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"
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 bidirectional_iterator<NodeTy, ptrdiff_t> {
146 typedef ilist_traits<NodeTy> Traits;
147 typedef bidirectional_iterator<NodeTy, ptrdiff_t> super;
149 typedef typename super::value_type value_type;
150 typedef typename super::difference_type difference_type;
151 typedef typename super::pointer pointer;
152 typedef typename super::reference reference;
156 // ilist_iterator is not a random-access iterator, but it has an
157 // implicit conversion to pointer-type, which is. Declare (but
158 // don't define) these functions as private to help catch
159 // accidental misuse.
160 void operator[](difference_type) const;
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 template<class T> void operator<(T) 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;
172 ilist_iterator(pointer NP) : NodePtr(NP) {}
173 ilist_iterator(reference NR) : NodePtr(&NR) {}
174 ilist_iterator() : NodePtr(0) {}
176 // This is templated so that we can allow constructing a const iterator from
177 // a nonconst iterator...
178 template<class node_ty>
179 ilist_iterator(const ilist_iterator<node_ty> &RHS)
180 : NodePtr(RHS.getNodePtrUnchecked()) {}
182 // This is templated so that we can allow assigning to a const iterator from
183 // a nonconst iterator...
184 template<class node_ty>
185 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
186 NodePtr = RHS.getNodePtrUnchecked();
191 operator pointer() const {
195 reference operator*() const {
198 pointer operator->() const { return &operator*(); }
200 // Comparison operators
201 bool operator==(const ilist_iterator &RHS) const {
202 return NodePtr == RHS.NodePtr;
204 bool operator!=(const ilist_iterator &RHS) const {
205 return NodePtr != RHS.NodePtr;
208 // Increment and decrement operators...
209 ilist_iterator &operator--() { // predecrement - Back up
210 NodePtr = Traits::getPrev(NodePtr);
211 assert(NodePtr && "--'d off the beginning of an ilist!");
214 ilist_iterator &operator++() { // preincrement - Advance
215 NodePtr = Traits::getNext(NodePtr);
218 ilist_iterator operator--(int) { // postdecrement operators...
219 ilist_iterator tmp = *this;
223 ilist_iterator operator++(int) { // postincrement operators...
224 ilist_iterator tmp = *this;
229 // Internal interface, do not use...
230 pointer getNodePtrUnchecked() const { return NodePtr; }
233 // do not implement. this is to catch errors when people try to use
234 // them as random access iterators
236 void operator-(int, ilist_iterator<T>);
238 void operator-(ilist_iterator<T>,int);
241 void operator+(int, ilist_iterator<T>);
243 void operator+(ilist_iterator<T>,int);
245 // operator!=/operator== - Allow mixed comparisons without dereferencing
246 // the iterator, which could very likely be pointing to end().
248 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
249 return LHS != RHS.getNodePtrUnchecked();
252 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
253 return LHS == RHS.getNodePtrUnchecked();
256 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
257 return LHS != RHS.getNodePtrUnchecked();
260 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
261 return LHS == RHS.getNodePtrUnchecked();
265 // Allow ilist_iterators to convert into pointers to a node automatically when
266 // used by the dyn_cast, cast, isa mechanisms...
268 template<typename From> struct simplify_type;
270 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
271 typedef NodeTy* SimpleType;
273 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
277 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
278 typedef NodeTy* SimpleType;
280 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
286 //===----------------------------------------------------------------------===//
288 /// iplist - The subset of list functionality that can safely be used on nodes
289 /// of polymorphic types, i.e. a heterogenous list with a common base class that
290 /// holds the next/prev pointers. The only state of the list itself is a single
291 /// pointer to the head of the list.
293 /// This list can be in one of three interesting states:
294 /// 1. The list may be completely unconstructed. In this case, the head
295 /// pointer is null. When in this form, any query for an iterator (e.g.
296 /// begin() or end()) causes the list to transparently change to state #2.
297 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
298 /// sentinel is created by the Traits::createSentinel method and is a link
299 /// in the list. When the list is empty, the pointer in the iplist points
300 /// to the sentinel. Once the sentinel is constructed, it
301 /// is not destroyed until the list is.
302 /// 3. The list may contain actual objects in it, which are stored as a doubly
303 /// linked list of nodes. One invariant of the list is that the predecessor
304 /// of the first node in the list always points to the last node in the list,
305 /// and the successor pointer for the sentinel (which always stays at the
306 /// end of the list) is always null.
308 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
309 class iplist : public Traits {
310 mutable NodeTy *Head;
312 // Use the prev node pointer of 'head' as the tail pointer. This is really a
313 // circularly linked list where we snip the 'next' link from the sentinel node
314 // back to the first node in the list (to preserve assertions about going off
315 // the end of the list).
316 NodeTy *getTail() { return this->ensureHead(Head); }
317 const NodeTy *getTail() const { return this->ensureHead(Head); }
318 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
320 /// CreateLazySentinel - This method verifies whether the sentinel for the
321 /// list has been created and lazily makes it if not.
322 void CreateLazySentinel() const {
323 this->ensureHead(Head);
326 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
327 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
329 // No fundamental reason why iplist can't be copyable, but the default
330 // copy/copy-assign won't do.
331 iplist(const iplist &); // do not implement
332 void operator=(const iplist &); // do not implement
335 typedef NodeTy *pointer;
336 typedef const NodeTy *const_pointer;
337 typedef NodeTy &reference;
338 typedef const NodeTy &const_reference;
339 typedef NodeTy value_type;
340 typedef ilist_iterator<NodeTy> iterator;
341 typedef ilist_iterator<const NodeTy> const_iterator;
342 typedef size_t size_type;
343 typedef ptrdiff_t difference_type;
344 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
345 typedef std::reverse_iterator<iterator> reverse_iterator;
347 iplist() : Head(this->provideInitialHead()) {}
351 Traits::destroySentinel(getTail());
354 // Iterator creation methods.
356 CreateLazySentinel();
357 return iterator(Head);
359 const_iterator begin() const {
360 CreateLazySentinel();
361 return const_iterator(Head);
364 CreateLazySentinel();
365 return iterator(getTail());
367 const_iterator end() const {
368 CreateLazySentinel();
369 return const_iterator(getTail());
372 // reverse iterator creation methods.
373 reverse_iterator rbegin() { return reverse_iterator(end()); }
374 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
375 reverse_iterator rend() { return reverse_iterator(begin()); }
376 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
379 // Miscellaneous inspection routines.
380 size_type max_size() const { return size_type(-1); }
381 bool empty() const { return Head == 0 || Head == getTail(); }
383 // Front and back accessor functions...
385 assert(!empty() && "Called front() on empty list!");
388 const_reference front() const {
389 assert(!empty() && "Called front() on empty list!");
393 assert(!empty() && "Called back() on empty list!");
394 return *this->getPrev(getTail());
396 const_reference back() const {
397 assert(!empty() && "Called back() on empty list!");
398 return *this->getPrev(getTail());
401 void swap(iplist &RHS) {
402 assert(0 && "Swap does not use list traits callback correctly yet!");
403 std::swap(Head, RHS.Head);
406 iterator insert(iterator where, NodeTy *New) {
407 NodeTy *CurNode = where.getNodePtrUnchecked();
408 NodeTy *PrevNode = this->getPrev(CurNode);
409 this->setNext(New, CurNode);
410 this->setPrev(New, PrevNode);
412 if (CurNode != Head) // Is PrevNode off the beginning of the list?
413 this->setNext(PrevNode, New);
416 this->setPrev(CurNode, New);
418 this->addNodeToList(New); // Notify traits that we added a node...
422 iterator insertAfter(iterator where, NodeTy *New) {
424 return insert(begin(), New);
426 return insert(++where, New);
429 NodeTy *remove(iterator &IT) {
430 assert(IT != end() && "Cannot remove end of list!");
432 NodeTy *NextNode = this->getNext(Node);
433 NodeTy *PrevNode = this->getPrev(Node);
435 if (Node != Head) // Is PrevNode off the beginning of the list?
436 this->setNext(PrevNode, NextNode);
439 this->setPrev(NextNode, PrevNode);
441 this->removeNodeFromList(Node); // Notify traits that we removed a node...
443 // Set the next/prev pointers of the current node to null. This isn't
444 // strictly required, but this catches errors where a node is removed from
445 // an ilist (and potentially deleted) with iterators still pointing at it.
446 // When those iterators are incremented or decremented, they will assert on
447 // the null next/prev pointer instead of "usually working".
448 this->setNext(Node, 0);
449 this->setPrev(Node, 0);
453 NodeTy *remove(const iterator &IT) {
455 return remove(MutIt);
458 // erase - remove a node from the controlled sequence... and delete it.
459 iterator erase(iterator where) {
460 this->deleteNode(remove(where));
466 // transfer - The heart of the splice function. Move linked list nodes from
467 // [first, last) into position.
469 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
470 assert(first != last && "Should be checked by callers");
472 if (position != last) {
473 // Note: we have to be careful about the case when we move the first node
474 // in the list. This node is the list sentinel node and we can't move it.
475 NodeTy *ThisSentinel = getTail();
477 NodeTy *L2Sentinel = L2.getTail();
480 // Remove [first, last) from its old position.
481 NodeTy *First = &*first, *Prev = this->getPrev(First);
482 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
484 this->setNext(Prev, Next);
487 this->setPrev(Next, Prev);
489 // Splice [first, last) into its new position.
490 NodeTy *PosNext = position.getNodePtrUnchecked();
491 NodeTy *PosPrev = this->getPrev(PosNext);
493 // Fix head of list...
495 this->setNext(PosPrev, First);
498 this->setPrev(First, PosPrev);
500 // Fix end of list...
501 this->setNext(Last, PosNext);
502 this->setPrev(PosNext, Last);
504 this->transferNodesFromList(L2, First, PosNext);
506 // Now that everything is set, restore the pointers to the list sentinels.
507 L2.setTail(L2Sentinel);
508 setTail(ThisSentinel);
514 //===----------------------------------------------------------------------===
515 // Functionality derived from other functions defined above...
518 size_type size() const {
519 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
520 return std::distance(begin(), end());
523 iterator erase(iterator first, iterator last) {
524 while (first != last)
525 first = erase(first);
529 void clear() { if (Head) erase(begin(), end()); }
531 // Front and back inserters...
532 void push_front(NodeTy *val) { insert(begin(), val); }
533 void push_back(NodeTy *val) { insert(end(), val); }
535 assert(!empty() && "pop_front() on empty list!");
539 assert(!empty() && "pop_back() on empty list!");
540 iterator t = end(); erase(--t);
543 // Special forms of insert...
544 template<class InIt> void insert(iterator where, InIt first, InIt last) {
545 for (; first != last; ++first) insert(where, *first);
548 // Splice members - defined in terms of transfer...
549 void splice(iterator where, iplist &L2) {
551 transfer(where, L2, L2.begin(), L2.end());
553 void splice(iterator where, iplist &L2, iterator first) {
554 iterator last = first; ++last;
555 if (where == first || where == last) return; // No change
556 transfer(where, L2, first, last);
558 void splice(iterator where, iplist &L2, iterator first, iterator last) {
559 if (first != last) transfer(where, L2, first, last);
564 //===----------------------------------------------------------------------===
565 // High-Level Functionality that shouldn't really be here, but is part of list
568 // These two functions are actually called remove/remove_if in list<>, but
569 // they actually do the job of erase, rename them accordingly.
571 void erase(const NodeTy &val) {
572 for (iterator I = begin(), E = end(); I != E; ) {
573 iterator next = I; ++next;
574 if (*I == val) erase(I);
578 template<class Pr1> void erase_if(Pr1 pred) {
579 for (iterator I = begin(), E = end(); I != E; ) {
580 iterator next = I; ++next;
581 if (pred(*I)) erase(I);
586 template<class Pr2> void unique(Pr2 pred) {
588 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
596 void unique() { unique(op_equal); }
598 template<class Pr3> void merge(iplist &right, Pr3 pred) {
599 iterator first1 = begin(), last1 = end();
600 iterator first2 = right.begin(), last2 = right.end();
601 while (first1 != last1 && first2 != last2)
602 if (pred(*first2, *first1)) {
603 iterator next = first2;
604 transfer(first1, right, first2, ++next);
609 if (first2 != last2) transfer(last1, right, first2, last2);
611 void merge(iplist &right) { return merge(right, op_less); }
613 template<class Pr3> void sort(Pr3 pred);
614 void sort() { sort(op_less); }
619 template<typename NodeTy>
620 struct ilist : public iplist<NodeTy> {
621 typedef typename iplist<NodeTy>::size_type size_type;
622 typedef typename iplist<NodeTy>::iterator iterator;
625 ilist(const ilist &right) {
626 insert(this->begin(), right.begin(), right.end());
628 explicit ilist(size_type count) {
629 insert(this->begin(), count, NodeTy());
631 ilist(size_type count, const NodeTy &val) {
632 insert(this->begin(), count, val);
634 template<class InIt> ilist(InIt first, InIt last) {
635 insert(this->begin(), first, last);
638 // bring hidden functions into scope
639 using iplist<NodeTy>::insert;
640 using iplist<NodeTy>::push_front;
641 using iplist<NodeTy>::push_back;
643 // Main implementation here - Insert for a node passed by value...
644 iterator insert(iterator where, const NodeTy &val) {
645 return insert(where, createNode(val));
649 // Front and back inserters...
650 void push_front(const NodeTy &val) { insert(this->begin(), val); }
651 void push_back(const NodeTy &val) { insert(this->end(), val); }
653 // Special forms of insert...
654 template<class InIt> void insert(iterator where, InIt first, InIt last) {
655 for (; first != last; ++first) insert(where, *first);
657 void insert(iterator where, size_type count, const NodeTy &val) {
658 for (; count != 0; --count) insert(where, val);
661 // Assign special forms...
662 void assign(size_type count, const NodeTy &val) {
663 iterator I = this->begin();
664 for (; I != this->end() && count != 0; ++I, --count)
667 insert(this->end(), val, val);
669 erase(I, this->end());
671 template<class InIt> void assign(InIt first1, InIt last1) {
672 iterator first2 = this->begin(), last2 = this->end();
673 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
676 erase(first1, last1);
678 insert(last1, first2, last2);
683 void resize(size_type newsize, NodeTy val) {
684 iterator i = this->begin();
686 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
689 erase(i, this->end());
691 insert(this->end(), newsize - len, val);
693 void resize(size_type newsize) { resize(newsize, NodeTy()); }
696 } // End llvm namespace
699 // Ensure that swap uses the fast list swap...
701 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
704 } // End 'std' extensions...
706 #endif // LLVM_ADT_ILIST_H