Simple rewrite of generate-bindings.pl in Python

Source/bindings/scripts/json_import_export.py

+# Copyright (C) 2013 Google Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import json
+
+
+def strip_types(subtree):
+    """Clean up IR converted through JSON.
+
+    The Perl IDL IR consists of objects, lists, and leaves.
+    Perl's JSON.pm converts objects to dictionaries with keys type::key.
+    This strips the 'type::' and stores it in an element called TYPE.
+    """
+    if isinstance(subtree, dict):
+        new_dict = {}
+        prefix = None
+        for type_key, value in subtree.iteritems():
+            new_prefix, _, key = type_key.partition('::')
+            if prefix is None:
+                prefix = new_prefix
+                new_dict['TYPE'] = prefix
+            else:
+                if prefix != new_prefix:
+                    raise ValueError('Got multiple prefixes: %s %s' % prefix, new_prefix)
+            new_dict[key] = strip_types(value)
+        return new_dict
+    elif isinstance(subtree, list):
+        new_list = []
+        for item in subtree:
+            new_list.append(strip_types(item))
+            return new_list
+    else:
+        return subtree
+
+
+def none_to_empty_list(document):
+    """Replace various None values with [], so loops work properly."""
+    for interface in document['interfaces']:
+        if interface['attributes'] is None:
+            interface['attributes'] = []
+        if interface['functions'] is None:
+            interface['functions'] = []
+        else:
+            for function in interface['functions']:
+                if function['parameters'] is None:
+                    function['parameters'] = []
+    return document
+
+
+def read_json(json_filename):
+    with open(json_filename) as json_file:
+        perl_ir_as_json = json_file.read()
+    raw_dict = json.loads(perl_ir_as_json)
+    clean_dict = strip_types(raw_dict)
+    return none_to_empty_list(clean_dict)