Added a PolicySchema class.

chrome/browser/policy/policy_schema.h

+// Copyright (c) 2013 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_BROWSER_POLICY_POLICY_SCHEMA_H_
+#define CHROME_BROWSER_POLICY_POLICY_SCHEMA_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/values.h"
+
+namespace policy {
+
+class PolicySchema;
+typedef std::map<std::string, PolicySchema*> PolicySchemaMap;
+
+// Maps known policy keys to their expected types, and recursively describes
+// the known keys within dictionary or list types.
+class PolicySchema {
+ public:
+
+  // Parses |schema| as a JSON v3 schema, and additionally verifies that:
+  // - the version is JSON schema v3;
+  // - the top-level entry is of type "object";
+  // - the top-level object doesn't contain "additionalProperties" nor
+  //   "patternProperties";
+  // - each "property" maps to a schema with one "type";
+  // - the type "any" is not used.
+  // If all the checks pass then the parsed PolicySchema is returned; otherwise
+  // returns NULL.
+  static scoped_ptr<PolicySchema> Parse(const std::string& schema,
+                                        std::string* error);
+
+  explicit PolicySchema(base::Value::Type type);
+  virtual ~PolicySchema();
+
+  // Returns the expected type for this policy. At the top-level PolicySchema
+  // this is always TYPE_DICTIONARY.
+  base::Value::Type type() const { return type_; }
+
+  // It is invalid to call these methods when type() is not TYPE_DICTIONARY.
+  //
+  // GetProperties() returns a map of the known property names to their schemas;
+  // the map is never NULL.
+  // GetSchemaForAdditionalProperties() returns the schema that should be used
+  // for keys not found in the map, and may be NULL.
+  // GetSchemaForProperty() is a utility method that combines both, returning
+  // the mapped schema if found in GetProperties(), otherwise returning
+  // GetSchemaForAdditionalProperties().
+  virtual const PolicySchemaMap* GetProperties() const;
+  virtual const PolicySchema* GetSchemaForAdditionalProperties() const;
+  const PolicySchema* GetSchemaForProperty(const std::string& key) const;
+
+  // It is invalid to call this method when type() is not TYPE_LIST.
+  // Returns the type of the entries of this "array", which is never NULL.
+  virtual const PolicySchema* GetSchemaForItems() const;
+
+ private:
+  const base::Value::Type type_;
+
+  DISALLOW_COPY_AND_ASSIGN(PolicySchema);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_POLICY_SCHEMA_H_