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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkTRelay_DEFINED
#define SkTRelay_DEFINED
#include "SkRefCnt.h"
/**
* Similar to a weakptr in java, a Relay allows for a back-ptr to an
* object to be "safe", without using a hard reference-count.
*
* Typically, the target creates a Relay with a pointer to itself. Whenever it
* wants to have another object maintain a safe-ptr to it, it gives them a
* Relay, which they ref()/unref(). Through the Relay each external object can
* retrieve a pointer to the Target. However, when the Target goes away, it
* clears the Relay pointer to it (relay->set(NULL)) and then unref()s the
* Relay. The other objects still have a ref on the Relay, but now when they
* call get() the receive a NULL.
*/
template <template T> class SkTRelay : public SkRefCnt {
public:
SkTRelay(T* ptr) : fPtr(ptr) {}
// consumers call this
T* get() const { return fPtr; }
// producer calls this
void set(T* ptr) { fPtr = ptr; }
void clear() { this->set(NULL); }
private:
T* fPtr;
};
#endif
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