freebsd-dev/include/llvm/ADT/ImmutableList.h

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//==--- ImmutableList.h - Immutable (functional) list interface --*- 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 ImmutableList class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_IMLIST_H
#define LLVM_ADT_IMLIST_H
#include "llvm/Support/Allocator.h"
#include "llvm/ADT/FoldingSet.h"
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#include "llvm/System/DataTypes.h"
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#include <cassert>
namespace llvm {
template <typename T> class ImmutableListFactory;
template <typename T>
class ImmutableListImpl : public FoldingSetNode {
T Head;
const ImmutableListImpl* Tail;
ImmutableListImpl(const T& head, const ImmutableListImpl* tail = 0)
: Head(head), Tail(tail) {}
friend class ImmutableListFactory<T>;
// Do not implement.
void operator=(const ImmutableListImpl&);
ImmutableListImpl(const ImmutableListImpl&);
public:
const T& getHead() const { return Head; }
const ImmutableListImpl* getTail() const { return Tail; }
static inline void Profile(FoldingSetNodeID& ID, const T& H,
const ImmutableListImpl* L){
ID.AddPointer(L);
ID.Add(H);
}
void Profile(FoldingSetNodeID& ID) {
Profile(ID, Head, Tail);
}
};
/// ImmutableList - This class represents an immutable (functional) list.
/// It is implemented as a smart pointer (wraps ImmutableListImpl), so it
/// it is intended to always be copied by value as if it were a pointer.
/// This interface matches ImmutableSet and ImmutableMap. ImmutableList
/// objects should almost never be created directly, and instead should
/// be created by ImmutableListFactory objects that manage the lifetime
/// of a group of lists. When the factory object is reclaimed, all lists
/// created by that factory are released as well.
template <typename T>
class ImmutableList {
public:
typedef T value_type;
typedef ImmutableListFactory<T> Factory;
private:
const ImmutableListImpl<T>* X;
public:
// This constructor should normally only be called by ImmutableListFactory<T>.
// There may be cases, however, when one needs to extract the internal pointer
// and reconstruct a list object from that pointer.
ImmutableList(const ImmutableListImpl<T>* x = 0) : X(x) {}
const ImmutableListImpl<T>* getInternalPointer() const {
return X;
}
class iterator {
const ImmutableListImpl<T>* L;
public:
iterator() : L(0) {}
iterator(ImmutableList l) : L(l.getInternalPointer()) {}
iterator& operator++() { L = L->getTail(); return *this; }
bool operator==(const iterator& I) const { return L == I.L; }
bool operator!=(const iterator& I) const { return L != I.L; }
const value_type& operator*() const { return L->getHead(); }
ImmutableList getList() const { return L; }
};
/// begin - Returns an iterator referring to the head of the list, or
/// an iterator denoting the end of the list if the list is empty.
iterator begin() const { return iterator(X); }
/// end - Returns an iterator denoting the end of the list. This iterator
/// does not refer to a valid list element.
iterator end() const { return iterator(); }
/// isEmpty - Returns true if the list is empty.
bool isEmpty() const { return !X; }
/// isEqual - Returns true if two lists are equal. Because all lists created
/// from the same ImmutableListFactory are uniqued, this has O(1) complexity
/// because it the contents of the list do not need to be compared. Note
/// that you should only compare two lists created from the same
/// ImmutableListFactory.
bool isEqual(const ImmutableList& L) const { return X == L.X; }
bool operator==(const ImmutableList& L) const { return isEqual(L); }
/// getHead - Returns the head of the list.
const T& getHead() {
assert (!isEmpty() && "Cannot get the head of an empty list.");
return X->getHead();
}
/// getTail - Returns the tail of the list, which is another (possibly empty)
/// ImmutableList.
ImmutableList getTail() {
return X ? X->getTail() : 0;
}
void Profile(FoldingSetNodeID& ID) const {
ID.AddPointer(X);
}
};
template <typename T>
class ImmutableListFactory {
typedef ImmutableListImpl<T> ListTy;
typedef FoldingSet<ListTy> CacheTy;
CacheTy Cache;
uintptr_t Allocator;
bool ownsAllocator() const {
return Allocator & 0x1 ? false : true;
}
BumpPtrAllocator& getAllocator() const {
return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1);
}
public:
ImmutableListFactory()
: Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {}
ImmutableListFactory(BumpPtrAllocator& Alloc)
: Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {}
~ImmutableListFactory() {
if (ownsAllocator()) delete &getAllocator();
}
ImmutableList<T> Concat(const T& Head, ImmutableList<T> Tail) {
// Profile the new list to see if it already exists in our cache.
FoldingSetNodeID ID;
void* InsertPos;
const ListTy* TailImpl = Tail.getInternalPointer();
ListTy::Profile(ID, Head, TailImpl);
ListTy* L = Cache.FindNodeOrInsertPos(ID, InsertPos);
if (!L) {
// The list does not exist in our cache. Create it.
BumpPtrAllocator& A = getAllocator();
L = (ListTy*) A.Allocate<ListTy>();
new (L) ListTy(Head, TailImpl);
// Insert the new list into the cache.
Cache.InsertNode(L, InsertPos);
}
return L;
}
ImmutableList<T> Add(const T& D, ImmutableList<T> L) {
return Concat(D, L);
}
ImmutableList<T> GetEmptyList() const {
return ImmutableList<T>(0);
}
ImmutableList<T> Create(const T& X) {
return Concat(X, GetEmptyList());
}
};
//===----------------------------------------------------------------------===//
// Partially-specialized Traits.
//===----------------------------------------------------------------------===//
template<typename T> struct DenseMapInfo;
template<typename T> struct DenseMapInfo<ImmutableList<T> > {
static inline ImmutableList<T> getEmptyKey() {
return reinterpret_cast<ImmutableListImpl<T>*>(-1);
}
static inline ImmutableList<T> getTombstoneKey() {
return reinterpret_cast<ImmutableListImpl<T>*>(-2);
}
static unsigned getHashValue(ImmutableList<T> X) {
uintptr_t PtrVal = reinterpret_cast<uintptr_t>(X.getInternalPointer());
return (unsigned((uintptr_t)PtrVal) >> 4) ^
(unsigned((uintptr_t)PtrVal) >> 9);
}
static bool isEqual(ImmutableList<T> X1, ImmutableList<T> X2) {
return X1 == X2;
}
static bool isPod() { return true; }
};
} // end llvm namespace
#endif