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"
47 template<typename NodeTy, typename Traits> class iplist;
48 template<typename NodeTy> class ilist_iterator;
50 // Template traits for intrusive list. By specializing this template class, you
51 // can change what next/prev fields are used to store the links...
52 template<typename NodeTy>
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); }
62 static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
63 static void deleteNode(NodeTy *V) { delete V; }
65 static NodeTy *createSentinel() { return new NodeTy(); }
66 static void destroySentinel(NodeTy *N) { delete N; }
68 void addNodeToList(NodeTy *NTy) {}
69 void removeNodeFromList(NodeTy *NTy) {}
70 void transferNodesFromList(iplist<NodeTy, ilist_traits> &L2,
71 ilist_iterator<NodeTy> first,
72 ilist_iterator<NodeTy> last) {}
75 // Const traits are the same as nonconst traits...
77 struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
80 //===----------------------------------------------------------------------===//
81 // ilist_iterator<Node> - Iterator for intrusive list.
83 template<typename NodeTy>
85 : public bidirectional_iterator<NodeTy, ptrdiff_t> {
88 typedef ilist_traits<NodeTy> Traits;
89 typedef bidirectional_iterator<NodeTy, ptrdiff_t> super;
91 typedef size_t size_type;
92 typedef typename super::pointer pointer;
93 typedef typename super::reference reference;
98 ilist_iterator(pointer NP) : NodePtr(NP) {}
99 ilist_iterator(reference NR) : NodePtr(&NR) {}
100 ilist_iterator() : NodePtr(0) {}
102 // This is templated so that we can allow constructing a const iterator from
103 // a nonconst iterator...
104 template<class node_ty>
105 ilist_iterator(const ilist_iterator<node_ty> &RHS)
106 : NodePtr(RHS.getNodePtrUnchecked()) {}
108 // This is templated so that we can allow assigning to a const iterator from
109 // a nonconst iterator...
110 template<class node_ty>
111 const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
112 NodePtr = RHS.getNodePtrUnchecked();
117 operator pointer() const {
118 assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
122 reference operator*() const {
123 assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
126 pointer operator->() const { return &operator*(); }
128 // Comparison operators
129 bool operator==(const ilist_iterator &RHS) const {
130 return NodePtr == RHS.NodePtr;
132 bool operator!=(const ilist_iterator &RHS) const {
133 return NodePtr != RHS.NodePtr;
136 // Increment and decrement operators...
137 ilist_iterator &operator--() { // predecrement - Back up
138 NodePtr = Traits::getPrev(NodePtr);
139 assert(Traits::getNext(NodePtr) && "--'d off the beginning of an ilist!");
142 ilist_iterator &operator++() { // preincrement - Advance
143 NodePtr = Traits::getNext(NodePtr);
144 assert(NodePtr && "++'d off the end of an ilist!");
147 ilist_iterator operator--(int) { // postdecrement operators...
148 ilist_iterator tmp = *this;
152 ilist_iterator operator++(int) { // postincrement operators...
153 ilist_iterator tmp = *this;
158 // Internal interface, do not use...
159 pointer getNodePtrUnchecked() const { return NodePtr; }
162 // do not implement. this is to catch errors when people try to use
163 // them as random access iterators
165 void operator-(int, ilist_iterator<T>);
167 void operator-(ilist_iterator<T>,int);
170 void operator+(int, ilist_iterator<T>);
172 void operator+(ilist_iterator<T>,int);
174 // operator!=/operator== - Allow mixed comparisons without dereferencing
175 // the iterator, which could very likely be pointing to end().
177 bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
178 return LHS != RHS.getNodePtrUnchecked();
181 bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
182 return LHS == RHS.getNodePtrUnchecked();
185 bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
186 return LHS != RHS.getNodePtrUnchecked();
189 bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
190 return LHS == RHS.getNodePtrUnchecked();
194 // Allow ilist_iterators to convert into pointers to a node automatically when
195 // used by the dyn_cast, cast, isa mechanisms...
197 template<typename From> struct simplify_type;
199 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
200 typedef NodeTy* SimpleType;
202 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
206 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
207 typedef NodeTy* SimpleType;
209 static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
215 //===----------------------------------------------------------------------===//
217 /// iplist - The subset of list functionality that can safely be used on nodes
218 /// of polymorphic types, i.e. a heterogenous list with a common base class that
219 /// holds the next/prev pointers. The only state of the list itself is a single
220 /// pointer to the head of the list.
222 /// This list can be in one of three interesting states:
223 /// 1. The list may be completely unconstructed. In this case, the head
224 /// pointer is null. When in this form, any query for an iterator (e.g.
225 /// begin() or end()) causes the list to transparently change to state #2.
226 /// 2. The list may be empty, but contain a sentinal for the end iterator. This
227 /// sentinal is created by the Traits::createSentinel method and is a link
228 /// in the list. When the list is empty, the pointer in the iplist points
229 /// to the sentinal. Once the sentinal is constructed, it
230 /// is not destroyed until the list is.
231 /// 3. The list may contain actual objects in it, which are stored as a doubly
232 /// linked list of nodes. One invariant of the list is that the predecessor
233 /// of the first node in the list always points to the last node in the list,
234 /// and the successor pointer for the sentinal (which always stays at the
235 /// end of the list) is always null.
237 template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
238 class iplist : public Traits {
239 mutable NodeTy *Head;
241 // Use the prev node pointer of 'head' as the tail pointer. This is really a
242 // circularly linked list where we snip the 'next' link from the sentinel node
243 // back to the first node in the list (to preserve assertions about going off
244 // the end of the list).
245 NodeTy *getTail() { return getPrev(Head); }
246 const NodeTy *getTail() const { return getPrev(Head); }
247 void setTail(NodeTy *N) const { setPrev(Head, N); }
249 /// CreateLazySentinal - This method verifies whether the sentinal for the
250 /// list has been created and lazily makes it if not.
251 void CreateLazySentinal() const {
252 if (Head != 0) return;
253 Head = Traits::createSentinel();
258 static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
259 static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
261 // No fundamental reason why iplist can't by copyable, but the default
262 // copy/copy-assign won't do.
263 iplist(const iplist &); // do not implement
264 void operator=(const iplist &); // do not implement
267 typedef NodeTy *pointer;
268 typedef const NodeTy *const_pointer;
269 typedef NodeTy &reference;
270 typedef const NodeTy &const_reference;
271 typedef NodeTy value_type;
272 typedef ilist_iterator<NodeTy> iterator;
273 typedef ilist_iterator<const NodeTy> const_iterator;
274 typedef size_t size_type;
275 typedef ptrdiff_t difference_type;
276 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
277 typedef std::reverse_iterator<iterator> reverse_iterator;
279 iplist() : Head(0) {}
283 Traits::destroySentinel(getTail());
286 // Iterator creation methods.
288 CreateLazySentinal();
289 return iterator(Head);
291 const_iterator begin() const {
292 CreateLazySentinal();
293 return const_iterator(Head);
296 CreateLazySentinal();
297 return iterator(getTail());
299 const_iterator end() const {
300 CreateLazySentinal();
301 return const_iterator(getTail());
304 // reverse iterator creation methods.
305 reverse_iterator rbegin() { return reverse_iterator(end()); }
306 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
307 reverse_iterator rend() { return reverse_iterator(begin()); }
308 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
311 // Miscellaneous inspection routines.
312 size_type max_size() const { return size_type(-1); }
313 bool empty() const { return Head == 0 || Head == getTail(); }
315 // Front and back accessor functions...
317 assert(!empty() && "Called front() on empty list!");
320 const_reference front() const {
321 assert(!empty() && "Called front() on empty list!");
325 assert(!empty() && "Called back() on empty list!");
326 return *getPrev(getTail());
328 const_reference back() const {
329 assert(!empty() && "Called back() on empty list!");
330 return *getPrev(getTail());
333 void swap(iplist &RHS) {
334 abort(); // Swap does not use list traits callback correctly yet!
335 std::swap(Head, RHS.Head);
338 iterator insert(iterator where, NodeTy *New) {
339 NodeTy *CurNode = where.getNodePtrUnchecked(), *PrevNode = getPrev(CurNode);
340 setNext(New, CurNode);
341 setPrev(New, PrevNode);
343 if (CurNode != Head) // Is PrevNode off the beginning of the list?
344 setNext(PrevNode, New);
347 setPrev(CurNode, New);
349 addNodeToList(New); // Notify traits that we added a node...
353 NodeTy *remove(iterator &IT) {
354 assert(IT != end() && "Cannot remove end of list!");
356 NodeTy *NextNode = getNext(Node);
357 NodeTy *PrevNode = getPrev(Node);
359 if (Node != Head) // Is PrevNode off the beginning of the list?
360 setNext(PrevNode, NextNode);
363 setPrev(NextNode, PrevNode);
365 removeNodeFromList(Node); // Notify traits that we removed a node...
367 // Set the next/prev pointers of the current node to null. This isn't
368 // strictly required, but this catches errors where a node is removed from
369 // an ilist (and potentially deleted) with iterators still pointing at it.
370 // When those iterators are incremented or decremented, they will assert on
371 // the null next/prev pointer instead of "usually working".
377 NodeTy *remove(const iterator &IT) {
379 return remove(MutIt);
382 // erase - remove a node from the controlled sequence... and delete it.
383 iterator erase(iterator where) {
384 deleteNode(remove(where));
390 // transfer - The heart of the splice function. Move linked list nodes from
391 // [first, last) into position.
393 void transfer(iterator position, iplist &L2, iterator first, iterator last) {
394 assert(first != last && "Should be checked by callers");
396 if (position != last) {
397 // Note: we have to be careful about the case when we move the first node
398 // in the list. This node is the list sentinel node and we can't move it.
399 NodeTy *ThisSentinel = getTail();
401 NodeTy *L2Sentinel = L2.getTail();
404 // Remove [first, last) from its old position.
405 NodeTy *First = &*first, *Prev = getPrev(First);
406 NodeTy *Next = last.getNodePtrUnchecked(), *Last = getPrev(Next);
413 // Splice [first, last) into its new position.
414 NodeTy *PosNext = position.getNodePtrUnchecked();
415 NodeTy *PosPrev = getPrev(PosNext);
417 // Fix head of list...
419 setNext(PosPrev, First);
422 setPrev(First, PosPrev);
424 // Fix end of list...
425 setNext(Last, PosNext);
426 setPrev(PosNext, Last);
428 transferNodesFromList(L2, First, PosNext);
430 // Now that everything is set, restore the pointers to the list sentinals.
431 L2.setTail(L2Sentinel);
432 setTail(ThisSentinel);
438 //===----------------------------------------------------------------------===
439 // Functionality derived from other functions defined above...
442 size_type size() const {
443 if (Head == 0) return 0; // Don't require construction of sentinal if empty.
445 // GCC 2.95 has a broken std::distance
446 size_type Result = 0;
447 std::distance(begin(), end(), Result);
450 return std::distance(begin(), end());
454 iterator erase(iterator first, iterator last) {
455 while (first != last)
456 first = erase(first);
460 void clear() { if (Head) erase(begin(), end()); }
462 // Front and back inserters...
463 void push_front(NodeTy *val) { insert(begin(), val); }
464 void push_back(NodeTy *val) { insert(end(), val); }
466 assert(!empty() && "pop_front() on empty list!");
470 assert(!empty() && "pop_back() on empty list!");
471 iterator t = end(); erase(--t);
474 // Special forms of insert...
475 template<class InIt> void insert(iterator where, InIt first, InIt last) {
476 for (; first != last; ++first) insert(where, *first);
479 // Splice members - defined in terms of transfer...
480 void splice(iterator where, iplist &L2) {
482 transfer(where, L2, L2.begin(), L2.end());
484 void splice(iterator where, iplist &L2, iterator first) {
485 iterator last = first; ++last;
486 if (where == first || where == last) return; // No change
487 transfer(where, L2, first, last);
489 void splice(iterator where, iplist &L2, iterator first, iterator last) {
490 if (first != last) transfer(where, L2, first, last);
495 //===----------------------------------------------------------------------===
496 // High-Level Functionality that shouldn't really be here, but is part of list
499 // These two functions are actually called remove/remove_if in list<>, but
500 // they actually do the job of erase, rename them accordingly.
502 void erase(const NodeTy &val) {
503 for (iterator I = begin(), E = end(); I != E; ) {
504 iterator next = I; ++next;
505 if (*I == val) erase(I);
509 template<class Pr1> void erase_if(Pr1 pred) {
510 for (iterator I = begin(), E = end(); I != E; ) {
511 iterator next = I; ++next;
512 if (pred(*I)) erase(I);
517 template<class Pr2> void unique(Pr2 pred) {
519 for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
527 void unique() { unique(op_equal); }
529 template<class Pr3> void merge(iplist &right, Pr3 pred) {
530 iterator first1 = begin(), last1 = end();
531 iterator first2 = right.begin(), last2 = right.end();
532 while (first1 != last1 && first2 != last2)
533 if (pred(*first2, *first1)) {
534 iterator next = first2;
535 transfer(first1, right, first2, ++next);
540 if (first2 != last2) transfer(last1, right, first2, last2);
542 void merge(iplist &right) { return merge(right, op_less); }
544 template<class Pr3> void sort(Pr3 pred);
545 void sort() { sort(op_less); }
550 template<typename NodeTy>
551 struct ilist : public iplist<NodeTy> {
552 typedef typename iplist<NodeTy>::size_type size_type;
553 typedef typename iplist<NodeTy>::iterator iterator;
556 ilist(const ilist &right) {
557 insert(this->begin(), right.begin(), right.end());
559 explicit ilist(size_type count) {
560 insert(this->begin(), count, NodeTy());
562 ilist(size_type count, const NodeTy &val) {
563 insert(this->begin(), count, val);
565 template<class InIt> ilist(InIt first, InIt last) {
566 insert(this->begin(), first, last);
570 // Forwarding functions: A workaround for GCC 2.95 which does not correctly
571 // support 'using' declarations to bring a hidden member into scope.
573 iterator insert(iterator a, NodeTy *b){ return iplist<NodeTy>::insert(a, b); }
574 void push_front(NodeTy *a) { iplist<NodeTy>::push_front(a); }
575 void push_back(NodeTy *a) { iplist<NodeTy>::push_back(a); }
578 // Main implementation here - Insert for a node passed by value...
579 iterator insert(iterator where, const NodeTy &val) {
580 return insert(where, createNode(val));
584 // Front and back inserters...
585 void push_front(const NodeTy &val) { insert(this->begin(), val); }
586 void push_back(const NodeTy &val) { insert(this->end(), val); }
588 // Special forms of insert...
589 template<class InIt> void insert(iterator where, InIt first, InIt last) {
590 for (; first != last; ++first) insert(where, *first);
592 void insert(iterator where, size_type count, const NodeTy &val) {
593 for (; count != 0; --count) insert(where, val);
596 // Assign special forms...
597 void assign(size_type count, const NodeTy &val) {
598 iterator I = this->begin();
599 for (; I != this->end() && count != 0; ++I, --count)
602 insert(this->end(), val, val);
604 erase(I, this->end());
606 template<class InIt> void assign(InIt first1, InIt last1) {
607 iterator first2 = this->begin(), last2 = this->end();
608 for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
611 erase(first1, last1);
613 insert(last1, first2, last2);
618 void resize(size_type newsize, NodeTy val) {
619 iterator i = this->begin();
621 for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
624 erase(i, this->end());
626 insert(this->end(), newsize - len, val);
628 void resize(size_type newsize) { resize(newsize, NodeTy()); }
631 } // End llvm namespace
634 // Ensure that swap uses the fast list swap...
636 void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
639 } // End 'std' extensions...
641 #endif // LLVM_ADT_ILIST_H