Added a validator for JSON v3 schemas.

chrome/common/json_schema/json_schema_validator.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_
 #define CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 class StringValue;
 class Value;
 }
 
 //==============================================================================
 // This class implements a subset of JSON Schema.
@@ skipping 68 matching lines @@
 
   // Utility methods to format error messages. The first method can have one
   // wildcard represented by '*', which is replaced with s1. The second method
   // can have two, which are replaced by s1 and s2.
   static std::string FormatErrorMessage(const std::string& format,
                                         const std::string& s1);
   static std::string FormatErrorMessage(const std::string& format,
                                         const std::string& s1,
                                         const std::string& s2);
 
+  // Verifies if |schema| is a valid JSON v3 schema. When this validation passes
+  // then |schema| is valid JSON that can be parsed into a DictionaryValue,
+  // and that DictionaryValue can be used to build a JSONSchemaValidator.
+  // Returns the parsed DictionaryValue when |schema| validated, otherwise
+  // returns NULL. In that case, |error| contains an error description.
+  static scoped_ptr<base::DictionaryValue> IsValidSchema(
+      const std::string& schema,
+      std::string* error);

[not at google - send to devlin, 2013/05/16 17:08:20]

a static Create method which takes a std::string schema / error* and returns a
scoped_ptr<JSONSchemaValidator> would be easier to use. Transferring
dependencies (i.e. constructing a JSV depends on something that came from
IsValidSchema) is better factored that way.

However, it would probably require more invasive changes/restructuring to
json_schema_validator.cc. 

[Joao da Silva, 2013/05/19 13:16:29]

The returned DictionaryValue can be used to build a JSV, but for the
policy-for-extensions work it'll be used to build a PolicySchema instead. So I'd
leave the types signature as is, but I'm cool with moving this somewhere else or
renaming it, if you have better ideas.

+
   // Creates a validator for the specified schema.
   //
   // NOTE: This constructor assumes that |schema| is well formed and valid.
   // Errors will result in CHECK at runtime; this constructor should not be used
   // with untrusted schemas.
   explicit JSONSchemaValidator(base::DictionaryValue* schema);
 
   // Creates a validator for the specified schema and user-defined types. Each
   // type must be a valid JSONSchema type description with an additional "id"
   // field. Schema objects in |schema| can refer to these types with the "$ref"
@@ skipping 105 matching lines @@
   bool default_allow_additional_properties_;
 
   // Errors accumulated since the last call to Validate().
   std::vector<Error> errors_;
 
 
   DISALLOW_COPY_AND_ASSIGN(JSONSchemaValidator);
 };
 
 #endif  // CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_