1//==-- llvm/ADT/ilist.h - Intrusive Linked List Template ---------*- C++ -*-==//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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
12// list.
13//
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.
18//
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.
23//
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.
29//
30// Requirements for a user of this list:
31//
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
34//      prev links.
35//
36//===----------------------------------------------------------------------===//
37
38#ifndef LLVM_ADT_ILIST_H
39#define LLVM_ADT_ILIST_H
40
41#include "llvm/Support/Compiler.h"
42#include <algorithm>
43#include <cassert>
44#include <cstddef>
45#include <iterator>
46
47namespace llvm {
48
49template<typename NodeTy, typename Traits> class iplist;
50template<typename NodeTy> class ilist_iterator;
51
52/// ilist_nextprev_traits - A fragment for template traits for intrusive list
53/// that provides default next/prev implementations for common operations.
54///
55template<typename NodeTy>
56struct ilist_nextprev_traits {
57  static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
58  static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
59  static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
60  static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
61
62  static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
63  static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
64};
65
66template<typename NodeTy>
67struct ilist_traits;
68
69/// ilist_sentinel_traits - A fragment for template traits for intrusive list
70/// that provides default sentinel implementations for common operations.
71///
72/// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
73/// strategy. The sentinel is stored in the prev field of ilist's Head.
74///
75template<typename NodeTy>
76struct ilist_sentinel_traits {
77  /// createSentinel - create the dynamic sentinel
78  static NodeTy *createSentinel() { return new NodeTy(); }
79
80  /// destroySentinel - deallocate the dynamic sentinel
81  static void destroySentinel(NodeTy *N) { delete N; }
82
83  /// provideInitialHead - when constructing an ilist, provide a starting
84  /// value for its Head
85  /// @return null node to indicate that it needs to be allocated later
86  static NodeTy *provideInitialHead() { return nullptr; }
87
88  /// ensureHead - make sure that Head is either already
89  /// initialized or assigned a fresh sentinel
90  /// @return the sentinel
91  static NodeTy *ensureHead(NodeTy *&Head) {
92    if (!Head) {
93      Head = ilist_traits<NodeTy>::createSentinel();
94      ilist_traits<NodeTy>::noteHead(Head, Head);
95      ilist_traits<NodeTy>::setNext(Head, nullptr);
96      return Head;
97    }
98    return ilist_traits<NodeTy>::getPrev(Head);
99  }
100
101  /// noteHead - stash the sentinel into its default location
102  static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
103    ilist_traits<NodeTy>::setPrev(NewHead, Sentinel);
104  }
105};
106
107/// ilist_node_traits - A fragment for template traits for intrusive list
108/// that provides default node related operations.
109///
110template<typename NodeTy>
111struct ilist_node_traits {
112  static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
113  static void deleteNode(NodeTy *V) { delete V; }
114
115  void addNodeToList(NodeTy *) {}
116  void removeNodeFromList(NodeTy *) {}
117  void transferNodesFromList(ilist_node_traits &    /*SrcTraits*/,
118                             ilist_iterator<NodeTy> /*first*/,
119                             ilist_iterator<NodeTy> /*last*/) {}
120};
121
122/// ilist_default_traits - Default template traits for intrusive list.
123/// By inheriting from this, you can easily use default implementations
124/// for all common operations.
125///
126template<typename NodeTy>
127struct ilist_default_traits : public ilist_nextprev_traits<NodeTy>,
128                              public ilist_sentinel_traits<NodeTy>,
129                              public ilist_node_traits<NodeTy> {
130};
131
132// Template traits for intrusive list.  By specializing this template class, you
133// can change what next/prev fields are used to store the links...
134template<typename NodeTy>
135struct ilist_traits : public ilist_default_traits<NodeTy> {};
136
137// Const traits are the same as nonconst traits...
138template<typename Ty>
139struct ilist_traits<const Ty> : public ilist_traits<Ty> {};
140
141//===----------------------------------------------------------------------===//
142// ilist_iterator<Node> - Iterator for intrusive list.
143//
144template<typename NodeTy>
145class ilist_iterator
146  : public std::iterator<std::bidirectional_iterator_tag, NodeTy, ptrdiff_t> {
147
148public:
149  typedef ilist_traits<NodeTy> Traits;
150  typedef std::iterator<std::bidirectional_iterator_tag,
151                        NodeTy, ptrdiff_t> super;
152
153  typedef typename super::value_type value_type;
154  typedef typename super::difference_type difference_type;
155  typedef typename super::pointer pointer;
156  typedef typename super::reference reference;
157private:
158  pointer NodePtr;
159
160  // ilist_iterator is not a random-access iterator, but it has an
161  // implicit conversion to pointer-type, which is. Declare (but
162  // don't define) these functions as private to help catch
163  // accidental misuse.
164  void operator[](difference_type) const;
165  void operator+(difference_type) const;
166  void operator-(difference_type) const;
167  void operator+=(difference_type) const;
168  void operator-=(difference_type) 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;
172  template<class T> void operator>=(T) const;
173  template<class T> void operator-(T) const;
174public:
175
176  ilist_iterator(pointer NP) : NodePtr(NP) {}
177  ilist_iterator(reference NR) : NodePtr(&NR) {}
178  ilist_iterator() : NodePtr(nullptr) {}
179
180  // This is templated so that we can allow constructing a const iterator from
181  // a nonconst iterator...
182  template<class node_ty>
183  ilist_iterator(const ilist_iterator<node_ty> &RHS)
184    : NodePtr(RHS.getNodePtrUnchecked()) {}
185
186  // This is templated so that we can allow assigning to a const iterator from
187  // a nonconst iterator...
188  template<class node_ty>
189  const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
190    NodePtr = RHS.getNodePtrUnchecked();
191    return *this;
192  }
193
194  // Accessors...
195  operator pointer() const {
196    return NodePtr;
197  }
198
199  reference operator*() const {
200    return *NodePtr;
201  }
202  pointer operator->() const { return &operator*(); }
203
204  // Comparison operators
205  bool operator==(const ilist_iterator &RHS) const {
206    return NodePtr == RHS.NodePtr;
207  }
208  bool operator!=(const ilist_iterator &RHS) const {
209    return NodePtr != RHS.NodePtr;
210  }
211
212  // Increment and decrement operators...
213  ilist_iterator &operator--() {      // predecrement - Back up
214    NodePtr = Traits::getPrev(NodePtr);
215    assert(NodePtr && "--'d off the beginning of an ilist!");
216    return *this;
217  }
218  ilist_iterator &operator++() {      // preincrement - Advance
219    NodePtr = Traits::getNext(NodePtr);
220    return *this;
221  }
222  ilist_iterator operator--(int) {    // postdecrement operators...
223    ilist_iterator tmp = *this;
224    --*this;
225    return tmp;
226  }
227  ilist_iterator operator++(int) {    // postincrement operators...
228    ilist_iterator tmp = *this;
229    ++*this;
230    return tmp;
231  }
232
233  // Internal interface, do not use...
234  pointer getNodePtrUnchecked() const { return NodePtr; }
235};
236
237// These are to catch errors when people try to use them as random access
238// iterators.
239template<typename T>
240void operator-(int, ilist_iterator<T>) LLVM_DELETED_FUNCTION;
241template<typename T>
242void operator-(ilist_iterator<T>,int) LLVM_DELETED_FUNCTION;
243
244template<typename T>
245void operator+(int, ilist_iterator<T>) LLVM_DELETED_FUNCTION;
246template<typename T>
247void operator+(ilist_iterator<T>,int) LLVM_DELETED_FUNCTION;
248
249// operator!=/operator== - Allow mixed comparisons without dereferencing
250// the iterator, which could very likely be pointing to end().
251template<typename T>
252bool operator!=(const T* LHS, const ilist_iterator<const T> &RHS) {
253  return LHS != RHS.getNodePtrUnchecked();
254}
255template<typename T>
256bool operator==(const T* LHS, const ilist_iterator<const T> &RHS) {
257  return LHS == RHS.getNodePtrUnchecked();
258}
259template<typename T>
260bool operator!=(T* LHS, const ilist_iterator<T> &RHS) {
261  return LHS != RHS.getNodePtrUnchecked();
262}
263template<typename T>
264bool operator==(T* LHS, const ilist_iterator<T> &RHS) {
265  return LHS == RHS.getNodePtrUnchecked();
266}
267
268
269// Allow ilist_iterators to convert into pointers to a node automatically when
270// used by the dyn_cast, cast, isa mechanisms...
271
272template<typename From> struct simplify_type;
273
274template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
275  typedef NodeTy* SimpleType;
276
277  static SimpleType getSimplifiedValue(ilist_iterator<NodeTy> &Node) {
278    return &*Node;
279  }
280};
281template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
282  typedef /*const*/ NodeTy* SimpleType;
283
284  static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
285    return &*Node;
286  }
287};
288
289
290//===----------------------------------------------------------------------===//
291//
292/// iplist - The subset of list functionality that can safely be used on nodes
293/// of polymorphic types, i.e. a heterogeneous list with a common base class that
294/// holds the next/prev pointers.  The only state of the list itself is a single
295/// pointer to the head of the list.
296///
297/// This list can be in one of three interesting states:
298/// 1. The list may be completely unconstructed.  In this case, the head
299///    pointer is null.  When in this form, any query for an iterator (e.g.
300///    begin() or end()) causes the list to transparently change to state #2.
301/// 2. The list may be empty, but contain a sentinel for the end iterator. This
302///    sentinel is created by the Traits::createSentinel method and is a link
303///    in the list.  When the list is empty, the pointer in the iplist points
304///    to the sentinel.  Once the sentinel is constructed, it
305///    is not destroyed until the list is.
306/// 3. The list may contain actual objects in it, which are stored as a doubly
307///    linked list of nodes.  One invariant of the list is that the predecessor
308///    of the first node in the list always points to the last node in the list,
309///    and the successor pointer for the sentinel (which always stays at the
310///    end of the list) is always null.
311///
312template<typename NodeTy, typename Traits=ilist_traits<NodeTy> >
313class iplist : public Traits {
314  mutable NodeTy *Head;
315
316  // Use the prev node pointer of 'head' as the tail pointer.  This is really a
317  // circularly linked list where we snip the 'next' link from the sentinel node
318  // back to the first node in the list (to preserve assertions about going off
319  // the end of the list).
320  NodeTy *getTail() { return this->ensureHead(Head); }
321  const NodeTy *getTail() const { return this->ensureHead(Head); }
322  void setTail(NodeTy *N) const { this->noteHead(Head, N); }
323
324  /// CreateLazySentinel - This method verifies whether the sentinel for the
325  /// list has been created and lazily makes it if not.
326  void CreateLazySentinel() const {
327    this->ensureHead(Head);
328  }
329
330  static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
331  static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
332
333  // No fundamental reason why iplist can't be copyable, but the default
334  // copy/copy-assign won't do.
335  iplist(const iplist &) LLVM_DELETED_FUNCTION;
336  void operator=(const iplist &) LLVM_DELETED_FUNCTION;
337
338public:
339  typedef NodeTy *pointer;
340  typedef const NodeTy *const_pointer;
341  typedef NodeTy &reference;
342  typedef const NodeTy &const_reference;
343  typedef NodeTy value_type;
344  typedef ilist_iterator<NodeTy> iterator;
345  typedef ilist_iterator<const NodeTy> const_iterator;
346  typedef size_t size_type;
347  typedef ptrdiff_t difference_type;
348  typedef std::reverse_iterator<const_iterator>  const_reverse_iterator;
349  typedef std::reverse_iterator<iterator>  reverse_iterator;
350
351  iplist() : Head(this->provideInitialHead()) {}
352  ~iplist() {
353    if (!Head) return;
354    clear();
355    Traits::destroySentinel(getTail());
356  }
357
358  // Iterator creation methods.
359  iterator begin() {
360    CreateLazySentinel();
361    return iterator(Head);
362  }
363  const_iterator begin() const {
364    CreateLazySentinel();
365    return const_iterator(Head);
366  }
367  iterator end() {
368    CreateLazySentinel();
369    return iterator(getTail());
370  }
371  const_iterator end() const {
372    CreateLazySentinel();
373    return const_iterator(getTail());
374  }
375
376  // reverse iterator creation methods.
377  reverse_iterator rbegin()            { return reverse_iterator(end()); }
378  const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
379  reverse_iterator rend()              { return reverse_iterator(begin()); }
380  const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
381
382
383  // Miscellaneous inspection routines.
384  size_type max_size() const { return size_type(-1); }
385  bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
386    return !Head || Head == getTail();
387  }
388
389  // Front and back accessor functions...
390  reference front() {
391    assert(!empty() && "Called front() on empty list!");
392    return *Head;
393  }
394  const_reference front() const {
395    assert(!empty() && "Called front() on empty list!");
396    return *Head;
397  }
398  reference back() {
399    assert(!empty() && "Called back() on empty list!");
400    return *this->getPrev(getTail());
401  }
402  const_reference back() const {
403    assert(!empty() && "Called back() on empty list!");
404    return *this->getPrev(getTail());
405  }
406
407  void swap(iplist &RHS) {
408    assert(0 && "Swap does not use list traits callback correctly yet!");
409    std::swap(Head, RHS.Head);
410  }
411
412  iterator insert(iterator where, NodeTy *New) {
413    NodeTy *CurNode = where.getNodePtrUnchecked();
414    NodeTy *PrevNode = this->getPrev(CurNode);
415    this->setNext(New, CurNode);
416    this->setPrev(New, PrevNode);
417
418    if (CurNode != Head)  // Is PrevNode off the beginning of the list?
419      this->setNext(PrevNode, New);
420    else
421      Head = New;
422    this->setPrev(CurNode, New);
423
424    this->addNodeToList(New);  // Notify traits that we added a node...
425    return New;
426  }
427
428  iterator insertAfter(iterator where, NodeTy *New) {
429    if (empty())
430      return insert(begin(), New);
431    else
432      return insert(++where, New);
433  }
434
435  NodeTy *remove(iterator &IT) {
436    assert(IT != end() && "Cannot remove end of list!");
437    NodeTy *Node = &*IT;
438    NodeTy *NextNode = this->getNext(Node);
439    NodeTy *PrevNode = this->getPrev(Node);
440
441    if (Node != Head)  // Is PrevNode off the beginning of the list?
442      this->setNext(PrevNode, NextNode);
443    else
444      Head = NextNode;
445    this->setPrev(NextNode, PrevNode);
446    IT = NextNode;
447    this->removeNodeFromList(Node);  // Notify traits that we removed a node...
448
449    // Set the next/prev pointers of the current node to null.  This isn't
450    // strictly required, but this catches errors where a node is removed from
451    // an ilist (and potentially deleted) with iterators still pointing at it.
452    // When those iterators are incremented or decremented, they will assert on
453    // the null next/prev pointer instead of "usually working".
454    this->setNext(Node, nullptr);
455    this->setPrev(Node, nullptr);
456    return Node;
457  }
458
459  NodeTy *remove(const iterator &IT) {
460    iterator MutIt = IT;
461    return remove(MutIt);
462  }
463
464  // erase - remove a node from the controlled sequence... and delete it.
465  iterator erase(iterator where) {
466    this->deleteNode(remove(where));
467    return where;
468  }
469
470  /// Remove all nodes from the list like clear(), but do not call
471  /// removeNodeFromList() or deleteNode().
472  ///
473  /// This should only be used immediately before freeing nodes in bulk to
474  /// avoid traversing the list and bringing all the nodes into cache.
475  void clearAndLeakNodesUnsafely() {
476    if (Head) {
477      Head = getTail();
478      this->setPrev(Head, Head);
479    }
480  }
481
482private:
483  // transfer - The heart of the splice function.  Move linked list nodes from
484  // [first, last) into position.
485  //
486  void transfer(iterator position, iplist &L2, iterator first, iterator last) {
487    assert(first != last && "Should be checked by callers");
488    // Position cannot be contained in the range to be transferred.
489    // Check for the most common mistake.
490    assert(position != first &&
491           "Insertion point can't be one of the transferred nodes");
492
493    if (position != last) {
494      // Note: we have to be careful about the case when we move the first node
495      // in the list.  This node is the list sentinel node and we can't move it.
496      NodeTy *ThisSentinel = getTail();
497      setTail(nullptr);
498      NodeTy *L2Sentinel = L2.getTail();
499      L2.setTail(nullptr);
500
501      // Remove [first, last) from its old position.
502      NodeTy *First = &*first, *Prev = this->getPrev(First);
503      NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
504      if (Prev)
505        this->setNext(Prev, Next);
506      else
507        L2.Head = Next;
508      this->setPrev(Next, Prev);
509
510      // Splice [first, last) into its new position.
511      NodeTy *PosNext = position.getNodePtrUnchecked();
512      NodeTy *PosPrev = this->getPrev(PosNext);
513
514      // Fix head of list...
515      if (PosPrev)
516        this->setNext(PosPrev, First);
517      else
518        Head = First;
519      this->setPrev(First, PosPrev);
520
521      // Fix end of list...
522      this->setNext(Last, PosNext);
523      this->setPrev(PosNext, Last);
524
525      this->transferNodesFromList(L2, First, PosNext);
526
527      // Now that everything is set, restore the pointers to the list sentinels.
528      L2.setTail(L2Sentinel);
529      setTail(ThisSentinel);
530    }
531  }
532
533public:
534
535  //===----------------------------------------------------------------------===
536  // Functionality derived from other functions defined above...
537  //
538
539  size_type LLVM_ATTRIBUTE_UNUSED_RESULT size() const {
540    if (!Head) return 0; // Don't require construction of sentinel if empty.
541    return std::distance(begin(), end());
542  }
543
544  iterator erase(iterator first, iterator last) {
545    while (first != last)
546      first = erase(first);
547    return last;
548  }
549
550  void clear() { if (Head) erase(begin(), end()); }
551
552  // Front and back inserters...
553  void push_front(NodeTy *val) { insert(begin(), val); }
554  void push_back(NodeTy *val) { insert(end(), val); }
555  void pop_front() {
556    assert(!empty() && "pop_front() on empty list!");
557    erase(begin());
558  }
559  void pop_back() {
560    assert(!empty() && "pop_back() on empty list!");
561    iterator t = end(); erase(--t);
562  }
563
564  // Special forms of insert...
565  template<class InIt> void insert(iterator where, InIt first, InIt last) {
566    for (; first != last; ++first) insert(where, *first);
567  }
568
569  // Splice members - defined in terms of transfer...
570  void splice(iterator where, iplist &L2) {
571    if (!L2.empty())
572      transfer(where, L2, L2.begin(), L2.end());
573  }
574  void splice(iterator where, iplist &L2, iterator first) {
575    iterator last = first; ++last;
576    if (where == first || where == last) return; // No change
577    transfer(where, L2, first, last);
578  }
579  void splice(iterator where, iplist &L2, iterator first, iterator last) {
580    if (first != last) transfer(where, L2, first, last);
581  }
582
583
584
585  //===----------------------------------------------------------------------===
586  // High-Level Functionality that shouldn't really be here, but is part of list
587  //
588
589  // These two functions are actually called remove/remove_if in list<>, but
590  // they actually do the job of erase, rename them accordingly.
591  //
592  void erase(const NodeTy &val) {
593    for (iterator I = begin(), E = end(); I != E; ) {
594      iterator next = I; ++next;
595      if (*I == val) erase(I);
596      I = next;
597    }
598  }
599  template<class Pr1> void erase_if(Pr1 pred) {
600    for (iterator I = begin(), E = end(); I != E; ) {
601      iterator next = I; ++next;
602      if (pred(*I)) erase(I);
603      I = next;
604    }
605  }
606
607  template<class Pr2> void unique(Pr2 pred) {
608    if (empty()) return;
609    for (iterator I = begin(), E = end(), Next = begin(); ++Next != E;) {
610      if (pred(*I))
611        erase(Next);
612      else
613        I = Next;
614      Next = I;
615    }
616  }
617  void unique() { unique(op_equal); }
618
619  template<class Pr3> void merge(iplist &right, Pr3 pred) {
620    iterator first1 = begin(), last1 = end();
621    iterator first2 = right.begin(), last2 = right.end();
622    while (first1 != last1 && first2 != last2)
623      if (pred(*first2, *first1)) {
624        iterator next = first2;
625        transfer(first1, right, first2, ++next);
626        first2 = next;
627      } else {
628        ++first1;
629      }
630    if (first2 != last2) transfer(last1, right, first2, last2);
631  }
632  void merge(iplist &right) { return merge(right, op_less); }
633
634  template<class Pr3> void sort(Pr3 pred);
635  void sort() { sort(op_less); }
636};
637
638
639template<typename NodeTy>
640struct ilist : public iplist<NodeTy> {
641  typedef typename iplist<NodeTy>::size_type size_type;
642  typedef typename iplist<NodeTy>::iterator iterator;
643
644  ilist() {}
645  ilist(const ilist &right) {
646    insert(this->begin(), right.begin(), right.end());
647  }
648  explicit ilist(size_type count) {
649    insert(this->begin(), count, NodeTy());
650  }
651  ilist(size_type count, const NodeTy &val) {
652    insert(this->begin(), count, val);
653  }
654  template<class InIt> ilist(InIt first, InIt last) {
655    insert(this->begin(), first, last);
656  }
657
658  // bring hidden functions into scope
659  using iplist<NodeTy>::insert;
660  using iplist<NodeTy>::push_front;
661  using iplist<NodeTy>::push_back;
662
663  // Main implementation here - Insert for a node passed by value...
664  iterator insert(iterator where, const NodeTy &val) {
665    return insert(where, this->createNode(val));
666  }
667
668
669  // Front and back inserters...
670  void push_front(const NodeTy &val) { insert(this->begin(), val); }
671  void push_back(const NodeTy &val) { insert(this->end(), val); }
672
673  void insert(iterator where, size_type count, const NodeTy &val) {
674    for (; count != 0; --count) insert(where, val);
675  }
676
677  // Assign special forms...
678  void assign(size_type count, const NodeTy &val) {
679    iterator I = this->begin();
680    for (; I != this->end() && count != 0; ++I, --count)
681      *I = val;
682    if (count != 0)
683      insert(this->end(), val, val);
684    else
685      erase(I, this->end());
686  }
687  template<class InIt> void assign(InIt first1, InIt last1) {
688    iterator first2 = this->begin(), last2 = this->end();
689    for ( ; first1 != last1 && first2 != last2; ++first1, ++first2)
690      *first1 = *first2;
691    if (first2 == last2)
692      erase(first1, last1);
693    else
694      insert(last1, first2, last2);
695  }
696
697
698  // Resize members...
699  void resize(size_type newsize, NodeTy val) {
700    iterator i = this->begin();
701    size_type len = 0;
702    for ( ; i != this->end() && len < newsize; ++i, ++len) /* empty*/ ;
703
704    if (len == newsize)
705      erase(i, this->end());
706    else                                          // i == end()
707      insert(this->end(), newsize - len, val);
708  }
709  void resize(size_type newsize) { resize(newsize, NodeTy()); }
710};
711
712} // End llvm namespace
713
714namespace std {
715  // Ensure that swap uses the fast list swap...
716  template<class Ty>
717  void swap(llvm::iplist<Ty> &Left, llvm::iplist<Ty> &Right) {
718    Left.swap(Right);
719  }
720}  // End 'std' extensions...
721
722#endif // LLVM_ADT_ILIST_H
723