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//===- llvm/Support/PointerLikeTypeTraits.h - Pointer Traits ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the PointerLikeTypeTraits class. This allows data
// structures to reason about pointers and other things that are pointer sized.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
#define LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
#include "llvm/Support/DataTypes.h"
namespace llvm {
/// PointerLikeTypeTraits - This is a traits object that is used to handle
/// pointer types and things that are just wrappers for pointers as a uniform
/// entity.
template <typename T>
class PointerLikeTypeTraits {
// getAsVoidPointer
// getFromVoidPointer
// getNumLowBitsAvailable
};
// Provide PointerLikeTypeTraits for non-cvr pointers.
template<typename T>
class PointerLikeTypeTraits<T*> {
public:
static inline void *getAsVoidPointer(T* P) { return P; }
static inline T *getFromVoidPointer(void *P) {
return static_cast<T*>(P);
}
/// Note, we assume here that malloc returns objects at least 4-byte aligned.
/// However, this may be wrong, or pointers may be from something other than
/// malloc. In this case, you should specialize this template to reduce this.
///
/// All clients should use assertions to do a run-time check to ensure that
/// this is actually true.
enum { NumLowBitsAvailable = 2 };
};
// Provide PointerLikeTypeTraits for const pointers.
template<typename T>
class PointerLikeTypeTraits<const T*> {
typedef PointerLikeTypeTraits<T*> NonConst;
public:
static inline const void *getAsVoidPointer(const T* P) {
return NonConst::getAsVoidPointer(const_cast<T*>(P));
}
static inline const T *getFromVoidPointer(const void *P) {
return NonConst::getFromVoidPointer(const_cast<void*>(P));
}
enum { NumLowBitsAvailable = NonConst::NumLowBitsAvailable };
};
// Provide PointerLikeTypeTraits for uintptr_t.
template<>
class PointerLikeTypeTraits<uintptr_t> {
public:
static inline void *getAsVoidPointer(uintptr_t P) {
return reinterpret_cast<void*>(P);
}
static inline uintptr_t getFromVoidPointer(void *P) {
return reinterpret_cast<uintptr_t>(P);
}
// No bits are available!
enum { NumLowBitsAvailable = 0 };
};
} // end namespace llvm
#endif
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