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
41 #include "llvm/ADT/iterator.h"
44 #undef LLVM_COMPACTIFY_SENTINELS
45 /// @brief activate small sentinel structs
46 /// Comment out if you want better debuggability
47 /// of ilist<> end() iterators.
48 /// See also llvm/ADT/ilist_node.h, where the
49 /// same change must be made.
51 #define LLVM_COMPACTIFY_SENTINELS 1
53 #if defined(LLVM_COMPACTIFY_SENTINELS) && LLVM_COMPACTIFY_SENTINELS
54 # define sentinel_tail_assert(COND)
56 # define sentinel_tail_assert(COND) assert(COND)
61 template<typename NodeTy, typename Traits> class iplist;
62 template<typename NodeTy> class ilist_iterator;
64 /// ilist_nextprev_traits - A fragment for template traits for intrusive list
65 /// that provides default next/prev implementations for common operations.
67 template<typename NodeTy>
68 struct ilist_nextprev_traits {
69 static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
70 static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
71 static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
72 static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
74 static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
75 static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
78 template<typename NodeTy>
81 /// ilist_sentinel_traits - A fragment for template traits for intrusive list
82 /// that provides default sentinel implementations for common operations.
84 /// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
85 /// strategy. The sentinel is stored in the prev field of ilist's Head.
87 template<typename NodeTy>
88 struct ilist_sentinel_traits {
89 /// createSentinel - create the dynamic sentinel
90 static NodeTy *createSentinel() { return new NodeTy(); }
92 /// destroySentinel - deallocate the dynamic sentinel
93 static void destroySentinel(NodeTy *N) { delete N; }
95 /// provideInitialHead - when constructing an ilist, provide a starting
96 /// value for its Head
97 /// @return null node to indicate that it needs to be allocated later
98 static NodeTy *provideInitialHead() { return 0; }
100 /// ensureHead - make sure that Head is either already
101 /// initialized or assigned a fresh sentinel
102 /// @return the sentinel
103 static NodeTy *ensureHead(NodeTy *&Head) {
105 Head = ilist_traits<NodeTy>::createSentinel();
106 ilist_traits<NodeTy>::noteHead(Head, Head);
107 ilist_traits<NodeTy>::setNext(Head, 0);
110 return ilist_traits<NodeTy>::getPrev(Head);
113 /// noteHead - stash the sentinel into its default location
114 static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
115 ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
119 /// ilist_node_traits - A fragment for template traits for intrusive list
120 /// that provides default node related operations.
122 template<typename NodeTy>
123 struct ilist_node_traits {
124 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
125 static void deleteNode(NodeTy *V) { delete V; }
127 void addNodeToList(NodeTy *) {}
128 void removeNodeFromList(NodeTy *) {}
129 void transferNodesFromList(ilist_node_traits & /*SrcTraits*/,
130 ilist_iterator<NodeTy> /*first*/,
131 ilist_iterator<NodeTy> /*last*/) {}
134 /// ilist_default_traits - Default template traits for intrusive list.
135 /// By inheriting from this, you can easily use default implementations
136 /// for all common operations.
138 template<typename NodeTy>
139 struct ilist_default_traits : ilist_nextprev_traits<NodeTy>,
140 ilist_sentinel_traits<NodeTy>,
141 ilist_node_traits<NodeTy> {
144 // Template traits for intrusive list. By specializing this template class, you
145 // can change what next/prev fields are used to store the links...
146 template<typename NodeTy>
147 struct ilist_traits : ilist_default_traits<NodeTy> {};
149 // Const traits are the same as nonconst traits...
150 template<typename Ty>
151 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
153 //===----------------------------------------------------------------------===//
154 // ilist_iterator<Node> - Iterator for intrusive list.
156 template<typename NodeTy>
158 : public bidirectional_iterator<NodeTy, ptrdiff_t> {
161 typedef ilist_traits<NodeTy> Traits;
162 typedef bidirectional_iterator<NodeTy, ptrdiff_t> super;
164 typedef typename super::value_type value_type;
165 typedef typename super::difference_type difference_type;
166 typedef typename super::pointer pointer;
167 typedef typename super::reference reference;
171 // ilist_iterator is not a random-access iterator, but it has an
172 // implicit conversion to pointer-type, which is. Declare (but
173 // don't define) these functions as private to help catch
174 // accidental misuse.
175 void operator[](difference_type) const;
176 void operator+(difference_type) const;
177 void operator-(difference_type) const;
178 void operator+=(difference_type) const;
179 void operator-=(difference_type) const;
180 template<class T> void operator<(T) const;
181 template<class T> void operator<=(T) const;
182 template<class T> void operator>(T) const;
183 template<class T> void operator>=(T) const;
184 template<class T> void operator-(T) const;
187 ilist_iterator(pointer NP) : NodePtr(NP) {}
188 ilist_iterator(reference NR) : NodePtr(&NR) {}
189 ilist_iterator() : NodePtr(0) {}
191 // This is templated so that we can allow constructing a const iterator from
192 // a nonconst iterator...
193 template<class node_ty>
194 ilist_iterator(const ilist_iterator<node_ty> &RHS)
195 : NodePtr(RHS.getNodePtrUnchecked()) {}
197 // This is templated so that we can allow assigning to a const iterator from
198 // a nonconst iterator...
199 template<class node_ty>
200 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
201 NodePtr = RHS.getNodePtrUnchecked();
206 operator pointer() const {
207 sentinel_tail_assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
211 reference operator*() const {
212 sentinel_tail_assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
215 pointer operator->() const { return &operator*(); }
217 // Comparison operators
218 bool operator==(const ilist_iterator &RHS) const {
219 return NodePtr == RHS.NodePtr;
221 bool operator!=(const ilist_iterator &RHS) const {
222 return NodePtr != RHS.NodePtr;
225 // Increment and decrement operators...
226 ilist_iterator &operator--() { // predecrement - Back up
227 NodePtr = Traits::getPrev(NodePtr);
228 assert(NodePtr && "--'d off the beginning of an ilist!");
231 ilist_iterator &operator++() { // preincrement - Advance
232 NodePtr = Traits::getNext(NodePtr);
233 sentinel_tail_assert(NodePtr && "++'d off the end of an ilist!");
236 ilist_iterator operator--(int) { // postdecrement operators...
237 ilist_iterator tmp = *this;
241 ilist_iterator operator++(int) { // postincrement operators...
242 ilist_iterator tmp = *this;
247 // Internal interface, do not use...
248 pointer getNodePtrUnchecked() const { return NodePtr; }
251 // do not implement. this is to catch errors when people try to use
252 // them as random access iterators
254 void operator-(int, ilist_iterator<T>);
256 void operator-(ilist_iterator<T>,int);
259 void operator+(int, ilist_iterator<T>);
261 void operator+(ilist_iterator<T>,int);
263 // operator!=/operator== - Allow mixed comparisons without dereferencing
264 // the iterator, which could very likely be pointing to end().
266 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
267 return LHS != RHS.getNodePtrUnchecked();
270 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
271 return LHS == RHS.getNodePtrUnchecked();
274 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
275 return LHS != RHS.getNodePtrUnchecked();
278 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
279 return LHS == RHS.getNodePtrUnchecked();
283 // Allow ilist_iterators to convert into pointers to a node automatically when
284 // used by the dyn_cast, cast, isa mechanisms...
286 template<typename From> struct simplify_type;
288 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
289 typedef NodeTy* SimpleType;
291 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
295 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
296 typedef NodeTy* SimpleType;
298 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
304 //===----------------------------------------------------------------------===//
306 /// iplist - The subset of list functionality that can safely be used on nodes
307 /// of polymorphic types, i.e. a heterogenous list with a common base class that
308 /// holds the next/prev pointers. The only state of the list itself is a single
309 /// pointer to the head of the list.
311 /// This list can be in one of three interesting states:
312 /// 1. The list may be completely unconstructed. In this case, the head
313 /// pointer is null. When in this form, any query for an iterator (e.g.
314 /// begin() or end()) causes the list to transparently change to state #2.
315 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
316 /// sentinel is created by the Traits::createSentinel method and is a link
317 /// in the list. When the list is empty, the pointer in the iplist points
318 /// to the sentinel. Once the sentinel is constructed, it
319 /// is not destroyed until the list is.
320 /// 3. The list may contain actual objects in it, which are stored as a doubly
321 /// linked list of nodes. One invariant of the list is that the predecessor
322 /// of the first node in the list always points to the last node in the list,
323 /// and the successor pointer for the sentinel (which always stays at the
324 /// end of the list) is always null.
326 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
327 class iplist : public Traits {
328 mutable NodeTy *Head;
330 // Use the prev node pointer of 'head' as the tail pointer. This is really a
331 // circularly linked list where we snip the 'next' link from the sentinel node
332 // back to the first node in the list (to preserve assertions about going off
333 // the end of the list).
334 NodeTy *getTail() { return this->ensureHead(Head); }
335 const NodeTy *getTail() const { return this->ensureHead(Head); }
336 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
338 /// CreateLazySentinel - This method verifies whether the sentinel for the
339 /// list has been created and lazily makes it if not.
340 void CreateLazySentinel() const {
341 this->ensureHead(Head);
344 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
345 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
347 // No fundamental reason why iplist can't be copyable, but the default
348 // copy/copy-assign won't do.
349 iplist(const iplist &); // do not implement
350 void operator=(const iplist &); // do not implement
353 typedef NodeTy *pointer;
354 typedef const NodeTy *const_pointer;
355 typedef NodeTy &reference;
356 typedef const NodeTy &const_reference;
357 typedef NodeTy value_type;
358 typedef ilist_iterator<NodeTy> iterator;
359 typedef ilist_iterator<const NodeTy> const_iterator;
360 typedef size_t size_type;
361 typedef ptrdiff_t difference_type;
362 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
363 typedef std::reverse_iterator<iterator> reverse_iterator;
365 iplist() : Head(this->provideInitialHead()) {}
369 Traits::destroySentinel(getTail());
372 // Iterator creation methods.
374 CreateLazySentinel();
375 return iterator(Head);
377 const_iterator begin() const {
378 CreateLazySentinel();
379 return const_iterator(Head);
382 CreateLazySentinel();
383 return iterator(getTail());
385 const_iterator end() const {
386 CreateLazySentinel();
387 return const_iterator(getTail());
390 // reverse iterator creation methods.
391 reverse_iterator rbegin() { return reverse_iterator(end()); }
392 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
393 reverse_iterator rend() { return reverse_iterator(begin()); }
394 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
397 // Miscellaneous inspection routines.
398 size_type max_size() const { return size_type(-1); }
399 bool empty() const { return Head == 0 || Head == getTail(); }
401 // Front and back accessor functions...
403 assert(!empty() && "Called front() on empty list!");
406 const_reference front() const {
407 assert(!empty() && "Called front() on empty list!");
411 assert(!empty() && "Called back() on empty list!");
412 return *this->getPrev(getTail());
414 const_reference back() const {
415 assert(!empty() && "Called back() on empty list!");
416 return *this->getPrev(getTail());
419 void swap(iplist &RHS) {
420 assert(0 && "Swap does not use list traits callback correctly yet!");
421 std::swap(Head, RHS.Head);
424 iterator insert(iterator where, NodeTy *New) {
425 NodeTy *CurNode = where.getNodePtrUnchecked();
426 NodeTy *PrevNode = this->getPrev(CurNode);
427 this->setNext(New, CurNode);
428 this->setPrev(New, PrevNode);
430 if (CurNode != Head) // Is PrevNode off the beginning of the list?
431 this->setNext(PrevNode, New);
434 this->setPrev(CurNode, New);
436 this->addNodeToList(New); // Notify traits that we added a node...
440 iterator insertAfter(iterator where, NodeTy *New) {
442 return insert(begin(), New);
444 return insert(++where, New);
447 NodeTy *remove(iterator &IT) {
448 assert(IT != end() && "Cannot remove end of list!");
450 NodeTy *NextNode = this->getNext(Node);
451 NodeTy *PrevNode = this->getPrev(Node);
453 if (Node != Head) // Is PrevNode off the beginning of the list?
454 this->setNext(PrevNode, NextNode);
457 this->setPrev(NextNode, PrevNode);
459 this->removeNodeFromList(Node); // Notify traits that we removed a node...
461 // Set the next/prev pointers of the current node to null. This isn't
462 // strictly required, but this catches errors where a node is removed from
463 // an ilist (and potentially deleted) with iterators still pointing at it.
464 // When those iterators are incremented or decremented, they will assert on
465 // the null next/prev pointer instead of "usually working".
466 this->setNext(Node, 0);
467 this->setPrev(Node, 0);
471 NodeTy *remove(const iterator &IT) {
473 return remove(MutIt);
476 // erase - remove a node from the controlled sequence... and delete it.
477 iterator erase(iterator where) {
478 this->deleteNode(remove(where));
484 // transfer - The heart of the splice function. Move linked list nodes from
485 // [first, last) into position.
487 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
488 assert(first != last && "Should be checked by callers");
490 if (position != last) {
491 // Note: we have to be careful about the case when we move the first node
492 // in the list. This node is the list sentinel node and we can't move it.
493 NodeTy *ThisSentinel = getTail();
495 NodeTy *L2Sentinel = L2.getTail();
498 // Remove [first, last) from its old position.
499 NodeTy *First = &*first, *Prev = this->getPrev(First);
500 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
502 this->setNext(Prev, Next);
505 this->setPrev(Next, Prev);
507 // Splice [first, last) into its new position.
508 NodeTy *PosNext = position.getNodePtrUnchecked();
509 NodeTy *PosPrev = this->getPrev(PosNext);
511 // Fix head of list...
513 this->setNext(PosPrev, First);
516 this->setPrev(First, PosPrev);
518 // Fix end of list...
519 this->setNext(Last, PosNext);
520 this->setPrev(PosNext, Last);
522 this->transferNodesFromList(L2, First, PosNext);
524 // Now that everything is set, restore the pointers to the list sentinels.
525 L2.setTail(L2Sentinel);
526 setTail(ThisSentinel);
532 //===----------------------------------------------------------------------===
533 // Functionality derived from other functions defined above...
536 size_type size() const {
537 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
538 return std::distance(begin(), end());
541 iterator erase(iterator first, iterator last) {
542 while (first != last)
543 first = erase(first);
547 void clear() { if (Head) erase(begin(), end()); }
549 // Front and back inserters...
550 void push_front(NodeTy *val) { insert(begin(), val); }
551 void push_back(NodeTy *val) { insert(end(), val); }
553 assert(!empty() && "pop_front() on empty list!");
557 assert(!empty() && "pop_back() on empty list!");
558 iterator t = end(); erase(--t);
561 // Special forms of insert...
562 template<class InIt> void insert(iterator where, InIt first, InIt last) {
563 for (; first != last; ++first) insert(where, *first);
566 // Splice members - defined in terms of transfer...
567 void splice(iterator where, iplist &L2) {
569 transfer(where, L2, L2.begin(), L2.end());
571 void splice(iterator where, iplist &L2, iterator first) {
572 iterator last = first; ++last;
573 if (where == first || where == last) return; // No change
574 transfer(where, L2, first, last);
576 void splice(iterator where, iplist &L2, iterator first, iterator last) {
577 if (first != last) transfer(where, L2, first, last);
582 //===----------------------------------------------------------------------===
583 // High-Level Functionality that shouldn't really be here, but is part of list
586 // These two functions are actually called remove/remove_if in list<>, but
587 // they actually do the job of erase, rename them accordingly.
589 void erase(const NodeTy &val) {
590 for (iterator I = begin(), E = end(); I != E; ) {
591 iterator next = I; ++next;
592 if (*I == val) erase(I);
596 template<class Pr1> void erase_if(Pr1 pred) {
597 for (iterator I = begin(), E = end(); I != E; ) {
598 iterator next = I; ++next;
599 if (pred(*I)) erase(I);
604 template<class Pr2> void unique(Pr2 pred) {
606 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
614 void unique() { unique(op_equal); }
616 template<class Pr3> void merge(iplist &right, Pr3 pred) {
617 iterator first1 = begin(), last1 = end();
618 iterator first2 = right.begin(), last2 = right.end();
619 while (first1 != last1 && first2 != last2)
620 if (pred(*first2, *first1)) {
621 iterator next = first2;
622 transfer(first1, right, first2, ++next);
627 if (first2 != last2) transfer(last1, right, first2, last2);
629 void merge(iplist &right) { return merge(right, op_less); }
631 template<class Pr3> void sort(Pr3 pred);
632 void sort() { sort(op_less); }
637 template<typename NodeTy>
638 struct ilist : public iplist<NodeTy> {
639 typedef typename iplist<NodeTy>::size_type size_type;
640 typedef typename iplist<NodeTy>::iterator iterator;
643 ilist(const ilist &right) {
644 insert(this->begin(), right.begin(), right.end());
646 explicit ilist(size_type count) {
647 insert(this->begin(), count, NodeTy());
649 ilist(size_type count, const NodeTy &val) {
650 insert(this->begin(), count, val);
652 template<class InIt> ilist(InIt first, InIt last) {
653 insert(this->begin(), first, last);
656 // bring hidden functions into scope
657 using iplist<NodeTy>::insert;
658 using iplist<NodeTy>::push_front;
659 using iplist<NodeTy>::push_back;
661 // Main implementation here - Insert for a node passed by value...
662 iterator insert(iterator where, const NodeTy &val) {
663 return insert(where, createNode(val));
667 // Front and back inserters...
668 void push_front(const NodeTy &val) { insert(this->begin(), val); }
669 void push_back(const NodeTy &val) { insert(this->end(), val); }
671 // Special forms of insert...
672 template<class InIt> void insert(iterator where, InIt first, InIt last) {
673 for (; first != last; ++first) insert(where, *first);
675 void insert(iterator where, size_type count, const NodeTy &val) {
676 for (; count != 0; --count) insert(where, val);
679 // Assign special forms...
680 void assign(size_type count, const NodeTy &val) {
681 iterator I = this->begin();
682 for (; I != this->end() && count != 0; ++I, --count)
685 insert(this->end(), val, val);
687 erase(I, this->end());
689 template<class InIt> void assign(InIt first1, InIt last1) {
690 iterator first2 = this->begin(), last2 = this->end();
691 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
694 erase(first1, last1);
696 insert(last1, first2, last2);
701 void resize(size_type newsize, NodeTy val) {
702 iterator i = this->begin();
704 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
707 erase(i, this->end());
709 insert(this->end(), newsize - len, val);
711 void resize(size_type newsize) { resize(newsize, NodeTy()); }
714 } // End llvm namespace
717 // Ensure that swap uses the fast list swap...
719 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
722 } // End 'std' extensions...
724 #endif // LLVM_ADT_ILIST_H