1 //===- llvm/Support/PointerLikeTypeTraits.h - Pointer Traits ----*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines the PointerLikeTypeTraits class. This allows data 11 // structures to reason about pointers and other things that are pointer sized. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_POINTERLIKETYPETRAITS_H 16 #define LLVM_SUPPORT_POINTERLIKETYPETRAITS_H 17 18 #include "llvm/Support/DataTypes.h" 19 20 namespace llvm { 21 22 /// PointerLikeTypeTraits - This is a traits object that is used to handle 23 /// pointer types and things that are just wrappers for pointers as a uniform 24 /// entity. 25 template <typename T> 26 class PointerLikeTypeTraits { 27 // getAsVoidPointer 28 // getFromVoidPointer 29 // getNumLowBitsAvailable 30 }; 31 32 // Provide PointerLikeTypeTraits for non-cvr pointers. 33 template<typename T> 34 class PointerLikeTypeTraits<T*> { 35 public: 36 static inline void *getAsVoidPointer(T* P) { return P; } 37 static inline T *getFromVoidPointer(void *P) { 38 return static_cast<T*>(P); 39 } 40 41 /// Note, we assume here that malloc returns objects at least 4-byte aligned. 42 /// However, this may be wrong, or pointers may be from something other than 43 /// malloc. In this case, you should specialize this template to reduce this. 44 /// 45 /// All clients should use assertions to do a run-time check to ensure that 46 /// this is actually true. 47 enum { NumLowBitsAvailable = 2 }; 48 }; 49 50 // Provide PointerLikeTypeTraits for const pointers. 51 template<typename T> 52 class PointerLikeTypeTraits<const T*> { 53 typedef PointerLikeTypeTraits<T*> NonConst; 54 55 public: 56 static inline const void *getAsVoidPointer(const T* P) { 57 return NonConst::getAsVoidPointer(const_cast<T*>(P)); 58 } 59 static inline const T *getFromVoidPointer(const void *P) { 60 return NonConst::getFromVoidPointer(const_cast<void*>(P)); 61 } 62 enum { NumLowBitsAvailable = NonConst::NumLowBitsAvailable }; 63 }; 64 65 // Provide PointerLikeTypeTraits for uintptr_t. 66 template<> 67 class PointerLikeTypeTraits<uintptr_t> { 68 public: 69 static inline void *getAsVoidPointer(uintptr_t P) { 70 return reinterpret_cast<void*>(P); 71 } 72 static inline uintptr_t getFromVoidPointer(void *P) { 73 return reinterpret_cast<uintptr_t>(P); 74 } 75 // No bits are available! 76 enum { NumLowBitsAvailable = 0 }; 77 }; 78 79 } // end namespace llvm 80 81 #endif 82
