1 | //===- llvm/Support/Casting.h - Allow flexible, checked, casts --*- C++ -*-===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(), |
10 | // and dyn_cast_or_null<X>() templates. |
11 | // |
12 | //===----------------------------------------------------------------------===// |
13 | |
14 | #ifndef LLVM_SUPPORT_CASTING_H |
15 | #define LLVM_SUPPORT_CASTING_H |
16 | |
17 | #include "llvm/Support/Compiler.h" |
18 | #include "llvm/Support/type_traits.h" |
19 | #include <cassert> |
20 | #include <memory> |
21 | #include <type_traits> |
22 | |
23 | namespace llvm { |
24 | |
25 | //===----------------------------------------------------------------------===// |
26 | // isa<x> Support Templates |
27 | //===----------------------------------------------------------------------===// |
28 | |
29 | // Define a template that can be specialized by smart pointers to reflect the |
30 | // fact that they are automatically dereferenced, and are not involved with the |
31 | // template selection process... the default implementation is a noop. |
32 | // |
33 | template<typename From> struct simplify_type { |
34 | using SimpleType = From; // The real type this represents... |
35 | |
36 | // An accessor to get the real value... |
37 | static SimpleType &getSimplifiedValue(From &Val) { return Val; } |
38 | }; |
39 | |
40 | template<typename From> struct simplify_type<const From> { |
41 | using NonConstSimpleType = typename simplify_type<From>::SimpleType; |
42 | using SimpleType = |
43 | typename add_const_past_pointer<NonConstSimpleType>::type; |
44 | using RetType = |
45 | typename add_lvalue_reference_if_not_pointer<SimpleType>::type; |
46 | |
47 | static RetType getSimplifiedValue(const From& Val) { |
48 | return simplify_type<From>::getSimplifiedValue(const_cast<From&>(Val)); |
49 | } |
50 | }; |
51 | |
52 | // The core of the implementation of isa<X> is here; To and From should be |
53 | // the names of classes. This template can be specialized to customize the |
54 | // implementation of isa<> without rewriting it from scratch. |
55 | template <typename To, typename From, typename Enabler = void> |
56 | struct isa_impl { |
57 | static inline bool doit(const From &Val) { |
58 | return To::classof(&Val); |
59 | } |
60 | }; |
61 | |
62 | /// Always allow upcasts, and perform no dynamic check for them. |
63 | template <typename To, typename From> |
64 | struct isa_impl<To, From, std::enable_if_t<std::is_base_of<To, From>::value>> { |
65 | static inline bool doit(const From &) { return true; } |
66 | }; |
67 | |
68 | template <typename To, typename From> struct isa_impl_cl { |
69 | static inline bool doit(const From &Val) { |
70 | return isa_impl<To, From>::doit(Val); |
71 | } |
72 | }; |
73 | |
74 | template <typename To, typename From> struct isa_impl_cl<To, const From> { |
75 | static inline bool doit(const From &Val) { |
76 | return isa_impl<To, From>::doit(Val); |
77 | } |
78 | }; |
79 | |
80 | template <typename To, typename From> |
81 | struct isa_impl_cl<To, const std::unique_ptr<From>> { |
82 | static inline bool doit(const std::unique_ptr<From> &Val) { |
83 | assert(Val && "isa<> used on a null pointer" ); |
84 | return isa_impl_cl<To, From>::doit(*Val); |
85 | } |
86 | }; |
87 | |
88 | template <typename To, typename From> struct isa_impl_cl<To, From*> { |
89 | static inline bool doit(const From *Val) { |
90 | assert(Val && "isa<> used on a null pointer" ); |
91 | return isa_impl<To, From>::doit(*Val); |
92 | } |
93 | }; |
94 | |
95 | template <typename To, typename From> struct isa_impl_cl<To, From*const> { |
96 | static inline bool doit(const From *Val) { |
97 | assert(Val && "isa<> used on a null pointer" ); |
98 | return isa_impl<To, From>::doit(*Val); |
99 | } |
100 | }; |
101 | |
102 | template <typename To, typename From> struct isa_impl_cl<To, const From*> { |
103 | static inline bool doit(const From *Val) { |
104 | assert(Val && "isa<> used on a null pointer" ); |
105 | return isa_impl<To, From>::doit(*Val); |
106 | } |
107 | }; |
108 | |
109 | template <typename To, typename From> struct isa_impl_cl<To, const From*const> { |
110 | static inline bool doit(const From *Val) { |
111 | assert(Val && "isa<> used on a null pointer" ); |
112 | return isa_impl<To, From>::doit(*Val); |
113 | } |
114 | }; |
115 | |
116 | template<typename To, typename From, typename SimpleFrom> |
117 | struct isa_impl_wrap { |
118 | // When From != SimplifiedType, we can simplify the type some more by using |
119 | // the simplify_type template. |
120 | static bool doit(const From &Val) { |
121 | return isa_impl_wrap<To, SimpleFrom, |
122 | typename simplify_type<SimpleFrom>::SimpleType>::doit( |
123 | simplify_type<const From>::getSimplifiedValue(Val)); |
124 | } |
125 | }; |
126 | |
127 | template<typename To, typename FromTy> |
128 | struct isa_impl_wrap<To, FromTy, FromTy> { |
129 | // When From == SimpleType, we are as simple as we are going to get. |
130 | static bool doit(const FromTy &Val) { |
131 | return isa_impl_cl<To,FromTy>::doit(Val); |
132 | } |
133 | }; |
134 | |
135 | // isa<X> - Return true if the parameter to the template is an instance of one |
136 | // of the template type arguments. Used like this: |
137 | // |
138 | // if (isa<Type>(myVal)) { ... } |
139 | // if (isa<Type0, Type1, Type2>(myVal)) { ... } |
140 | // |
141 | template <class X, class Y> LLVM_NODISCARD inline bool isa(const Y &Val) { |
142 | return isa_impl_wrap<X, const Y, |
143 | typename simplify_type<const Y>::SimpleType>::doit(Val); |
144 | } |
145 | |
146 | template <typename First, typename Second, typename... Rest, typename Y> |
147 | LLVM_NODISCARD inline bool isa(const Y &Val) { |
148 | return isa<First>(Val) || isa<Second, Rest...>(Val); |
149 | } |
150 | |
151 | // isa_and_nonnull<X> - Functionally identical to isa, except that a null value |
152 | // is accepted. |
153 | // |
154 | template <typename... X, class Y> |
155 | LLVM_NODISCARD inline bool isa_and_nonnull(const Y &Val) { |
156 | if (!Val) |
157 | return false; |
158 | return isa<X...>(Val); |
159 | } |
160 | |
161 | //===----------------------------------------------------------------------===// |
162 | // cast<x> Support Templates |
163 | //===----------------------------------------------------------------------===// |
164 | |
165 | template<class To, class From> struct cast_retty; |
166 | |
167 | // Calculate what type the 'cast' function should return, based on a requested |
168 | // type of To and a source type of From. |
169 | template<class To, class From> struct cast_retty_impl { |
170 | using ret_type = To &; // Normal case, return Ty& |
171 | }; |
172 | template<class To, class From> struct cast_retty_impl<To, const From> { |
173 | using ret_type = const To &; // Normal case, return Ty& |
174 | }; |
175 | |
176 | template<class To, class From> struct cast_retty_impl<To, From*> { |
177 | using ret_type = To *; // Pointer arg case, return Ty* |
178 | }; |
179 | |
180 | template<class To, class From> struct cast_retty_impl<To, const From*> { |
181 | using ret_type = const To *; // Constant pointer arg case, return const Ty* |
182 | }; |
183 | |
184 | template<class To, class From> struct cast_retty_impl<To, const From*const> { |
185 | using ret_type = const To *; // Constant pointer arg case, return const Ty* |
186 | }; |
187 | |
188 | template <class To, class From> |
189 | struct cast_retty_impl<To, std::unique_ptr<From>> { |
190 | private: |
191 | using PointerType = typename cast_retty_impl<To, From *>::ret_type; |
192 | using ResultType = std::remove_pointer_t<PointerType>; |
193 | |
194 | public: |
195 | using ret_type = std::unique_ptr<ResultType>; |
196 | }; |
197 | |
198 | template<class To, class From, class SimpleFrom> |
199 | struct cast_retty_wrap { |
200 | // When the simplified type and the from type are not the same, use the type |
201 | // simplifier to reduce the type, then reuse cast_retty_impl to get the |
202 | // resultant type. |
203 | using ret_type = typename cast_retty<To, SimpleFrom>::ret_type; |
204 | }; |
205 | |
206 | template<class To, class FromTy> |
207 | struct cast_retty_wrap<To, FromTy, FromTy> { |
208 | // When the simplified type is equal to the from type, use it directly. |
209 | using ret_type = typename cast_retty_impl<To,FromTy>::ret_type; |
210 | }; |
211 | |
212 | template<class To, class From> |
213 | struct cast_retty { |
214 | using ret_type = typename cast_retty_wrap< |
215 | To, From, typename simplify_type<From>::SimpleType>::ret_type; |
216 | }; |
217 | |
218 | // Ensure the non-simple values are converted using the simplify_type template |
219 | // that may be specialized by smart pointers... |
220 | // |
221 | template<class To, class From, class SimpleFrom> struct cast_convert_val { |
222 | // This is not a simple type, use the template to simplify it... |
223 | static typename cast_retty<To, From>::ret_type doit(From &Val) { |
224 | return cast_convert_val<To, SimpleFrom, |
225 | typename simplify_type<SimpleFrom>::SimpleType>::doit( |
226 | simplify_type<From>::getSimplifiedValue(Val)); |
227 | } |
228 | }; |
229 | |
230 | template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> { |
231 | // This _is_ a simple type, just cast it. |
232 | static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) { |
233 | typename cast_retty<To, FromTy>::ret_type Res2 |
234 | = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val); |
235 | return Res2; |
236 | } |
237 | }; |
238 | |
239 | template <class X> struct is_simple_type { |
240 | static const bool value = |
241 | std::is_same<X, typename simplify_type<X>::SimpleType>::value; |
242 | }; |
243 | |
244 | // cast<X> - Return the argument parameter cast to the specified type. This |
245 | // casting operator asserts that the type is correct, so it does not return null |
246 | // on failure. It does not allow a null argument (use cast_or_null for that). |
247 | // It is typically used like this: |
248 | // |
249 | // cast<Instruction>(myVal)->getParent() |
250 | // |
251 | template <class X, class Y> |
252 | inline std::enable_if_t<!is_simple_type<Y>::value, |
253 | typename cast_retty<X, const Y>::ret_type> |
254 | cast(const Y &Val) { |
255 | assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!" ); |
256 | return cast_convert_val< |
257 | X, const Y, typename simplify_type<const Y>::SimpleType>::doit(Val); |
258 | } |
259 | |
260 | template <class X, class Y> |
261 | inline typename cast_retty<X, Y>::ret_type cast(Y &Val) { |
262 | assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!" ); |
263 | return cast_convert_val<X, Y, |
264 | typename simplify_type<Y>::SimpleType>::doit(Val); |
265 | } |
266 | |
267 | template <class X, class Y> |
268 | inline typename cast_retty<X, Y *>::ret_type cast(Y *Val) { |
269 | assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!" ); |
270 | return cast_convert_val<X, Y*, |
271 | typename simplify_type<Y*>::SimpleType>::doit(Val); |
272 | } |
273 | |
274 | template <class X, class Y> |
275 | inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type |
276 | cast(std::unique_ptr<Y> &&Val) { |
277 | assert(isa<X>(Val.get()) && "cast<Ty>() argument of incompatible type!" ); |
278 | using ret_type = typename cast_retty<X, std::unique_ptr<Y>>::ret_type; |
279 | return ret_type( |
280 | cast_convert_val<X, Y *, typename simplify_type<Y *>::SimpleType>::doit( |
281 | Val.release())); |
282 | } |
283 | |
284 | // cast_or_null<X> - Functionally identical to cast, except that a null value is |
285 | // accepted. |
286 | // |
287 | template <class X, class Y> |
288 | LLVM_NODISCARD inline std::enable_if_t< |
289 | !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type> |
290 | cast_or_null(const Y &Val) { |
291 | if (!Val) |
292 | return nullptr; |
293 | assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!" ); |
294 | return cast<X>(Val); |
295 | } |
296 | |
297 | template <class X, class Y> |
298 | LLVM_NODISCARD inline std::enable_if_t<!is_simple_type<Y>::value, |
299 | typename cast_retty<X, Y>::ret_type> |
300 | cast_or_null(Y &Val) { |
301 | if (!Val) |
302 | return nullptr; |
303 | assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!" ); |
304 | return cast<X>(Val); |
305 | } |
306 | |
307 | template <class X, class Y> |
308 | LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type |
309 | cast_or_null(Y *Val) { |
310 | if (!Val) return nullptr; |
311 | assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!" ); |
312 | return cast<X>(Val); |
313 | } |
314 | |
315 | template <class X, class Y> |
316 | inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type |
317 | cast_or_null(std::unique_ptr<Y> &&Val) { |
318 | if (!Val) |
319 | return nullptr; |
320 | return cast<X>(std::move(Val)); |
321 | } |
322 | |
323 | // dyn_cast<X> - Return the argument parameter cast to the specified type. This |
324 | // casting operator returns null if the argument is of the wrong type, so it can |
325 | // be used to test for a type as well as cast if successful. This should be |
326 | // used in the context of an if statement like this: |
327 | // |
328 | // if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... } |
329 | // |
330 | |
331 | template <class X, class Y> |
332 | LLVM_NODISCARD inline std::enable_if_t< |
333 | !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type> |
334 | dyn_cast(const Y &Val) { |
335 | return isa<X>(Val) ? cast<X>(Val) : nullptr; |
336 | } |
337 | |
338 | template <class X, class Y> |
339 | LLVM_NODISCARD inline typename cast_retty<X, Y>::ret_type dyn_cast(Y &Val) { |
340 | return isa<X>(Val) ? cast<X>(Val) : nullptr; |
341 | } |
342 | |
343 | template <class X, class Y> |
344 | LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type dyn_cast(Y *Val) { |
345 | return isa<X>(Val) ? cast<X>(Val) : nullptr; |
346 | } |
347 | |
348 | // dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null |
349 | // value is accepted. |
350 | // |
351 | template <class X, class Y> |
352 | LLVM_NODISCARD inline std::enable_if_t< |
353 | !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type> |
354 | dyn_cast_or_null(const Y &Val) { |
355 | return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
356 | } |
357 | |
358 | template <class X, class Y> |
359 | LLVM_NODISCARD inline std::enable_if_t<!is_simple_type<Y>::value, |
360 | typename cast_retty<X, Y>::ret_type> |
361 | dyn_cast_or_null(Y &Val) { |
362 | return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
363 | } |
364 | |
365 | template <class X, class Y> |
366 | LLVM_NODISCARD inline typename cast_retty<X, Y *>::ret_type |
367 | dyn_cast_or_null(Y *Val) { |
368 | return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr; |
369 | } |
370 | |
371 | // unique_dyn_cast<X> - Given a unique_ptr<Y>, try to return a unique_ptr<X>, |
372 | // taking ownership of the input pointer iff isa<X>(Val) is true. If the |
373 | // cast is successful, From refers to nullptr on exit and the casted value |
374 | // is returned. If the cast is unsuccessful, the function returns nullptr |
375 | // and From is unchanged. |
376 | template <class X, class Y> |
377 | LLVM_NODISCARD inline auto unique_dyn_cast(std::unique_ptr<Y> &Val) |
378 | -> decltype(cast<X>(Val)) { |
379 | if (!isa<X>(Val)) |
380 | return nullptr; |
381 | return cast<X>(std::move(Val)); |
382 | } |
383 | |
384 | template <class X, class Y> |
385 | LLVM_NODISCARD inline auto unique_dyn_cast(std::unique_ptr<Y> &&Val) { |
386 | return unique_dyn_cast<X, Y>(Val); |
387 | } |
388 | |
389 | // dyn_cast_or_null<X> - Functionally identical to unique_dyn_cast, except that |
390 | // a null value is accepted. |
391 | template <class X, class Y> |
392 | LLVM_NODISCARD inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &Val) |
393 | -> decltype(cast<X>(Val)) { |
394 | if (!Val) |
395 | return nullptr; |
396 | return unique_dyn_cast<X, Y>(Val); |
397 | } |
398 | |
399 | template <class X, class Y> |
400 | LLVM_NODISCARD inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &&Val) { |
401 | return unique_dyn_cast_or_null<X, Y>(Val); |
402 | } |
403 | |
404 | } // end namespace llvm |
405 | |
406 | #endif // LLVM_SUPPORT_CASTING_H |
407 | |