Added new policy Schema classes.

components/policy/core/common/schema.h

+// Copyright 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 COMPONENTS_POLICY_CORE_COMMON_SCHEMA_H_
+#define COMPONENTS_POLICY_CORE_COMMON_SCHEMA_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "base/values.h"
+#include "components/policy/policy_export.h"
+
+namespace policy {
+namespace internal {
+
+struct POLICY_EXPORT SchemaNode;
+struct POLICY_EXPORT PropertyNode;
+struct POLICY_EXPORT PropertiesNode;
+
+}  // namespace internal
+
+// Describes the expected type of one policy. Also recursively describes the
+// types of inner elements, for structured types.
+// Objects of this class refer to external, immutable data and are cheap to
+// copy.
+// Use the SchemaOwner class to parse a schema and get Schema objects.
+class POLICY_EXPORT Schema {
+ public:
+  explicit Schema(const internal::SchemaNode* schema);
+  Schema(const Schema& schema);
+
+  Schema& operator=(const Schema& schema);
+
+  // Returns true if this Schema is valid. Schemas returned by the methods below
+  // may be invalid, and in those cases the other methods must not be used.
+  bool valid() const { return schema_ != NULL; }
+
+  base::Value::Type type() const;
+
+  // Used to iterate over the known properties of TYPE_DICTIONARY schemas.
+  class POLICY_EXPORT Iterator {
+   public:
+    explicit Iterator(const internal::PropertiesNode* properties);
+    Iterator(const Iterator& iterator);
+    ~Iterator();
+
+    Iterator& operator=(const Iterator& iterator);
+
+    // The other methods must not be called if the iterator is at the end.
+    bool IsAtEnd() const;
+
+    // Advances the iterator to the next property.
+    void Advance();
+
+    // Returns the name of the current property.
+    const char* key() const;
+
+    // Returns the Schema for the current property. This Schema is always valid.
+    Schema schema() const;
+
+   private:
+    const internal::PropertyNode* it_;
+    const internal::PropertyNode* end_;
+  };
+
+  // These methods should be called only if type() == TYPE_DICTIONARY,
+  // otherwise invalid memory will be read. A CHECK is currently enforcing this.
+
+  // Returns an iterator that goes over the named properties of this schema.
+  // The returned iterator is at the beginning.
+  Iterator GetPropertiesIterator() const;
+
+  // Returns the Schema for the property named |key|. If |key| is not a known
+  // property name then the returned Schema is not valid.
+  Schema GetKnownProperty(const std::string& key) const;
+
+  // Returns the Schema for additional properties. If additional properties are
+  // not allowed for this Schema then the Schema returned is not valid.
+  Schema GetAdditionalProperties() const;
+
+  // Returns the Schema for |key| if it is a known property, otherwise returns
+  // the Schema for additional properties.
+  Schema GetProperty(const std::string& key) const;
+
+  // Returns the Schema for items of an array.
+  // This method should be called only if type() == TYPE_LIST,
+  // otherwise invalid memory will be read. A CHECK is currently enforcing this.
+  Schema GetItems() const;
+
+ private:
+  const internal::SchemaNode* schema_;
+};
+
+// Owns schemas for policies of a given component.
+class POLICY_EXPORT SchemaOwner {
+ public:
+  ~SchemaOwner();
+
+  // The returned Schema is valid only during the lifetime of the SchemaOwner
+  // that created it. It may be obtained multiple times.
+  Schema schema() const { return Schema(root_); }
+
+  // Returns a SchemaOwner that references static data. This can be used by
+  // the embedder to pass structures generated at compile time, which can then
+  // be quickly loaded at runtime.
+  // Note: PropertiesNodes must have their PropertyNodes sorted by key.
+  static scoped_ptr<SchemaOwner> Wrap(const internal::SchemaNode* schema);
+
+  // Parses the JSON schema in |schema| and returns a SchemaOwner that owns
+  // the internal representation. If |schema| is invalid then NULL is returned
+  // and |error| contains a reason for the failure.
+  static scoped_ptr<SchemaOwner> Parse(const std::string& schema,
+                                       std::string* error);
+
+ private:
+  explicit SchemaOwner(const internal::SchemaNode* root);
+
+  // Parses the JSON schema in |schema| and returns the root SchemaNode if
+  // successful, otherwise returns NULL. Any intermediate objects built by
+  // this method are appended to the ScopedVectors.
+  const internal::SchemaNode* Parse(const base::DictionaryValue& schema,
+                                    std::string* error);
+
+  // Helper for Parse().
+  const internal::SchemaNode* ParseDictionary(
+      const base::DictionaryValue& schema,
+      std::string* error);
+
+  // Helper for Parse().
+  const internal::SchemaNode* ParseList(const base::DictionaryValue& schema,
+                                        std::string* error);
+
+  const internal::SchemaNode* root_;
+  ScopedVector<internal::SchemaNode> schema_nodes_;
+  // Note: |property_nodes_| contains PropertyNode[] elements and must be
+  // cleared manually to properly use delete[].
+  std::vector<internal::PropertyNode*> property_nodes_;
+  ScopedVector<internal::PropertiesNode> properties_nodes_;
+  ScopedVector<std::string> keys_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchemaOwner);
+};
+
+}  // namespace policy
+
+#endif  // COMPONENTS_POLICY_CORE_COMMON_SCHEMA_H_