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// Copyright 2013 The Flutter 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 FLUTTER_FML_PLATFORM_DARWIN_SCOPED_NSOBJECT_H_
#define FLUTTER_FML_PLATFORM_DARWIN_SCOPED_NSOBJECT_H_
// Include NSObject.h directly because Foundation.h pulls in many dependencies.
// (Approx 100k lines of code versus 1.5k for NSObject.h). scoped_nsobject gets
// singled out because it is most typically included from other header files.
#import <Foundation/NSObject.h>
#include "flutter/fml/compiler_specific.h"
#include "flutter/fml/macros.h"
@class NSAutoreleasePool;
namespace fml {
// 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.
//
// scoped_nsobject<> takes ownership of an object (in the constructor or in
// reset()) by taking 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,
// callers have to call this manually if appropriate.
//
// scoped_nsprotocol<> has the same behavior as scoped_nsobject, but can be used
// with protocols.
//
// 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_nsprotocol {
public:
explicit scoped_nsprotocol(NST object = nil) : object_(object) {}
scoped_nsprotocol(const scoped_nsprotocol<NST>& that) : object_([that.object_ retain]) {}
template <typename NSU>
// NOLINTNEXTLINE(google-explicit-constructor)
scoped_nsprotocol(const scoped_nsprotocol<NSU>& that) : object_([that.get() retain]) {}
~scoped_nsprotocol() { [object_ release]; }
scoped_nsprotocol& operator=(const scoped_nsprotocol<NST>& that) {
reset([that.get() retain]);
return *this;
}
void reset(NST object = nil) {
// We intentionally do not check that object != object_ as the caller must
// either already have an ownership claim over whatever it passes to this
// method, or call it with the |RETAIN| policy which will have ensured that
// the object is retained once more when reaching this point.
[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_; } // NOLINT(google-explicit-constructor)
NST get() const { return object_; }
void swap(scoped_nsprotocol& that) {
NST temp = that.object_;
that.object_ = object_;
object_ = temp;
}
// Shift reference to the autorelease pool to be released later.
NST autorelease() { return [release() autorelease]; }
private:
NST object_;
// scoped_nsprotocol<>::release() is like scoped_ptr<>::release. It is NOT a
// wrapper for [object_ release]. To force a scoped_nsprotocol<> to call
// [object_ release], use scoped_nsprotocol<>::reset().
[[nodiscard]] NST release() {
NST temp = object_;
object_ = nil;
return temp;
}
};
// Free functions
template <class C>
void swap(scoped_nsprotocol<C>& p1, scoped_nsprotocol<C>& p2) {
p1.swap(p2);
}
template <class C>
bool operator==(C p1, const scoped_nsprotocol<C>& p2) {
return p1 == p2.get();
}
template <class C>
bool operator!=(C p1, const scoped_nsprotocol<C>& p2) {
return p1 != p2.get();
}
template <typename NST>
class scoped_nsobject : public scoped_nsprotocol<NST*> {
public:
explicit scoped_nsobject(NST* object = nil) : scoped_nsprotocol<NST*>(object) {}
scoped_nsobject(const scoped_nsobject<NST>& that) : scoped_nsprotocol<NST*>(that) {}
template <typename NSU>
// NOLINTNEXTLINE(google-explicit-constructor)
scoped_nsobject(const scoped_nsobject<NSU>& that) : scoped_nsprotocol<NST*>(that) {}
scoped_nsobject& operator=(const scoped_nsobject<NST>& that) {
scoped_nsprotocol<NST*>::operator=(that);
return *this;
}
};
// Specialization to make scoped_nsobject<id> work.
template <>
class scoped_nsobject<id> : public scoped_nsprotocol<id> {
public:
explicit scoped_nsobject(id object = nil) : scoped_nsprotocol<id>(object) {}
scoped_nsobject(const scoped_nsobject<id>& that) : scoped_nsprotocol<id>(that) {}
template <typename NSU>
// NOLINTNEXTLINE(google-explicit-constructor)
scoped_nsobject(const scoped_nsobject<NSU>& that) : scoped_nsprotocol<id>(that) {}
scoped_nsobject& operator=(const scoped_nsobject<id>& that) {
scoped_nsprotocol<id>::operator=(that);
return *this;
}
};
// 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);
FML_DISALLOW_COPY_AND_ASSIGN(scoped_nsobject);
};
} // namespace fml
#endif // FLUTTER_FML_PLATFORM_DARWIN_SCOPED_NSOBJECT_H_