        merge_interface_dependencies(definitions,
94                                     target_interface,
95                                     interface_info['dependencies_full_paths'],
96                                     self.reader)
97
98        for referenced_interface_name in interface_info['referenced_interfaces']:
99            referenced_definitions = self.reader.read_idl_definitions(
100                self.interfaces_info[referenced_interface_name]['full_path'])
101            definitions.update(referenced_definitions)
102
103
104def merge_interface_dependencies(definitions, target_interface, dependency_idl_filenames, reader):
105    """Merge dependencies ('partial interface' and 'implements') in dependency_idl_filenames into target_interface.
106
107    No return: modifies target_interface in place.
108    """
109    # Sort so order consistent, so can compare output from run to run.
110    for dependency_idl_filename in sorted(dependency_idl_filenames):
111        dependency_definitions = reader.read_idl_file(dependency_idl_filename)
112        dependency_interface = next(dependency_definitions.interfaces.itervalues())
113        dependency_interface_basename, _ = os.path.splitext(os.path.basename(dependency_idl_filename))
114
115        transfer_extended_attributes(dependency_interface,
116                                     dependency_interface_basename)
117        definitions.update(dependency_definitions)  # merges partial interfaces
118        if not dependency_interface.is_partial:
119            # Implemented interfaces (non-partial dependencies) are also merged
120            # into the target interface, so Code Generator can just iterate
121            # over one list (and not need to handle 'implements' itself).
122            target_interface.merge(dependency_interface)
123
124
125def transfer_extended_attributes(dependency_interface, dependency_interface_basename):
126    """Transfer extended attributes from dependency interface onto members.
127
128    Merging consists of storing certain interface-level data in extended
129    attributes of the *members* (because there is no separate dependency
130    interface post-merging).
131
132    The data storing consists of:
133    * applying certain extended attributes from the dependency interface
134      to its members
135    * storing the C++ class of the implementation in an internal
136      extended attribute of each member, [PartialInterfaceImplementedAs]
137
138    No return: modifies dependency_interface in place.
139    """
140    merged_extended_attributes = dict(
141        (key, value)
142        for key, value in dependency_interface.extended_attributes.iteritems()
143        if key in DEPENDENCY_EXTENDED_ATTRIBUTES)
144
145    # A partial interface's members are implemented as static member functions
146    # in a separate C++ class. This class name is stored in
147    # [PartialInterfaceImplementedAs] which defaults to the basename of
148    # dependency IDL file.
149    # This class name can be overridden by [ImplementedAs] on the partial
150    # interface definition.
151    #
152    # Note that implemented interfaces do *not* need [ImplementedAs], since
153    # they are implemented on the C++ object |impl| itself, just like members of
154    # the main interface definition, so the bindings do not need to know in
155    # which class implemented interfaces are implemented.
156    #
157    # Currently [LegacyTreatAsPartialInterface] can be used to have partial
158    # interface behavior on implemented interfaces, but this is being removed
159    # as legacy cruft:
160    # FIXME: Remove [LegacyTreatAsPartialInterface]
161    # http://crbug.com/360435
162    #
163    # Note that [ImplementedAs] is used with different meanings on interfaces
164    # and members:
165    # for Blink class name and function name (or constant name), respectively.
166    # Thus we do not want to copy this from the interface to the member, but
167    # instead extract it and handle it separately.
168    if (dependency_interface.is_partial or
169        'LegacyTreatAsPartialInterface' in dependency_interface.extended_attributes):
170        merged_extended_attributes['PartialInterfaceImplementedAs'] = (
171            dependency_interface.extended_attributes.get(
172                'ImplementedAs', dependency_interface_basename))
173
174    for attribute in dependency_interface.attributes:
175        attribute.extended_attributes.update(merged_extended_attributes)
176    for constant in dependency_interface.constants:
177        constant.extended_attributes.update(merged_extended_attributes)
178    for operation in dependency_interface.operations:
179        operation.extended_attributes.update(merged_extended_attributes)
180