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
47 template<typename NodeTy, typename Traits> class iplist;
48 template<typename NodeTy> class ilist_iterator;
50 /// ilist_nextprev_traits - A fragment for template traits for intrusive list
51 /// that provides default next/prev implementations for common operations.
53 template<typename NodeTy>
54 struct ilist_nextprev_traits {
55 static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
56 static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
57 static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
58 static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
60 static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
61 static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
64 template<typename NodeTy>
67 /// ilist_sentinel_traits - A fragment for template traits for intrusive list
68 /// that provides default sentinel implementations for common operations.
70 /// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
71 /// strategy. The sentinel is stored in the prev field of ilist's Head.
73 template<typename NodeTy>
74 struct ilist_sentinel_traits {
75 /// createSentinel - create the dynamic sentinel
76 static NodeTy *createSentinel() { return new NodeTy(); }
78 /// destroySentinel - deallocate the dynamic sentinel
79 static void destroySentinel(NodeTy *N) { delete N; }
81 /// provideInitialHead - when constructing an ilist, provide a starting
82 /// value for its Head
83 /// @return null node to indicate that it needs to be allocated later
84 static NodeTy *provideInitialHead() { return 0; }
86 /// ensureHead - make sure that Head is either already
87 /// initialized or assigned a fresh sentinel
88 /// @return the sentinel
89 static NodeTy *ensureHead(NodeTy *&Head) {
91 Head = ilist_traits<NodeTy>::createSentinel();
92 ilist_traits<NodeTy>::noteHead(Head, Head);
93 ilist_traits<NodeTy>::setNext(Head, 0);
96 return ilist_traits<NodeTy>::getPrev(Head);
99 /// noteHead - stash the sentinel into its default location
100 static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
101 ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
105 /// ilist_node_traits - A fragment for template traits for intrusive list
106 /// that provides default node related operations.
108 template<typename NodeTy>
109 struct ilist_node_traits {
110 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
111 static void deleteNode(NodeTy *V) { delete V; }
113 void addNodeToList(NodeTy *) {}
114 void removeNodeFromList(NodeTy *) {}
115 void transferNodesFromList(ilist_node_traits & /*SrcTraits*/,
116 ilist_iterator<NodeTy> /*first*/,
117 ilist_iterator<NodeTy> /*last*/) {}
120 /// ilist_default_traits - Default template traits for intrusive list.
121 /// By inheriting from this, you can easily use default implementations
122 /// for all common operations.
124 template<typename NodeTy>
125 struct ilist_default_traits : public ilist_nextprev_traits<NodeTy>,
126 public ilist_sentinel_traits<NodeTy>,
127 public ilist_node_traits<NodeTy> {
130 // Template traits for intrusive list. By specializing this template class, you
131 // can change what next/prev fields are used to store the links...
132 template<typename NodeTy>
133 struct ilist_traits : public ilist_default_traits<NodeTy> {};
135 // Const traits are the same as nonconst traits...
136 template<typename Ty>
137 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
139 //===----------------------------------------------------------------------===//
140 // ilist_iterator<Node> - Iterator for intrusive list.
142 template<typename NodeTy>
144 : public std::iterator<std::bidirectional_iterator_tag, NodeTy, ptrdiff_t> {
147 typedef ilist_traits<NodeTy> Traits;
148 typedef std::iterator<std::bidirectional_iterator_tag,
149 NodeTy, ptrdiff_t> super;
151 typedef typename super::value_type value_type;
152 typedef typename super::difference_type difference_type;
153 typedef typename super::pointer pointer;
154 typedef typename super::reference reference;
158 // ilist_iterator is not a random-access iterator, but it has an
159 // implicit conversion to pointer-type, which is. Declare (but
160 // don't define) these functions as private to help catch
161 // accidental misuse.
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 void operator-=(difference_type) 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;
171 template<class T> void operator-(T) const;
174 ilist_iterator(pointer NP) : NodePtr(NP) {}
175 ilist_iterator(reference NR) : NodePtr(&NR) {}
176 ilist_iterator() : NodePtr(0) {}
178 // This is templated so that we can allow constructing a const iterator from
179 // a nonconst iterator...
180 template<class node_ty>
181 ilist_iterator(const ilist_iterator<node_ty> &RHS)
182 : NodePtr(RHS.getNodePtrUnchecked()) {}
184 // This is templated so that we can allow assigning to a const iterator from
185 // a nonconst iterator...
186 template<class node_ty>
187 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
188 NodePtr = RHS.getNodePtrUnchecked();
193 operator pointer() const {
197 reference operator*() const {
200 pointer operator->() const { return &operator*(); }
202 // Comparison operators
203 bool operator==(const ilist_iterator &RHS) const {
204 return NodePtr == RHS.NodePtr;
206 bool operator!=(const ilist_iterator &RHS) const {
207 return NodePtr != RHS.NodePtr;
210 // Increment and decrement operators...
211 ilist_iterator &operator--() { // predecrement - Back up
212 NodePtr = Traits::getPrev(NodePtr);
213 assert(NodePtr && "--'d off the beginning of an ilist!");
216 ilist_iterator &operator++() { // preincrement - Advance
217 NodePtr = Traits::getNext(NodePtr);
220 ilist_iterator operator--(int) { // postdecrement operators...
221 ilist_iterator tmp = *this;
225 ilist_iterator operator++(int) { // postincrement operators...
226 ilist_iterator tmp = *this;
231 // Internal interface, do not use...
232 pointer getNodePtrUnchecked() const { return NodePtr; }
235 // do not implement. this is to catch errors when people try to use
236 // them as random access iterators
238 void operator-(int, ilist_iterator<T>);
240 void operator-(ilist_iterator<T>,int);
243 void operator+(int, ilist_iterator<T>);
245 void operator+(ilist_iterator<T>,int);
247 // operator!=/operator== - Allow mixed comparisons without dereferencing
248 // the iterator, which could very likely be pointing to end().
250 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
251 return LHS != RHS.getNodePtrUnchecked();
254 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
255 return LHS == RHS.getNodePtrUnchecked();
258 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
259 return LHS != RHS.getNodePtrUnchecked();
262 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
263 return LHS == RHS.getNodePtrUnchecked();
267 // Allow ilist_iterators to convert into pointers to a node automatically when
268 // used by the dyn_cast, cast, isa mechanisms...
270 template<typename From> struct simplify_type;
272 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
273 typedef NodeTy* SimpleType;
275 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
279 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
280 typedef NodeTy* SimpleType;
282 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
288 //===----------------------------------------------------------------------===//
290 /// iplist - The subset of list functionality that can safely be used on nodes
291 /// of polymorphic types, i.e. a heterogenous list with a common base class that
292 /// holds the next/prev pointers. The only state of the list itself is a single
293 /// pointer to the head of the list.
295 /// This list can be in one of three interesting states:
296 /// 1. The list may be completely unconstructed. In this case, the head
297 /// pointer is null. When in this form, any query for an iterator (e.g.
298 /// begin() or end()) causes the list to transparently change to state #2.
299 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
300 /// sentinel is created by the Traits::createSentinel method and is a link
301 /// in the list. When the list is empty, the pointer in the iplist points
302 /// to the sentinel. Once the sentinel is constructed, it
303 /// is not destroyed until the list is.
304 /// 3. The list may contain actual objects in it, which are stored as a doubly
305 /// linked list of nodes. One invariant of the list is that the predecessor
306 /// of the first node in the list always points to the last node in the list,
307 /// and the successor pointer for the sentinel (which always stays at the
308 /// end of the list) is always null.
310 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
311 class iplist : public Traits {
312 mutable NodeTy *Head;
314 // Use the prev node pointer of 'head' as the tail pointer. This is really a
315 // circularly linked list where we snip the 'next' link from the sentinel node
316 // back to the first node in the list (to preserve assertions about going off
317 // the end of the list).
318 NodeTy *getTail() { return this->ensureHead(Head); }
319 const NodeTy *getTail() const { return this->ensureHead(Head); }
320 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
322 /// CreateLazySentinel - This method verifies whether the sentinel for the
323 /// list has been created and lazily makes it if not.
324 void CreateLazySentinel() const {
325 this->ensureHead(Head);
328 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
329 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
331 // No fundamental reason why iplist can't be copyable, but the default
332 // copy/copy-assign won't do.
333 iplist(const iplist &); // do not implement
334 void operator=(const iplist &); // do not implement
337 typedef NodeTy *pointer;
338 typedef const NodeTy *const_pointer;
339 typedef NodeTy &reference;
340 typedef const NodeTy &const_reference;
341 typedef NodeTy value_type;
342 typedef ilist_iterator<NodeTy> iterator;
343 typedef ilist_iterator<const NodeTy> const_iterator;
344 typedef size_t size_type;
345 typedef ptrdiff_t difference_type;
346 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
347 typedef std::reverse_iterator<iterator> reverse_iterator;
349 iplist() : Head(this->provideInitialHead()) {}
353 Traits::destroySentinel(getTail());
356 // Iterator creation methods.
358 CreateLazySentinel();
359 return iterator(Head);
361 const_iterator begin() const {
362 CreateLazySentinel();
363 return const_iterator(Head);
366 CreateLazySentinel();
367 return iterator(getTail());
369 const_iterator end() const {
370 CreateLazySentinel();
371 return const_iterator(getTail());
374 // reverse iterator creation methods.
375 reverse_iterator rbegin() { return reverse_iterator(end()); }
376 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
377 reverse_iterator rend() { return reverse_iterator(begin()); }
378 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
381 // Miscellaneous inspection routines.
382 size_type max_size() const { return size_type(-1); }
383 bool empty() const { return Head == 0 || Head == getTail(); }
385 // Front and back accessor functions...
387 assert(!empty() && "Called front() on empty list!");
390 const_reference front() const {
391 assert(!empty() && "Called front() on empty list!");
395 assert(!empty() && "Called back() on empty list!");
396 return *this->getPrev(getTail());
398 const_reference back() const {
399 assert(!empty() && "Called back() on empty list!");
400 return *this->getPrev(getTail());
403 void swap(iplist &RHS) {
404 assert(0 && "Swap does not use list traits callback correctly yet!");
405 std::swap(Head, RHS.Head);
408 iterator insert(iterator where, NodeTy *New) {
409 NodeTy *CurNode = where.getNodePtrUnchecked();
410 NodeTy *PrevNode = this->getPrev(CurNode);
411 this->setNext(New, CurNode);
412 this->setPrev(New, PrevNode);
414 if (CurNode != Head) // Is PrevNode off the beginning of the list?
415 this->setNext(PrevNode, New);
418 this->setPrev(CurNode, New);
420 this->addNodeToList(New); // Notify traits that we added a node...
424 iterator insertAfter(iterator where, NodeTy *New) {
426 return insert(begin(), New);
428 return insert(++where, New);
431 NodeTy *remove(iterator &IT) {
432 assert(IT != end() && "Cannot remove end of list!");
434 NodeTy *NextNode = this->getNext(Node);
435 NodeTy *PrevNode = this->getPrev(Node);
437 if (Node != Head) // Is PrevNode off the beginning of the list?
438 this->setNext(PrevNode, NextNode);
441 this->setPrev(NextNode, PrevNode);
443 this->removeNodeFromList(Node); // Notify traits that we removed a node...
445 // Set the next/prev pointers of the current node to null. This isn't
446 // strictly required, but this catches errors where a node is removed from
447 // an ilist (and potentially deleted) with iterators still pointing at it.
448 // When those iterators are incremented or decremented, they will assert on
449 // the null next/prev pointer instead of "usually working".
450 this->setNext(Node, 0);
451 this->setPrev(Node, 0);
455 NodeTy *remove(const iterator &IT) {
457 return remove(MutIt);
460 // erase - remove a node from the controlled sequence... and delete it.
461 iterator erase(iterator where) {
462 this->deleteNode(remove(where));
468 // transfer - The heart of the splice function. Move linked list nodes from
469 // [first, last) into position.
471 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
472 assert(first != last && "Should be checked by callers");
474 if (position != last) {
475 // Note: we have to be careful about the case when we move the first node
476 // in the list. This node is the list sentinel node and we can't move it.
477 NodeTy *ThisSentinel = getTail();
479 NodeTy *L2Sentinel = L2.getTail();
482 // Remove [first, last) from its old position.
483 NodeTy *First = &*first, *Prev = this->getPrev(First);
484 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
486 this->setNext(Prev, Next);
489 this->setPrev(Next, Prev);
491 // Splice [first, last) into its new position.
492 NodeTy *PosNext = position.getNodePtrUnchecked();
493 NodeTy *PosPrev = this->getPrev(PosNext);
495 // Fix head of list...
497 this->setNext(PosPrev, First);
500 this->setPrev(First, PosPrev);
502 // Fix end of list...
503 this->setNext(Last, PosNext);
504 this->setPrev(PosNext, Last);
506 this->transferNodesFromList(L2, First, PosNext);
508 // Now that everything is set, restore the pointers to the list sentinels.
509 L2.setTail(L2Sentinel);
510 setTail(ThisSentinel);
516 //===----------------------------------------------------------------------===
517 // Functionality derived from other functions defined above...
520 size_type size() const {
521 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
522 return std::distance(begin(), end());
525 iterator erase(iterator first, iterator last) {
526 while (first != last)
527 first = erase(first);
531 void clear() { if (Head) erase(begin(), end()); }
533 // Front and back inserters...
534 void push_front(NodeTy *val) { insert(begin(), val); }
535 void push_back(NodeTy *val) { insert(end(), val); }
537 assert(!empty() && "pop_front() on empty list!");
541 assert(!empty() && "pop_back() on empty list!");
542 iterator t = end(); erase(--t);
545 // Special forms of insert...
546 template<class InIt> void insert(iterator where, InIt first, InIt last) {
547 for (; first != last; ++first) insert(where, *first);
550 // Splice members - defined in terms of transfer...
551 void splice(iterator where, iplist &L2) {
553 transfer(where, L2, L2.begin(), L2.end());
555 void splice(iterator where, iplist &L2, iterator first) {
556 iterator last = first; ++last;
557 if (where == first || where == last) return; // No change
558 transfer(where, L2, first, last);
560 void splice(iterator where, iplist &L2, iterator first, iterator last) {
561 if (first != last) transfer(where, L2, first, last);
566 //===----------------------------------------------------------------------===
567 // High-Level Functionality that shouldn't really be here, but is part of list
570 // These two functions are actually called remove/remove_if in list<>, but
571 // they actually do the job of erase, rename them accordingly.
573 void erase(const NodeTy &val) {
574 for (iterator I = begin(), E = end(); I != E; ) {
575 iterator next = I; ++next;
576 if (*I == val) erase(I);
580 template<class Pr1> void erase_if(Pr1 pred) {
581 for (iterator I = begin(), E = end(); I != E; ) {
582 iterator next = I; ++next;
583 if (pred(*I)) erase(I);
588 template<class Pr2> void unique(Pr2 pred) {
590 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
598 void unique() { unique(op_equal); }
600 template<class Pr3> void merge(iplist &right, Pr3 pred) {
601 iterator first1 = begin(), last1 = end();
602 iterator first2 = right.begin(), last2 = right.end();
603 while (first1 != last1 && first2 != last2)
604 if (pred(*first2, *first1)) {
605 iterator next = first2;
606 transfer(first1, right, first2, ++next);
611 if (first2 != last2) transfer(last1, right, first2, last2);
613 void merge(iplist &right) { return merge(right, op_less); }
615 template<class Pr3> void sort(Pr3 pred);
616 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, this->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