/3rd_party/llvm/include/llvm/ADT/PointerUnion.h

  1//===- llvm/ADT/PointerUnion.h - Discriminated Union of 2 Ptrs --*- C++ -*-===//
  2//
  3//                     The LLVM Compiler Infrastructure
  4//
  5// This file is distributed under the University of Illinois Open Source
  6// License. See LICENSE.TXT for details.
  7//
  8//===----------------------------------------------------------------------===//
  9//
 10// This file defines the PointerUnion class, which is a discriminated union of
 11// pointer types.
 12//
 13//===----------------------------------------------------------------------===//
 14
 15#ifndef LLVM_ADT_POINTERUNION_H
 16#define LLVM_ADT_POINTERUNION_H
 17
 18#include "llvm/Support/Compiler.h"
 19#include "llvm/ADT/PointerIntPair.h"
 20
 21namespace llvm {
 22
 23  template <typename T>
 24  struct PointerUnionTypeSelectorReturn {
 25    typedef T Return;
 26  };
 27
 28  /// \brief Get a type based on whether two types are the same or not. For:
 29  /// @code
 30  /// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret;
 31  /// @endcode
 32  /// Ret will be EQ type if T1 is same as T2 or NE type otherwise.
 33  template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
 34  struct PointerUnionTypeSelector {
 35    typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return;
 36  };
 37
 38  template <typename T, typename RET_EQ, typename RET_NE>
 39  struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
 40    typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return Return;
 41  };
 42
 43  template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
 44  struct PointerUnionTypeSelectorReturn<
 45                            PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE> > {
 46    typedef typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return
 47        Return;
 48  };
 49
 50  /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
 51  /// for the two template arguments.
 52  template <typename PT1, typename PT2>
 53  class PointerUnionUIntTraits {
 54  public:
 55    static inline void *getAsVoidPointer(void *P) { return P; }
 56    static inline void *getFromVoidPointer(void *P) { return P; }
 57    enum {
 58      PT1BitsAv = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable),
 59      PT2BitsAv = (int)(PointerLikeTypeTraits<PT2>::NumLowBitsAvailable),
 60      NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
 61    };
 62  };
 63  
 64  /// PointerUnion - This implements a discriminated union of two pointer types,
 65  /// and keeps the discriminator bit-mangled into the low bits of the pointer.
 66  /// This allows the implementation to be extremely efficient in space, but
 67  /// permits a very natural and type-safe API.
 68  ///
 69  /// Common use patterns would be something like this:
 70  ///    PointerUnion<int*, float*> P;
 71  ///    P = (int*)0;
 72  ///    printf("%d %d", P.is<int*>(), P.is<float*>());  // prints "1 0"
 73  ///    X = P.get<int*>();     // ok.
 74  ///    Y = P.get<float*>();   // runtime assertion failure.
 75  ///    Z = P.get<double*>();  // compile time failure.
 76  ///    P = (float*)0;
 77  ///    Y = P.get<float*>();   // ok.
 78  ///    X = P.get<int*>();     // runtime assertion failure.
 79  template <typename PT1, typename PT2>
 80  class PointerUnion {
 81  public:
 82    typedef PointerIntPair<void*, 1, bool, 
 83                           PointerUnionUIntTraits<PT1,PT2> > ValTy;
 84  private:
 85    ValTy Val;
 86
 87    struct IsPT1 {
 88      static const int Num = 0;
 89    };
 90    struct IsPT2 {
 91      static const int Num = 1;
 92    };
 93    template <typename T>
 94    struct UNION_DOESNT_CONTAIN_TYPE { };
 95
 96  public:
 97    PointerUnion() {}
 98    
 99    PointerUnion(PT1 V) : Val(
100      const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {
101    }
102    PointerUnion(PT2 V) : Val(
103      const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)), 1) {
104    }
105    
106    /// isNull - Return true if the pointer held in the union is null,
107    /// regardless of which type it is.
108    bool isNull() const {
109      // Convert from the void* to one of the pointer types, to make sure that
110      // we recursively strip off low bits if we have a nested PointerUnion.
111      return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
112    }
113    LLVM_EXPLICIT operator bool() const { return !isNull(); }
114
115    /// is<T>() return true if the Union currently holds the type matching T.
116    template<typename T>
117    int is() const {
118      typedef typename
119        ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1,
120          ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
121                                    UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty;
122      int TyNo = Ty::Num;
123      return static_cast<int>(Val.getInt()) == TyNo;
124    }
125    
126    /// get<T>() - Return the value of the specified pointer type. If the
127    /// specified pointer type is incorrect, assert.
128    template<typename T>
129    T get() const {
130      assert(is<T>() && "Invalid accessor called");
131      return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
132    }
133    
134    /// dyn_cast<T>() - If the current value is of the specified pointer type,
135    /// return it, otherwise return null.
136    template<typename T>
137    T dyn_cast() const {
138      if (is<T>()) return get<T>();
139      return T();
140    }
141
142    /// \brief If the union is set to the first pointer type get an address
143    /// pointing to it.
144    PT1 const *getAddrOfPtr1() const {
145      return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
146    }
147
148    /// \brief If the union is set to the first pointer type get an address
149    /// pointing to it.
150    PT1 *getAddrOfPtr1() {
151      assert(is<PT1>() && "Val is not the first pointer");
152      assert(get<PT1>() == Val.getPointer() &&
153         "Can't get the address because PointerLikeTypeTraits changes the ptr");
154      return (PT1 *)Val.getAddrOfPointer();
155    }
156    
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) {
160      Val.initWithPointer(
161         const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
162      return *this;
163    }
164    const PointerUnion &operator=(const PT2 &RHS) {
165      Val.setPointerAndInt(
166        const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
167        1);
168      return *this;
169    }
170    
171    void *getOpaqueValue() const { return Val.getOpaqueValue(); }
172    static inline PointerUnion getFromOpaqueValue(void *VP) {
173      PointerUnion V;
174      V.Val = ValTy::getFromOpaqueValue(VP);
175      return V;
176    }
177  };
178
179  template<typename PT1, typename PT2>
180  static bool operator==(PointerUnion<PT1, PT2> lhs,
181                         PointerUnion<PT1, PT2> rhs) {
182    return lhs.getOpaqueValue() == rhs.getOpaqueValue();
183  }
184
185  template<typename PT1, typename PT2>
186  static bool operator!=(PointerUnion<PT1, PT2> lhs,
187                         PointerUnion<PT1, PT2> rhs) {
188    return lhs.getOpaqueValue() != rhs.getOpaqueValue();
189  }
190
191  // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
192  // # low bits available = min(PT1bits,PT2bits)-1.
193  template<typename PT1, typename PT2>
194  class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
195  public:
196    static inline void *
197    getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
198      return P.getOpaqueValue();
199    }
200    static inline PointerUnion<PT1, PT2>
201    getFromVoidPointer(void *P) {
202      return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
203    }
204    
205    // The number of bits available are the min of the two pointer types.
206    enum {
207      NumLowBitsAvailable = 
208        PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
209          ::NumLowBitsAvailable
210    };
211  };
212  
213  
214  /// PointerUnion3 - This is a pointer union of three pointer types.  See
215  /// documentation for PointerUnion for usage.
216  template <typename PT1, typename PT2, typename PT3>
217  class PointerUnion3 {
218  public:
219    typedef PointerUnion<PT1, PT2> InnerUnion;
220    typedef PointerUnion<InnerUnion, PT3> ValTy;
221  private:
222    ValTy Val;
223
224    struct IsInnerUnion {
225      ValTy Val;
226      IsInnerUnion(ValTy val) : Val(val) { }
227      template<typename T>
228      int is() const {
229        return Val.template is<InnerUnion>() && 
230               Val.template get<InnerUnion>().template is<T>();
231      }
232      template<typename T>
233      T get() const {
234        return Val.template get<InnerUnion>().template get<T>();
235      }
236    };
237
238    struct IsPT3 {
239      ValTy Val;
240      IsPT3(ValTy val) : Val(val) { }
241      template<typename T>
242      int is() const {
243        return Val.template is<T>();
244      }
245      template<typename T>
246      T get() const {
247        return Val.template get<T>();
248      }
249    };
250
251  public:
252    PointerUnion3() {}
253    
254    PointerUnion3(PT1 V) {
255      Val = InnerUnion(V);
256    }
257    PointerUnion3(PT2 V) {
258      Val = InnerUnion(V);
259    }
260    PointerUnion3(PT3 V) {
261      Val = V;
262    }
263    
264    /// isNull - Return true if the pointer held in the union is null,
265    /// regardless of which type it is.
266    bool isNull() const { return Val.isNull(); }
267    LLVM_EXPLICIT operator bool() const { return !isNull(); }
268    
269    /// is<T>() return true if the Union currently holds the type matching T.
270    template<typename T>
271    int is() const {
272      // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
273      typedef typename
274        ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
275          ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
276                                                                   >::Return Ty;
277      return Ty(Val).template is<T>();
278    }
279    
280    /// get<T>() - Return the value of the specified pointer type. If the
281    /// specified pointer type is incorrect, assert.
282    template<typename T>
283    T get() const {
284      assert(is<T>() && "Invalid accessor called");
285      // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
286      typedef typename
287        ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
288          ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
289                                                                   >::Return Ty;
290      return Ty(Val).template get<T>();
291    }
292    
293    /// dyn_cast<T>() - If the current value is of the specified pointer type,
294    /// return it, otherwise return null.
295    template<typename T>
296    T dyn_cast() const {
297      if (is<T>()) return get<T>();
298      return T();
299    }
300    
301    /// Assignment operators - Allow assigning into this union from either
302    /// pointer type, setting the discriminator to remember what it came from.
303    const PointerUnion3 &operator=(const PT1 &RHS) {
304      Val = InnerUnion(RHS);
305      return *this;
306    }
307    const PointerUnion3 &operator=(const PT2 &RHS) {
308      Val = InnerUnion(RHS);
309      return *this;
310    }
311    const PointerUnion3 &operator=(const PT3 &RHS) {
312      Val = RHS;
313      return *this;
314    }
315    
316    void *getOpaqueValue() const { return Val.getOpaqueValue(); }
317    static inline PointerUnion3 getFromOpaqueValue(void *VP) {
318      PointerUnion3 V;
319      V.Val = ValTy::getFromOpaqueValue(VP);
320      return V;
321    }
322  };
323 
324  // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
325  // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
326  template<typename PT1, typename PT2, typename PT3>
327  class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
328  public:
329    static inline void *
330    getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
331      return P.getOpaqueValue();
332    }
333    static inline PointerUnion3<PT1, PT2, PT3>
334    getFromVoidPointer(void *P) {
335      return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
336    }
337    
338    // The number of bits available are the min of the two pointer types.
339    enum {
340      NumLowBitsAvailable = 
341        PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
342          ::NumLowBitsAvailable
343    };
344  };
345
346  /// PointerUnion4 - This is a pointer union of four pointer types.  See
347  /// documentation for PointerUnion for usage.
348  template <typename PT1, typename PT2, typename PT3, typename PT4>
349  class PointerUnion4 {
350  public:
351    typedef PointerUnion<PT1, PT2> InnerUnion1;
352    typedef PointerUnion<PT3, PT4> InnerUnion2;
353    typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
354  private:
355    ValTy Val;
356  public:
357    PointerUnion4() {}
358    
359    PointerUnion4(PT1 V) {
360      Val = InnerUnion1(V);
361    }
362    PointerUnion4(PT2 V) {
363      Val = InnerUnion1(V);
364    }
365    PointerUnion4(PT3 V) {
366      Val = InnerUnion2(V);
367    }
368    PointerUnion4(PT4 V) {
369      Val = InnerUnion2(V);
370    }
371    
372    /// isNull - Return true if the pointer held in the union is null,
373    /// regardless of which type it is.
374    bool isNull() const { return Val.isNull(); }
375    LLVM_EXPLICIT operator bool() const { return !isNull(); }
376    
377    /// is<T>() return true if the Union currently holds the type matching T.
378    template<typename T>
379    int is() const {
380      // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
381      typedef typename
382        ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
383          ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
384                                                                   >::Return Ty;
385      return Val.template is<Ty>() && 
386             Val.template get<Ty>().template is<T>();
387    }
388    
389    /// get<T>() - Return the value of the specified pointer type. If the
390    /// specified pointer type is incorrect, assert.
391    template<typename T>
392    T get() const {
393      assert(is<T>() && "Invalid accessor called");
394      // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
395      typedef typename
396        ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
397          ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
398                                                                   >::Return Ty;
399      return Val.template get<Ty>().template get<T>();
400    }
401    
402    /// dyn_cast<T>() - If the current value is of the specified pointer type,
403    /// return it, otherwise return null.
404    template<typename T>
405    T dyn_cast() const {
406      if (is<T>()) return get<T>();
407      return T();
408    }
409    
410    /// Assignment operators - Allow assigning into this union from either
411    /// pointer type, setting the discriminator to remember what it came from.
412    const PointerUnion4 &operator=(const PT1 &RHS) {
413      Val = InnerUnion1(RHS);
414      return *this;
415    }
416    const PointerUnion4 &operator=(const PT2 &RHS) {
417      Val = InnerUnion1(RHS);
418      return *this;
419    }
420    const PointerUnion4 &operator=(const PT3 &RHS) {
421      Val = InnerUnion2(RHS);
422      return *this;
423    }
424    const PointerUnion4 &operator=(const PT4 &RHS) {
425      Val = InnerUnion2(RHS);
426      return *this;
427    }
428    
429    void *getOpaqueValue() const { return Val.getOpaqueValue(); }
430    static inline PointerUnion4 getFromOpaqueValue(void *VP) {
431      PointerUnion4 V;
432      V.Val = ValTy::getFromOpaqueValue(VP);
433      return V;
434    }
435  };
436  
437  // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
438  // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
439  template<typename PT1, typename PT2, typename PT3, typename PT4>
440  class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
441  public:
442    static inline void *
443    getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
444      return P.getOpaqueValue();
445    }
446    static inline PointerUnion4<PT1, PT2, PT3, PT4>
447    getFromVoidPointer(void *P) {
448      return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
449    }
450    
451    // The number of bits available are the min of the two pointer types.
452    enum {
453      NumLowBitsAvailable = 
454        PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
455          ::NumLowBitsAvailable
456    };
457  };
458}
459
460#endif