base: Add AsList() function to Value API.

base/values.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.
 
 // This file specifies a recursive data storage class called Value intended for
 // storing setting and other persistable data.  It includes the ability to
 // specify (recursive) lists and dictionaries, so it's fairly expressive.
 // However, the API is optimized for the common case, namely storing a
 // hierarchical tree of simple values.  Given a DictionaryValue root, you can
 // easily do things like:
@@ skipping 69 matching lines @@
   // Returns the type of the value stored by the current Value object.
   // Each type will be implemented by only one subclass of Value, so it's
   // safe to use the Type to determine whether you can cast from
   // Value* to (Implementing Class)*.  Also, a Value object never changes
   // its type after construction.
   Type GetType() const { return type_; }
 
   // Returns true if the current object represents a given type.
   bool IsType(Type type) const { return type == type_; }
 
+  virtual ListValue* AsList();
+
   // These methods allow the convenient retrieval of settings.
   // If the current setting object can be converted into the given type,
   // the value is returned through the |out_value| parameter and true is
   // returned;  otherwise, false is returned and |out_value| is unchanged.
   virtual bool GetAsBoolean(bool* out_value) const;
   virtual bool GetAsInteger(int* out_value) const;
   virtual bool GetAsDouble(double* out_value) const;
   virtual bool GetAsString(std::string* out_value) const;
   virtual bool GetAsString(string16* out_value) const;
   virtual bool GetAsList(ListValue** out_value);
@@ skipping 337 matching lines @@
   }
 
   // Iteration.
   iterator begin() { return list_.begin(); }
   iterator end() { return list_.end(); }
 
   const_iterator begin() const { return list_.begin(); }
   const_iterator end() const { return list_.end(); }
 
   // Overridden from Value:
+  virtual ListValue* AsList() OVERRIDE;
   virtual bool GetAsList(ListValue** out_value) OVERRIDE;
   virtual bool GetAsList(const ListValue** out_value) const OVERRIDE;
   virtual ListValue* DeepCopy() const OVERRIDE;
   virtual bool Equals(const Value* other) const OVERRIDE;
 
  private:
   ValueVector list_;
 
   DISALLOW_COPY_AND_ASSIGN(ListValue);
 };
@@ skipping 17 matching lines @@
 
 }  // namespace base
 
 // http://crbug.com/88666
 using base::DictionaryValue;
 using base::ListValue;
 using base::StringValue;
 using base::Value;
 
 #endif  // BASE_VALUES_H_