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"
42 #include "llvm/Config/config.h"
45 #if defined(LLVM_COMPACT_SENTINELS) && LLVM_COMPACT_SENTINELS
46 # define sentinel_tail_assert(COND)
48 # define sentinel_tail_assert(COND) assert(COND)
53 template<typename NodeTy, typename Traits> class iplist;
54 template<typename NodeTy> class ilist_iterator;
56 /// ilist_nextprev_traits - A fragment for template traits for intrusive list
57 /// that provides default next/prev implementations for common operations.
59 template<typename NodeTy>
60 struct ilist_nextprev_traits {
61 static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
62 static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
63 static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
64 static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
66 static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
67 static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
70 template<typename NodeTy>
73 /// ilist_sentinel_traits - A fragment for template traits for intrusive list
74 /// that provides default sentinel implementations for common operations.
76 /// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
77 /// strategy. The sentinel is stored in the prev field of ilist's Head.
79 template<typename NodeTy>
80 struct ilist_sentinel_traits {
81 /// createSentinel - create the dynamic sentinel
82 static NodeTy *createSentinel() { return new NodeTy(); }
84 /// destroySentinel - deallocate the dynamic sentinel
85 static void destroySentinel(NodeTy *N) { delete N; }
87 /// provideInitialHead - when constructing an ilist, provide a starting
88 /// value for its Head
89 /// @return null node to indicate that it needs to be allocated later
90 static NodeTy *provideInitialHead() { return 0; }
92 /// ensureHead - make sure that Head is either already
93 /// initialized or assigned a fresh sentinel
94 /// @return the sentinel
95 static NodeTy *ensureHead(NodeTy *&Head) {
97 Head = ilist_traits<NodeTy>::createSentinel();
98 ilist_traits<NodeTy>::noteHead(Head, Head);
99 ilist_traits<NodeTy>::setNext(Head, 0);
102 return ilist_traits<NodeTy>::getPrev(Head);
105 /// noteHead - stash the sentinel into its default location
106 static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
107 ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
111 /// ilist_node_traits - A fragment for template traits for intrusive list
112 /// that provides default node related operations.
114 template<typename NodeTy>
115 struct ilist_node_traits {
116 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
117 static void deleteNode(NodeTy *V) { delete V; }
119 void addNodeToList(NodeTy *) {}
120 void removeNodeFromList(NodeTy *) {}
121 void transferNodesFromList(ilist_node_traits & /*SrcTraits*/,
122 ilist_iterator<NodeTy> /*first*/,
123 ilist_iterator<NodeTy> /*last*/) {}
126 /// ilist_default_traits - Default template traits for intrusive list.
127 /// By inheriting from this, you can easily use default implementations
128 /// for all common operations.
130 template<typename NodeTy>
131 struct ilist_default_traits : ilist_nextprev_traits<NodeTy>,
132 ilist_sentinel_traits<NodeTy>,
133 ilist_node_traits<NodeTy> {
136 // Template traits for intrusive list. By specializing this template class, you
137 // can change what next/prev fields are used to store the links...
138 template<typename NodeTy>
139 struct ilist_traits : ilist_default_traits<NodeTy> {};
141 // Const traits are the same as nonconst traits...
142 template<typename Ty>
143 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
145 //===----------------------------------------------------------------------===//
146 // ilist_iterator<Node> - Iterator for intrusive list.
148 template<typename NodeTy>
150 : public bidirectional_iterator<NodeTy, ptrdiff_t> {
153 typedef ilist_traits<NodeTy> Traits;
154 typedef bidirectional_iterator<NodeTy, ptrdiff_t> super;
156 typedef typename super::value_type value_type;
157 typedef typename super::difference_type difference_type;
158 typedef typename super::pointer pointer;
159 typedef typename super::reference reference;
163 // ilist_iterator is not a random-access iterator, but it has an
164 // implicit conversion to pointer-type, which is. Declare (but
165 // don't define) these functions as private to help catch
166 // accidental misuse.
167 void operator[](difference_type) const;
168 void operator+(difference_type) const;
169 void operator-(difference_type) const;
170 void operator+=(difference_type) const;
171 void operator-=(difference_type) const;
172 template<class T> void operator<(T) const;
173 template<class T> void operator<=(T) const;
174 template<class T> void operator>(T) const;
175 template<class T> void operator>=(T) const;
176 template<class T> void operator-(T) const;
179 ilist_iterator(pointer NP) : NodePtr(NP) {}
180 ilist_iterator(reference NR) : NodePtr(&NR) {}
181 ilist_iterator() : NodePtr(0) {}
183 // This is templated so that we can allow constructing a const iterator from
184 // a nonconst iterator...
185 template<class node_ty>
186 ilist_iterator(const ilist_iterator<node_ty> &RHS)
187 : NodePtr(RHS.getNodePtrUnchecked()) {}
189 // This is templated so that we can allow assigning to a const iterator from
190 // a nonconst iterator...
191 template<class node_ty>
192 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
193 NodePtr = RHS.getNodePtrUnchecked();
198 operator pointer() const {
199 sentinel_tail_assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
203 reference operator*() const {
204 sentinel_tail_assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
207 pointer operator->() const { return &operator*(); }
209 // Comparison operators
210 bool operator==(const ilist_iterator &RHS) const {
211 return NodePtr == RHS.NodePtr;
213 bool operator!=(const ilist_iterator &RHS) const {
214 return NodePtr != RHS.NodePtr;
217 // Increment and decrement operators...
218 ilist_iterator &operator--() { // predecrement - Back up
219 NodePtr = Traits::getPrev(NodePtr);
220 assert(NodePtr && "--'d off the beginning of an ilist!");
223 ilist_iterator &operator++() { // preincrement - Advance
224 NodePtr = Traits::getNext(NodePtr);
225 sentinel_tail_assert(NodePtr && "++'d off the end of an ilist!");
228 ilist_iterator operator--(int) { // postdecrement operators...
229 ilist_iterator tmp = *this;
233 ilist_iterator operator++(int) { // postincrement operators...
234 ilist_iterator tmp = *this;
239 // Internal interface, do not use...
240 pointer getNodePtrUnchecked() const { return NodePtr; }
243 // do not implement. this is to catch errors when people try to use
244 // them as random access iterators
246 void operator-(int, ilist_iterator<T>);
248 void operator-(ilist_iterator<T>,int);
251 void operator+(int, ilist_iterator<T>);
253 void operator+(ilist_iterator<T>,int);
255 // operator!=/operator== - Allow mixed comparisons without dereferencing
256 // the iterator, which could very likely be pointing to end().
258 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
259 return LHS != RHS.getNodePtrUnchecked();
262 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
263 return LHS == RHS.getNodePtrUnchecked();
266 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
267 return LHS != RHS.getNodePtrUnchecked();
270 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
271 return LHS == RHS.getNodePtrUnchecked();
275 // Allow ilist_iterators to convert into pointers to a node automatically when
276 // used by the dyn_cast, cast, isa mechanisms...
278 template<typename From> struct simplify_type;
280 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
281 typedef NodeTy* SimpleType;
283 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
287 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
288 typedef NodeTy* SimpleType;
290 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
296 //===----------------------------------------------------------------------===//
298 /// iplist - The subset of list functionality that can safely be used on nodes
299 /// of polymorphic types, i.e. a heterogenous list with a common base class that
300 /// holds the next/prev pointers. The only state of the list itself is a single
301 /// pointer to the head of the list.
303 /// This list can be in one of three interesting states:
304 /// 1. The list may be completely unconstructed. In this case, the head
305 /// pointer is null. When in this form, any query for an iterator (e.g.
306 /// begin() or end()) causes the list to transparently change to state #2.
307 /// 2. The list may be empty, but contain a sentinel for the end iterator. This
308 /// sentinel is created by the Traits::createSentinel method and is a link
309 /// in the list. When the list is empty, the pointer in the iplist points
310 /// to the sentinel. Once the sentinel is constructed, it
311 /// is not destroyed until the list is.
312 /// 3. The list may contain actual objects in it, which are stored as a doubly
313 /// linked list of nodes. One invariant of the list is that the predecessor
314 /// of the first node in the list always points to the last node in the list,
315 /// and the successor pointer for the sentinel (which always stays at the
316 /// end of the list) is always null.
318 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
319 class iplist : public Traits {
320 mutable NodeTy *Head;
322 // Use the prev node pointer of 'head' as the tail pointer. This is really a
323 // circularly linked list where we snip the 'next' link from the sentinel node
324 // back to the first node in the list (to preserve assertions about going off
325 // the end of the list).
326 NodeTy *getTail() { return this->ensureHead(Head); }
327 const NodeTy *getTail() const { return this->ensureHead(Head); }
328 void setTail(NodeTy *N) const { this->noteHead(Head, N); }
330 /// CreateLazySentinel - This method verifies whether the sentinel for the
331 /// list has been created and lazily makes it if not.
332 void CreateLazySentinel() const {
333 this->ensureHead(Head);
336 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
337 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
339 // No fundamental reason why iplist can't be copyable, but the default
340 // copy/copy-assign won't do.
341 iplist(const iplist &); // do not implement
342 void operator=(const iplist &); // do not implement
345 typedef NodeTy *pointer;
346 typedef const NodeTy *const_pointer;
347 typedef NodeTy &reference;
348 typedef const NodeTy &const_reference;
349 typedef NodeTy value_type;
350 typedef ilist_iterator<NodeTy> iterator;
351 typedef ilist_iterator<const NodeTy> const_iterator;
352 typedef size_t size_type;
353 typedef ptrdiff_t difference_type;
354 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
355 typedef std::reverse_iterator<iterator> reverse_iterator;
357 iplist() : Head(this->provideInitialHead()) {}
361 Traits::destroySentinel(getTail());
364 // Iterator creation methods.
366 CreateLazySentinel();
367 return iterator(Head);
369 const_iterator begin() const {
370 CreateLazySentinel();
371 return const_iterator(Head);
374 CreateLazySentinel();
375 return iterator(getTail());
377 const_iterator end() const {
378 CreateLazySentinel();
379 return const_iterator(getTail());
382 // reverse iterator creation methods.
383 reverse_iterator rbegin() { return reverse_iterator(end()); }
384 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
385 reverse_iterator rend() { return reverse_iterator(begin()); }
386 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
389 // Miscellaneous inspection routines.
390 size_type max_size() const { return size_type(-1); }
391 bool empty() const { return Head == 0 || Head == getTail(); }
393 // Front and back accessor functions...
395 assert(!empty() && "Called front() on empty list!");
398 const_reference front() const {
399 assert(!empty() && "Called front() on empty list!");
403 assert(!empty() && "Called back() on empty list!");
404 return *this->getPrev(getTail());
406 const_reference back() const {
407 assert(!empty() && "Called back() on empty list!");
408 return *this->getPrev(getTail());
411 void swap(iplist &RHS) {
412 assert(0 && "Swap does not use list traits callback correctly yet!");
413 std::swap(Head, RHS.Head);
416 iterator insert(iterator where, NodeTy *New) {
417 NodeTy *CurNode = where.getNodePtrUnchecked();
418 NodeTy *PrevNode = this->getPrev(CurNode);
419 this->setNext(New, CurNode);
420 this->setPrev(New, PrevNode);
422 if (CurNode != Head) // Is PrevNode off the beginning of the list?
423 this->setNext(PrevNode, New);
426 this->setPrev(CurNode, New);
428 this->addNodeToList(New); // Notify traits that we added a node...
432 iterator insertAfter(iterator where, NodeTy *New) {
434 return insert(begin(), New);
436 return insert(++where, New);
439 NodeTy *remove(iterator &IT) {
440 assert(IT != end() && "Cannot remove end of list!");
442 NodeTy *NextNode = this->getNext(Node);
443 NodeTy *PrevNode = this->getPrev(Node);
445 if (Node != Head) // Is PrevNode off the beginning of the list?
446 this->setNext(PrevNode, NextNode);
449 this->setPrev(NextNode, PrevNode);
451 this->removeNodeFromList(Node); // Notify traits that we removed a node...
453 // Set the next/prev pointers of the current node to null. This isn't
454 // strictly required, but this catches errors where a node is removed from
455 // an ilist (and potentially deleted) with iterators still pointing at it.
456 // When those iterators are incremented or decremented, they will assert on
457 // the null next/prev pointer instead of "usually working".
458 this->setNext(Node, 0);
459 this->setPrev(Node, 0);
463 NodeTy *remove(const iterator &IT) {
465 return remove(MutIt);
468 // erase - remove a node from the controlled sequence... and delete it.
469 iterator erase(iterator where) {
470 this->deleteNode(remove(where));
476 // transfer - The heart of the splice function. Move linked list nodes from
477 // [first, last) into position.
479 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
480 assert(first != last && "Should be checked by callers");
482 if (position != last) {
483 // Note: we have to be careful about the case when we move the first node
484 // in the list. This node is the list sentinel node and we can't move it.
485 NodeTy *ThisSentinel = getTail();
487 NodeTy *L2Sentinel = L2.getTail();
490 // Remove [first, last) from its old position.
491 NodeTy *First = &*first, *Prev = this->getPrev(First);
492 NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
494 this->setNext(Prev, Next);
497 this->setPrev(Next, Prev);
499 // Splice [first, last) into its new position.
500 NodeTy *PosNext = position.getNodePtrUnchecked();
501 NodeTy *PosPrev = this->getPrev(PosNext);
503 // Fix head of list...
505 this->setNext(PosPrev, First);
508 this->setPrev(First, PosPrev);
510 // Fix end of list...
511 this->setNext(Last, PosNext);
512 this->setPrev(PosNext, Last);
514 this->transferNodesFromList(L2, First, PosNext);
516 // Now that everything is set, restore the pointers to the list sentinels.
517 L2.setTail(L2Sentinel);
518 setTail(ThisSentinel);
524 //===----------------------------------------------------------------------===
525 // Functionality derived from other functions defined above...
528 size_type size() const {
529 if (Head == 0) return 0; // Don't require construction of sentinel if empty.
530 return std::distance(begin(), end());
533 iterator erase(iterator first, iterator last) {
534 while (first != last)
535 first = erase(first);
539 void clear() { if (Head) erase(begin(), end()); }
541 // Front and back inserters...
542 void push_front(NodeTy *val) { insert(begin(), val); }
543 void push_back(NodeTy *val) { insert(end(), val); }
545 assert(!empty() && "pop_front() on empty list!");
549 assert(!empty() && "pop_back() on empty list!");
550 iterator t = end(); erase(--t);
553 // Special forms of insert...
554 template<class InIt> void insert(iterator where, InIt first, InIt last) {
555 for (; first != last; ++first) insert(where, *first);
558 // Splice members - defined in terms of transfer...
559 void splice(iterator where, iplist &L2) {
561 transfer(where, L2, L2.begin(), L2.end());
563 void splice(iterator where, iplist &L2, iterator first) {
564 iterator last = first; ++last;
565 if (where == first || where == last) return; // No change
566 transfer(where, L2, first, last);
568 void splice(iterator where, iplist &L2, iterator first, iterator last) {
569 if (first != last) transfer(where, L2, first, last);
574 //===----------------------------------------------------------------------===
575 // High-Level Functionality that shouldn't really be here, but is part of list
578 // These two functions are actually called remove/remove_if in list<>, but
579 // they actually do the job of erase, rename them accordingly.
581 void erase(const NodeTy &val) {
582 for (iterator I = begin(), E = end(); I != E; ) {
583 iterator next = I; ++next;
584 if (*I == val) erase(I);
588 template<class Pr1> void erase_if(Pr1 pred) {
589 for (iterator I = begin(), E = end(); I != E; ) {
590 iterator next = I; ++next;
591 if (pred(*I)) erase(I);
596 template<class Pr2> void unique(Pr2 pred) {
598 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
606 void unique() { unique(op_equal); }
608 template<class Pr3> void merge(iplist &right, Pr3 pred) {
609 iterator first1 = begin(), last1 = end();
610 iterator first2 = right.begin(), last2 = right.end();
611 while (first1 != last1 && first2 != last2)
612 if (pred(*first2, *first1)) {
613 iterator next = first2;
614 transfer(first1, right, first2, ++next);
619 if (first2 != last2) transfer(last1, right, first2, last2);
621 void merge(iplist &right) { return merge(right, op_less); }
623 template<class Pr3> void sort(Pr3 pred);
624 void sort() { sort(op_less); }
629 template<typename NodeTy>
630 struct ilist : public iplist<NodeTy> {
631 typedef typename iplist<NodeTy>::size_type size_type;
632 typedef typename iplist<NodeTy>::iterator iterator;
635 ilist(const ilist &right) {
636 insert(this->begin(), right.begin(), right.end());
638 explicit ilist(size_type count) {
639 insert(this->begin(), count, NodeTy());
641 ilist(size_type count, const NodeTy &val) {
642 insert(this->begin(), count, val);
644 template<class InIt> ilist(InIt first, InIt last) {
645 insert(this->begin(), first, last);
648 // bring hidden functions into scope
649 using iplist<NodeTy>::insert;
650 using iplist<NodeTy>::push_front;
651 using iplist<NodeTy>::push_back;
653 // Main implementation here - Insert for a node passed by value...
654 iterator insert(iterator where, const NodeTy &val) {
655 return insert(where, createNode(val));
659 // Front and back inserters...
660 void push_front(const NodeTy &val) { insert(this->begin(), val); }
661 void push_back(const NodeTy &val) { insert(this->end(), val); }
663 // Special forms of insert...
664 template<class InIt> void insert(iterator where, InIt first, InIt last) {
665 for (; first != last; ++first) insert(where, *first);
667 void insert(iterator where, size_type count, const NodeTy &val) {
668 for (; count != 0; --count) insert(where, val);
671 // Assign special forms...
672 void assign(size_type count, const NodeTy &val) {
673 iterator I = this->begin();
674 for (; I != this->end() && count != 0; ++I, --count)
677 insert(this->end(), val, val);
679 erase(I, this->end());
681 template<class InIt> void assign(InIt first1, InIt last1) {
682 iterator first2 = this->begin(), last2 = this->end();
683 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
686 erase(first1, last1);
688 insert(last1, first2, last2);
693 void resize(size_type newsize, NodeTy val) {
694 iterator i = this->begin();
696 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
699 erase(i, this->end());
701 insert(this->end(), newsize - len, val);
703 void resize(size_type newsize) { resize(newsize, NodeTy()); }
706 } // End llvm namespace
709 // Ensure that swap uses the fast list swap...
711 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
714 } // End 'std' extensions...
716 #endif // LLVM_ADT_ILIST_H