1 //==--- ImmutableList.h - Immutable (functional) list interface --*- 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 ImmutableList class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_IMMUTABLELIST_H
15 #define LLVM_ADT_IMMUTABLELIST_H
17 #include "llvm/ADT/FoldingSet.h"
18 #include "llvm/Support/Allocator.h"
19 #include "llvm/Support/DataTypes.h"
24 template <typename T> class ImmutableListFactory;
27 class ImmutableListImpl : public FoldingSetNode {
29 const ImmutableListImpl* Tail;
31 ImmutableListImpl(const T& head, const ImmutableListImpl* tail = 0)
32 : Head(head), Tail(tail) {}
34 friend class ImmutableListFactory<T>;
36 void operator=(const ImmutableListImpl&) LLVM_DELETED_FUNCTION;
37 ImmutableListImpl(const ImmutableListImpl&) LLVM_DELETED_FUNCTION;
40 const T& getHead() const { return Head; }
41 const ImmutableListImpl* getTail() const { return Tail; }
43 static inline void Profile(FoldingSetNodeID& ID, const T& H,
44 const ImmutableListImpl* L){
49 void Profile(FoldingSetNodeID& ID) {
50 Profile(ID, Head, Tail);
54 /// ImmutableList - This class represents an immutable (functional) list.
55 /// It is implemented as a smart pointer (wraps ImmutableListImpl), so it
56 /// it is intended to always be copied by value as if it were a pointer.
57 /// This interface matches ImmutableSet and ImmutableMap. ImmutableList
58 /// objects should almost never be created directly, and instead should
59 /// be created by ImmutableListFactory objects that manage the lifetime
60 /// of a group of lists. When the factory object is reclaimed, all lists
61 /// created by that factory are released as well.
66 typedef ImmutableListFactory<T> Factory;
69 const ImmutableListImpl<T>* X;
72 // This constructor should normally only be called by ImmutableListFactory<T>.
73 // There may be cases, however, when one needs to extract the internal pointer
74 // and reconstruct a list object from that pointer.
75 ImmutableList(const ImmutableListImpl<T>* x = 0) : X(x) {}
77 const ImmutableListImpl<T>* getInternalPointer() const {
82 const ImmutableListImpl<T>* L;
85 iterator(ImmutableList l) : L(l.getInternalPointer()) {}
87 iterator& operator++() { L = L->getTail(); return *this; }
88 bool operator==(const iterator& I) const { return L == I.L; }
89 bool operator!=(const iterator& I) const { return L != I.L; }
90 const value_type& operator*() const { return L->getHead(); }
91 ImmutableList getList() const { return L; }
94 /// begin - Returns an iterator referring to the head of the list, or
95 /// an iterator denoting the end of the list if the list is empty.
96 iterator begin() const { return iterator(X); }
98 /// end - Returns an iterator denoting the end of the list. This iterator
99 /// does not refer to a valid list element.
100 iterator end() const { return iterator(); }
102 /// isEmpty - Returns true if the list is empty.
103 bool isEmpty() const { return !X; }
105 bool contains(const T& V) const {
106 for (iterator I = begin(), E = end(); I != E; ++I) {
113 /// isEqual - Returns true if two lists are equal. Because all lists created
114 /// from the same ImmutableListFactory are uniqued, this has O(1) complexity
115 /// because it the contents of the list do not need to be compared. Note
116 /// that you should only compare two lists created from the same
117 /// ImmutableListFactory.
118 bool isEqual(const ImmutableList& L) const { return X == L.X; }
120 bool operator==(const ImmutableList& L) const { return isEqual(L); }
122 /// getHead - Returns the head of the list.
124 assert (!isEmpty() && "Cannot get the head of an empty list.");
128 /// getTail - Returns the tail of the list, which is another (possibly empty)
130 ImmutableList getTail() {
131 return X ? X->getTail() : 0;
134 void Profile(FoldingSetNodeID& ID) const {
139 template <typename T>
140 class ImmutableListFactory {
141 typedef ImmutableListImpl<T> ListTy;
142 typedef FoldingSet<ListTy> CacheTy;
147 bool ownsAllocator() const {
148 return Allocator & 0x1 ? false : true;
151 BumpPtrAllocator& getAllocator() const {
152 return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1);
156 ImmutableListFactory()
157 : Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {}
159 ImmutableListFactory(BumpPtrAllocator& Alloc)
160 : Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {}
162 ~ImmutableListFactory() {
163 if (ownsAllocator()) delete &getAllocator();
166 ImmutableList<T> concat(const T& Head, ImmutableList<T> Tail) {
167 // Profile the new list to see if it already exists in our cache.
171 const ListTy* TailImpl = Tail.getInternalPointer();
172 ListTy::Profile(ID, Head, TailImpl);
173 ListTy* L = Cache.FindNodeOrInsertPos(ID, InsertPos);
176 // The list does not exist in our cache. Create it.
177 BumpPtrAllocator& A = getAllocator();
178 L = (ListTy*) A.Allocate<ListTy>();
179 new (L) ListTy(Head, TailImpl);
181 // Insert the new list into the cache.
182 Cache.InsertNode(L, InsertPos);
188 ImmutableList<T> add(const T& D, ImmutableList<T> L) {
192 ImmutableList<T> getEmptyList() const {
193 return ImmutableList<T>(0);
196 ImmutableList<T> create(const T& X) {
197 return Concat(X, getEmptyList());
201 //===----------------------------------------------------------------------===//
202 // Partially-specialized Traits.
203 //===----------------------------------------------------------------------===//
205 template<typename T> struct DenseMapInfo;
206 template<typename T> struct DenseMapInfo<ImmutableList<T> > {
207 static inline ImmutableList<T> getEmptyKey() {
208 return reinterpret_cast<ImmutableListImpl<T>*>(-1);
210 static inline ImmutableList<T> getTombstoneKey() {
211 return reinterpret_cast<ImmutableListImpl<T>*>(-2);
213 static unsigned getHashValue(ImmutableList<T> X) {
214 uintptr_t PtrVal = reinterpret_cast<uintptr_t>(X.getInternalPointer());
215 return (unsigned((uintptr_t)PtrVal) >> 4) ^
216 (unsigned((uintptr_t)PtrVal) >> 9);
218 static bool isEqual(ImmutableList<T> X1, ImmutableList<T> X2) {
223 template <typename T> struct isPodLike;
224 template <typename T>
225 struct isPodLike<ImmutableList<T> > { static const bool value = true; };
227 } // end llvm namespace