1 //===--- ImmutableSet.h - Immutable (functional) set interface --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Ted Kremenek and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the ImutAVLTree and ImmutableSet classes.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_IMSET_H
15 #define LLVM_ADT_IMSET_H
17 #include "llvm/Support/Allocator.h"
18 #include "llvm/ADT/FoldingSet.h"
23 //===----------------------------------------------------------------------===//
24 // Immutable AVL-Tree Definition.
25 //===----------------------------------------------------------------------===//
27 template <typename ImutInfo> class ImutAVLFactory;
29 template <typename ImutInfo> class ImutAVLTreeInOrderIterator;
31 template <typename ImutInfo >
32 class ImutAVLTree : public FoldingSetNode {
34 typedef typename ImutInfo::key_type_ref key_type_ref;
35 typedef typename ImutInfo::value_type value_type;
36 typedef typename ImutInfo::value_type_ref value_type_ref;
38 typedef ImutAVLFactory<ImutInfo> Factory;
39 friend class ImutAVLFactory<ImutInfo>;
41 typedef ImutAVLTreeInOrderIterator<ImutInfo> iterator;
43 //===----------------------------------------------------===//
45 //===----------------------------------------------------===//
47 /// getLeft - Returns a pointer to the left subtree. This value
48 /// is NULL if there is no left subtree.
49 ImutAVLTree* getLeft() const {
50 assert (!isMutable() && "Node is incorrectly marked mutable.");
52 return reinterpret_cast<ImutAVLTree*>(Left);
55 /// getRight - Returns a pointer to the right subtree. This value is
56 /// NULL if there is no right subtree.
57 ImutAVLTree* getRight() const { return Right; }
60 /// getHeight - Returns the height of the tree. A tree with no subtrees
61 /// has a height of 1.
62 unsigned getHeight() const { return Height; }
64 /// getValue - Returns the data value associated with the tree node.
65 const value_type& getValue() const { return Value; }
67 /// find - Finds the subtree associated with the specified key value.
68 /// This method returns NULL if no matching subtree is found.
69 ImutAVLTree* find(key_type_ref K) {
70 ImutAVLTree *T = this;
73 key_type_ref CurrentKey = ImutInfo::KeyOfValue(T->getValue());
75 if (ImutInfo::isEqual(K,CurrentKey))
77 else if (ImutInfo::isLess(K,CurrentKey))
86 /// size - Returns the number of nodes in the tree, which includes
87 /// both leaves and non-leaf nodes.
88 unsigned size() const {
91 if (const ImutAVLTree* L = getLeft()) n += L->size();
92 if (const ImutAVLTree* R = getRight()) n += R->size();
97 /// begin - Returns an iterator that iterates over the nodes of the tree
98 /// in an inorder traversal. The returned iterator thus refers to the
99 /// the tree node with the minimum data element.
100 iterator begin() const { return iterator(this); }
102 /// end - Returns an iterator for the tree that denotes the end of an
103 /// inorder traversal.
104 iterator end() const { return iterator(); }
106 /// isEqual - Compares two trees for structural equality and returns true
107 /// if they are equal. This worst case performance of this operation is
108 // linear in the sizes of the trees.
109 bool isEqual(const ImutAVLTree& RHS) const {
113 iterator LItr = begin(), LEnd = end();
114 iterator RItr = RHS.begin(), REnd = RHS.end();
116 while (LItr != LEnd && RItr != REnd) {
117 if (*LItr == *RItr) {
123 // FIXME: need to compare data values, not key values, but our
124 // traits don't support this yet.
125 if (!ImutInfo::isEqual(ImutInfo::KeyOfValue(LItr->getValue()),
126 ImutInfo::KeyOfValue(RItr->getValue())))
133 return LItr == LEnd && RItr == REnd;
136 /// isNotEqual - Compares two trees for structural inequality. Performance
137 /// is the same is isEqual.
138 bool isNotEqual(const ImutAVLTree& RHS) const { return !isEqual(RHS); }
140 /// contains - Returns true if this tree contains a subtree (node) that
141 /// has an data element that matches the specified key. Complexity
142 /// is logarithmic in the size of the tree.
143 bool contains(const key_type_ref K) { return (bool) find(K); }
145 /// foreach - A member template the accepts invokes operator() on a functor
146 /// object (specifed by Callback) for every node/subtree in the tree.
147 /// Nodes are visited using an inorder traversal.
148 template <typename Callback>
149 void foreach(Callback& C) {
150 if (ImutAVLTree* L = getLeft()) L->foreach(C);
154 if (ImutAVLTree* R = getRight()) R->foreach(C);
157 /// verify - A utility method that checks that the balancing and
158 /// ordering invariants of the tree are satisifed. It is a recursive
159 /// method that returns the height of the tree, which is then consumed
160 /// by the enclosing verify call. External callers should ignore the
161 /// return value. An invalid tree will cause an assertion to fire in
163 unsigned verify() const {
164 unsigned HL = getLeft() ? getLeft()->verify() : 0;
165 unsigned HR = getRight() ? getRight()->verify() : 0;
167 assert (getHeight() == ( HL > HR ? HL : HR ) + 1
168 && "Height calculation wrong.");
170 assert ((HL > HR ? HL-HR : HR-HL) <= 2
171 && "Balancing invariant violated.");
175 || ImutInfo::isLess(ImutInfo::KeyOfValue(getLeft()->getValue()),
176 ImutInfo::KeyOfValue(getValue()))
177 && "Value in left child is not less that current value.");
181 || ImutInfo::isLess(ImutInfo::KeyOfValue(getValue()),
182 ImutInfo::KeyOfValue(getRight()->getValue()))
183 && "Current value is not less that value of right child.");
188 //===----------------------------------------------------===//
190 //===----------------------------------------------------===//
198 //===----------------------------------------------------===//
199 // Profiling or FoldingSet.
200 //===----------------------------------------------------===//
203 void Profile(FoldingSetNodeID& ID, ImutAVLTree* L, ImutAVLTree* R,
207 ImutInfo::Profile(ID,V);
212 void Profile(FoldingSetNodeID& ID) {
213 Profile(ID,getSafeLeft(),getRight(),getValue());
216 //===----------------------------------------------------===//
217 // Internal methods (node manipulation; used by Factory).
218 //===----------------------------------------------------===//
222 ImutAVLTree(ImutAVLTree* l, ImutAVLTree* r, value_type_ref v, unsigned height)
223 : Left(reinterpret_cast<uintptr_t>(l) | 0x1),
224 Right(r), Height(height), Value(v) {}
226 bool isMutable() const { return Left & 0x1; }
228 ImutAVLTree* getSafeLeft() const {
229 return reinterpret_cast<ImutAVLTree*>(Left & ~0x1);
232 // Mutating operations. A tree root can be manipulated as long as
233 // its reference has not "escaped" from internal methods of a
234 // factory object (see below). When a tree pointer is externally
235 // viewable by client code, the internal "mutable bit" is cleared
236 // to mark the tree immutable. Note that a tree that still has
237 // its mutable bit set may have children (subtrees) that are themselves
240 void RemoveMutableFlag() {
241 assert (Left & 0x1 && "Mutable flag already removed.");
245 void setLeft(ImutAVLTree* NewLeft) {
246 assert (isMutable());
247 Left = reinterpret_cast<uintptr_t>(NewLeft) | 0x1;
250 void setRight(ImutAVLTree* NewRight) {
251 assert (isMutable());
255 void setHeight(unsigned h) {
256 assert (isMutable());
261 //===----------------------------------------------------------------------===//
262 // Immutable AVL-Tree Factory class.
263 //===----------------------------------------------------------------------===//
265 template <typename ImutInfo >
266 class ImutAVLFactory {
267 typedef ImutAVLTree<ImutInfo> TreeTy;
268 typedef typename TreeTy::value_type_ref value_type_ref;
269 typedef typename TreeTy::key_type_ref key_type_ref;
271 typedef FoldingSet<TreeTy> CacheTy;
274 BumpPtrAllocator Allocator;
276 //===--------------------------------------------------===//
278 //===--------------------------------------------------===//
283 TreeTy* Add(TreeTy* T, value_type_ref V) {
284 T = Add_internal(V,T);
289 TreeTy* Remove(TreeTy* T, key_type_ref V) {
290 T = Remove_internal(V,T);
295 TreeTy* GetEmptyTree() const { return NULL; }
297 //===--------------------------------------------------===//
298 // A bunch of quick helper functions used for reasoning
299 // about the properties of trees and their children.
300 // These have succinct names so that the balancing code
301 // is as terse (and readable) as possible.
302 //===--------------------------------------------------===//
305 bool isEmpty(TreeTy* T) const {
309 unsigned Height(TreeTy* T) const {
310 return T ? T->getHeight() : 0;
313 TreeTy* Left(TreeTy* T) const {
315 return T->getSafeLeft();
318 TreeTy* Right(TreeTy* T) const {
320 return T->getRight();
323 value_type_ref Value(TreeTy* T) const {
328 unsigned IncrementHeight(TreeTy* L, TreeTy* R) const {
329 unsigned hl = Height(L);
330 unsigned hr = Height(R);
331 return ( hl > hr ? hl : hr ) + 1;
334 //===--------------------------------------------------===//
335 // "CreateNode" is used to generate new tree roots that link
336 // to other trees. The functon may also simply move links
337 // in an existing root if that root is still marked mutable.
338 // This is necessary because otherwise our balancing code
339 // would leak memory as it would create nodes that are
340 // then discarded later before the finished tree is
341 // returned to the caller.
342 //===--------------------------------------------------===//
344 TreeTy* CreateNode(TreeTy* L, value_type_ref V, TreeTy* R) {
346 TreeTy::Profile(ID,L,R,V);
349 if (TreeTy* T = Cache.FindNodeOrInsertPos(ID,InsertPos))
352 assert (InsertPos != NULL);
354 // FIXME: more intelligent calculation of alignment.
355 TreeTy* T = (TreeTy*) Allocator.Allocate(sizeof(*T),16);
356 new (T) TreeTy(L,R,V,IncrementHeight(L,R));
358 Cache.InsertNode(T,InsertPos);
362 TreeTy* CreateNode(TreeTy* L, TreeTy* OldTree, TreeTy* R) {
363 assert (!isEmpty(OldTree));
365 if (OldTree->isMutable()) {
367 OldTree->setRight(R);
368 OldTree->setHeight(IncrementHeight(L,R));
371 else return CreateNode(L, Value(OldTree), R);
374 /// Balance - Used by Add_internal and Remove_internal to
375 /// balance a newly created tree.
376 TreeTy* Balance(TreeTy* L, value_type_ref V, TreeTy* R) {
378 unsigned hl = Height(L);
379 unsigned hr = Height(R);
382 assert (!isEmpty(L) &&
383 "Left tree cannot be empty to have a height >= 2.");
385 TreeTy* LL = Left(L);
386 TreeTy* LR = Right(L);
388 if (Height(LL) >= Height(LR))
389 return CreateNode(LL, L, CreateNode(LR,V,R));
391 assert (!isEmpty(LR) &&
392 "LR cannot be empty because it has a height >= 1.");
394 TreeTy* LRL = Left(LR);
395 TreeTy* LRR = Right(LR);
397 return CreateNode(CreateNode(LL,L,LRL), LR, CreateNode(LRR,V,R));
399 else if (hr > hl + 2) {
400 assert (!isEmpty(R) &&
401 "Right tree cannot be empty to have a height >= 2.");
403 TreeTy* RL = Left(R);
404 TreeTy* RR = Right(R);
406 if (Height(RR) >= Height(RL))
407 return CreateNode(CreateNode(L,V,RL), R, RR);
409 assert (!isEmpty(RL) &&
410 "RL cannot be empty because it has a height >= 1.");
412 TreeTy* RLL = Left(RL);
413 TreeTy* RLR = Right(RL);
415 return CreateNode(CreateNode(L,V,RLL), RL, CreateNode(RLR,R,RR));
418 return CreateNode(L,V,R);
421 /// Add_internal - Creates a new tree that includes the specified
422 /// data and the data from the original tree. If the original tree
423 /// already contained the data item, the original tree is returned.
424 TreeTy* Add_internal(value_type_ref V, TreeTy* T) {
426 return CreateNode(T, V, T);
428 assert (!T->isMutable());
430 key_type_ref K = ImutInfo::KeyOfValue(V);
431 key_type_ref KCurrent = ImutInfo::KeyOfValue(Value(T));
433 if (ImutInfo::isEqual(K,KCurrent))
434 return CreateNode(Left(T), V, Right(T));
435 else if (ImutInfo::isLess(K,KCurrent))
436 return Balance(Add_internal(V,Left(T)), Value(T), Right(T));
438 return Balance(Left(T), Value(T), Add_internal(V,Right(T)));
441 /// Remove_interal - Creates a new tree that includes all the data
442 /// from the original tree except the specified data. If the
443 /// specified data did not exist in the original tree, the original
444 /// tree is returned.
445 TreeTy* Remove_internal(key_type_ref K, TreeTy* T) {
449 assert (!T->isMutable());
451 key_type_ref KCurrent = ImutInfo::KeyOfValue(Value(T));
453 if (ImutInfo::isEqual(K,KCurrent))
454 return CombineLeftRightTrees(Left(T),Right(T));
455 else if (ImutInfo::isLess(K,KCurrent))
456 return Balance(Remove_internal(K,Left(T)), Value(T), Right(T));
458 return Balance(Left(T), Value(T), Remove_internal(K,Right(T)));
461 TreeTy* CombineLeftRightTrees(TreeTy* L, TreeTy* R) {
462 if (isEmpty(L)) return R;
463 if (isEmpty(R)) return L;
466 TreeTy* NewRight = RemoveMinBinding(R,OldNode);
467 return Balance(L,Value(OldNode),NewRight);
470 TreeTy* RemoveMinBinding(TreeTy* T, TreeTy*& NodeRemoved) {
471 assert (!isEmpty(T));
473 if (isEmpty(Left(T))) {
478 return Balance(RemoveMinBinding(Left(T),NodeRemoved),Value(T),Right(T));
481 /// MarkImmutable - Clears the mutable bits of a root and all of its
483 void MarkImmutable(TreeTy* T) {
484 if (!T || !T->isMutable())
487 T->RemoveMutableFlag();
488 MarkImmutable(Left(T));
489 MarkImmutable(Right(T));
494 //===----------------------------------------------------------------------===//
495 // Immutable AVL-Tree Iterators.
496 //===----------------------------------------------------------------------===//
498 template <typename ImutInfo>
499 class ImutAVLTreeGenericIterator {
500 SmallVector<uintptr_t,20> stack;
502 enum VisitFlag { VisitedNone=0x0, VisitedLeft=0x1, VisitedRight=0x3,
505 typedef ImutAVLTree<ImutInfo> TreeTy;
506 typedef ImutAVLTreeGenericIterator<ImutInfo> _Self;
508 inline ImutAVLTreeGenericIterator() {}
509 inline ImutAVLTreeGenericIterator(const TreeTy* Root) {
510 if (Root) stack.push_back(reinterpret_cast<uintptr_t>(Root));
513 TreeTy* operator*() const {
514 assert (!stack.empty());
515 return reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
518 uintptr_t getVisitState() {
519 assert (!stack.empty());
520 return stack.back() & Flags;
524 bool AtEnd() const { return stack.empty(); }
526 bool AtBeginning() const {
527 return stack.size() == 1 && getVisitState() == VisitedNone;
530 void SkipToParent() {
531 assert (!stack.empty());
537 switch (getVisitState()) {
539 stack.back() |= VisitedLeft;
542 stack.back() |= VisitedRight;
545 assert (false && "Unreachable.");
549 inline bool operator==(const _Self& x) const {
550 if (stack.size() != x.stack.size())
553 for (unsigned i = 0 ; i < stack.size(); i++)
554 if (stack[i] != x.stack[i])
560 inline bool operator!=(const _Self& x) const { return !operator==(x); }
562 _Self& operator++() {
563 assert (!stack.empty());
565 TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
568 switch (getVisitState()) {
570 if (TreeTy* L = Current->getLeft())
571 stack.push_back(reinterpret_cast<uintptr_t>(L));
573 stack.back() |= VisitedLeft;
578 if (TreeTy* R = Current->getRight())
579 stack.push_back(reinterpret_cast<uintptr_t>(R));
581 stack.back() |= VisitedRight;
590 assert (false && "Unreachable.");
596 _Self& operator--() {
597 assert (!stack.empty());
599 TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
602 switch (getVisitState()) {
608 stack.back() &= ~Flags; // Set state to "VisitedNone."
610 if (TreeTy* L = Current->getLeft())
611 stack.push_back(reinterpret_cast<uintptr_t>(L) | VisitedRight);
616 stack.back() &= ~Flags;
617 stack.back() |= VisitedLeft;
619 if (TreeTy* R = Current->getRight())
620 stack.push_back(reinterpret_cast<uintptr_t>(R) | VisitedRight);
625 assert (false && "Unreachable.");
632 template <typename ImutInfo>
633 class ImutAVLTreeInOrderIterator {
634 typedef ImutAVLTreeGenericIterator<ImutInfo> InternalIteratorTy;
635 InternalIteratorTy InternalItr;
638 typedef ImutAVLTree<ImutInfo> TreeTy;
639 typedef ImutAVLTreeInOrderIterator<ImutInfo> _Self;
641 ImutAVLTreeInOrderIterator(const TreeTy* Root) : InternalItr(Root) {
642 if (Root) operator++(); // Advance to first element.
645 ImutAVLTreeInOrderIterator() : InternalItr() {}
647 inline bool operator==(const _Self& x) const {
648 return InternalItr == x.InternalItr;
651 inline bool operator!=(const _Self& x) const { return !operator==(x); }
653 inline TreeTy* operator*() { return *InternalItr; }
654 inline TreeTy* operator->() { return *InternalItr; }
656 inline _Self& operator++() {
658 while (!InternalItr.AtEnd() &&
659 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
664 inline _Self& operator--() {
666 while (!InternalItr.AtBeginning() &&
667 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
672 inline void SkipSubTree() {
673 InternalItr.SkipToParent();
675 while (!InternalItr.AtEnd() &&
676 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft)
681 //===----------------------------------------------------------------------===//
682 // Trait classes for Profile information.
683 //===----------------------------------------------------------------------===//
685 /// Generic profile template. The default behavior is to invoke the
686 /// profile method of an object. Specializations for primitive integers
687 /// and generic handling of pointers is done below.
688 template <typename T>
689 struct ImutProfileInfo {
690 typedef const T value_type;
691 typedef const T& value_type_ref;
693 static inline void Profile(FoldingSetNodeID& ID, value_type_ref X) {
698 /// Profile traits for integers.
699 template <typename T>
700 struct ImutProfileInteger {
701 typedef const T value_type;
702 typedef const T& value_type_ref;
704 static inline void Profile(FoldingSetNodeID& ID, value_type_ref X) {
709 #define PROFILE_INTEGER_INFO(X)\
710 template<> struct ImutProfileInfo<X> : ImutProfileInteger<X> {};
712 PROFILE_INTEGER_INFO(char)
713 PROFILE_INTEGER_INFO(unsigned char)
714 PROFILE_INTEGER_INFO(short)
715 PROFILE_INTEGER_INFO(unsigned short)
716 PROFILE_INTEGER_INFO(unsigned)
717 PROFILE_INTEGER_INFO(signed)
718 PROFILE_INTEGER_INFO(long)
719 PROFILE_INTEGER_INFO(unsigned long)
720 PROFILE_INTEGER_INFO(long long)
721 PROFILE_INTEGER_INFO(unsigned long long)
723 #undef PROFILE_INTEGER_INFO
725 /// Generic profile trait for pointer types. We treat pointers as
726 /// references to unique objects.
727 template <typename T>
728 struct ImutProfileInfo<T*> {
729 typedef const T* value_type;
730 typedef value_type value_type_ref;
732 static inline void Profile(FoldingSetNodeID &ID, value_type_ref X) {
737 //===----------------------------------------------------------------------===//
738 // Trait classes that contain element comparison operators and type
739 // definitions used by ImutAVLTree, ImmutableSet, and ImmutableMap. These
740 // inherit from the profile traits (ImutProfileInfo) to include operations
741 // for element profiling.
742 //===----------------------------------------------------------------------===//
745 /// ImutContainerInfo - Generic definition of comparison operations for
746 /// elements of immutable containers that defaults to using
747 /// std::equal_to<> and std::less<> to perform comparison of elements.
748 template <typename T>
749 struct ImutContainerInfo : public ImutProfileInfo<T> {
750 typedef typename ImutProfileInfo<T>::value_type value_type;
751 typedef typename ImutProfileInfo<T>::value_type_ref value_type_ref;
752 typedef value_type key_type;
753 typedef value_type_ref key_type_ref;
755 static inline key_type_ref KeyOfValue(value_type_ref D) { return D; }
757 static inline bool isEqual(key_type_ref LHS, key_type_ref RHS) {
758 return std::equal_to<key_type>()(LHS,RHS);
761 static inline bool isLess(key_type_ref LHS, key_type_ref RHS) {
762 return std::less<key_type>()(LHS,RHS);
766 /// ImutContainerInfo - Specialization for pointer values to treat pointers
767 /// as references to unique objects. Pointers are thus compared by
769 template <typename T>
770 struct ImutContainerInfo<T*> : public ImutProfileInfo<T*> {
771 typedef typename ImutProfileInfo<T*>::value_type value_type;
772 typedef typename ImutProfileInfo<T*>::value_type_ref value_type_ref;
773 typedef value_type key_type;
774 typedef value_type_ref key_type_ref;
776 static inline key_type_ref KeyOfValue(value_type_ref D) { return D; }
778 static inline bool isEqual(key_type_ref LHS, key_type_ref RHS) {
782 static inline bool isLess(key_type_ref LHS, key_type_ref RHS) {
787 //===----------------------------------------------------------------------===//
789 //===----------------------------------------------------------------------===//
791 template <typename ValT, typename ValInfo = ImutContainerInfo<ValT> >
794 typedef typename ValInfo::value_type value_type;
795 typedef typename ValInfo::value_type_ref value_type_ref;
798 typedef ImutAVLTree<ValInfo> TreeTy;
801 ImmutableSet(TreeTy* R) : Root(R) {}
806 typename TreeTy::Factory F;
811 ImmutableSet GetEmptySet() { return ImmutableSet(F.GetEmptyTree()); }
813 ImmutableSet Add(ImmutableSet Old, value_type_ref V) {
814 return ImmutableSet(F.Add(Old.Root,V));
817 ImmutableSet Remove(ImmutableSet Old, value_type_ref V) {
818 return ImmutableSet(F.Remove(Old.Root,V));
822 Factory(const Factory& RHS) {};
823 void operator=(const Factory& RHS) {};
826 friend class Factory;
828 bool contains(const value_type_ref V) const {
829 return Root ? Root->contains(V) : false;
832 bool operator==(ImmutableSet RHS) const {
833 return Root && RHS.Root ? Root->isEqual(*RHS.Root) : Root == RHS.Root;
836 bool operator!=(ImmutableSet RHS) const {
837 return Root && RHS.Root ? Root->isNotEqual(*RHS.Root) : Root != RHS.Root;
840 bool isEmpty() const { return !Root; }
842 template <typename Callback>
843 void foreach(Callback& C) { if (Root) Root->foreach(C); }
845 template <typename Callback>
846 void foreach() { if (Root) { Callback C; Root->foreach(C); } }
848 //===--------------------------------------------------===//
850 //===--------------------------------------------------===//
852 void verify() const { if (Root) Root->verify(); }
853 unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
856 } // end namespace llvm