1 //==-- llvm/ADT/ilist.h - Intrusive Linked List Template ---------*- 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 classes to implement an intrusive doubly linked list class
11 // (i.e. each node of the list must contain a next and previous field for the
14 // The ilist_traits trait class is used to gain access to the next and previous
15 // fields of the node type that the list is instantiated with. If it is not
16 // specialized, the list defaults to using the getPrev(), getNext() method calls
17 // to get the next and previous pointers.
19 // The ilist class itself, should be a plug in replacement for list, assuming
20 // that the nodes contain next/prev pointers. This list replacement does not
21 // provide a constant time size() method, so be careful to use empty() when you
22 // really want to know if it's empty.
24 // The ilist class is implemented by allocating a 'tail' node when the list is
25 // created (using ilist_traits<>::createSentinel()). This tail node is
26 // absolutely required because the user must be able to compute end()-1. Because
27 // of this, users of the direct next/prev links will see an extra link on the
28 // end of the list, which should be ignored.
30 // Requirements for a user of this list:
32 // 1. The user must provide {g|s}et{Next|Prev} methods, or specialize
33 // ilist_traits to provide an alternate way of getting and setting next and
36 //===----------------------------------------------------------------------===//
38 #ifndef LLVM_ADT_ILIST_H
39 #define LLVM_ADT_ILIST_H
48 template<typename NodeTy, typename Traits> class iplist;
49 template<typename NodeTy> class ilist_iterator;
51 /// ilist_nextprev_traits - A fragment for template traits for intrusive list
52 /// that provides default next/prev implementations for common operations.
54 template<typename NodeTy>
55 struct ilist_nextprev_traits {
56 static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
57 static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
58 static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
59 static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
61 static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
62 static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
65 template<typename NodeTy>
68 /// ilist_sentinel_traits - A fragment for template traits for intrusive list
69 /// that provides default sentinel implementations for common operations.
71 /// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
72 /// strategy. The sentinel is stored in the prev field of ilist's Head.
74 template<typename NodeTy>
75 struct ilist_sentinel_traits {
76 /// createSentinel - create the dynamic sentinel
77 static NodeTy *createSentinel() { return new NodeTy(); }
79 /// destroySentinel - deallocate the dynamic sentinel
80 static void destroySentinel(NodeTy *N) { delete N; }
82 /// provideInitialHead - when constructing an ilist, provide a starting
83 /// value for its Head
84 /// @return null node to indicate that it needs to be allocated later
85 static NodeTy *provideInitialHead() { return 0; }
87 /// ensureHead - make sure that Head is either already
88 /// initialized or assigned a fresh sentinel
89 /// @return the sentinel
90 static NodeTy *ensureHead(NodeTy *&Head) {
92 Head = ilist_traits<NodeTy>::createSentinel();
93 ilist_traits<NodeTy>::noteHead(Head, Head);
94 ilist_traits<NodeTy>::setNext(Head, 0);
97 return ilist_traits<NodeTy>::getPrev(Head);
100 /// noteHead - stash the sentinel into its default location
101 static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
102 ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
106 /// ilist_node_traits - A fragment for template traits for intrusive list
107 /// that provides default node related operations.
109 template<typename NodeTy>
110 struct ilist_node_traits {
111 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
112 static void deleteNode(NodeTy *V) { delete V; }
114 void addNodeToList(NodeTy *) {}
115 void removeNodeFromList(NodeTy *) {}
116 void transferNodesFromList(ilist_node_traits & /*SrcTraits*/,
117 ilist_iterator<NodeTy> /*first*/,
118 ilist_iterator<NodeTy> /*last*/) {}
121 /// ilist_default_traits - Default template traits for intrusive list.
122 /// By inheriting from this, you can easily use default implementations
123 /// for all common operations.
125 template<typename NodeTy>
126 struct ilist_default_traits : public ilist_nextprev_traits<NodeTy>,
127 public ilist_sentinel_traits<NodeTy>,
128 public ilist_node_traits<NodeTy> {
131 // Template traits for intrusive list. By specializing this template class, you
132 // can change what next/prev fields are used to store the links...
133 template<typename NodeTy>
134 struct ilist_traits : public ilist_default_traits<NodeTy> {};
136 // Const traits are the same as nonconst traits...
137 template<typename Ty>
138 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
140 //===----------------------------------------------------------------------===//
141 // ilist_iterator<Node> - Iterator for intrusive list.
143 template<typename NodeTy>
145 : public std::iterator<std::bidirectional_iterator_tag, NodeTy, ptrdiff_t> {
148 typedef ilist_traits<NodeTy> Traits;
149 typedef std::iterator<std::bidirectional_iterator_tag,
150 NodeTy, ptrdiff_t> super;
152 typedef typename super::value_type value_type;
153 typedef typename super::difference_type difference_type;
154 typedef typename super::pointer pointer;
155 typedef typename super::reference reference;
159 // ilist_iterator is not a random-access iterator, but it has an
160 // implicit conversion to pointer-type, which is. Declare (but
161 // don't define) these functions as private to help catch
162 // accidental misuse.
163 void operator[](difference_type) const;
164 void operator+(difference_type) const;
165 void operator-(difference_type) const;
166 void operator+=(difference_type) const;
167 void operator-=(difference_type) const;
168 template<class T> void operator<(T) const;
169 template<class T> void operator<=(T) const;
170 template<class T> void operator>(T) const;
171 template<class T> void operator>=(T) const;
172 template<class T> void operator-(T) const;
175 ilist_iterator(pointer NP) : NodePtr(NP) {}
176 ilist_iterator(reference NR) : NodePtr(&NR) {}
177 ilist_iterator() : NodePtr(0) {}
179 // This is templated so that we can allow constructing a const iterator from
180 // a nonconst iterator...
181 template<class node_ty>
182 ilist_iterator(const ilist_iterator<node_ty> &RHS)
183 : NodePtr(RHS.getNodePtrUnchecked()) {}
185 // This is templated so that we can allow assigning to a const iterator from
186 // a nonconst iterator...
187 template<class node_ty>
188 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
189 NodePtr = RHS.getNodePtrUnchecked();
194 operator pointer() const {
198 reference operator*() const {
201 pointer operator->() const { return &operator*(); }
203 // Comparison operators
204 bool operator==(const ilist_iterator &RHS) const {
205 return NodePtr == RHS.NodePtr;
207 bool operator!=(const ilist_iterator &RHS) const {
208 return NodePtr != RHS.NodePtr;
211 // Increment and decrement operators...
212 ilist_iterator &operator--() { // predecrement - Back up
213 NodePtr = Traits::getPrev(NodePtr);
214 assert(NodePtr && "--'d off the beginning of an ilist!");
217 ilist_iterator &operator++() { // preincrement - Advance
218 NodePtr = Traits::getNext(NodePtr);
221 ilist_iterator operator--(int) { // postdecrement operators...
222 ilist_iterator tmp = *this;
226 ilist_iterator operator++(int) { // postincrement operators...
227 ilist_iterator tmp = *this;
232 // Internal interface, do not use...
233 pointer getNodePtrUnchecked() const { return NodePtr; }
236 // do not implement. this is to catch errors when people try to use
237 // them as random access iterators
239 void operator-(int, ilist_iterator<T>);
241 void operator-(ilist_iterator<T>,int);
244 void operator+(int, ilist_iterator<T>);
246 void operator+(ilist_iterator<T>,int);
248 // operator!=/operator== - Allow mixed comparisons without dereferencing
249 // the iterator, which could very likely be pointing to end().
251 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
252 return LHS != RHS.getNodePtrUnchecked();
255 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
256 return LHS == RHS.getNodePtrUnchecked();
259 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
260 return LHS != RHS.getNodePtrUnchecked();
263 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
264 return LHS == RHS.getNodePtrUnchecked();
268 // Allow ilist_iterators to convert into pointers to a node automatically when
269 // used by the dyn_cast, cast, isa mechanisms...
271 template<typename From> struct simplify_type;
273 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
274 typedef NodeTy* SimpleType;
276 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
280 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
281 typedef NodeTy* SimpleType;
283 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
289 //===----------------------------------------------------------------------===//
291 /// iplist - The subset of list functionality that can safely be used on nodes
292 /// of polymorphic types, i.e. a heterogeneous list with a common base class that
293 /// holds the next/prev pointers. The only state of the list itself is a single
294 /// pointer to the head of the list.
296 /// This list can be in one of three interesting states:
297 /// 1. The list may be completely unconstructed. In this case, the head
298 /// pointer is null. When in this form, any query for an iterator (e.g.
299 /// begin() or end()) causes the list to transparently change to state #2.
300 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
301 /// sentinel is created by the Traits::createSentinel method and is a link
302 /// in the list. When the list is empty, the pointer in the iplist points
303 /// to the sentinel. Once the sentinel is constructed, it
304 /// is not destroyed until the list is.
305 /// 3. The list may contain actual objects in it, which are stored as a doubly
306 /// linked list of nodes. One invariant of the list is that the predecessor
307 /// of the first node in the list always points to the last node in the list,
308 /// and the successor pointer for the sentinel (which always stays at the
309 /// end of the list) is always null.
311 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
312 class iplist : public Traits {
313 mutable NodeTy *Head;
315 // Use the prev node pointer of 'head' as the tail pointer. This is really a
316 // circularly linked list where we snip the 'next' link from the sentinel node
317 // back to the first node in the list (to preserve assertions about going off
318 // the end of the list).
319 NodeTy *getTail() { return this->ensureHead(Head); }
320 const NodeTy *getTail() const { return this->ensureHead(Head); }
321 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
323 /// CreateLazySentinel - This method verifies whether the sentinel for the
324 /// list has been created and lazily makes it if not.
325 void CreateLazySentinel() const {
326 this->ensureHead(Head);
329 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
330 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
332 // No fundamental reason why iplist can't be copyable, but the default
333 // copy/copy-assign won't do.
334 iplist(const iplist &); // do not implement
335 void operator=(const iplist &); // do not implement
338 typedef NodeTy *pointer;
339 typedef const NodeTy *const_pointer;
340 typedef NodeTy &reference;
341 typedef const NodeTy &const_reference;
342 typedef NodeTy value_type;
343 typedef ilist_iterator<NodeTy> iterator;
344 typedef ilist_iterator<const NodeTy> const_iterator;
345 typedef size_t size_type;
346 typedef ptrdiff_t difference_type;
347 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
348 typedef std::reverse_iterator<iterator> reverse_iterator;
350 iplist() : Head(this->provideInitialHead()) {}
354 Traits::destroySentinel(getTail());
357 // Iterator creation methods.
359 CreateLazySentinel();
360 return iterator(Head);
362 const_iterator begin() const {
363 CreateLazySentinel();
364 return const_iterator(Head);
367 CreateLazySentinel();
368 return iterator(getTail());
370 const_iterator end() const {
371 CreateLazySentinel();
372 return const_iterator(getTail());
375 // reverse iterator creation methods.
376 reverse_iterator rbegin() { return reverse_iterator(end()); }
377 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
378 reverse_iterator rend() { return reverse_iterator(begin()); }
379 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
382 // Miscellaneous inspection routines.
383 size_type max_size() const { return size_type(-1); }
384 bool empty() const { return Head == 0 || Head == getTail(); }
386 // Front and back accessor functions...
388 assert(!empty() && "Called front() on empty list!");
391 const_reference front() const {
392 assert(!empty() && "Called front() on empty list!");
396 assert(!empty() && "Called back() on empty list!");
397 return *this->getPrev(getTail());
399 const_reference back() const {
400 assert(!empty() && "Called back() on empty list!");
401 return *this->getPrev(getTail());
404 void swap(iplist &RHS) {
405 assert(0 && "Swap does not use list traits callback correctly yet!");
406 std::swap(Head, RHS.Head);
409 iterator insert(iterator where, NodeTy *New) {
410 NodeTy *CurNode = where.getNodePtrUnchecked();
411 NodeTy *PrevNode = this->getPrev(CurNode);
412 this->setNext(New, CurNode);
413 this->setPrev(New, PrevNode);
415 if (CurNode != Head) // Is PrevNode off the beginning of the list?
416 this->setNext(PrevNode, New);
419 this->setPrev(CurNode, New);
421 this->addNodeToList(New); // Notify traits that we added a node...
425 iterator insertAfter(iterator where, NodeTy *New) {
427 return insert(begin(), New);
429 return insert(++where, New);
432 NodeTy *remove(iterator &IT) {
433 assert(IT != end() && "Cannot remove end of list!");
435 NodeTy *NextNode = this->getNext(Node);
436 NodeTy *PrevNode = this->getPrev(Node);
438 if (Node != Head) // Is PrevNode off the beginning of the list?
439 this->setNext(PrevNode, NextNode);
442 this->setPrev(NextNode, PrevNode);
444 this->removeNodeFromList(Node); // Notify traits that we removed a node...
446 // Set the next/prev pointers of the current node to null. This isn't
447 // strictly required, but this catches errors where a node is removed from
448 // an ilist (and potentially deleted) with iterators still pointing at it.
449 // When those iterators are incremented or decremented, they will assert on
450 // the null next/prev pointer instead of "usually working".
451 this->setNext(Node, 0);
452 this->setPrev(Node, 0);
456 NodeTy *remove(const iterator &IT) {
458 return remove(MutIt);
461 // erase - remove a node from the controlled sequence... and delete it.
462 iterator erase(iterator where) {
463 this->deleteNode(remove(where));
469 // transfer - The heart of the splice function. Move linked list nodes from
470 // [first, last) into position.
472 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
473 assert(first != last && "Should be checked by callers");
475 if (position != last) {
476 // Note: we have to be careful about the case when we move the first node
477 // in the list. This node is the list sentinel node and we can't move it.
478 NodeTy *ThisSentinel = getTail();
480 NodeTy *L2Sentinel = L2.getTail();
483 // Remove [first, last) from its old position.
484 NodeTy *First = &*first, *Prev = this->getPrev(First);
485 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
487 this->setNext(Prev, Next);
490 this->setPrev(Next, Prev);
492 // Splice [first, last) into its new position.
493 NodeTy *PosNext = position.getNodePtrUnchecked();
494 NodeTy *PosPrev = this->getPrev(PosNext);
496 // Fix head of list...
498 this->setNext(PosPrev, First);
501 this->setPrev(First, PosPrev);
503 // Fix end of list...
504 this->setNext(Last, PosNext);
505 this->setPrev(PosNext, Last);
507 this->transferNodesFromList(L2, First, PosNext);
509 // Now that everything is set, restore the pointers to the list sentinels.
510 L2.setTail(L2Sentinel);
511 setTail(ThisSentinel);
517 //===----------------------------------------------------------------------===
518 // Functionality derived from other functions defined above...
521 size_type size() const {
522 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
523 return std::distance(begin(), end());
526 iterator erase(iterator first, iterator last) {
527 while (first != last)
528 first = erase(first);
532 void clear() { if (Head) erase(begin(), end()); }
534 // Front and back inserters...
535 void push_front(NodeTy *val) { insert(begin(), val); }
536 void push_back(NodeTy *val) { insert(end(), val); }
538 assert(!empty() && "pop_front() on empty list!");
542 assert(!empty() && "pop_back() on empty list!");
543 iterator t = end(); erase(--t);
546 // Special forms of insert...
547 template<class InIt> void insert(iterator where, InIt first, InIt last) {
548 for (; first != last; ++first) insert(where, *first);
551 // Splice members - defined in terms of transfer...
552 void splice(iterator where, iplist &L2) {
554 transfer(where, L2, L2.begin(), L2.end());
556 void splice(iterator where, iplist &L2, iterator first) {
557 iterator last = first; ++last;
558 if (where == first || where == last) return; // No change
559 transfer(where, L2, first, last);
561 void splice(iterator where, iplist &L2, iterator first, iterator last) {
562 if (first != last) transfer(where, L2, first, last);
567 //===----------------------------------------------------------------------===
568 // High-Level Functionality that shouldn't really be here, but is part of list
571 // These two functions are actually called remove/remove_if in list<>, but
572 // they actually do the job of erase, rename them accordingly.
574 void erase(const NodeTy &val) {
575 for (iterator I = begin(), E = end(); I != E; ) {
576 iterator next = I; ++next;
577 if (*I == val) erase(I);
581 template<class Pr1> void erase_if(Pr1 pred) {
582 for (iterator I = begin(), E = end(); I != E; ) {
583 iterator next = I; ++next;
584 if (pred(*I)) erase(I);
589 template<class Pr2> void unique(Pr2 pred) {
591 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
599 void unique() { unique(op_equal); }
601 template<class Pr3> void merge(iplist &right, Pr3 pred) {
602 iterator first1 = begin(), last1 = end();
603 iterator first2 = right.begin(), last2 = right.end();
604 while (first1 != last1 && first2 != last2)
605 if (pred(*first2, *first1)) {
606 iterator next = first2;
607 transfer(first1, right, first2, ++next);
612 if (first2 != last2) transfer(last1, right, first2, last2);
614 void merge(iplist &right) { return merge(right, op_less); }
616 template<class Pr3> void sort(Pr3 pred);
617 void sort() { sort(op_less); }
621 template<typename NodeTy>
622 struct ilist : public iplist<NodeTy> {
623 typedef typename iplist<NodeTy>::size_type size_type;
624 typedef typename iplist<NodeTy>::iterator iterator;
627 ilist(const ilist &right) {
628 insert(this->begin(), right.begin(), right.end());
630 explicit ilist(size_type count) {
631 insert(this->begin(), count, NodeTy());
633 ilist(size_type count, const NodeTy &val) {
634 insert(this->begin(), count, val);
636 template<class InIt> ilist(InIt first, InIt last) {
637 insert(this->begin(), first, last);
640 // bring hidden functions into scope
641 using iplist<NodeTy>::insert;
642 using iplist<NodeTy>::push_front;
643 using iplist<NodeTy>::push_back;
645 // Main implementation here - Insert for a node passed by value...
646 iterator insert(iterator where, const NodeTy &val) {
647 return insert(where, this->createNode(val));
651 // Front and back inserters...
652 void push_front(const NodeTy &val) { insert(this->begin(), val); }
653 void push_back(const NodeTy &val) { insert(this->end(), val); }
655 // Special forms of insert...
656 template<class InIt> void insert(iterator where, InIt first, InIt last) {
657 for (; first != last; ++first) insert(where, *first);
659 void insert(iterator where, size_type count, const NodeTy &val) {
660 for (; count != 0; --count) insert(where, val);
663 // Assign special forms...
664 void assign(size_type count, const NodeTy &val) {
665 iterator I = this->begin();
666 for (; I != this->end() && count != 0; ++I, --count)
669 insert(this->end(), val, val);
671 erase(I, this->end());
673 template<class InIt> void assign(InIt first1, InIt last1) {
674 iterator first2 = this->begin(), last2 = this->end();
675 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
678 erase(first1, last1);
680 insert(last1, first2, last2);
685 void resize(size_type newsize, NodeTy val) {
686 iterator i = this->begin();
688 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
691 erase(i, this->end());
693 insert(this->end(), newsize - len, val);
695 void resize(size_type newsize) { resize(newsize, NodeTy()); }
698 } // End llvm namespace
701 // Ensure that swap uses the fast list swap...
703 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
706 } // End 'std' extensions...
708 #endif // LLVM_ADT_ILIST_H