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_IMLIST_H
15 #define LLVM_ADT_IMLIST_H
17 #include "llvm/Support/Allocator.h"
18 #include "llvm/ADT/FoldingSet.h"
19 #include "llvm/Support/DataTypes.h"
24 template <typename T> class ImmutableListFactory;
27 class ImmutableListImpl : public FoldingSetNode {
29 ImmutableListImpl* Tail;
31 ImmutableListImpl(const T& head, ImmutableListImpl* tail = 0)
32 : Head(head), Tail(tail) {}
34 friend class ImmutableListFactory<T>;
37 void operator=(const ImmutableListImpl&);
38 ImmutableListImpl(const ImmutableListImpl&);
41 const T& getHead() const { return Head; }
42 ImmutableListImpl* getTail() const { return Tail; }
44 static inline void Profile(FoldingSetNodeID& ID, const T& H,
45 ImmutableListImpl* L){
50 void Profile(FoldingSetNodeID& ID) {
51 Profile(ID, Head, Tail);
55 /// ImmutableList - This class represents an immutable (functional) list.
56 /// It is implemented as a smart pointer (wraps ImmutableListImpl), so it
57 /// it is intended to always be copied by value as if it were a pointer.
58 /// This interface matches ImmutableSet and ImmutableMap. ImmutableList
59 /// objects should almost never be created directly, and instead should
60 /// be created by ImmutableListFactory objects that manage the lifetime
61 /// of a group of lists. When the factory object is reclaimed, all lists
62 /// created by that factory are released as well.
67 typedef ImmutableListFactory<T> Factory;
70 ImmutableListImpl<T>* X;
73 // This constructor should normally only be called by ImmutableListFactory<T>.
74 // There may be cases, however, when one needs to extract the internal pointer
75 // and reconstruct a list object from that pointer.
76 ImmutableList(ImmutableListImpl<T>* x) : X(x) {}
78 ImmutableListImpl<T>* getInternalPointer() const {
83 ImmutableListImpl<T>* L;
86 iterator(ImmutableList l) : L(l.getInternalPointer()) {}
88 iterator& operator++() { L = L->Tail; return *this; }
89 bool operator==(const iterator& I) const { return L == I.L; }
90 ImmutableList operator*() const { return L; }
93 /// begin - Returns an iterator referring to the head of the list, or
94 /// an iterator denoting the end of the list if the list is empty.
95 iterator begin() const { return iterator(X); }
97 /// end - Returns an iterator denoting the end of the list. This iterator
98 /// does not refer to a valid list element.
99 iterator end() const { return iterator(); }
101 /// isEmpty - Returns true if the list is empty.
102 bool isEmpty() const { return !X; }
104 /// isEqual - Returns true if two lists are equal. Because all lists created
105 /// from the same ImmutableListFactory are uniqued, this has O(1) complexity
106 /// because it the contents of the list do not need to be compared. Note
107 /// that you should only compare two lists created from the same
108 /// ImmutableListFactory.
109 bool isEqual(const ImmutableList& L) const { return X == L.X; }
111 bool operator==(const ImmutableList& L) const { return isEqual(L); }
113 /// getHead - Returns the head of the list.
115 assert (!isEmpty() && "Cannot get the head of an empty list.");
119 /// getTail - Returns the tail of the list, which is another (possibly empty)
121 ImmutableList getTail() {
122 return X ? X->getTail() : 0;
126 template <typename T>
127 class ImmutableListFactory {
128 typedef ImmutableListImpl<T> ListTy;
129 typedef FoldingSet<ListTy> CacheTy;
134 bool ownsAllocator() const {
135 return Allocator & 0x1 ? false : true;
138 BumpPtrAllocator& getAllocator() const {
139 return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1);
143 ImmutableListFactory()
144 : Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {}
146 ImmutableListFactory(BumpPtrAllocator& Alloc)
147 : Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {}
149 ~ImmutableListFactory() {
150 if (ownsAllocator()) delete &getAllocator();
153 ImmutableList<T> Concat(const T& Head, ImmutableList<T> Tail) {
154 // Profile the new list to see if it already exists in our cache.
158 ListTy* TailImpl = Tail.getInternalPointer();
159 ListTy::Profile(ID, Head, TailImpl);
160 ListTy* L = Cache.FindNodeOrInsertPos(ID, InsertPos);
163 // The list does not exist in our cache. Create it.
164 BumpPtrAllocator& A = getAllocator();
165 L = (ListTy*) A.Allocate<ListTy>();
166 new (L) ListTy(Head, TailImpl);
168 // Insert the new list into the cache.
169 Cache.InsertNode(L, InsertPos);
175 ImmutableList<T> Add(const T& D, ImmutableList<T> L) {
179 ImmutableList<T> GetEmptyList() const {
180 return ImmutableList<T>(0);
183 ImmutableList<T> Create(const T& X) {
184 return Concat(X, GetEmptyList());
188 } // end llvm namespace