Line data Source code
1 : //===-- llvm/Support/Casting.h - Allow flexible, checked, casts -*- 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 isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(),
11 : // and dyn_cast_or_null<X>() templates.
12 : //
13 : //===----------------------------------------------------------------------===//
14 :
15 : #ifndef LLVM_SUPPORT_CASTING_H
16 : #define LLVM_SUPPORT_CASTING_H
17 :
18 : #include "llvm/Support/Compiler.h"
19 : #include "llvm/Support/type_traits.h"
20 : #include <cassert>
21 :
22 : namespace llvm {
23 :
24 : //===----------------------------------------------------------------------===//
25 : // isa<x> Support Templates
26 : //===----------------------------------------------------------------------===//
27 :
28 : // Define a template that can be specialized by smart pointers to reflect the
29 : // fact that they are automatically dereferenced, and are not involved with the
30 : // template selection process... the default implementation is a noop.
31 : //
32 : template<typename From> struct simplify_type {
33 : typedef From SimpleType; // The real type this represents...
34 :
35 : // An accessor to get the real value...
36 1113 : static SimpleType &getSimplifiedValue(From &Val) { return Val; }
37 : };
38 :
39 : template<typename From> struct simplify_type<const From> {
40 : typedef typename simplify_type<From>::SimpleType NonConstSimpleType;
41 : typedef typename add_const_past_pointer<NonConstSimpleType>::type
42 : SimpleType;
43 : typedef typename add_lvalue_reference_if_not_pointer<SimpleType>::type
44 : RetType;
45 : static RetType getSimplifiedValue(const From& Val) {
46 1113 : return simplify_type<From>::getSimplifiedValue(const_cast<From&>(Val));
47 : }
48 : };
49 :
50 : // The core of the implementation of isa<X> is here; To and From should be
51 : // the names of classes. This template can be specialized to customize the
52 : // implementation of isa<> without rewriting it from scratch.
53 : template <typename To, typename From, typename Enabler = void>
54 : struct isa_impl {
55 : static inline bool doit(const From &Val) {
56 1050 : return To::classof(&Val);
57 : }
58 : };
59 :
60 : /// \brief Always allow upcasts, and perform no dynamic check for them.
61 : template <typename To, typename From>
62 : struct isa_impl<
63 : To, From, typename std::enable_if<std::is_base_of<To, From>::value>::type> {
64 63 : static inline bool doit(const From &) { return true; }
65 : };
66 :
67 : template <typename To, typename From> struct isa_impl_cl {
68 : static inline bool doit(const From &Val) {
69 : return isa_impl<To, From>::doit(Val);
70 : }
71 : };
72 :
73 : template <typename To, typename From> struct isa_impl_cl<To, const From> {
74 : static inline bool doit(const From &Val) {
75 : return isa_impl<To, From>::doit(Val);
76 : }
77 : };
78 :
79 : template <typename To, typename From> struct isa_impl_cl<To, From*> {
80 : static inline bool doit(const From *Val) {
81 : assert(Val && "isa<> used on a null pointer");
82 : return isa_impl<To, From>::doit(*Val);
83 : }
84 : };
85 :
86 : template <typename To, typename From> struct isa_impl_cl<To, From*const> {
87 : static inline bool doit(const From *Val) {
88 : assert(Val && "isa<> used on a null pointer");
89 : return isa_impl<To, From>::doit(*Val);
90 : }
91 : };
92 :
93 : template <typename To, typename From> struct isa_impl_cl<To, const From*> {
94 : static inline bool doit(const From *Val) {
95 2226 : assert(Val && "isa<> used on a null pointer");
96 1113 : return isa_impl<To, From>::doit(*Val);
97 : }
98 : };
99 :
100 : template <typename To, typename From> struct isa_impl_cl<To, const From*const> {
101 : static inline bool doit(const From *Val) {
102 : assert(Val && "isa<> used on a null pointer");
103 : return isa_impl<To, From>::doit(*Val);
104 : }
105 : };
106 :
107 : template<typename To, typename From, typename SimpleFrom>
108 : struct isa_impl_wrap {
109 : // When From != SimplifiedType, we can simplify the type some more by using
110 : // the simplify_type template.
111 : static bool doit(const From &Val) {
112 1113 : return isa_impl_wrap<To, SimpleFrom,
113 : typename simplify_type<SimpleFrom>::SimpleType>::doit(
114 1113 : simplify_type<const From>::getSimplifiedValue(Val));
115 : }
116 : };
117 :
118 : template<typename To, typename FromTy>
119 : struct isa_impl_wrap<To, FromTy, FromTy> {
120 : // When From == SimpleType, we are as simple as we are going to get.
121 : static bool doit(const FromTy &Val) {
122 1113 : return isa_impl_cl<To,FromTy>::doit(Val);
123 : }
124 : };
125 :
126 : // isa<X> - Return true if the parameter to the template is an instance of the
127 : // template type argument. Used like this:
128 : //
129 : // if (isa<Type>(myVal)) { ... }
130 : //
131 : template <class X, class Y>
132 : LLVM_ATTRIBUTE_UNUSED_RESULT inline bool isa(const Y &Val) {
133 1113 : return isa_impl_wrap<X, const Y,
134 1113 : typename simplify_type<const Y>::SimpleType>::doit(Val);
135 : }
136 :
137 : //===----------------------------------------------------------------------===//
138 : // cast<x> Support Templates
139 : //===----------------------------------------------------------------------===//
140 :
141 : template<class To, class From> struct cast_retty;
142 :
143 :
144 : // Calculate what type the 'cast' function should return, based on a requested
145 : // type of To and a source type of From.
146 : template<class To, class From> struct cast_retty_impl {
147 : typedef To& ret_type; // Normal case, return Ty&
148 : };
149 : template<class To, class From> struct cast_retty_impl<To, const From> {
150 : typedef const To &ret_type; // Normal case, return Ty&
151 : };
152 :
153 : template<class To, class From> struct cast_retty_impl<To, From*> {
154 : typedef To* ret_type; // Pointer arg case, return Ty*
155 : };
156 :
157 : template<class To, class From> struct cast_retty_impl<To, const From*> {
158 : typedef const To* ret_type; // Constant pointer arg case, return const Ty*
159 : };
160 :
161 : template<class To, class From> struct cast_retty_impl<To, const From*const> {
162 : typedef const To* ret_type; // Constant pointer arg case, return const Ty*
163 : };
164 :
165 :
166 : template<class To, class From, class SimpleFrom>
167 : struct cast_retty_wrap {
168 : // When the simplified type and the from type are not the same, use the type
169 : // simplifier to reduce the type, then reuse cast_retty_impl to get the
170 : // resultant type.
171 : typedef typename cast_retty<To, SimpleFrom>::ret_type ret_type;
172 : };
173 :
174 : template<class To, class FromTy>
175 : struct cast_retty_wrap<To, FromTy, FromTy> {
176 : // When the simplified type is equal to the from type, use it directly.
177 : typedef typename cast_retty_impl<To,FromTy>::ret_type ret_type;
178 : };
179 :
180 : template<class To, class From>
181 : struct cast_retty {
182 : typedef typename cast_retty_wrap<To, From,
183 : typename simplify_type<From>::SimpleType>::ret_type ret_type;
184 : };
185 :
186 : // Ensure the non-simple values are converted using the simplify_type template
187 : // that may be specialized by smart pointers...
188 : //
189 : template<class To, class From, class SimpleFrom> struct cast_convert_val {
190 : // This is not a simple type, use the template to simplify it...
191 : static typename cast_retty<To, From>::ret_type doit(From &Val) {
192 : return cast_convert_val<To, SimpleFrom,
193 : typename simplify_type<SimpleFrom>::SimpleType>::doit(
194 : simplify_type<From>::getSimplifiedValue(Val));
195 : }
196 : };
197 :
198 : template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> {
199 : // This _is_ a simple type, just cast it.
200 : static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) {
201 298 : typename cast_retty<To, FromTy>::ret_type Res2
202 298 : = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val);
203 298 : return Res2;
204 : }
205 : };
206 :
207 : template <class X> struct is_simple_type {
208 : static const bool value =
209 : std::is_same<X, typename simplify_type<X>::SimpleType>::value;
210 : };
211 :
212 : // cast<X> - Return the argument parameter cast to the specified type. This
213 : // casting operator asserts that the type is correct, so it does not return null
214 : // on failure. It does not allow a null argument (use cast_or_null for that).
215 : // It is typically used like this:
216 : //
217 : // cast<Instruction>(myVal)->getParent()
218 : //
219 : template <class X, class Y>
220 : inline typename std::enable_if<!is_simple_type<Y>::value,
221 : typename cast_retty<X, const Y>::ret_type>::type
222 : cast(const Y &Val) {
223 : assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
224 : return cast_convert_val<
225 : X, const Y, typename simplify_type<const Y>::SimpleType>::doit(Val);
226 : }
227 :
228 : template <class X, class Y>
229 : inline typename cast_retty<X, Y>::ret_type cast(Y &Val) {
230 : assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
231 : return cast_convert_val<X, Y,
232 : typename simplify_type<Y>::SimpleType>::doit(Val);
233 : }
234 :
235 : template <class X, class Y>
236 : inline typename cast_retty<X, Y *>::ret_type cast(Y *Val) {
237 646 : assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
238 323 : return cast_convert_val<X, Y*,
239 25 : typename simplify_type<Y*>::SimpleType>::doit(Val);
240 : }
241 :
242 : // cast_or_null<X> - Functionally identical to cast, except that a null value is
243 : // accepted.
244 : //
245 : template <class X, class Y>
246 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
247 : !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type>::type
248 : cast_or_null(const Y &Val) {
249 : if (!Val)
250 : return nullptr;
251 : assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!");
252 : return cast<X>(Val);
253 : }
254 :
255 : template <class X, class Y>
256 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
257 : !is_simple_type<Y>::value, typename cast_retty<X, Y>::ret_type>::type
258 : cast_or_null(Y &Val) {
259 : if (!Val)
260 : return nullptr;
261 : assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!");
262 : return cast<X>(Val);
263 : }
264 :
265 : template <class X, class Y>
266 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename cast_retty<X, Y *>::ret_type
267 : cast_or_null(Y *Val) {
268 0 : if (!Val) return nullptr;
269 0 : assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!");
270 0 : return cast<X>(Val);
271 0 : }
272 :
273 :
274 : // dyn_cast<X> - Return the argument parameter cast to the specified type. This
275 : // casting operator returns null if the argument is of the wrong type, so it can
276 : // be used to test for a type as well as cast if successful. This should be
277 : // used in the context of an if statement like this:
278 : //
279 : // if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... }
280 : //
281 :
282 : template <class X, class Y>
283 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
284 : !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type>::type
285 : dyn_cast(const Y &Val) {
286 : return isa<X>(Val) ? cast<X>(Val) : nullptr;
287 : }
288 :
289 : template <class X, class Y>
290 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename cast_retty<X, Y>::ret_type
291 : dyn_cast(Y &Val) {
292 : return isa<X>(Val) ? cast<X>(Val) : nullptr;
293 : }
294 :
295 : template <class X, class Y>
296 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename cast_retty<X, Y *>::ret_type
297 : dyn_cast(Y *Val) {
298 636 : return isa<X>(Val) ? cast<X>(Val) : nullptr;
299 : }
300 :
301 : // dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null
302 : // value is accepted.
303 : //
304 : template <class X, class Y>
305 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
306 : !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type>::type
307 : dyn_cast_or_null(const Y &Val) {
308 : return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
309 : }
310 :
311 : template <class X, class Y>
312 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
313 : !is_simple_type<Y>::value, typename cast_retty<X, Y>::ret_type>::type
314 : dyn_cast_or_null(Y &Val) {
315 : return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
316 : }
317 :
318 : template <class X, class Y>
319 : LLVM_ATTRIBUTE_UNUSED_RESULT inline typename cast_retty<X, Y *>::ret_type
320 : dyn_cast_or_null(Y *Val) {
321 0 : return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
322 : }
323 :
324 : } // End llvm namespace
325 :
326 : #endif
|
