1193323Sed//===-- llvm/Support/Casting.h - Allow flexible, checked, casts -*- C++ -*-===// 2193323Sed// 3193323Sed// The LLVM Compiler Infrastructure 4193323Sed// 5193323Sed// This file is distributed under the University of Illinois Open Source 6193323Sed// License. See LICENSE.TXT for details. 7193323Sed// 8193323Sed//===----------------------------------------------------------------------===// 9193323Sed// 10193323Sed// This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(), 11193323Sed// and dyn_cast_or_null<X>() templates. 12193323Sed// 13193323Sed//===----------------------------------------------------------------------===// 14193323Sed 15193323Sed#ifndef LLVM_SUPPORT_CASTING_H 16193323Sed#define LLVM_SUPPORT_CASTING_H 17193323Sed 18243830Sdim#include "llvm/Support/type_traits.h" 19193323Sed#include <cassert> 20193323Sed 21193323Sednamespace llvm { 22193323Sed 23193323Sed//===----------------------------------------------------------------------===// 24193323Sed// isa<x> Support Templates 25193323Sed//===----------------------------------------------------------------------===// 26193323Sed 27193323Sed// Define a template that can be specialized by smart pointers to reflect the 28193323Sed// fact that they are automatically dereferenced, and are not involved with the 29193323Sed// template selection process... the default implementation is a noop. 30193323Sed// 31193323Sedtemplate<typename From> struct simplify_type { 32193323Sed typedef From SimpleType; // The real type this represents... 33193323Sed 34193323Sed // An accessor to get the real value... 35193323Sed static SimpleType &getSimplifiedValue(From &Val) { return Val; } 36193323Sed}; 37193323Sed 38193323Sedtemplate<typename From> struct simplify_type<const From> { 39249423Sdim typedef typename simplify_type<From>::SimpleType NonConstSimpleType; 40249423Sdim typedef typename add_const_past_pointer<NonConstSimpleType>::type 41249423Sdim SimpleType; 42249423Sdim typedef typename add_lvalue_reference_if_not_pointer<SimpleType>::type 43249423Sdim RetType; 44249423Sdim static RetType getSimplifiedValue(const From& Val) { 45249423Sdim return simplify_type<From>::getSimplifiedValue(const_cast<From&>(Val)); 46193323Sed } 47193323Sed}; 48193323Sed 49223017Sdim// The core of the implementation of isa<X> is here; To and From should be 50223017Sdim// the names of classes. This template can be specialized to customize the 51223017Sdim// implementation of isa<> without rewriting it from scratch. 52243830Sdimtemplate <typename To, typename From, typename Enabler = void> 53206083Srdivackystruct isa_impl { 54206083Srdivacky static inline bool doit(const From &Val) { 55206083Srdivacky return To::classof(&Val); 56206083Srdivacky } 57206083Srdivacky}; 58193323Sed 59243830Sdim/// \brief Always allow upcasts, and perform no dynamic check for them. 60243830Sdimtemplate <typename To, typename From> 61243830Sdimstruct isa_impl<To, From, 62249423Sdim typename enable_if< 63249423Sdim llvm::is_base_of<To, From> 64243830Sdim >::type 65243830Sdim > { 66243830Sdim static inline bool doit(const From &) { return true; } 67243830Sdim}; 68243830Sdim 69223017Sdimtemplate <typename To, typename From> struct isa_impl_cl { 70223017Sdim static inline bool doit(const From &Val) { 71223017Sdim return isa_impl<To, From>::doit(Val); 72193323Sed } 73193323Sed}; 74193323Sed 75223017Sdimtemplate <typename To, typename From> struct isa_impl_cl<To, const From> { 76223017Sdim static inline bool doit(const From &Val) { 77223017Sdim return isa_impl<To, From>::doit(Val); 78193323Sed } 79193323Sed}; 80193323Sed 81223017Sdimtemplate <typename To, typename From> struct isa_impl_cl<To, From*> { 82223017Sdim static inline bool doit(const From *Val) { 83243830Sdim assert(Val && "isa<> used on a null pointer"); 84223017Sdim return isa_impl<To, From>::doit(*Val); 85193323Sed } 86193323Sed}; 87193323Sed 88249423Sdimtemplate <typename To, typename From> struct isa_impl_cl<To, From*const> { 89249423Sdim static inline bool doit(const From *Val) { 90249423Sdim assert(Val && "isa<> used on a null pointer"); 91249423Sdim return isa_impl<To, From>::doit(*Val); 92249423Sdim } 93249423Sdim}; 94249423Sdim 95223017Sdimtemplate <typename To, typename From> struct isa_impl_cl<To, const From*> { 96223017Sdim static inline bool doit(const From *Val) { 97243830Sdim assert(Val && "isa<> used on a null pointer"); 98223017Sdim return isa_impl<To, From>::doit(*Val); 99193323Sed } 100193323Sed}; 101193323Sed 102223017Sdimtemplate <typename To, typename From> struct isa_impl_cl<To, const From*const> { 103223017Sdim static inline bool doit(const From *Val) { 104243830Sdim assert(Val && "isa<> used on a null pointer"); 105223017Sdim return isa_impl<To, From>::doit(*Val); 106193323Sed } 107193323Sed}; 108193323Sed 109223017Sdimtemplate<typename To, typename From, typename SimpleFrom> 110223017Sdimstruct isa_impl_wrap { 111223017Sdim // When From != SimplifiedType, we can simplify the type some more by using 112223017Sdim // the simplify_type template. 113223017Sdim static bool doit(const From &Val) { 114223017Sdim return isa_impl_wrap<To, SimpleFrom, 115223017Sdim typename simplify_type<SimpleFrom>::SimpleType>::doit( 116249423Sdim simplify_type<const From>::getSimplifiedValue(Val)); 117193323Sed } 118193323Sed}; 119193323Sed 120223017Sdimtemplate<typename To, typename FromTy> 121223017Sdimstruct isa_impl_wrap<To, FromTy, FromTy> { 122223017Sdim // When From == SimpleType, we are as simple as we are going to get. 123223017Sdim static bool doit(const FromTy &Val) { 124223017Sdim return isa_impl_cl<To,FromTy>::doit(Val); 125223017Sdim } 126223017Sdim}; 127223017Sdim 128223017Sdim// isa<X> - Return true if the parameter to the template is an instance of the 129223017Sdim// template type argument. Used like this: 130223017Sdim// 131223017Sdim// if (isa<Type>(myVal)) { ... } 132223017Sdim// 133193323Sedtemplate <class X, class Y> 134193323Sedinline bool isa(const Y &Val) { 135249423Sdim return isa_impl_wrap<X, const Y, 136249423Sdim typename simplify_type<const Y>::SimpleType>::doit(Val); 137193323Sed} 138193323Sed 139193323Sed//===----------------------------------------------------------------------===// 140193323Sed// cast<x> Support Templates 141193323Sed//===----------------------------------------------------------------------===// 142193323Sed 143193323Sedtemplate<class To, class From> struct cast_retty; 144193323Sed 145193323Sed 146193323Sed// Calculate what type the 'cast' function should return, based on a requested 147193323Sed// type of To and a source type of From. 148193323Sedtemplate<class To, class From> struct cast_retty_impl { 149193323Sed typedef To& ret_type; // Normal case, return Ty& 150193323Sed}; 151193323Sedtemplate<class To, class From> struct cast_retty_impl<To, const From> { 152193323Sed typedef const To &ret_type; // Normal case, return Ty& 153193323Sed}; 154193323Sed 155193323Sedtemplate<class To, class From> struct cast_retty_impl<To, From*> { 156193323Sed typedef To* ret_type; // Pointer arg case, return Ty* 157193323Sed}; 158193323Sed 159193323Sedtemplate<class To, class From> struct cast_retty_impl<To, const From*> { 160193323Sed typedef const To* ret_type; // Constant pointer arg case, return const Ty* 161193323Sed}; 162193323Sed 163193323Sedtemplate<class To, class From> struct cast_retty_impl<To, const From*const> { 164193323Sed typedef const To* ret_type; // Constant pointer arg case, return const Ty* 165193323Sed}; 166193323Sed 167193323Sed 168193323Sedtemplate<class To, class From, class SimpleFrom> 169193323Sedstruct cast_retty_wrap { 170193323Sed // When the simplified type and the from type are not the same, use the type 171193323Sed // simplifier to reduce the type, then reuse cast_retty_impl to get the 172193323Sed // resultant type. 173193323Sed typedef typename cast_retty<To, SimpleFrom>::ret_type ret_type; 174193323Sed}; 175193323Sed 176193323Sedtemplate<class To, class FromTy> 177193323Sedstruct cast_retty_wrap<To, FromTy, FromTy> { 178193323Sed // When the simplified type is equal to the from type, use it directly. 179193323Sed typedef typename cast_retty_impl<To,FromTy>::ret_type ret_type; 180193323Sed}; 181193323Sed 182193323Sedtemplate<class To, class From> 183193323Sedstruct cast_retty { 184193323Sed typedef typename cast_retty_wrap<To, From, 185193323Sed typename simplify_type<From>::SimpleType>::ret_type ret_type; 186193323Sed}; 187193323Sed 188193323Sed// Ensure the non-simple values are converted using the simplify_type template 189193323Sed// that may be specialized by smart pointers... 190193323Sed// 191193323Sedtemplate<class To, class From, class SimpleFrom> struct cast_convert_val { 192193323Sed // This is not a simple type, use the template to simplify it... 193249423Sdim static typename cast_retty<To, From>::ret_type doit(From &Val) { 194193323Sed return cast_convert_val<To, SimpleFrom, 195193323Sed typename simplify_type<SimpleFrom>::SimpleType>::doit( 196193323Sed simplify_type<From>::getSimplifiedValue(Val)); 197193323Sed } 198193323Sed}; 199193323Sed 200193323Sedtemplate<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> { 201193323Sed // This _is_ a simple type, just cast it. 202193323Sed static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) { 203203954Srdivacky typename cast_retty<To, FromTy>::ret_type Res2 204203954Srdivacky = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val); 205203954Srdivacky return Res2; 206193323Sed } 207193323Sed}; 208193323Sed 209193323Sed 210193323Sed 211193323Sed// cast<X> - Return the argument parameter cast to the specified type. This 212193323Sed// casting operator asserts that the type is correct, so it does not return null 213221345Sdim// on failure. It does not allow a null argument (use cast_or_null for that). 214221345Sdim// It is typically used like this: 215193323Sed// 216193323Sed// cast<Instruction>(myVal)->getParent() 217193323Sed// 218193323Sedtemplate <class X, class Y> 219249423Sdiminline typename cast_retty<X, const Y>::ret_type cast(const Y &Val) { 220193323Sed assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); 221249423Sdim return cast_convert_val<X, const Y, 222249423Sdim typename simplify_type<const Y>::SimpleType>::doit(Val); 223249423Sdim} 224249423Sdim 225249423Sdimtemplate <class X, class Y> 226249423Sdiminline typename cast_retty<X, Y>::ret_type cast(Y &Val) { 227249423Sdim assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); 228193323Sed return cast_convert_val<X, Y, 229193323Sed typename simplify_type<Y>::SimpleType>::doit(Val); 230193323Sed} 231193323Sed 232249423Sdimtemplate <class X, class Y> 233249423Sdiminline typename enable_if< 234249423Sdim is_same<Y, typename simplify_type<Y>::SimpleType>, 235249423Sdim typename cast_retty<X, Y*>::ret_type 236249423Sdim>::type cast(Y *Val) { 237249423Sdim assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!"); 238249423Sdim return cast_convert_val<X, Y*, 239249423Sdim typename simplify_type<Y*>::SimpleType>::doit(Val); 240249423Sdim} 241249423Sdim 242193323Sed// cast_or_null<X> - Functionally identical to cast, except that a null value is 243193323Sed// accepted. 244193323Sed// 245193323Sedtemplate <class X, class Y> 246193323Sedinline typename cast_retty<X, Y*>::ret_type cast_or_null(Y *Val) { 247193323Sed if (Val == 0) return 0; 248193323Sed assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"); 249193323Sed return cast<X>(Val); 250193323Sed} 251193323Sed 252193323Sed 253193323Sed// dyn_cast<X> - Return the argument parameter cast to the specified type. This 254193323Sed// casting operator returns null if the argument is of the wrong type, so it can 255193323Sed// be used to test for a type as well as cast if successful. This should be 256193323Sed// used in the context of an if statement like this: 257193323Sed// 258193323Sed// if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... } 259193323Sed// 260193323Sed 261193323Sedtemplate <class X, class Y> 262249423Sdiminline typename cast_retty<X, const Y>::ret_type dyn_cast(const Y &Val) { 263249423Sdim return isa<X>(Val) ? cast<X>(Val) : 0; 264193323Sed} 265193323Sed 266249423Sdimtemplate <class X, class Y> 267249423Sdiminline typename cast_retty<X, Y>::ret_type dyn_cast(Y &Val) { 268249423Sdim return isa<X>(Val) ? cast<X>(Val) : 0; 269249423Sdim} 270249423Sdim 271249423Sdimtemplate <class X, class Y> 272249423Sdiminline typename enable_if< 273249423Sdim is_same<Y, typename simplify_type<Y>::SimpleType>, 274249423Sdim typename cast_retty<X, Y*>::ret_type 275249423Sdim>::type dyn_cast(Y *Val) { 276249423Sdim return isa<X>(Val) ? cast<X>(Val) : 0; 277249423Sdim} 278249423Sdim 279193323Sed// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null 280193323Sed// value is accepted. 281193323Sed// 282193323Sedtemplate <class X, class Y> 283218893Sdiminline typename cast_retty<X, Y*>::ret_type dyn_cast_or_null(Y *Val) { 284218893Sdim return (Val && isa<X>(Val)) ? cast<X>(Val) : 0; 285193323Sed} 286193323Sed 287193323Sed} // End llvm namespace 288193323Sed 289193323Sed#endif 290