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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 {
template <typename T>
struct PointerUnionTypeSelectorReturn {
typedef T Return;
};
/// \brief Get a type based on whether two types are the same or not. For:
/// @code
/// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret;
/// @endcode
/// Ret will be EQ type if T1 is same as T2 or NE type otherwise.
template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
struct PointerUnionTypeSelector {
typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return;
};
template <typename T, typename RET_EQ, typename RET_NE>
struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return Return;
};
template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
struct PointerUnionTypeSelectorReturn<
PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE> > {
typedef typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return
Return;
};
/// 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;
struct IsPT1 {
static const int Num = 0;
};
struct IsPT2 {
static const int Num = 1;
};
template <typename T>
struct UNION_DOESNT_CONTAIN_TYPE { };
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 held in the union is null,
/// regardless of which type it is.
bool isNull() const {
// Convert from the void* to one of the pointer types, to make sure that
// we recursively strip off low bits if we have a nested PointerUnion.
return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
}
operator bool() const { return !isNull(); }
/// is<T>() return true if the Union currently holds the type matching T.
template<typename T>
int is() const {
typedef typename
::llvm::PointerUnionTypeSelector<PT1, T, IsPT1,
::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty;
int TyNo = Ty::Num;
return static_cast<int>(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();
}
/// \brief If the union is set to the first pointer type get an address
/// pointing to it.
PT1 const *getAddrOfPtr1() const {
return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
}
/// \brief If the union is set to the first pointer type get an address
/// pointing to it.
PT1 *getAddrOfPtr1() {
assert(is<PT1>() && "Val is not the first pointer");
assert(get<PT1>() == Val.getPointer() &&
"Can't get the address because PointerLikeTypeTraits changes the ptr");
return (PT1 *)Val.getAddrOfPointer();
}
/// 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 inline 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;
struct IsInnerUnion {
ValTy Val;
IsInnerUnion(ValTy val) : Val(val) { }
template<typename T>
int is() const {
return Val.template is<InnerUnion>() &&
Val.template get<InnerUnion>().template is<T>();
}
template<typename T>
T get() const {
return Val.template get<InnerUnion>().template get<T>();
}
};
struct IsPT3 {
ValTy Val;
IsPT3(ValTy val) : Val(val) { }
template<typename T>
int is() const {
return Val.template is<T>();
}
template<typename T>
T get() const {
return Val.template get<T>();
}
};
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 held 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 {
// If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
typedef typename
::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
>::Return Ty;
return Ty(Val).template 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");
// If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
typedef typename
::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
>::Return Ty;
return Ty(Val).template 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 inline 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
};
};
/// PointerUnion4 - This is a pointer union of four pointer types. See
/// documentation for PointerUnion for usage.
template <typename PT1, typename PT2, typename PT3, typename PT4>
class PointerUnion4 {
public:
typedef PointerUnion<PT1, PT2> InnerUnion1;
typedef PointerUnion<PT3, PT4> InnerUnion2;
typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
private:
ValTy Val;
public:
PointerUnion4() {}
PointerUnion4(PT1 V) {
Val = InnerUnion1(V);
}
PointerUnion4(PT2 V) {
Val = InnerUnion1(V);
}
PointerUnion4(PT3 V) {
Val = InnerUnion2(V);
}
PointerUnion4(PT4 V) {
Val = InnerUnion2(V);
}
/// isNull - Return true if the pointer held 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 {
// If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
typedef typename
::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
>::Return Ty;
return Val.template is<Ty>() &&
Val.template get<Ty>().template 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");
// If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
typedef typename
::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
>::Return Ty;
return Val.template get<Ty>().template 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 PointerUnion4 &operator=(const PT1 &RHS) {
Val = InnerUnion1(RHS);
return *this;
}
const PointerUnion4 &operator=(const PT2 &RHS) {
Val = InnerUnion1(RHS);
return *this;
}
const PointerUnion4 &operator=(const PT3 &RHS) {
Val = InnerUnion2(RHS);
return *this;
}
const PointerUnion4 &operator=(const PT4 &RHS) {
Val = InnerUnion2(RHS);
return *this;
}
void *getOpaqueValue() const { return Val.getOpaqueValue(); }
static inline PointerUnion4 getFromOpaqueValue(void *VP) {
PointerUnion4 V;
V.Val = ValTy::getFromOpaqueValue(VP);
return V;
}
};
// Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
// # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
template<typename PT1, typename PT2, typename PT3, typename PT4>
class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
public:
static inline void *
getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
return P.getOpaqueValue();
}
static inline PointerUnion4<PT1, PT2, PT3, PT4>
getFromVoidPointer(void *P) {
return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
}
// The number of bits available are the min of the two pointer types.
enum {
NumLowBitsAvailable =
PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
::NumLowBitsAvailable
};
};
}
#endif