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// 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 BASE_MEMORY_SCOPED_NSOBJECT_H_
#define BASE_MEMORY_SCOPED_NSOBJECT_H_
#pragma once
#import <Foundation/Foundation.h>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
// scoped_nsobject<> is patterned after scoped_ptr<>, but maintains ownership
// of an NSObject subclass object. Style deviations here are solely for
// compatibility with scoped_ptr<>'s interface, with which everyone is already
// familiar.
//
// When scoped_nsobject<> takes ownership of an object (in the constructor or
// in reset()), it takes over the caller's existing ownership claim. The
// caller must own the object it gives to scoped_nsobject<>, and relinquishes
// an ownership claim to that object. scoped_nsobject<> does not call
// -retain.
//
// scoped_nsobject<> is not to be used for NSAutoreleasePools. For
// NSAutoreleasePools use ScopedNSAutoreleasePool from
// scoped_nsautorelease_pool.h instead.
// We check for bad uses of scoped_nsobject and NSAutoreleasePool at compile
// time with a template specialization (see below).
template<typename NST>
class scoped_nsobject {
public:
explicit scoped_nsobject(NST* object = nil)
: object_(object) {
}
~scoped_nsobject() {
[object_ release];
}
void reset(NST* object = nil) {
// We intentionally do not check that object != object_ as the caller must
// already have an ownership claim over whatever it gives to
// scoped_nsobject and ScopedCFTypeRef, whether it's in the constructor or
// in a call to reset(). In either case, it relinquishes that claim and
// the scoper assumes it.
[object_ release];
object_ = object;
}
bool operator==(NST* that) const { return object_ == that; }
bool operator!=(NST* that) const { return object_ != that; }
operator NST*() const {
return object_;
}
NST* get() const {
return object_;
}
void swap(scoped_nsobject& that) {
NST* temp = that.object_;
that.object_ = object_;
object_ = temp;
}
// scoped_nsobject<>::release() is like scoped_ptr<>::release. It is NOT
// a wrapper for [object_ release]. To force a scoped_nsobject<> object to
// call [object_ release], use scoped_nsobject<>::reset().
NST* release() WARN_UNUSED_RESULT {
NST* temp = object_;
object_ = nil;
return temp;
}
private:
NST* object_;
DISALLOW_COPY_AND_ASSIGN(scoped_nsobject);
};
// Free functions
template <class C>
void swap(scoped_nsobject<C>& p1, scoped_nsobject<C>& p2) {
p1.swap(p2);
}
template <class C>
bool operator==(C* p1, const scoped_nsobject<C>& p2) {
return p1 == p2.get();
}
template <class C>
bool operator!=(C* p1, const scoped_nsobject<C>& p2) {
return p1 != p2.get();
}
// Specialization to make scoped_nsobject<id> work.
template<>
class scoped_nsobject<id> {
public:
explicit scoped_nsobject(id object = nil)
: object_(object) {
}
~scoped_nsobject() {
[object_ release];
}
void reset(id object = nil) {
// We intentionally do not check that object != object_ as the caller must
// already have an ownership claim over whatever it gives to
// scoped_nsobject and ScopedCFTypeRef, whether it's in the constructor or
// in a call to reset(). In either case, it relinquishes that claim and
// the scoper assumes it.
[object_ release];
object_ = object;
}
bool operator==(id that) const { return object_ == that; }
bool operator!=(id that) const { return object_ != that; }
operator id() const {
return object_;
}
id get() const {
return object_;
}
void swap(scoped_nsobject& that) {
id temp = that.object_;
that.object_ = object_;
object_ = temp;
}
// scoped_nsobject<>::release() is like scoped_ptr<>::release. It is NOT
// a wrapper for [object_ release]. To force a scoped_nsobject<> object to
// call [object_ release], use scoped_nsobject<>::reset().
id release() WARN_UNUSED_RESULT {
id temp = object_;
object_ = nil;
return temp;
}
private:
id object_;
DISALLOW_COPY_AND_ASSIGN(scoped_nsobject);
};
// Do not use scoped_nsobject for NSAutoreleasePools, use
// ScopedNSAutoreleasePool instead. This is a compile time check. See details
// at top of header.
template<>
class scoped_nsobject<NSAutoreleasePool> {
private:
explicit scoped_nsobject(NSAutoreleasePool* object = nil);
DISALLOW_COPY_AND_ASSIGN(scoped_nsobject);
};
#endif // BASE_MEMORY_SCOPED_NSOBJECT_H_
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