mirror of https://github.com/axmolengine/axmol.git
51 lines
1.6 KiB
C
51 lines
1.6 KiB
C
|
/*
|
||
|
|
Copyright 2010 Google Inc.
|
||
|
|
|
||
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
you may not use this file except in compliance with the License.
|
||
|
|
You may obtain a copy of the License at
|
||
|
|
|
||
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
|
||
|
|
Unless required by applicable law or agreed to in writing, software
|
||
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
See the License for the specific language governing permissions and
|
||
|
|
limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#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
|