1 //===- llvm/ADT/PointerUnion.h - Discriminated Union of 2 Ptrs --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PointerUnion class, which is a discriminated union of
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ADT_POINTERUNION_H
16 #define LLVM_ADT_POINTERUNION_H
18 #include "llvm/ADT/PointerIntPair.h"
23 struct PointerUnionTypeSelectorReturn {
27 /// \brief Get a type based on whether two types are the same or not. For:
29 /// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret;
31 /// Ret will be EQ type if T1 is same as T2 or NE type otherwise.
32 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
33 struct PointerUnionTypeSelector {
34 typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return;
37 template <typename T, typename RET_EQ, typename RET_NE>
38 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
39 typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return Return;
42 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
43 struct PointerUnionTypeSelectorReturn<
44 PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE> > {
45 typedef typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return
49 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
50 /// for the two template arguments.
51 template <typename PT1, typename PT2>
52 class PointerUnionUIntTraits {
54 static inline void *getAsVoidPointer(void *P) { return P; }
55 static inline void *getFromVoidPointer(void *P) { return P; }
57 PT1BitsAv = PointerLikeTypeTraits<PT1>::NumLowBitsAvailable,
58 PT2BitsAv = PointerLikeTypeTraits<PT2>::NumLowBitsAvailable,
59 NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
63 /// PointerUnion - This implements a discriminated union of two pointer types,
64 /// and keeps the discriminator bit-mangled into the low bits of the pointer.
65 /// This allows the implementation to be extremely efficient in space, but
66 /// permits a very natural and type-safe API.
68 /// Common use patterns would be something like this:
69 /// PointerUnion<int*, float*> P;
71 /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0"
72 /// X = P.get<int*>(); // ok.
73 /// Y = P.get<float*>(); // runtime assertion failure.
74 /// Z = P.get<double*>(); // runtime assertion failure (regardless of tag)
76 /// Y = P.get<float*>(); // ok.
77 /// X = P.get<int*>(); // runtime assertion failure.
78 template <typename PT1, typename PT2>
81 typedef PointerIntPair<void*, 1, bool,
82 PointerUnionUIntTraits<PT1,PT2> > ValTy;
87 static const int Num = 0;
90 static const int Num = 1;
93 struct UNION_DOESNT_CONTAIN_TYPE { };
100 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V)));
103 PointerUnion(PT2 V) {
105 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)));
109 /// isNull - Return true if the pointer held in the union is null,
110 /// regardless of which type it is.
111 bool isNull() const {
112 // Convert from the void* to one of the pointer types, to make sure that
113 // we recursively strip off low bits if we have a nested PointerUnion.
114 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
116 operator bool() const { return !isNull(); }
118 /// is<T>() return true if the Union currently holds the type matching T.
122 ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1,
123 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
124 UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty;
126 return static_cast<int>(Val.getInt()) == TyNo;
129 /// get<T>() - Return the value of the specified pointer type. If the
130 /// specified pointer type is incorrect, assert.
133 assert(is<T>() && "Invalid accessor called");
134 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
137 /// dyn_cast<T>() - If the current value is of the specified pointer type,
138 /// return it, otherwise return null.
141 if (is<T>()) return get<T>();
145 /// \brief If the union is set to the first pointer type we can get an
146 /// address pointing to it.
147 template <typename T>
148 PT1 const *getAddrOf() const {
149 assert(is<PT1>() && "Val is not the first pointer");
150 assert(get<PT1>() == Val.getPointer() &&
151 "Can't get the address because PointerLikeTypeTraits changes the ptr");
152 T const *can_only_get_address_of_first_pointer_type
153 = reinterpret_cast<PT1 const *>(Val.getAddrOfPointer());
154 return can_only_get_address_of_first_pointer_type;
157 /// Assignment operators - Allow assigning into this union from either
158 /// pointer type, setting the discriminator to remember what it came from.
159 const PointerUnion &operator=(const PT1 &RHS) {
161 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
165 const PointerUnion &operator=(const PT2 &RHS) {
167 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)));
172 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
173 static inline PointerUnion getFromOpaqueValue(void *VP) {
175 V.Val = ValTy::getFromOpaqueValue(VP);
180 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
181 // # low bits available = min(PT1bits,PT2bits)-1.
182 template<typename PT1, typename PT2>
183 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
186 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
187 return P.getOpaqueValue();
189 static inline PointerUnion<PT1, PT2>
190 getFromVoidPointer(void *P) {
191 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
194 // The number of bits available are the min of the two pointer types.
196 NumLowBitsAvailable =
197 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
198 ::NumLowBitsAvailable
203 /// PointerUnion3 - This is a pointer union of three pointer types. See
204 /// documentation for PointerUnion for usage.
205 template <typename PT1, typename PT2, typename PT3>
206 class PointerUnion3 {
208 typedef PointerUnion<PT1, PT2> InnerUnion;
209 typedef PointerUnion<InnerUnion, PT3> ValTy;
213 struct IsInnerUnion {
215 IsInnerUnion(ValTy val) : Val(val) { }
218 return Val.template is<InnerUnion>() &&
219 Val.template get<InnerUnion>().template is<T>();
223 return Val.template get<InnerUnion>().template get<T>();
229 IsPT3(ValTy val) : Val(val) { }
232 return Val.template is<T>();
236 return Val.template get<T>();
243 PointerUnion3(PT1 V) {
246 PointerUnion3(PT2 V) {
249 PointerUnion3(PT3 V) {
253 /// isNull - Return true if the pointer held in the union is null,
254 /// regardless of which type it is.
255 bool isNull() const { return Val.isNull(); }
256 operator bool() const { return !isNull(); }
258 /// is<T>() return true if the Union currently holds the type matching T.
261 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
263 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
264 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
266 return Ty(Val).is<T>();
269 /// get<T>() - Return the value of the specified pointer type. If the
270 /// specified pointer type is incorrect, assert.
273 assert(is<T>() && "Invalid accessor called");
274 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
276 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
277 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
279 return Ty(Val).get<T>();
282 /// dyn_cast<T>() - If the current value is of the specified pointer type,
283 /// return it, otherwise return null.
286 if (is<T>()) return get<T>();
290 /// Assignment operators - Allow assigning into this union from either
291 /// pointer type, setting the discriminator to remember what it came from.
292 const PointerUnion3 &operator=(const PT1 &RHS) {
293 Val = InnerUnion(RHS);
296 const PointerUnion3 &operator=(const PT2 &RHS) {
297 Val = InnerUnion(RHS);
300 const PointerUnion3 &operator=(const PT3 &RHS) {
305 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
306 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
308 V.Val = ValTy::getFromOpaqueValue(VP);
313 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
314 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
315 template<typename PT1, typename PT2, typename PT3>
316 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
319 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
320 return P.getOpaqueValue();
322 static inline PointerUnion3<PT1, PT2, PT3>
323 getFromVoidPointer(void *P) {
324 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
327 // The number of bits available are the min of the two pointer types.
329 NumLowBitsAvailable =
330 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
331 ::NumLowBitsAvailable
335 /// PointerUnion4 - This is a pointer union of four pointer types. See
336 /// documentation for PointerUnion for usage.
337 template <typename PT1, typename PT2, typename PT3, typename PT4>
338 class PointerUnion4 {
340 typedef PointerUnion<PT1, PT2> InnerUnion1;
341 typedef PointerUnion<PT3, PT4> InnerUnion2;
342 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
348 PointerUnion4(PT1 V) {
349 Val = InnerUnion1(V);
351 PointerUnion4(PT2 V) {
352 Val = InnerUnion1(V);
354 PointerUnion4(PT3 V) {
355 Val = InnerUnion2(V);
357 PointerUnion4(PT4 V) {
358 Val = InnerUnion2(V);
361 /// isNull - Return true if the pointer held in the union is null,
362 /// regardless of which type it is.
363 bool isNull() const { return Val.isNull(); }
364 operator bool() const { return !isNull(); }
366 /// is<T>() return true if the Union currently holds the type matching T.
369 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
371 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
372 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
374 return Val.template is<Ty>() &&
375 Val.template get<Ty>().template is<T>();
378 /// get<T>() - Return the value of the specified pointer type. If the
379 /// specified pointer type is incorrect, assert.
382 assert(is<T>() && "Invalid accessor called");
383 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
385 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
386 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
388 return Val.template get<Ty>().template get<T>();
391 /// dyn_cast<T>() - If the current value is of the specified pointer type,
392 /// return it, otherwise return null.
395 if (is<T>()) return get<T>();
399 /// Assignment operators - Allow assigning into this union from either
400 /// pointer type, setting the discriminator to remember what it came from.
401 const PointerUnion4 &operator=(const PT1 &RHS) {
402 Val = InnerUnion1(RHS);
405 const PointerUnion4 &operator=(const PT2 &RHS) {
406 Val = InnerUnion1(RHS);
409 const PointerUnion4 &operator=(const PT3 &RHS) {
410 Val = InnerUnion2(RHS);
413 const PointerUnion4 &operator=(const PT4 &RHS) {
414 Val = InnerUnion2(RHS);
418 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
419 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
421 V.Val = ValTy::getFromOpaqueValue(VP);
426 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
427 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
428 template<typename PT1, typename PT2, typename PT3, typename PT4>
429 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
432 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
433 return P.getOpaqueValue();
435 static inline PointerUnion4<PT1, PT2, PT3, PT4>
436 getFromVoidPointer(void *P) {
437 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
440 // The number of bits available are the min of the two pointer types.
442 NumLowBitsAvailable =
443 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
444 ::NumLowBitsAvailable