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
46 template<typename NodeTy, typename Traits> class iplist;
47 template<typename NodeTy> class ilist_iterator;
49 /// ilist_nextprev_traits - A fragment for template traits for intrusive list
50 /// that provides default next/prev implementations for common operations.
52 template<typename NodeTy>
53 struct ilist_nextprev_traits {
54 static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
55 static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
56 static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
57 static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
59 static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
60 static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
63 template<typename NodeTy>
66 /// ilist_sentinel_traits - A fragment for template traits for intrusive list
67 /// that provides default sentinel implementations for common operations.
69 /// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
70 /// strategy. The sentinel is stored in the prev field of ilist's Head.
72 template<typename NodeTy>
73 struct ilist_sentinel_traits {
74 /// createSentinel - create the dynamic sentinel
75 static NodeTy *createSentinel() { return new NodeTy(); }
77 /// destroySentinel - deallocate the dynamic sentinel
78 static void destroySentinel(NodeTy *N) { delete N; }
80 /// provideInitialHead - when constructing an ilist, provide a starting
81 /// value for its Head
82 /// @return null node to indicate that it needs to be allocated later
83 static NodeTy *provideInitialHead() { return 0; }
85 /// ensureHead - make sure that Head is either already
86 /// initialized or assigned a fresh sentinel
87 /// @return the sentinel
88 static NodeTy *ensureHead(NodeTy *&Head) {
90 Head = ilist_traits<NodeTy>::createSentinel();
91 ilist_traits<NodeTy>::noteHead(Head, Head);
92 ilist_traits<NodeTy>::setNext(Head, 0);
95 return ilist_traits<NodeTy>::getPrev(Head);
98 /// noteHead - stash the sentinel into its default location
99 static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
100 ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
104 /// ilist_node_traits - A fragment for template traits for intrusive list
105 /// that provides default node related operations.
107 template<typename NodeTy>
108 struct ilist_node_traits {
109 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
110 static void deleteNode(NodeTy *V) { delete V; }
112 void addNodeToList(NodeTy *) {}
113 void removeNodeFromList(NodeTy *) {}
114 void transferNodesFromList(ilist_node_traits & /*SrcTraits*/,
115 ilist_iterator<NodeTy> /*first*/,
116 ilist_iterator<NodeTy> /*last*/) {}
119 /// ilist_default_traits - Default template traits for intrusive list.
120 /// By inheriting from this, you can easily use default implementations
121 /// for all common operations.
123 template<typename NodeTy>
124 struct ilist_default_traits : ilist_nextprev_traits<NodeTy>,
125 ilist_sentinel_traits<NodeTy>,
126 ilist_node_traits<NodeTy> {
129 // Template traits for intrusive list. By specializing this template class, you
130 // can change what next/prev fields are used to store the links...
131 template<typename NodeTy>
132 struct ilist_traits : ilist_default_traits<NodeTy> {};
134 // Const traits are the same as nonconst traits...
135 template<typename Ty>
136 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
138 //===----------------------------------------------------------------------===//
139 // ilist_iterator<Node> - Iterator for intrusive list.
141 template<typename NodeTy>
143 : public std::iterator<std::bidirectional_iterator_tag, NodeTy, ptrdiff_t> {
146 typedef ilist_traits<NodeTy> Traits;
147 typedef std::iterator<std::bidirectional_iterator_tag,
148 NodeTy, ptrdiff_t> super;
150 typedef typename super::value_type value_type;
151 typedef typename super::difference_type difference_type;
152 typedef typename super::pointer pointer;
153 typedef typename super::reference reference;
157 // ilist_iterator is not a random-access iterator, but it has an
158 // implicit conversion to pointer-type, which is. Declare (but
159 // don't define) these functions as private to help catch
160 // accidental misuse.
161 void operator[](difference_type) const;
162 void operator+(difference_type) const;
163 void operator-(difference_type) const;
164 void operator+=(difference_type) const;
165 void operator-=(difference_type) const;
166 template<class T> void operator<(T) const;
167 template<class T> void operator<=(T) 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;
173 ilist_iterator(pointer NP) : NodePtr(NP) {}
174 ilist_iterator(reference NR) : NodePtr(&NR) {}
175 ilist_iterator() : NodePtr(0) {}
177 // This is templated so that we can allow constructing a const iterator from
178 // a nonconst iterator...
179 template<class node_ty>
180 ilist_iterator(const ilist_iterator<node_ty> &RHS)
181 : NodePtr(RHS.getNodePtrUnchecked()) {}
183 // This is templated so that we can allow assigning to a const iterator from
184 // a nonconst iterator...
185 template<class node_ty>
186 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
187 NodePtr = RHS.getNodePtrUnchecked();
192 operator pointer() const {
196 reference operator*() const {
199 pointer operator->() const { return &operator*(); }
201 // Comparison operators
202 bool operator==(const ilist_iterator &RHS) const {
203 return NodePtr == RHS.NodePtr;
205 bool operator!=(const ilist_iterator &RHS) const {
206 return NodePtr != RHS.NodePtr;
209 // Increment and decrement operators...
210 ilist_iterator &operator--() { // predecrement - Back up
211 NodePtr = Traits::getPrev(NodePtr);
212 assert(NodePtr && "--'d off the beginning of an ilist!");
215 ilist_iterator &operator++() { // preincrement - Advance
216 NodePtr = Traits::getNext(NodePtr);
219 ilist_iterator operator--(int) { // postdecrement operators...
220 ilist_iterator tmp = *this;
224 ilist_iterator operator++(int) { // postincrement operators...
225 ilist_iterator tmp = *this;
230 // Internal interface, do not use...
231 pointer getNodePtrUnchecked() const { return NodePtr; }
234 // do not implement. this is to catch errors when people try to use
235 // them as random access iterators
237 void operator-(int, ilist_iterator<T>);
239 void operator-(ilist_iterator<T>,int);
242 void operator+(int, ilist_iterator<T>);
244 void operator+(ilist_iterator<T>,int);
246 // operator!=/operator== - Allow mixed comparisons without dereferencing
247 // the iterator, which could very likely be pointing to end().
249 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
250 return LHS != RHS.getNodePtrUnchecked();
253 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
254 return LHS == RHS.getNodePtrUnchecked();
257 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
258 return LHS != RHS.getNodePtrUnchecked();
261 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
262 return LHS == RHS.getNodePtrUnchecked();
266 // Allow ilist_iterators to convert into pointers to a node automatically when
267 // used by the dyn_cast, cast, isa mechanisms...
269 template<typename From> struct simplify_type;
271 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
272 typedef NodeTy* SimpleType;
274 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
278 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
279 typedef NodeTy* SimpleType;
281 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
287 //===----------------------------------------------------------------------===//
289 /// iplist - The subset of list functionality that can safely be used on nodes
290 /// of polymorphic types, i.e. a heterogenous list with a common base class that
291 /// holds the next/prev pointers. The only state of the list itself is a single
292 /// pointer to the head of the list.
294 /// This list can be in one of three interesting states:
295 /// 1. The list may be completely unconstructed. In this case, the head
296 /// pointer is null. When in this form, any query for an iterator (e.g.
297 /// begin() or end()) causes the list to transparently change to state #2.
298 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
299 /// sentinel is created by the Traits::createSentinel method and is a link
300 /// in the list. When the list is empty, the pointer in the iplist points
301 /// to the sentinel. Once the sentinel is constructed, it
302 /// is not destroyed until the list is.
303 /// 3. The list may contain actual objects in it, which are stored as a doubly
304 /// linked list of nodes. One invariant of the list is that the predecessor
305 /// of the first node in the list always points to the last node in the list,
306 /// and the successor pointer for the sentinel (which always stays at the
307 /// end of the list) is always null.
309 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
310 class iplist : public Traits {
311 mutable NodeTy *Head;
313 // Use the prev node pointer of 'head' as the tail pointer. This is really a
314 // circularly linked list where we snip the 'next' link from the sentinel node
315 // back to the first node in the list (to preserve assertions about going off
316 // the end of the list).
317 NodeTy *getTail() { return this->ensureHead(Head); }
318 const NodeTy *getTail() const { return this->ensureHead(Head); }
319 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
321 /// CreateLazySentinel - This method verifies whether the sentinel for the
322 /// list has been created and lazily makes it if not.
323 void CreateLazySentinel() const {
324 this->ensureHead(Head);
327 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
328 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
330 // No fundamental reason why iplist can't be copyable, but the default
331 // copy/copy-assign won't do.
332 iplist(const iplist &); // do not implement
333 void operator=(const iplist &); // do not implement
336 typedef NodeTy *pointer;
337 typedef const NodeTy *const_pointer;
338 typedef NodeTy &reference;
339 typedef const NodeTy &const_reference;
340 typedef NodeTy value_type;
341 typedef ilist_iterator<NodeTy> iterator;
342 typedef ilist_iterator<const NodeTy> const_iterator;
343 typedef size_t size_type;
344 typedef ptrdiff_t difference_type;
345 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
346 typedef std::reverse_iterator<iterator> reverse_iterator;
348 iplist() : Head(this->provideInitialHead()) {}
352 Traits::destroySentinel(getTail());
355 // Iterator creation methods.
357 CreateLazySentinel();
358 return iterator(Head);
360 const_iterator begin() const {
361 CreateLazySentinel();
362 return const_iterator(Head);
365 CreateLazySentinel();
366 return iterator(getTail());
368 const_iterator end() const {
369 CreateLazySentinel();
370 return const_iterator(getTail());
373 // reverse iterator creation methods.
374 reverse_iterator rbegin() { return reverse_iterator(end()); }
375 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
376 reverse_iterator rend() { return reverse_iterator(begin()); }
377 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
380 // Miscellaneous inspection routines.
381 size_type max_size() const { return size_type(-1); }
382 bool empty() const { return Head == 0 || Head == getTail(); }
384 // Front and back accessor functions...
386 assert(!empty() && "Called front() on empty list!");
389 const_reference front() const {
390 assert(!empty() && "Called front() on empty list!");
394 assert(!empty() && "Called back() on empty list!");
395 return *this->getPrev(getTail());
397 const_reference back() const {
398 assert(!empty() && "Called back() on empty list!");
399 return *this->getPrev(getTail());
402 void swap(iplist &RHS) {
403 assert(0 && "Swap does not use list traits callback correctly yet!");
404 std::swap(Head, RHS.Head);
407 iterator insert(iterator where, NodeTy *New) {
408 NodeTy *CurNode = where.getNodePtrUnchecked();
409 NodeTy *PrevNode = this->getPrev(CurNode);
410 this->setNext(New, CurNode);
411 this->setPrev(New, PrevNode);
413 if (CurNode != Head) // Is PrevNode off the beginning of the list?
414 this->setNext(PrevNode, New);
417 this->setPrev(CurNode, New);
419 this->addNodeToList(New); // Notify traits that we added a node...
423 iterator insertAfter(iterator where, NodeTy *New) {
425 return insert(begin(), New);
427 return insert(++where, New);
430 NodeTy *remove(iterator &IT) {
431 assert(IT != end() && "Cannot remove end of list!");
433 NodeTy *NextNode = this->getNext(Node);
434 NodeTy *PrevNode = this->getPrev(Node);
436 if (Node != Head) // Is PrevNode off the beginning of the list?
437 this->setNext(PrevNode, NextNode);
440 this->setPrev(NextNode, PrevNode);
442 this->removeNodeFromList(Node); // Notify traits that we removed a node...
444 // Set the next/prev pointers of the current node to null. This isn't
445 // strictly required, but this catches errors where a node is removed from
446 // an ilist (and potentially deleted) with iterators still pointing at it.
447 // When those iterators are incremented or decremented, they will assert on
448 // the null next/prev pointer instead of "usually working".
449 this->setNext(Node, 0);
450 this->setPrev(Node, 0);
454 NodeTy *remove(const iterator &IT) {
456 return remove(MutIt);
459 // erase - remove a node from the controlled sequence... and delete it.
460 iterator erase(iterator where) {
461 this->deleteNode(remove(where));
467 // transfer - The heart of the splice function. Move linked list nodes from
468 // [first, last) into position.
470 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
471 assert(first != last && "Should be checked by callers");
473 if (position != last) {
474 // Note: we have to be careful about the case when we move the first node
475 // in the list. This node is the list sentinel node and we can't move it.
476 NodeTy *ThisSentinel = getTail();
478 NodeTy *L2Sentinel = L2.getTail();
481 // Remove [first, last) from its old position.
482 NodeTy *First = &*first, *Prev = this->getPrev(First);
483 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
485 this->setNext(Prev, Next);
488 this->setPrev(Next, Prev);
490 // Splice [first, last) into its new position.
491 NodeTy *PosNext = position.getNodePtrUnchecked();
492 NodeTy *PosPrev = this->getPrev(PosNext);
494 // Fix head of list...
496 this->setNext(PosPrev, First);
499 this->setPrev(First, PosPrev);
501 // Fix end of list...
502 this->setNext(Last, PosNext);
503 this->setPrev(PosNext, Last);
505 this->transferNodesFromList(L2, First, PosNext);
507 // Now that everything is set, restore the pointers to the list sentinels.
508 L2.setTail(L2Sentinel);
509 setTail(ThisSentinel);
515 //===----------------------------------------------------------------------===
516 // Functionality derived from other functions defined above...
519 size_type size() const {
520 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
521 return std::distance(begin(), end());
524 iterator erase(iterator first, iterator last) {
525 while (first != last)
526 first = erase(first);
530 void clear() { if (Head) erase(begin(), end()); }
532 // Front and back inserters...
533 void push_front(NodeTy *val) { insert(begin(), val); }
534 void push_back(NodeTy *val) { insert(end(), val); }
536 assert(!empty() && "pop_front() on empty list!");
540 assert(!empty() && "pop_back() on empty list!");
541 iterator t = end(); erase(--t);
544 // Special forms of insert...
545 template<class InIt> void insert(iterator where, InIt first, InIt last) {
546 for (; first != last; ++first) insert(where, *first);
549 // Splice members - defined in terms of transfer...
550 void splice(iterator where, iplist &L2) {
552 transfer(where, L2, L2.begin(), L2.end());
554 void splice(iterator where, iplist &L2, iterator first) {
555 iterator last = first; ++last;
556 if (where == first || where == last) return; // No change
557 transfer(where, L2, first, last);
559 void splice(iterator where, iplist &L2, iterator first, iterator last) {
560 if (first != last) transfer(where, L2, first, last);
565 //===----------------------------------------------------------------------===
566 // High-Level Functionality that shouldn't really be here, but is part of list
569 // These two functions are actually called remove/remove_if in list<>, but
570 // they actually do the job of erase, rename them accordingly.
572 void erase(const NodeTy &val) {
573 for (iterator I = begin(), E = end(); I != E; ) {
574 iterator next = I; ++next;
575 if (*I == val) erase(I);
579 template<class Pr1> void erase_if(Pr1 pred) {
580 for (iterator I = begin(), E = end(); I != E; ) {
581 iterator next = I; ++next;
582 if (pred(*I)) erase(I);
587 template<class Pr2> void unique(Pr2 pred) {
589 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
597 void unique() { unique(op_equal); }
599 template<class Pr3> void merge(iplist &right, Pr3 pred) {
600 iterator first1 = begin(), last1 = end();
601 iterator first2 = right.begin(), last2 = right.end();
602 while (first1 != last1 && first2 != last2)
603 if (pred(*first2, *first1)) {
604 iterator next = first2;
605 transfer(first1, right, first2, ++next);
610 if (first2 != last2) transfer(last1, right, first2, last2);
612 void merge(iplist &right) { return merge(right, op_less); }
614 template<class Pr3> void sort(Pr3 pred);
615 void sort() { sort(op_less); }
620 template<typename NodeTy>
621 struct ilist : public iplist<NodeTy> {
622 typedef typename iplist<NodeTy>::size_type size_type;
623 typedef typename iplist<NodeTy>::iterator iterator;
626 ilist(const ilist &right) {
627 insert(this->begin(), right.begin(), right.end());
629 explicit ilist(size_type count) {
630 insert(this->begin(), count, NodeTy());
632 ilist(size_type count, const NodeTy &val) {
633 insert(this->begin(), count, val);
635 template<class InIt> ilist(InIt first, InIt last) {
636 insert(this->begin(), first, last);
639 // bring hidden functions into scope
640 using iplist<NodeTy>::insert;
641 using iplist<NodeTy>::push_front;
642 using iplist<NodeTy>::push_back;
644 // Main implementation here - Insert for a node passed by value...
645 iterator insert(iterator where, const NodeTy &val) {
646 return insert(where, createNode(val));
650 // Front and back inserters...
651 void push_front(const NodeTy &val) { insert(this->begin(), val); }
652 void push_back(const NodeTy &val) { insert(this->end(), val); }
654 // Special forms of insert...
655 template<class InIt> void insert(iterator where, InIt first, InIt last) {
656 for (; first != last; ++first) insert(where, *first);
658 void insert(iterator where, size_type count, const NodeTy &val) {
659 for (; count != 0; --count) insert(where, val);
662 // Assign special forms...
663 void assign(size_type count, const NodeTy &val) {
664 iterator I = this->begin();
665 for (; I != this->end() && count != 0; ++I, --count)
668 insert(this->end(), val, val);
670 erase(I, this->end());
672 template<class InIt> void assign(InIt first1, InIt last1) {
673 iterator first2 = this->begin(), last2 = this->end();
674 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
677 erase(first1, last1);
679 insert(last1, first2, last2);
684 void resize(size_type newsize, NodeTy val) {
685 iterator i = this->begin();
687 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
690 erase(i, this->end());
692 insert(this->end(), newsize - len, val);
694 void resize(size_type newsize) { resize(newsize, NodeTy()); }
697 } // End llvm namespace
700 // Ensure that swap uses the fast list swap...
702 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
705 } // End 'std' extensions...
707 #endif // LLVM_ADT_ILIST_H