1b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Copyright (c) 2011 The Chromium Authors. All rights reserved. 2b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Use of this source code is governed by a BSD-style license that can be 3b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// found in the LICENSE file. 4b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 5b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Support for using the Singleton<T> pattern with Objective-C objects. A 6b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// SingletonObjC is the same as a Singleton, except the default traits are 7b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// appropriate for Objective-C objects. A typical Objective-C object of type 8b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// NSExampleType can be maintained as a singleton and accessed with: 9b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// 10b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// NSExampleType* exampleSingleton = SingletonObjC<NSExampleType>::get(); 11b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// 12b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// The first time this is used, it will create exampleSingleton as the result 13b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// of [[NSExampleType alloc] init]. Subsequent calls will return the same 14b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// NSExampleType* object. The object will be released by calling 15b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// -[NSExampleType release] when Singleton's atexit routines run 16b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// (see singleton.h). 17b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// 18b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// For Objective-C objects initialized through means other than the 19b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// no-parameter -init selector, DefaultSingletonObjCTraits may be extended 20b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// as needed: 21b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// 22b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// struct FooSingletonTraits : public DefaultSingletonObjCTraits<Foo> { 23b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// static Foo* New() { 24b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// return [[Foo alloc] initWithName:@"selecty"]; 25b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// } 26b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// }; 27b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// ... 28b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Foo* widgetSingleton = SingletonObjC<Foo, FooSingletonTraits>::get(); 29b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 30b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat#ifndef BASE_MEMORY_SINGLETON_OBJC_H_ 31b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat#define BASE_MEMORY_SINGLETON_OBJC_H_ 32b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 33b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat#import <Foundation/Foundation.h> 34b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat#include "base/memory/singleton.h" 35b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 36b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Singleton traits usable to manage traditional Objective-C objects, which 37b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// are instantiated by sending |alloc| and |init| messages, and are deallocated 38b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// in a memory-managed environment when their retain counts drop to 0 by 39b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// sending |release| messages. 40b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erattemplate<typename Type> 41b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Eratstruct DefaultSingletonObjCTraits : public DefaultSingletonTraits<Type> { 42b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat static Type* New() { 43b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat return [[Type alloc] init]; 44b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat } 45b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 46b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat static void Delete(Type* object) { 47b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat [object release]; 48b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat } 49b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat}; 50b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 51b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// Exactly like Singleton, but without the DefaultSingletonObjCTraits as the 52b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// default trait class. This makes it straightforward for Objective-C++ code 53b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat// to hold Objective-C objects as singletons. 54b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erattemplate<typename Type, 55b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat typename Traits = DefaultSingletonObjCTraits<Type>, 56b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat typename DifferentiatingType = Type> 57b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Eratclass SingletonObjC : public Singleton<Type, Traits, DifferentiatingType> { 58b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat}; 59b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat 60b8cf94937c52feb53b55c39e3f82094d27de464cDaniel Erat#endif // BASE_MEMORY_SINGLETON_OBJC_H_ 61