Casting.h revision 5fc25cccff3cdbfd34d08b9c1233f9af1879018c
15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)//===-- llvm/Support/Casting.h - Allow flexible, checked, casts -*- C++ -*-===// 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The LLVM Compiler Infrastructure 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This file is distributed under the University of Illinois Open Source 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// License. See LICENSE.TXT for details. 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)//===----------------------------------------------------------------------===// 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(), 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// and dyn_cast_or_null<X>() templates. 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)//===----------------------------------------------------------------------===// 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef LLVM_SUPPORT_CASTING_H 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define LLVM_SUPPORT_CASTING_H 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <cassert> 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace llvm { 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)//===----------------------------------------------------------------------===// 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// isa<x> Support Templates 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)//===----------------------------------------------------------------------===// 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template<typename FromCl> struct isa_impl_cl; 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Define a template that can be specialized by smart pointers to reflect the 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// fact that they are automatically dereferenced, and are not involved with the 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// template selection process... the default implementation is a noop. 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template<typename From> struct simplify_type { 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef From SimpleType; // The real type this represents... 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // An accessor to get the real value... 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static SimpleType &getSimplifiedValue(From &Val) { return Val; } 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 38 39template<typename From> struct simplify_type<const From> { 40 typedef const From SimpleType; 41 static SimpleType &getSimplifiedValue(const From &Val) { 42 return simplify_type<From>::getSimplifiedValue(static_cast<From&>(Val)); 43 } 44}; 45 46 47// isa<X> - Return true if the parameter to the template is an instance of the 48// template type argument. Used like this: 49// 50// if (isa<Type*>(myVal)) { ... } 51// 52template <typename To, typename From> 53struct isa_impl { 54 static inline bool doit(const From &Val) { 55 return To::classof(&Val); 56 } 57}; 58 59template<typename To, typename From, typename SimpleType> 60struct isa_impl_wrap { 61 // When From != SimplifiedType, we can simplify the type some more by using 62 // the simplify_type template. 63 static bool doit(const From &Val) { 64 return isa_impl_cl<const SimpleType>::template 65 isa<To>(simplify_type<const From>::getSimplifiedValue(Val)); 66 } 67}; 68 69template<typename To, typename FromTy> 70struct isa_impl_wrap<To, const FromTy, const FromTy> { 71 // When From == SimpleType, we are as simple as we are going to get. 72 static bool doit(const FromTy &Val) { 73 return isa_impl<To,FromTy>::doit(Val); 74 } 75}; 76 77// isa_impl_cl - Use class partial specialization to transform types to a single 78// canonical form for isa_impl. 79// 80template<typename FromCl> 81struct isa_impl_cl { 82 template<class ToCl> 83 static bool isa(const FromCl &Val) { 84 return isa_impl_wrap<ToCl,const FromCl, 85 typename simplify_type<const FromCl>::SimpleType>::doit(Val); 86 } 87}; 88 89// Specialization used to strip const qualifiers off of the FromCl type... 90template<typename FromCl> 91struct isa_impl_cl<const FromCl> { 92 template<class ToCl> 93 static bool isa(const FromCl &Val) { 94 return isa_impl_cl<FromCl>::template isa<ToCl>(Val); 95 } 96}; 97 98// Define pointer traits in terms of base traits... 99template<class FromCl> 100struct isa_impl_cl<FromCl*> { 101 template<class ToCl> 102 static bool isa(FromCl *Val) { 103 return isa_impl_cl<FromCl>::template isa<ToCl>(*Val); 104 } 105}; 106 107// Define reference traits in terms of base traits... 108template<class FromCl> 109struct isa_impl_cl<FromCl&> { 110 template<class ToCl> 111 static bool isa(FromCl &Val) { 112 return isa_impl_cl<FromCl>::template isa<ToCl>(&Val); 113 } 114}; 115 116template <class X, class Y> 117inline bool isa(const Y &Val) { 118 return isa_impl_cl<Y>::template isa<X>(Val); 119} 120 121//===----------------------------------------------------------------------===// 122// cast<x> Support Templates 123//===----------------------------------------------------------------------===// 124 125template<class To, class From> struct cast_retty; 126 127 128// Calculate what type the 'cast' function should return, based on a requested 129// type of To and a source type of From. 130template<class To, class From> struct cast_retty_impl { 131 typedef To& ret_type; // Normal case, return Ty& 132}; 133template<class To, class From> struct cast_retty_impl<To, const From> { 134 typedef const To &ret_type; // Normal case, return Ty& 135}; 136 137template<class To, class From> struct cast_retty_impl<To, From*> { 138 typedef To* ret_type; // Pointer arg case, return Ty* 139}; 140 141template<class To, class From> struct cast_retty_impl<To, const From*> { 142 typedef const To* ret_type; // Constant pointer arg case, return const Ty* 143}; 144 145template<class To, class From> struct cast_retty_impl<To, const From*const> { 146 typedef const To* ret_type; // Constant pointer arg case, return const Ty* 147}; 148 149 150template<class To, class From, class SimpleFrom> 151struct cast_retty_wrap { 152 // When the simplified type and the from type are not the same, use the type 153 // simplifier to reduce the type, then reuse cast_retty_impl to get the 154 // resultant type. 155 typedef typename cast_retty<To, SimpleFrom>::ret_type ret_type; 156}; 157 158template<class To, class FromTy> 159struct cast_retty_wrap<To, FromTy, FromTy> { 160 // When the simplified type is equal to the from type, use it directly. 161 typedef typename cast_retty_impl<To,FromTy>::ret_type ret_type; 162}; 163 164template<class To, class From> 165struct cast_retty { 166 typedef typename cast_retty_wrap<To, From, 167 typename simplify_type<From>::SimpleType>::ret_type ret_type; 168}; 169 170// Ensure the non-simple values are converted using the simplify_type template 171// that may be specialized by smart pointers... 172// 173template<class To, class From, class SimpleFrom> struct cast_convert_val { 174 // This is not a simple type, use the template to simplify it... 175 static typename cast_retty<To, From>::ret_type doit(const From &Val) { 176 return cast_convert_val<To, SimpleFrom, 177 typename simplify_type<SimpleFrom>::SimpleType>::doit( 178 simplify_type<From>::getSimplifiedValue(Val)); 179 } 180}; 181 182template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> { 183 // This _is_ a simple type, just cast it. 184 static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) { 185 typename cast_retty<To, FromTy>::ret_type Res2 186 = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val); 187 return Res2; 188 } 189}; 190 191 192 193// cast<X> - Return the argument parameter cast to the specified type. This 194// casting operator asserts that the type is correct, so it does not return null 195// on failure. It does not allow a null argument (use cast_or_null for that). 196// It is typically used like this: 197// 198// cast<Instruction>(myVal)->getParent() 199// 200template <class X, class Y> 201inline typename cast_retty<X, Y>::ret_type cast(const Y &Val) { 202 assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); 203 return cast_convert_val<X, Y, 204 typename simplify_type<Y>::SimpleType>::doit(Val); 205} 206 207// cast_or_null<X> - Functionally identical to cast, except that a null value is 208// accepted. 209// 210template <class X, class Y> 211inline typename cast_retty<X, Y*>::ret_type cast_or_null(Y *Val) { 212 if (Val == 0) return 0; 213 assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); 214 return cast<X>(Val); 215} 216 217 218// dyn_cast<X> - Return the argument parameter cast to the specified type. This 219// casting operator returns null if the argument is of the wrong type, so it can 220// be used to test for a type as well as cast if successful. This should be 221// used in the context of an if statement like this: 222// 223// if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... } 224// 225 226template <class X, class Y> 227inline typename cast_retty<X, Y>::ret_type dyn_cast(const Y &Val) { 228 return isa<X>(Val) ? cast<X, Y>(Val) : 0; 229} 230 231// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null 232// value is accepted. 233// 234template <class X, class Y> 235inline typename cast_retty<X, Y*>::ret_type dyn_cast_or_null(Y *Val) { 236 return (Val && isa<X>(Val)) ? cast<X>(Val) : 0; 237} 238 239} // End llvm namespace 240 241#endif 242