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 { return Val.getPointer() == 0; }
112 operator bool() const { return !isNull(); }
114 /// is<T>() return true if the Union currently holds the type matching T.
118 ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1,
119 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
120 UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty;
122 return static_cast<int>(Val.getInt()) == TyNo;
125 /// get<T>() - Return the value of the specified pointer type. If the
126 /// specified pointer type is incorrect, assert.
129 assert(is<T>() && "Invalid accessor called");
130 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
133 /// dyn_cast<T>() - If the current value is of the specified pointer type,
134 /// return it, otherwise return null.
137 if (is<T>()) return get<T>();
141 /// \brief If the union is set to the first pointer type we can get an
142 /// address pointing to it.
143 template <typename T>
144 PT1 const *getAddrOf() const {
145 assert(is<PT1>() && "Val is not the first pointer");
146 assert(get<PT1>() == Val.getPointer() &&
147 "Can't get the address because PointerLikeTypeTraits changes the ptr");
148 T const *can_only_get_address_of_first_pointer_type
149 = reinterpret_cast<PT1 const *>(Val.getAddrOfPointer());
150 return can_only_get_address_of_first_pointer_type;
153 /// Assignment operators - Allow assigning into this union from either
154 /// pointer type, setting the discriminator to remember what it came from.
155 const PointerUnion &operator=(const PT1 &RHS) {
157 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
161 const PointerUnion &operator=(const PT2 &RHS) {
163 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)));
168 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
169 static inline PointerUnion getFromOpaqueValue(void *VP) {
171 V.Val = ValTy::getFromOpaqueValue(VP);
176 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
177 // # low bits available = min(PT1bits,PT2bits)-1.
178 template<typename PT1, typename PT2>
179 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
182 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
183 return P.getOpaqueValue();
185 static inline PointerUnion<PT1, PT2>
186 getFromVoidPointer(void *P) {
187 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
190 // The number of bits available are the min of the two pointer types.
192 NumLowBitsAvailable =
193 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
194 ::NumLowBitsAvailable
199 /// PointerUnion3 - This is a pointer union of three pointer types. See
200 /// documentation for PointerUnion for usage.
201 template <typename PT1, typename PT2, typename PT3>
202 class PointerUnion3 {
204 typedef PointerUnion<PT1, PT2> InnerUnion;
205 typedef PointerUnion<InnerUnion, PT3> ValTy;
209 struct IsInnerUnion {
211 IsInnerUnion(ValTy val) : Val(val) { }
214 return Val.template is<InnerUnion>() &&
215 Val.template get<InnerUnion>().template is<T>();
219 return Val.template get<InnerUnion>().template get<T>();
225 IsPT3(ValTy val) : Val(val) { }
228 return Val.template is<T>();
232 return Val.template get<T>();
239 PointerUnion3(PT1 V) {
242 PointerUnion3(PT2 V) {
245 PointerUnion3(PT3 V) {
249 /// isNull - Return true if the pointer held in the union is null,
250 /// regardless of which type it is.
251 bool isNull() const { return Val.isNull(); }
252 operator bool() const { return !isNull(); }
254 /// is<T>() return true if the Union currently holds the type matching T.
257 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
259 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
260 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
262 return Ty(Val).is<T>();
265 /// get<T>() - Return the value of the specified pointer type. If the
266 /// specified pointer type is incorrect, assert.
269 assert(is<T>() && "Invalid accessor called");
270 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
272 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
273 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
275 return Ty(Val).get<T>();
278 /// dyn_cast<T>() - If the current value is of the specified pointer type,
279 /// return it, otherwise return null.
282 if (is<T>()) return get<T>();
286 /// Assignment operators - Allow assigning into this union from either
287 /// pointer type, setting the discriminator to remember what it came from.
288 const PointerUnion3 &operator=(const PT1 &RHS) {
289 Val = InnerUnion(RHS);
292 const PointerUnion3 &operator=(const PT2 &RHS) {
293 Val = InnerUnion(RHS);
296 const PointerUnion3 &operator=(const PT3 &RHS) {
301 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
302 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
304 V.Val = ValTy::getFromOpaqueValue(VP);
309 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
310 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
311 template<typename PT1, typename PT2, typename PT3>
312 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
315 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
316 return P.getOpaqueValue();
318 static inline PointerUnion3<PT1, PT2, PT3>
319 getFromVoidPointer(void *P) {
320 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
323 // The number of bits available are the min of the two pointer types.
325 NumLowBitsAvailable =
326 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
327 ::NumLowBitsAvailable
331 /// PointerUnion4 - This is a pointer union of four pointer types. See
332 /// documentation for PointerUnion for usage.
333 template <typename PT1, typename PT2, typename PT3, typename PT4>
334 class PointerUnion4 {
336 typedef PointerUnion<PT1, PT2> InnerUnion1;
337 typedef PointerUnion<PT3, PT4> InnerUnion2;
338 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
344 PointerUnion4(PT1 V) {
345 Val = InnerUnion1(V);
347 PointerUnion4(PT2 V) {
348 Val = InnerUnion1(V);
350 PointerUnion4(PT3 V) {
351 Val = InnerUnion2(V);
353 PointerUnion4(PT4 V) {
354 Val = InnerUnion2(V);
357 /// isNull - Return true if the pointer held in the union is null,
358 /// regardless of which type it is.
359 bool isNull() const { return Val.isNull(); }
360 operator bool() const { return !isNull(); }
362 /// is<T>() return true if the Union currently holds the type matching T.
365 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
367 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
368 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
370 return Val.template is<Ty>() &&
371 Val.template get<Ty>().template is<T>();
374 /// get<T>() - Return the value of the specified pointer type. If the
375 /// specified pointer type is incorrect, assert.
378 assert(is<T>() && "Invalid accessor called");
379 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
381 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
382 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
384 return Val.template get<Ty>().template get<T>();
387 /// dyn_cast<T>() - If the current value is of the specified pointer type,
388 /// return it, otherwise return null.
391 if (is<T>()) return get<T>();
395 /// Assignment operators - Allow assigning into this union from either
396 /// pointer type, setting the discriminator to remember what it came from.
397 const PointerUnion4 &operator=(const PT1 &RHS) {
398 Val = InnerUnion1(RHS);
401 const PointerUnion4 &operator=(const PT2 &RHS) {
402 Val = InnerUnion1(RHS);
405 const PointerUnion4 &operator=(const PT3 &RHS) {
406 Val = InnerUnion2(RHS);
409 const PointerUnion4 &operator=(const PT4 &RHS) {
410 Val = InnerUnion2(RHS);
414 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
415 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
417 V.Val = ValTy::getFromOpaqueValue(VP);
422 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
423 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
424 template<typename PT1, typename PT2, typename PT3, typename PT4>
425 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
428 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
429 return P.getOpaqueValue();
431 static inline PointerUnion4<PT1, PT2, PT3, PT4>
432 getFromVoidPointer(void *P) {
433 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
436 // The number of bits available are the min of the two pointer types.
438 NumLowBitsAvailable =
439 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
440 ::NumLowBitsAvailable