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"
22 /// getPointerUnionTypeNum - If the argument has type PT1* or PT2* return
23 /// false or true respectively.
24 template <typename PT1, typename PT2>
25 static inline int getPointerUnionTypeNum(PT1 *P) { return 0; }
26 template <typename PT1, typename PT2>
27 static inline int getPointerUnionTypeNum(PT2 *P) { return 1; }
28 template <typename PT1, typename PT2>
29 static inline int getPointerUnionTypeNum(...) { return -1; }
32 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
33 /// for the two template arguments.
34 template <typename PT1, typename PT2>
35 class PointerUnionUIntTraits {
37 static inline void *getAsVoidPointer(void *P) { return P; }
38 static inline void *getFromVoidPointer(void *P) { return P; }
40 PT1BitsAv = PointerLikeTypeTraits<PT1>::NumLowBitsAvailable,
41 PT2BitsAv = PointerLikeTypeTraits<PT2>::NumLowBitsAvailable,
42 NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
46 /// PointerUnion - This implements a discriminated union of two pointer types,
47 /// and keeps the discriminator bit-mangled into the low bits of the pointer.
48 /// This allows the implementation to be extremely efficient in space, but
49 /// permits a very natural and type-safe API.
51 /// Common use patterns would be something like this:
52 /// PointerUnion<int*, float*> P;
54 /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0"
55 /// X = P.get<int*>(); // ok.
56 /// Y = P.get<float*>(); // runtime assertion failure.
57 /// Z = P.get<double*>(); // runtime assertion failure (regardless of tag)
59 /// Y = P.get<float*>(); // ok.
60 /// X = P.get<int*>(); // runtime assertion failure.
61 template <typename PT1, typename PT2>
64 typedef PointerIntPair<void*, 1, bool,
65 PointerUnionUIntTraits<PT1,PT2> > ValTy;
73 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V)));
78 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)));
82 /// isNull - Return true if the pointer held in the union is null,
83 /// regardless of which type it is.
84 bool isNull() const { return Val.getPointer() == 0; }
85 operator bool() const { return !isNull(); }
87 /// is<T>() return true if the Union currently holds the type matching T.
90 int TyNo = ::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0);
91 assert(TyNo != -1 && "Type query could never succeed on PointerUnion!");
92 return static_cast<int>(Val.getInt()) == TyNo;
95 /// get<T>() - Return the value of the specified pointer type. If the
96 /// specified pointer type is incorrect, assert.
99 assert(is<T>() && "Invalid accessor called");
100 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
103 /// dyn_cast<T>() - If the current value is of the specified pointer type,
104 /// return it, otherwise return null.
107 if (is<T>()) return get<T>();
111 /// Assignment operators - Allow assigning into this union from either
112 /// pointer type, setting the discriminator to remember what it came from.
113 const PointerUnion &operator=(const PT1 &RHS) {
115 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
119 const PointerUnion &operator=(const PT2 &RHS) {
121 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)));
126 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
127 static PointerUnion getFromOpaqueValue(void *VP) {
129 V.Val = ValTy::getFromOpaqueValue(VP);
134 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
135 // # low bits available = min(PT1bits,PT2bits)-1.
136 template<typename PT1, typename PT2>
137 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
140 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
141 return P.getOpaqueValue();
143 static inline PointerUnion<PT1, PT2>
144 getFromVoidPointer(void *P) {
145 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
148 // The number of bits available are the min of the two pointer types.
150 NumLowBitsAvailable =
151 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
152 ::NumLowBitsAvailable
157 /// PointerUnion3 - This is a pointer union of three pointer types. See
158 /// documentation for PointerUnion for usage.
159 template <typename PT1, typename PT2, typename PT3>
160 class PointerUnion3 {
162 typedef PointerUnion<PT1, PT2> InnerUnion;
163 typedef PointerUnion<InnerUnion, PT3> ValTy;
169 PointerUnion3(PT1 V) {
172 PointerUnion3(PT2 V) {
175 PointerUnion3(PT3 V) {
179 /// isNull - Return true if the pointer held in the union is null,
180 /// regardless of which type it is.
181 bool isNull() const { return Val.isNull(); }
182 operator bool() const { return !isNull(); }
184 /// is<T>() return true if the Union currently holds the type matching T.
188 if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
189 return Val.template is<InnerUnion>() &&
190 Val.template get<InnerUnion>().template is<T>();
191 return Val.template is<T>();
194 /// get<T>() - Return the value of the specified pointer type. If the
195 /// specified pointer type is incorrect, assert.
198 assert(is<T>() && "Invalid accessor called");
200 if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
201 return Val.template get<InnerUnion>().template get<T>();
203 return Val.template get<T>();
206 /// dyn_cast<T>() - If the current value is of the specified pointer type,
207 /// return it, otherwise return null.
210 if (is<T>()) return get<T>();
214 /// Assignment operators - Allow assigning into this union from either
215 /// pointer type, setting the discriminator to remember what it came from.
216 const PointerUnion3 &operator=(const PT1 &RHS) {
217 Val = InnerUnion(RHS);
220 const PointerUnion3 &operator=(const PT2 &RHS) {
221 Val = InnerUnion(RHS);
224 const PointerUnion3 &operator=(const PT3 &RHS) {
229 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
230 static PointerUnion3 getFromOpaqueValue(void *VP) {
232 V.Val = ValTy::getFromOpaqueValue(VP);
237 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
238 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
239 template<typename PT1, typename PT2, typename PT3>
240 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
243 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
244 return P.getOpaqueValue();
246 static inline PointerUnion3<PT1, PT2, PT3>
247 getFromVoidPointer(void *P) {
248 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
251 // The number of bits available are the min of the two pointer types.
253 NumLowBitsAvailable =
254 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
255 ::NumLowBitsAvailable
259 /// PointerUnion4 - This is a pointer union of four pointer types. See
260 /// documentation for PointerUnion for usage.
261 template <typename PT1, typename PT2, typename PT3, typename PT4>
262 class PointerUnion4 {
264 typedef PointerUnion<PT1, PT2> InnerUnion1;
265 typedef PointerUnion<PT3, PT4> InnerUnion2;
266 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
272 PointerUnion4(PT1 V) {
273 Val = InnerUnion1(V);
275 PointerUnion4(PT2 V) {
276 Val = InnerUnion1(V);
278 PointerUnion4(PT3 V) {
279 Val = InnerUnion2(V);
281 PointerUnion4(PT4 V) {
282 Val = InnerUnion2(V);
285 /// isNull - Return true if the pointer held in the union is null,
286 /// regardless of which type it is.
287 bool isNull() const { return Val.isNull(); }
288 operator bool() const { return !isNull(); }
290 /// is<T>() return true if the Union currently holds the type matching T.
294 if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
295 return Val.template is<InnerUnion1>() &&
296 Val.template get<InnerUnion1>().template is<T>();
297 return Val.template is<InnerUnion2>() &&
298 Val.template get<InnerUnion2>().template is<T>();
301 /// get<T>() - Return the value of the specified pointer type. If the
302 /// specified pointer type is incorrect, assert.
305 assert(is<T>() && "Invalid accessor called");
307 if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
308 return Val.template get<InnerUnion1>().template get<T>();
310 return Val.template get<InnerUnion2>().template get<T>();
313 /// dyn_cast<T>() - If the current value is of the specified pointer type,
314 /// return it, otherwise return null.
317 if (is<T>()) return get<T>();
321 /// Assignment operators - Allow assigning into this union from either
322 /// pointer type, setting the discriminator to remember what it came from.
323 const PointerUnion4 &operator=(const PT1 &RHS) {
324 Val = InnerUnion1(RHS);
327 const PointerUnion4 &operator=(const PT2 &RHS) {
328 Val = InnerUnion1(RHS);
331 const PointerUnion4 &operator=(const PT3 &RHS) {
332 Val = InnerUnion2(RHS);
335 const PointerUnion4 &operator=(const PT4 &RHS) {
336 Val = InnerUnion2(RHS);
340 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
341 static PointerUnion4 getFromOpaqueValue(void *VP) {
343 V.Val = ValTy::getFromOpaqueValue(VP);
348 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
349 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
350 template<typename PT1, typename PT2, typename PT3, typename PT4>
351 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
354 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
355 return P.getOpaqueValue();
357 static inline PointerUnion4<PT1, PT2, PT3, PT4>
358 getFromVoidPointer(void *P) {
359 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
362 // The number of bits available are the min of the two pointer types.
364 NumLowBitsAvailable =
365 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
366 ::NumLowBitsAvailable