Make a dictionary that expresses a diff between two json files including AST.

third_party/WebKit/Source/bindings/scripts/generate_idl_diff.py

Index: third_party/WebKit/Source/bindings/scripts/generate_idl_diff.py
diff --git a/third_party/WebKit/Source/bindings/scripts/generate_idl_diff.py b/third_party/WebKit/Source/bindings/scripts/generate_idl_diff.py
new file mode 100755
index 0000000000000000000000000000000000000000..ae98695aa495fcc8895202d8f49a22d7aa9aeed7
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/scripts/generate_idl_diff.py
@@ -0,0 +1,184 @@
+#!/usr/bin/env python
+# Copyright 2015 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.
+
+"""generate_idl_diff.py is a script that generates a diff of two given IDL files.
+Usage: generate_idl_diff.py old_file.json new_file.json diff_file.json
+    old_file.json: An input json file including idl data of old Chrome version
+    new_file.json: An input json file including idl data of new Chrome version
+    diff_file.json: An output json file expressing a diff between old_file.json
+        and new_file.json
+"""
+
+import json
+import os
+import sys
+
+
+"""Data structure of input files of this script.
+The format of the json files is as follows. Each json file contains multiple
+"interface"s. Each "interface" contains 'ExtAttributes', 'Consts', 'Attributes'
+and 'Operations'. Each item in them are called a "member".
+    {'InterfaceName': {
+            'ExtAttributes': [{'Name': '...'},
+                               ...,
+                             ],
+            'Consts': [{'Type': '...',
+                        'Name': '...',
+                        'Value': '...'
+                       },
+                       ...,
+                      ],
+            'Attributes': [{'Type': '...',
+                            'Name': '...',
+                            'ExtAttributes':[{'Name': '...'},
+                                              ...,
+                                            ]
+                           },
+                           ...,
+                          ],
+            'Operations': [{'Type': '...',
+                            'Name': '...',
+                            'ExtAttributes': [{'Name': '...'},
+                                               ...,
+                                             ]
+                            'Arguments': [{'Type': '...',
+                                           'Name': '...'},
+                                           ...,
+                                         ]
+                           },
+                           ...,
+                          ],
+            'Name': '...'
+        },
+        ...,
+    }
+"""
+
+
+EXTATTRIBUTES_AND_MEMBER_TYPES = ['ExtAttributes', 'Consts', 'Attributes', 'Operations']
+DIFF_INSENSITIVE_FIELDS = ['Name']
+DIFF_TAG = 'diff_tag'
+DIFF_TAG_ADDED = 'added'
+DIFF_TAG_DELETED = 'deleted'
+
+
+def load_json_file(filepath):
+    """Load a json file into a dictionary.
+    Args:
+        filepath: A json file path of a json file that we want to load
+    Returns:
+        An "interfaces" object loaded from the json file
+    """
+    with open(filepath, 'r') as f:
+        return json.load(f)
+
+
+def members_diff(old_interface, new_interface):
+    """Create a diff between two "interface" objects by adding annotations to
+    "member" objects that are not common in them.
+    Args:
+        old_interface: An "interface" object
+        new_interface: An "interface" object
+    Returns:
+        (annotated, is_changed) where
+        annotated: An annotated "interface" object
+        is_changed: True if two interfaces are not identical, otherwise False
+    """
+    annotated = {}
+    is_changed = False
+    for member_type in EXTATTRIBUTES_AND_MEMBER_TYPES:
+        annotated_members = []
+        unannotated_members = []
+        for member in new_interface[member_type]:
+            if member in old_interface[member_type]:
+                unannotated_members.append(member)
+                old_interface[member_type].remove(member)
+            else:
+                is_changed = True
+                member[DIFF_TAG] = DIFF_TAG_ADDED
+                annotated_members.append(member)
+        annotated[member_type] = annotated_members
+        annotated[member_type].extend(unannotated_members)
+    for member_type in EXTATTRIBUTES_AND_MEMBER_TYPES:
+        for member in old_interface[member_type]:
+            is_changed = True
+            member[DIFF_TAG] = DIFF_TAG_DELETED
+        annotated[member_type].extend(old_interface[member_type])
+    for field in DIFF_INSENSITIVE_FIELDS:
+        annotated[field] = old_interface[field]
+    return (annotated, is_changed)
+
+
+def annotate_all_members(interface, diff_tag):
+    """Add annotations to all "member" objects of |interface|.
+    Args:
+        interface: An "interface" object whose members should be annotated with
+            |diff_tag|.
+        diff_tag: DIFF_TAG_ADDED or DIFF_TAG_DELETED
+    Returns:
+        Annotated "interface" object
+    """
+    for member_type in EXTATTRIBUTES_AND_MEMBER_TYPES:
+        for member in interface[member_type]:
+            member[DIFF_TAG] = diff_tag
+    return interface
+
+
+def interfaces_diff(old_interfaces, new_interfaces):
+    """Compare two "interfaces" objects and create a diff between them by
+    adding annotations (DIFF_TAG_ADDED or DIFF_TAG_DELETED) to each member
+    and/or interface.
+    Args:
+        old_interfaces: An "interfaces" object
+        new_interfaces: An "interfaces" object
+    Returns:
+        An "interfaces" object representing diff between |old_interfaces| and
+        |new_interfaces|
+    """
+    annotated = {}
+    for interface_name, interface in new_interfaces.items():
+        if interface_name in old_interfaces:
+            annotated_interface, is_changed = members_diff(old_interfaces[interface_name], interface)
+            if is_changed:
+                annotated[interface_name] = annotated_interface
+            del old_interfaces[interface_name]
+        else:
+            interface = annotate_all_members(interface, DIFF_TAG_ADDED)
+            interface[DIFF_TAG] = DIFF_TAG_ADDED
+            annotated[interface_name] = interface
+    for interface_name, interface in old_interfaces.items():
+        interface = annotate_all_members(interface, DIFF_TAG_DELETED)
+        interface[DIFF_TAG] = DIFF_TAG_DELETED
+    annotated.update(old_interfaces)
+    return annotated
+
+
+def write_diff(diff, filepath):
+    """Write a diff dictionary to a json file.
+    Args:
+        diff: An "interfaces" object that represents a diff
+        filepath: An output file path
+    """
+    with open(filepath, 'w') as f:
+        json.dump(diff, f, indent=4)
+
+
+def main(argv):
+    if len(argv) != 3:
+        sys.stdout.write(
+            'Usage: make_diff.py <old_file.json> <new_file.json> '
+            '<diff_file.json>\n')
+        exit(1)
+    old_json_file = argv[0]
+    new_json_file = argv[1]
+    output_file = argv[2]
+    old_interfaces = load_json_file(old_json_file)
+    new_interfaces = load_json_file(new_json_file)
+    diff = interfaces_diff(old_interfaces, new_interfaces)
+    write_diff(diff, output_file)
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])