Moving prepopulated search engines to a JSON file.

tools/json_to_struct/element_generator.py

+# Copyright (c) 2012 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.
+
+import json
+import struct_generator
+
+def _JSONToCString16(json_string_literal):
+  """Converts a JSON string literal to a C++ UTF-16 string literal. This is
+  done by converting \\u#### to \\x####.
+  """
+  c_string_literal = json_string_literal
+  i = 0
+  while 1:
+    i = json_string_literal.find('\\', i)
+    if i == -1: break
+    if json_string_literal[i + 1] == 'u':
+      c_string_literal = (json_string_literal[0:i + 1] + 'x' +
+                          json_string_literal[i + 2:])
+    i += 2
+  return c_string_literal
+
+def _GenerateInt(field_info, content, lines):
+  """Generates an int to be included in a static structure initializer. If
+  content is not specified, generates the default int for this field.
+  """
+  if content is None:
+    content = field_info['default']
+  lines.append('  %s,' % content)
+
+def _GenerateString(field_info, content, lines):
+  """Generates an UTF-8 string to be included in a static structure initializer.
+  If content is not specified, uses this field's default string or NULL if it
+  doesn't have any default.
+  """
+  try:
+    if content is None:
+      content = field_info['default']

[not at google - send to devlin, 2012/11/13 20:28:07]

content = field_info.get('default', 'NULL') rather than keyerror?

[beaudoin, 2012/11/13 21:42:04]

Thanks. First Python patch so I have likely missed a couple of idioms. :)

Done.

+    # json.dumps quotes the string and escape characters as required.
+    lines.append('  %s,' % json.dumps(content))
+  except KeyError:
+    lines.append('  NULL,')
+
+def _GenerateString16(field_info, content, lines):
+  """Generates an UTF-16 string to be included in a static structure
+  initializer. If content is not specified, uses this field's default string or
+  NULL if it doesn't have any default.
+  """
+  try:
+    if content is None:
+      content = field_info['default']
+    # json.dumps quotes the string and escape characters as required.
+    lines.append('  L%s,' % _JSONToCString16(json.dumps(content)))
+  except KeyError:

[not at google - send to devlin, 2012/11/13 20:28:07]

etc

It would actually be nice not to need to repeat all this code and have the
callee of this functions do this "content is None" business. See comment below.

[beaudoin, 2012/11/13 21:42:04]

Done.

+    lines.append('  NULL,')
+
+def _GenerateEnum(field_info, content, lines):
+  """Generates an enum to be included in a static structure initializer. If
+  content is not specified, generates the default enum for this field.
+  """
+  if content is None:
+    content = field_info['default']
+  lines.append('  %s,' % content)
+
+def _GenerateArray(field_info, content, lines):
+  """Generates an array to be included in a static structure initializer. If
+  content is not specified, uses NULL. The array is assigned to a temporary
+  variable which is initilized before the structure.
+  """
+  if content is None:
+    lines.append('  NULL,')
+    lines.append('  0,')  # Size of the array.

[not at google - send to devlin, 2012/11/13 20:28:07]

nit: return, no else.

[beaudoin, 2012/11/13 21:42:04]

Done.

+  else:
+    # Create a new array variable and use it in the structure initializer.
+    # This prohibits nested arrays. Add a clash detection and renaming mechanism
+    # to solve the problem.
+    var = 'array_%s' % field_info['field'];
+    lines.append('  %s,' % var)
+    lines.append('  %s,' % len(content))  # Size of the array.
+    # Generate the array content.
+    array_lines = []
+    field_info['contents']['field'] = var;
+    array_lines.append(struct_generator.GenerateField(
+                       field_info['contents']) + '[] = {')
+    for subcontent in content:
+      GenerateFieldContent(field_info['contents'], subcontent, array_lines)
+    array_lines.append('};')
+    # Prepend the generated array so it is initialized before the structure.
+    lines.reverse()
+    array_lines.reverse()
+    lines.extend(array_lines)
+    lines.reverse()
+
+# Map of supported types to generator functions.
+_content_generators = {
+  "int": _GenerateInt,
+  "string": _GenerateString,
+  "string16": _GenerateString16,
+  "enum": _GenerateEnum,
+  "array": _GenerateArray,
+}

[not at google - send to devlin, 2012/11/13 20:28:07]

I think that using this is obfuscating the code in _GenerateFieldContent, over
that just comparing to the type. It might make the structure of those _Generate
functions less contrived.

[beaudoin, 2012/11/13 21:42:04]

Done.

+
+def GenerateFieldContent(field_info, content, lines):
+  """Generate the content of a field to be included in the static structure
+  initializer.
+  """
+  return _content_generators[field_info['type']](field_info, content, lines)
+
+def GenerateElement(type_name, schema, element_name, element):
+  """Generate the static structure initializer for one element.
+  """
+  lines = [];
+  lines.append('const %s %s = {' % (type_name, element_name));
+  for field_info in schema:
+    content = element.get(field_info['field'], None)
+    if (content == None and not field_info.get('optional', False)):
+      raise RuntimeError('Mandatory field "%s" omitted in element "%s".' %
+          (field_info['field'], element_name))
+    GenerateFieldContent(field_info, content, lines)
+  lines.append('};')
+  return '\n'.join(lines)
+
+def GenerateElements(type_name, schema, description):
+  """Generate the static structure initializer for all the elements in the
+  description['elements'] dictionary, as well as for any variables in
+  description['int_variables'].
+  """
+  result = [];
+  try:
+    for var_name, value in description['int_variables'].items():
+      result.append('const int %s = %s;' % (var_name, value))
+    result.append('')
+  except KeyError:

[not at google - send to devlin, 2012/11/13 20:28:07]

keyerror etc

[beaudoin, 2012/11/13 21:42:04]

Done.

+    pass
+  for element_name, element in description['elements'].items():
+    result.append(GenerateElement(type_name, schema, element_name, element))
+    result.append('')
+  return '\n'.join(result)