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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 GrTemplates_DEFINED
#define GrTemplates_DEFINED
#include "GrNoncopyable.h"
/**
* Use to cast a ptr to a different type, and maintain strict-aliasing
*/
template <typename Dst, typename Src> Dst GrTCast(Src src) {
union {
Src src;
Dst dst;
} data;
data.src = src;
return data.dst;
}
/**
* Reserves memory that is aligned on double and pointer boundaries.
* Hopefully this is sufficient for all practical purposes.
*/
template <size_t N> class GrAlignedSStorage : GrNoncopyable {
public:
void* get() { return fData; }
private:
union {
void* fPtr;
double fDouble;
char fData[N];
};
};
/**
* Reserves memory that is aligned on double and pointer boundaries.
* Hopefully this is sufficient for all practical purposes. Otherwise,
* we have to do some arcane trickery to determine alignment of non-POD
* types. Lifetime of the memory is the lifetime of the object.
*/
template <int N, typename T> class GrAlignedSTStorage : GrNoncopyable {
public:
/**
* Returns void* because this object does not initialize the
* memory. Use placement new for types that require a cons.
*/
void* get() { return fStorage.get(); }
private:
GrAlignedSStorage<sizeof(T)*N> fStorage;
};
/**
* saves value of T* in and restores in destructor
* e.g.:
* {
* GrAutoTPtrValueRestore<int*> autoCountRestore;
* if (useExtra) {
* autoCountRestore.save(&fCount);
* fCount += fExtraCount;
* }
* ...
* } // fCount is restored
*/
template <typename T> class GrAutoTPtrValueRestore : public GrNoncopyable {
public:
GrAutoTPtrValueRestore() : fPtr(NULL), fVal() {}
GrAutoTPtrValueRestore(T* ptr) {
fPtr = ptr;
if (NULL != ptr) {
fVal = *ptr;
}
}
~GrAutoTPtrValueRestore() {
if (NULL != fPtr) {
*fPtr = fVal;
}
}
// restores previously saved value (if any) and saves value for passed T*
void save(T* ptr) {
if (NULL != fPtr) {
*fPtr = fVal;
}
fPtr = ptr;
fVal = *ptr;
}
private:
T* fPtr;
T fVal;
};
#endif
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