Generate the Chrome policy schema at compile time.

chrome/tools/build/generate_policy_source.py

Index: chrome/tools/build/generate_policy_source.py
diff --git a/chrome/tools/build/generate_policy_source.py b/chrome/tools/build/generate_policy_source.py
index d88374d173342f98a96c3f951e641c090256ae58..9c99b50994f52f8a217104df0b5aa08727e31f15 100755
--- a/chrome/tools/build/generate_policy_source.py
+++ b/chrome/tools/build/generate_policy_source.py
@@ -53,6 +53,7 @@ class PolicyDetails:
     self.name = policy['name']
     self.is_deprecated = policy.get('deprecated', False)
     self.is_device_only = policy.get('device_only', False)
+    self.schema = policy.get('schema', {})
 
     if is_chromium_os:
       expected_platform = 'chrome_os'
@@ -216,7 +217,11 @@ def _WritePolicyConstantHeader(policies, os, f):
           '#include "base/basictypes.h"\n'
           '#include "base/values.h"\n'
           '\n'
-          'namespace policy {\n\n')
+          'namespace policy {\n'
+          '\n'
+          'namespace internal {\n'
+          'struct SchemaNode;\n'
+          '}\n\n')
 
   if os == 'win':
     f.write('// The windows registry path where Chrome policy '
@@ -243,7 +248,11 @@ def _WritePolicyConstantHeader(policies, os, f):
           'bool IsDeprecatedPolicy(const std::string& policy);\n'
           '\n'
           '// Returns the default policy definition list for Chrome.\n'
-          'const PolicyDefinitionList* GetChromePolicyDefinitionList();\n\n')
+          'const PolicyDefinitionList* GetChromePolicyDefinitionList();\n'
+          '\n'
+          '// Returns the root node of the Chrome policy schema.\n'
+          'const internal::SchemaNode* GetChromeSchemaNode();\n'
+          '\n')
   f.write('// Key names for the policy settings.\n'
           'namespace key {\n\n')
   for policy in policies:
@@ -263,9 +272,75 @@ def _GetValueType(policy_type):
   return policy_type if policy_type != 'TYPE_EXTERNAL' else 'TYPE_DICTIONARY'
 
 
+# Map simple schema types to the address of a static SchemaNode that
+# represents that type.
+SIMPLE_SCHEMA_NAME_MAP = {
+  'boolean': '&kSchema_boolean',
+  'integer': '&kSchema_integer',
+  'null'   : '&kSchema_null',
+  'number' : '&kSchema_number',
+  'string' : '&kSchema_string',
+}
+
+
+# Generates SchemaNodes, PropertyNodes and PropertiesNodes for |schema| and
+# its sub-schemas, and writes them to |f|.
+# |prefix| is prepended to the generated variable names.
+# |shared_keys_map| is optional. If present, then property names are looked up
+# there to reuse shared strings. Otherwise a new static C string is generated.
+# Returns an expression that evaluates to a SchemaNode*.
+def _GenerateSchema(f, schema, prefix, shared_keys_map={}):
+  # Simple types use the shared structures.
+  if schema['type'] in SIMPLE_SCHEMA_NAME_MAP:
+    return SIMPLE_SCHEMA_NAME_MAP[schema['type']]
+
+  if schema['type'] == 'array':
+    # Special case for lists of strings, which is a common policy type.
+    if schema['items']['type'] == 'string':
+      return '&kSchema_stringlist'
+    value_type = 'TYPE_LIST'
+    extra = _GenerateSchema(f, schema['items'], prefix + '_items')
+  elif schema['type'] == 'object':
+    value_type = 'TYPE_DICTIONARY'
+
+    if 'additionalProperties' in schema:
+      additionalProperties = _GenerateSchema(
+          f, schema['additionalProperties'], prefix + '_additionalProperties')
+    else:
+      additionalProperties = 'NULL'
+
+    properties = []
+    sorted_properties = sorted(schema.get('properties', {}).items())
+    for property_name, property_schema in sorted_properties:
+      schema_ptr = _GenerateSchema(
+          f, property_schema, prefix + '_property_' + property_name)
+      properties.append((property_name, schema_ptr))
+
+    f.write('const PropertyNode %s_propertyNodes[] = {\n' % prefix)
+    for key, ptr in properties:
+      f.write('  { %s, %s },\n' % (shared_keys_map.get(key, '"%s"' % key), ptr))
+    f.write('};\n\n')
+
+    f.write('const PropertiesNode %s_properties = {\n'
+            '  %s_propertyNodes,\n'
+            '  %s_propertyNodes + ARRAYSIZE_UNSAFE(%s_propertyNodes),\n'
+            '  %s,\n'
+            '};\n\n' % (prefix, prefix, prefix, prefix, additionalProperties))
+
+    extra = '&%s_properties' % prefix
+
+  f.write('const SchemaNode %s = {\n'
+          '  base::Value::%s,\n'
+          '  %s,\n'
+          '};\n\n' % (prefix, value_type, extra))
+
+  return '&%s' % prefix
+
+
 def _WritePolicyConstantSource(policies, os, f):
   f.write('#include "base/basictypes.h"\n'
           '#include "base/logging.h"\n'
+          '#include "components/policy/core/common/schema_internal.h"\n'
           '#include "policy/policy_constants.h"\n'
           '\n'
           'namespace policy {\n\n')
@@ -299,6 +374,38 @@ def _WritePolicyConstantSource(policies, os, f):
 
   f.write('}  // namespace\n\n')
 
+  f.write('namespace internal {\n'
+          'namespace {\n\n')
+
+  # Write shared SchemaNodes for the simple types, and the string list.
+  for node in [ ('boolean',    'BOOLEAN', 'NULL'),
+                ('integer',    'INTEGER', 'NULL'),
+                ('null',       'NULL',    'NULL'),
+                ('number',     'DOUBLE',  'NULL'),
+                ('string',     'STRING',  'NULL'),
+                ('stringlist', 'LIST',    '&kSchema_string') ]:
+    f.write('const SchemaNode kSchema_%s = {\n'
+            '  base::Value::TYPE_%s,\n'
+            '  %s,\n'
+            '};\n\n' % node)
+
+  # Generate the Chrome schema.
+  chrome_schema = {
+    'type': 'object',
+    'properties': {},
+  }
+  shared_keys_map = {}
+  for policy in policies:
+    if policy.is_supported:
+      chrome_schema['properties'][policy.name] = policy.schema
+      shared_keys_map[policy.name] = 'key::k%s' % policy.name
+
+  # And write it.
+  _GenerateSchema(f, chrome_schema, 'kSchema', shared_keys_map)
+
+  f.write('}  // namespace\n'
+          '}  // namespace internal\n\n')
+
   if os == 'win':
     f.write('#if defined(GOOGLE_CHROME_BUILD)\n'
             'const wchar_t kRegistryChromePolicyKey[] = '
@@ -323,6 +430,10 @@ def _WritePolicyConstantSource(policies, os, f):
           '  return &kChromePolicyList;\n'
           '}\n\n')
 
+  f.write('const internal::SchemaNode* GetChromeSchemaNode() {\n'
+          '  return &internal::kSchema;\n'
+          '}\n\n')
+
   f.write('namespace key {\n\n')
   for policy in policies:
     # TODO(joaodasilva): Include only supported policies in