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+//===- llvm/ADT/PointerUnion.h - Discriminated Union of 2 Ptrs --*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the PointerUnion class, which is a discriminated union of
+// pointer types.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_POINTERUNION_H
+#define LLVM_ADT_POINTERUNION_H
+
+#include "llvm/ADT/PointerIntPair.h"
+
+namespace llvm {
+
+ /// getPointerUnionTypeNum - If the argument has type PT1* or PT2* return
+ /// false or true respectively.
+ template <typename PT1, typename PT2>
+ static inline int getPointerUnionTypeNum(PT1 *P) { return 0; }
+ template <typename PT1, typename PT2>
+ static inline int getPointerUnionTypeNum(PT2 *P) { return 1; }
+ template <typename PT1, typename PT2>
+ static inline int getPointerUnionTypeNum(...) { return -1; }
+
+
+ /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
+ /// for the two template arguments.
+ template <typename PT1, typename PT2>
+ class PointerUnionUIntTraits {
+ public:
+ static inline void *getAsVoidPointer(void *P) { return P; }
+ static inline void *getFromVoidPointer(void *P) { return P; }
+ enum {
+ PT1BitsAv = PointerLikeTypeTraits<PT1>::NumLowBitsAvailable,
+ PT2BitsAv = PointerLikeTypeTraits<PT2>::NumLowBitsAvailable,
+ NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
+ };
+ };
+
+ /// PointerUnion - This implements a discriminated union of two pointer types,
+ /// and keeps the discriminator bit-mangled into the low bits of the pointer.
+ /// This allows the implementation to be extremely efficient in space, but
+ /// permits a very natural and type-safe API.
+ ///
+ /// Common use patterns would be something like this:
+ /// PointerUnion<int*, float*> P;
+ /// P = (int*)0;
+ /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0"
+ /// X = P.get<int*>(); // ok.
+ /// Y = P.get<float*>(); // runtime assertion failure.
+ /// Z = P.get<double*>(); // runtime assertion failure (regardless of tag)
+ /// P = (float*)0;
+ /// Y = P.get<float*>(); // ok.
+ /// X = P.get<int*>(); // runtime assertion failure.
+ template <typename PT1, typename PT2>
+ class PointerUnion {
+ public:
+ typedef PointerIntPair<void*, 1, bool,
+ PointerUnionUIntTraits<PT1,PT2> > ValTy;
+ private:
+ ValTy Val;
+ public:
+ PointerUnion() {}
+
+ PointerUnion(PT1 V) {
+ Val.setPointer(
+ const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V)));
+ Val.setInt(0);
+ }
+ PointerUnion(PT2 V) {
+ Val.setPointer(
+ const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)));
+ Val.setInt(1);
+ }
+
+ /// isNull - Return true if the pointer help in the union is null,
+ /// regardless of which type it is.
+ bool isNull() const { return Val.getPointer() == 0; }
+ operator bool() const { return !isNull(); }
+
+ /// is<T>() return true if the Union currently holds the type matching T.
+ template<typename T>
+ int is() const {
+ int TyNo = ::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0);
+ assert(TyNo != -1 && "Type query could never succeed on PointerUnion!");
+ return Val.getInt() == TyNo;
+ }
+
+ /// get<T>() - Return the value of the specified pointer type. If the
+ /// specified pointer type is incorrect, assert.
+ template<typename T>
+ T get() const {
+ assert(is<T>() && "Invalid accessor called");
+ return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
+ }
+
+ /// dyn_cast<T>() - If the current value is of the specified pointer type,
+ /// return it, otherwise return null.
+ template<typename T>
+ T dyn_cast() const {
+ if (is<T>()) return get<T>();
+ return T();
+ }
+
+ /// Assignment operators - Allow assigning into this union from either
+ /// pointer type, setting the discriminator to remember what it came from.
+ const PointerUnion &operator=(const PT1 &RHS) {
+ Val.setPointer(
+ const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
+ Val.setInt(0);
+ return *this;
+ }
+ const PointerUnion &operator=(const PT2 &RHS) {
+ Val.setPointer(
+ const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)));
+ Val.setInt(1);
+ return *this;
+ }
+
+ void *getOpaqueValue() const { return Val.getOpaqueValue(); }
+ static PointerUnion getFromOpaqueValue(void *VP) {
+ PointerUnion V;
+ V.Val = ValTy::getFromOpaqueValue(VP);
+ return V;
+ }
+ };
+
+ // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
+ // # low bits available = min(PT1bits,PT2bits)-1.
+ template<typename PT1, typename PT2>
+ class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
+ public:
+ static inline void *
+ getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
+ return P.getOpaqueValue();
+ }
+ static inline PointerUnion<PT1, PT2>
+ getFromVoidPointer(void *P) {
+ return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
+ }
+
+ // The number of bits available are the min of the two pointer types.
+ enum {
+ NumLowBitsAvailable =
+ PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
+ ::NumLowBitsAvailable
+ };
+ };
+
+
+ /// PointerUnion3 - This is a pointer union of three pointer types. See
+ /// documentation for PointerUnion for usage.
+ template <typename PT1, typename PT2, typename PT3>
+ class PointerUnion3 {
+ public:
+ typedef PointerUnion<PT1, PT2> InnerUnion;
+ typedef PointerUnion<InnerUnion, PT3> ValTy;
+ private:
+ ValTy Val;
+ public:
+ PointerUnion3() {}
+
+ PointerUnion3(PT1 V) {
+ Val = InnerUnion(V);
+ }
+ PointerUnion3(PT2 V) {
+ Val = InnerUnion(V);
+ }
+ PointerUnion3(PT3 V) {
+ Val = V;
+ }
+
+ /// isNull - Return true if the pointer help in the union is null,
+ /// regardless of which type it is.
+ bool isNull() const { return Val.isNull(); }
+ operator bool() const { return !isNull(); }
+
+ /// is<T>() return true if the Union currently holds the type matching T.
+ template<typename T>
+ int is() const {
+ // Is it PT1/PT2?
+ if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
+ return Val.is<InnerUnion>() && Val.get<InnerUnion>().is<T>();
+ return Val.is<T>();
+ }
+
+ /// get<T>() - Return the value of the specified pointer type. If the
+ /// specified pointer type is incorrect, assert.
+ template<typename T>
+ T get() const {
+ assert(is<T>() && "Invalid accessor called");
+ // Is it PT1/PT2?
+ if (::llvm::getPointerUnionTypeNum<PT1, PT2>((T*)0) != -1)
+ return Val.get<InnerUnion>().get<T>();
+
+ return Val.get<T>();
+ }
+
+ /// dyn_cast<T>() - If the current value is of the specified pointer type,
+ /// return it, otherwise return null.
+ template<typename T>
+ T dyn_cast() const {
+ if (is<T>()) return get<T>();
+ return T();
+ }
+
+ /// Assignment operators - Allow assigning into this union from either
+ /// pointer type, setting the discriminator to remember what it came from.
+ const PointerUnion3 &operator=(const PT1 &RHS) {
+ Val = InnerUnion(RHS);
+ return *this;
+ }
+ const PointerUnion3 &operator=(const PT2 &RHS) {
+ Val = InnerUnion(RHS);
+ return *this;
+ }
+ const PointerUnion3 &operator=(const PT3 &RHS) {
+ Val = RHS;
+ return *this;
+ }
+
+ void *getOpaqueValue() const { return Val.getOpaqueValue(); }
+ static PointerUnion3 getFromOpaqueValue(void *VP) {
+ PointerUnion3 V;
+ V.Val = ValTy::getFromOpaqueValue(VP);
+ return V;
+ }
+ };
+
+ // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
+ // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
+ template<typename PT1, typename PT2, typename PT3>
+ class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
+ public:
+ static inline void *
+ getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
+ return P.getOpaqueValue();
+ }
+ static inline PointerUnion3<PT1, PT2, PT3>
+ getFromVoidPointer(void *P) {
+ return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
+ }
+
+ // The number of bits available are the min of the two pointer types.
+ enum {
+ NumLowBitsAvailable =
+ PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
+ ::NumLowBitsAvailable
+ };
+ };
+}
+
+#endif
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