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 = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable),
58 PT2BitsAv = (int)(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 { };
98 PointerUnion(PT1 V) : Val(
99 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {
101 PointerUnion(PT2 V) : Val(
102 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)), 1) {
105 /// isNull - Return true if the pointer held in the union is null,
106 /// regardless of which type it is.
107 bool isNull() const {
108 // Convert from the void* to one of the pointer types, to make sure that
109 // we recursively strip off low bits if we have a nested PointerUnion.
110 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
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 get an address
143 PT1 const *getAddrOfPtr1() const {
144 return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
147 /// \brief If the union is set to the first pointer type get an address
149 PT1 *getAddrOfPtr1() {
150 assert(is<PT1>() && "Val is not the first pointer");
151 assert(get<PT1>() == Val.getPointer() &&
152 "Can't get the address because PointerLikeTypeTraits changes the ptr");
153 return (PT1 *)Val.getAddrOfPointer();
156 /// Assignment operators - Allow assigning into this union from either
157 /// pointer type, setting the discriminator to remember what it came from.
158 const PointerUnion &operator=(const PT1 &RHS) {
160 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
163 const PointerUnion &operator=(const PT2 &RHS) {
164 Val.setPointerAndInt(
165 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
170 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
171 static inline PointerUnion getFromOpaqueValue(void *VP) {
173 V.Val = ValTy::getFromOpaqueValue(VP);
178 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
179 // # low bits available = min(PT1bits,PT2bits)-1.
180 template<typename PT1, typename PT2>
181 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
184 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
185 return P.getOpaqueValue();
187 static inline PointerUnion<PT1, PT2>
188 getFromVoidPointer(void *P) {
189 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
192 // The number of bits available are the min of the two pointer types.
194 NumLowBitsAvailable =
195 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
196 ::NumLowBitsAvailable
201 /// PointerUnion3 - This is a pointer union of three pointer types. See
202 /// documentation for PointerUnion for usage.
203 template <typename PT1, typename PT2, typename PT3>
204 class PointerUnion3 {
206 typedef PointerUnion<PT1, PT2> InnerUnion;
207 typedef PointerUnion<InnerUnion, PT3> ValTy;
211 struct IsInnerUnion {
213 IsInnerUnion(ValTy val) : Val(val) { }
216 return Val.template is<InnerUnion>() &&
217 Val.template get<InnerUnion>().template is<T>();
221 return Val.template get<InnerUnion>().template get<T>();
227 IsPT3(ValTy val) : Val(val) { }
230 return Val.template is<T>();
234 return Val.template get<T>();
241 PointerUnion3(PT1 V) {
244 PointerUnion3(PT2 V) {
247 PointerUnion3(PT3 V) {
251 /// isNull - Return true if the pointer held in the union is null,
252 /// regardless of which type it is.
253 bool isNull() const { return Val.isNull(); }
254 operator bool() const { return !isNull(); }
256 /// is<T>() return true if the Union currently holds the type matching T.
259 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
261 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
262 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
264 return Ty(Val).template is<T>();
267 /// get<T>() - Return the value of the specified pointer type. If the
268 /// specified pointer type is incorrect, assert.
271 assert(is<T>() && "Invalid accessor called");
272 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
274 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
275 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
277 return Ty(Val).template get<T>();
280 /// dyn_cast<T>() - If the current value is of the specified pointer type,
281 /// return it, otherwise return null.
284 if (is<T>()) return get<T>();
288 /// Assignment operators - Allow assigning into this union from either
289 /// pointer type, setting the discriminator to remember what it came from.
290 const PointerUnion3 &operator=(const PT1 &RHS) {
291 Val = InnerUnion(RHS);
294 const PointerUnion3 &operator=(const PT2 &RHS) {
295 Val = InnerUnion(RHS);
298 const PointerUnion3 &operator=(const PT3 &RHS) {
303 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
304 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
306 V.Val = ValTy::getFromOpaqueValue(VP);
311 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
312 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
313 template<typename PT1, typename PT2, typename PT3>
314 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
317 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
318 return P.getOpaqueValue();
320 static inline PointerUnion3<PT1, PT2, PT3>
321 getFromVoidPointer(void *P) {
322 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
325 // The number of bits available are the min of the two pointer types.
327 NumLowBitsAvailable =
328 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
329 ::NumLowBitsAvailable
333 /// PointerUnion4 - This is a pointer union of four pointer types. See
334 /// documentation for PointerUnion for usage.
335 template <typename PT1, typename PT2, typename PT3, typename PT4>
336 class PointerUnion4 {
338 typedef PointerUnion<PT1, PT2> InnerUnion1;
339 typedef PointerUnion<PT3, PT4> InnerUnion2;
340 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
346 PointerUnion4(PT1 V) {
347 Val = InnerUnion1(V);
349 PointerUnion4(PT2 V) {
350 Val = InnerUnion1(V);
352 PointerUnion4(PT3 V) {
353 Val = InnerUnion2(V);
355 PointerUnion4(PT4 V) {
356 Val = InnerUnion2(V);
359 /// isNull - Return true if the pointer held in the union is null,
360 /// regardless of which type it is.
361 bool isNull() const { return Val.isNull(); }
362 operator bool() const { return !isNull(); }
364 /// is<T>() return true if the Union currently holds the type matching T.
367 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
369 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
370 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
372 return Val.template is<Ty>() &&
373 Val.template get<Ty>().template is<T>();
376 /// get<T>() - Return the value of the specified pointer type. If the
377 /// specified pointer type is incorrect, assert.
380 assert(is<T>() && "Invalid accessor called");
381 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
383 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
384 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
386 return Val.template get<Ty>().template get<T>();
389 /// dyn_cast<T>() - If the current value is of the specified pointer type,
390 /// return it, otherwise return null.
393 if (is<T>()) return get<T>();
397 /// Assignment operators - Allow assigning into this union from either
398 /// pointer type, setting the discriminator to remember what it came from.
399 const PointerUnion4 &operator=(const PT1 &RHS) {
400 Val = InnerUnion1(RHS);
403 const PointerUnion4 &operator=(const PT2 &RHS) {
404 Val = InnerUnion1(RHS);
407 const PointerUnion4 &operator=(const PT3 &RHS) {
408 Val = InnerUnion2(RHS);
411 const PointerUnion4 &operator=(const PT4 &RHS) {
412 Val = InnerUnion2(RHS);
416 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
417 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
419 V.Val = ValTy::getFromOpaqueValue(VP);
424 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
425 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
426 template<typename PT1, typename PT2, typename PT3, typename PT4>
427 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
430 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
431 return P.getOpaqueValue();
433 static inline PointerUnion4<PT1, PT2, PT3, PT4>
434 getFromVoidPointer(void *P) {
435 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
438 // The number of bits available are the min of the two pointer types.
440 NumLowBitsAvailable =
441 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
442 ::NumLowBitsAvailable