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,
204 unsigned H, value_type_ref V) {
208 ImutInfo::Profile(ID,V);
213 void Profile(FoldingSetNodeID& ID) {
214 Profile(ID,getSafeLeft(),getRight(),getHeight(),getValue());
217 //===----------------------------------------------------===//
218 // Internal methods (node manipulation; used by Factory).
219 //===----------------------------------------------------===//
223 ImutAVLTree(ImutAVLTree* l, ImutAVLTree* r, value_type_ref v, unsigned height)
224 : Left(reinterpret_cast<uintptr_t>(l) | 0x1),
225 Right(r), Height(height), Value(v) {}
227 bool isMutable() const { return Left & 0x1; }
229 ImutAVLTree* getSafeLeft() const {
230 return reinterpret_cast<ImutAVLTree*>(Left & ~0x1);
233 // Mutating operations. A tree root can be manipulated as long as
234 // its reference has not "escaped" from internal methods of a
235 // factory object (see below). When a tree pointer is externally
236 // viewable by client code, the internal "mutable bit" is cleared
237 // to mark the tree immutable. Note that a tree that still has
238 // its mutable bit set may have children (subtrees) that are themselves
241 void RemoveMutableFlag() {
242 assert (Left & 0x1 && "Mutable flag already removed.");
246 void setLeft(ImutAVLTree* NewLeft) {
247 assert (isMutable());
248 Left = reinterpret_cast<uintptr_t>(NewLeft) | 0x1;
251 void setRight(ImutAVLTree* NewRight) {
252 assert (isMutable());
256 void setHeight(unsigned h) {
257 assert (isMutable());
262 //===----------------------------------------------------------------------===//
263 // Immutable AVL-Tree Factory class.
264 //===----------------------------------------------------------------------===//
266 template <typename ImutInfo >
267 class ImutAVLFactory {
268 typedef ImutAVLTree<ImutInfo> TreeTy;
269 typedef typename TreeTy::value_type_ref value_type_ref;
270 typedef typename TreeTy::key_type_ref key_type_ref;
272 typedef FoldingSet<TreeTy> CacheTy;
275 BumpPtrAllocator Allocator;
277 //===--------------------------------------------------===//
279 //===--------------------------------------------------===//
284 TreeTy* Add(TreeTy* T, value_type_ref V) {
285 T = Add_internal(V,T);
290 TreeTy* Remove(TreeTy* T, key_type_ref V) {
291 T = Remove_internal(V,T);
296 TreeTy* GetEmptyTree() const { return NULL; }
298 //===--------------------------------------------------===//
299 // A bunch of quick helper functions used for reasoning
300 // about the properties of trees and their children.
301 // These have succinct names so that the balancing code
302 // is as terse (and readable) as possible.
303 //===--------------------------------------------------===//
306 bool isEmpty(TreeTy* T) const {
310 unsigned Height(TreeTy* T) const {
311 return T ? T->getHeight() : 0;
314 TreeTy* Left(TreeTy* T) const {
316 return T->getSafeLeft();
319 TreeTy* Right(TreeTy* T) const {
321 return T->getRight();
324 value_type_ref Value(TreeTy* T) const {
329 unsigned IncrementHeight(TreeTy* L, TreeTy* R) const {
330 unsigned hl = Height(L);
331 unsigned hr = Height(R);
332 return ( hl > hr ? hl : hr ) + 1;
335 //===--------------------------------------------------===//
336 // "CreateNode" is used to generate new tree roots that link
337 // to other trees. The functon may also simply move links
338 // in an existing root if that root is still marked mutable.
339 // This is necessary because otherwise our balancing code
340 // would leak memory as it would create nodes that are
341 // then discarded later before the finished tree is
342 // returned to the caller.
343 //===--------------------------------------------------===//
345 TreeTy* CreateNode(TreeTy* L, value_type_ref V, TreeTy* R) {
347 unsigned height = IncrementHeight(L,R);
349 TreeTy::Profile(ID,L,R,height,V);
352 if (TreeTy* T = Cache.FindNodeOrInsertPos(ID,InsertPos))
355 assert (InsertPos != NULL);
357 // FIXME: more intelligent calculation of alignment.
358 TreeTy* T = (TreeTy*) Allocator.Allocate(sizeof(*T),16);
359 new (T) TreeTy(L,R,V,height);
361 Cache.InsertNode(T,InsertPos);
365 TreeTy* CreateNode(TreeTy* L, TreeTy* OldTree, TreeTy* R) {
366 assert (!isEmpty(OldTree));
368 if (OldTree->isMutable()) {
370 OldTree->setRight(R);
371 OldTree->setHeight(IncrementHeight(L,R));
374 else return CreateNode(L, Value(OldTree), R);
377 /// Balance - Used by Add_internal and Remove_internal to
378 /// balance a newly created tree.
379 TreeTy* Balance(TreeTy* L, value_type_ref V, TreeTy* R) {
381 unsigned hl = Height(L);
382 unsigned hr = Height(R);
385 assert (!isEmpty(L) &&
386 "Left tree cannot be empty to have a height >= 2.");
388 TreeTy* LL = Left(L);
389 TreeTy* LR = Right(L);
391 if (Height(LL) >= Height(LR))
392 return CreateNode(LL, L, CreateNode(LR,V,R));
394 assert (!isEmpty(LR) &&
395 "LR cannot be empty because it has a height >= 1.");
397 TreeTy* LRL = Left(LR);
398 TreeTy* LRR = Right(LR);
400 return CreateNode(CreateNode(LL,L,LRL), LR, CreateNode(LRR,V,R));
402 else if (hr > hl + 2) {
403 assert (!isEmpty(R) &&
404 "Right tree cannot be empty to have a height >= 2.");
406 TreeTy* RL = Left(R);
407 TreeTy* RR = Right(R);
409 if (Height(RR) >= Height(RL))
410 return CreateNode(CreateNode(L,V,RL), R, RR);
412 assert (!isEmpty(RL) &&
413 "RL cannot be empty because it has a height >= 1.");
415 TreeTy* RLL = Left(RL);
416 TreeTy* RLR = Right(RL);
418 return CreateNode(CreateNode(L,V,RLL), RL, CreateNode(RLR,R,RR));
421 return CreateNode(L,V,R);
424 /// Add_internal - Creates a new tree that includes the specified
425 /// data and the data from the original tree. If the original tree
426 /// already contained the data item, the original tree is returned.
427 TreeTy* Add_internal(value_type_ref V, TreeTy* T) {
429 return CreateNode(T, V, T);
431 assert (!T->isMutable());
433 key_type_ref K = ImutInfo::KeyOfValue(V);
434 key_type_ref KCurrent = ImutInfo::KeyOfValue(Value(T));
436 if (ImutInfo::isEqual(K,KCurrent))
437 return CreateNode(Left(T), V, Right(T));
438 else if (ImutInfo::isLess(K,KCurrent))
439 return Balance(Add_internal(V,Left(T)), Value(T), Right(T));
441 return Balance(Left(T), Value(T), Add_internal(V,Right(T)));
444 /// Remove_interal - Creates a new tree that includes all the data
445 /// from the original tree except the specified data. If the
446 /// specified data did not exist in the original tree, the original
447 /// tree is returned.
448 TreeTy* Remove_internal(key_type_ref K, TreeTy* T) {
452 assert (!T->isMutable());
454 key_type_ref KCurrent = ImutInfo::KeyOfValue(Value(T));
456 if (ImutInfo::isEqual(K,KCurrent))
457 return CombineLeftRightTrees(Left(T),Right(T));
458 else if (ImutInfo::isLess(K,KCurrent))
459 return Balance(Remove_internal(K,Left(T)), Value(T), Right(T));
461 return Balance(Left(T), Value(T), Remove_internal(K,Right(T)));
464 TreeTy* CombineLeftRightTrees(TreeTy* L, TreeTy* R) {
465 if (isEmpty(L)) return R;
466 if (isEmpty(R)) return L;
469 TreeTy* NewRight = RemoveMinBinding(R,OldNode);
470 return Balance(L,Value(OldNode),NewRight);
473 TreeTy* RemoveMinBinding(TreeTy* T, TreeTy*& NodeRemoved) {
474 assert (!isEmpty(T));
476 if (isEmpty(Left(T))) {
481 return Balance(RemoveMinBinding(Left(T),NodeRemoved),Value(T),Right(T));
484 /// MarkImmutable - Clears the mutable bits of a root and all of its
486 void MarkImmutable(TreeTy* T) {
487 if (!T || !T->isMutable())
490 T->RemoveMutableFlag();
491 MarkImmutable(Left(T));
492 MarkImmutable(Right(T));
497 //===----------------------------------------------------------------------===//
498 // Immutable AVL-Tree Iterators.
499 //===----------------------------------------------------------------------===//
501 template <typename ImutInfo>
502 class ImutAVLTreeGenericIterator {
503 SmallVector<uintptr_t,20> stack;
505 enum VisitFlag { VisitedNone=0x0, VisitedLeft=0x1, VisitedRight=0x3,
508 typedef ImutAVLTree<ImutInfo> TreeTy;
509 typedef ImutAVLTreeGenericIterator<ImutInfo> _Self;
511 inline ImutAVLTreeGenericIterator() {}
512 inline ImutAVLTreeGenericIterator(const TreeTy* Root) {
513 if (Root) stack.push_back(reinterpret_cast<uintptr_t>(Root));
516 TreeTy* operator*() const {
517 assert (!stack.empty());
518 return reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
521 uintptr_t getVisitState() {
522 assert (!stack.empty());
523 return stack.back() & Flags;
527 bool AtEnd() const { return stack.empty(); }
529 bool AtBeginning() const {
530 return stack.size() == 1 && getVisitState() == VisitedNone;
533 void SkipToParent() {
534 assert (!stack.empty());
540 switch (getVisitState()) {
542 stack.back() |= VisitedLeft;
545 stack.back() |= VisitedRight;
548 assert (false && "Unreachable.");
552 inline bool operator==(const _Self& x) const {
553 if (stack.size() != x.stack.size())
556 for (unsigned i = 0 ; i < stack.size(); i++)
557 if (stack[i] != x.stack[i])
563 inline bool operator!=(const _Self& x) const { return !operator==(x); }
565 _Self& operator++() {
566 assert (!stack.empty());
568 TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
571 switch (getVisitState()) {
573 if (TreeTy* L = Current->getLeft())
574 stack.push_back(reinterpret_cast<uintptr_t>(L));
576 stack.back() |= VisitedLeft;
581 if (TreeTy* R = Current->getRight())
582 stack.push_back(reinterpret_cast<uintptr_t>(R));
584 stack.back() |= VisitedRight;
593 assert (false && "Unreachable.");
599 _Self& operator--() {
600 assert (!stack.empty());
602 TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
605 switch (getVisitState()) {
611 stack.back() &= ~Flags; // Set state to "VisitedNone."
613 if (TreeTy* L = Current->getLeft())
614 stack.push_back(reinterpret_cast<uintptr_t>(L) | VisitedRight);
619 stack.back() &= ~Flags;
620 stack.back() |= VisitedLeft;
622 if (TreeTy* R = Current->getRight())
623 stack.push_back(reinterpret_cast<uintptr_t>(R) | VisitedRight);
628 assert (false && "Unreachable.");
635 template <typename ImutInfo>
636 class ImutAVLTreeInOrderIterator {
637 typedef ImutAVLTreeGenericIterator<ImutInfo> InternalIteratorTy;
638 InternalIteratorTy InternalItr;
641 typedef ImutAVLTree<ImutInfo> TreeTy;
642 typedef ImutAVLTreeInOrderIterator<ImutInfo> _Self;
644 ImutAVLTreeInOrderIterator(const TreeTy* Root) : InternalItr(Root) {
645 if (Root) operator++(); // Advance to first element.
648 ImutAVLTreeInOrderIterator() : InternalItr() {}
650 inline bool operator==(const _Self& x) const {
651 return InternalItr == x.InternalItr;
654 inline bool operator!=(const _Self& x) const { return !operator==(x); }
656 inline TreeTy* operator*() { return *InternalItr; }
657 inline TreeTy* operator->() { return *InternalItr; }
659 inline _Self& operator++() {
661 while (!InternalItr.AtEnd() &&
662 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
667 inline _Self& operator--() {
669 while (!InternalItr.AtBeginning() &&
670 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
675 inline void SkipSubTree() {
676 InternalItr.SkipToParent();
678 while (!InternalItr.AtEnd() &&
679 InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft)
684 //===----------------------------------------------------------------------===//
685 // Trait classes for Profile information.
686 //===----------------------------------------------------------------------===//
688 /// Generic profile template. The default behavior is to invoke the
689 /// profile method of an object. Specializations for primitive integers
690 /// and generic handling of pointers is done below.
691 template <typename T>
692 struct ImutProfileInfo {
693 typedef const T value_type;
694 typedef const T& value_type_ref;
696 static inline void Profile(FoldingSetNodeID& ID, value_type_ref X) {
701 /// Profile traits for integers.
702 template <typename T>
703 struct ImutProfileInteger {
704 typedef const T value_type;
705 typedef const T& value_type_ref;
707 static inline void Profile(FoldingSetNodeID& ID, value_type_ref X) {
712 #define PROFILE_INTEGER_INFO(X)\
713 template<> struct ImutProfileInfo<X> : ImutProfileInteger<X> {};
715 PROFILE_INTEGER_INFO(char)
716 PROFILE_INTEGER_INFO(unsigned char)
717 PROFILE_INTEGER_INFO(short)
718 PROFILE_INTEGER_INFO(unsigned short)
719 PROFILE_INTEGER_INFO(unsigned)
720 PROFILE_INTEGER_INFO(signed)
721 PROFILE_INTEGER_INFO(long)
722 PROFILE_INTEGER_INFO(unsigned long)
723 PROFILE_INTEGER_INFO(long long)
724 PROFILE_INTEGER_INFO(unsigned long long)
726 #undef PROFILE_INTEGER_INFO
728 /// Generic profile trait for pointer types. We treat pointers as
729 /// references to unique objects.
730 template <typename T>
731 struct ImutProfileInfo<T*> {
732 typedef const T* value_type;
733 typedef value_type value_type_ref;
735 static inline void Profile(FoldingSetNodeID &ID, value_type_ref X) {
740 //===----------------------------------------------------------------------===//
741 // Trait classes that contain element comparison operators and type
742 // definitions used by ImutAVLTree, ImmutableSet, and ImmutableMap. These
743 // inherit from the profile traits (ImutProfileInfo) to include operations
744 // for element profiling.
745 //===----------------------------------------------------------------------===//
748 /// ImutContainerInfo - Generic definition of comparison operations for
749 /// elements of immutable containers that defaults to using
750 /// std::equal_to<> and std::less<> to perform comparison of elements.
751 template <typename T>
752 struct ImutContainerInfo : public ImutProfileInfo<T> {
753 typedef typename ImutProfileInfo<T>::value_type value_type;
754 typedef typename ImutProfileInfo<T>::value_type_ref value_type_ref;
755 typedef value_type key_type;
756 typedef value_type_ref key_type_ref;
758 static inline key_type_ref KeyOfValue(value_type_ref D) { return D; }
760 static inline bool isEqual(key_type_ref LHS, key_type_ref RHS) {
761 return std::equal_to<key_type>()(LHS,RHS);
764 static inline bool isLess(key_type_ref LHS, key_type_ref RHS) {
765 return std::less<key_type>()(LHS,RHS);
769 /// ImutContainerInfo - Specialization for pointer values to treat pointers
770 /// as references to unique objects. Pointers are thus compared by
772 template <typename T>
773 struct ImutContainerInfo<T*> : public ImutProfileInfo<T*> {
774 typedef typename ImutProfileInfo<T*>::value_type value_type;
775 typedef typename ImutProfileInfo<T*>::value_type_ref value_type_ref;
776 typedef value_type key_type;
777 typedef value_type_ref key_type_ref;
779 static inline key_type_ref KeyOfValue(value_type_ref D) { return D; }
781 static inline bool isEqual(key_type_ref LHS, key_type_ref RHS) {
785 static inline bool isLess(key_type_ref LHS, key_type_ref RHS) {
790 //===----------------------------------------------------------------------===//
792 //===----------------------------------------------------------------------===//
794 template <typename ValT, typename ValInfo = ImutContainerInfo<ValT> >
797 typedef typename ValInfo::value_type value_type;
798 typedef typename ValInfo::value_type_ref value_type_ref;
801 typedef ImutAVLTree<ValInfo> TreeTy;
804 ImmutableSet(TreeTy* R) : Root(R) {}
809 typename TreeTy::Factory F;
814 ImmutableSet GetEmptySet() { return ImmutableSet(F.GetEmptyTree()); }
816 ImmutableSet Add(ImmutableSet Old, value_type_ref V) {
817 return ImmutableSet(F.Add(Old.Root,V));
820 ImmutableSet Remove(ImmutableSet Old, value_type_ref V) {
821 return ImmutableSet(F.Remove(Old.Root,V));
825 Factory(const Factory& RHS) {};
826 void operator=(const Factory& RHS) {};
829 friend class Factory;
831 bool contains(const value_type_ref V) const {
832 return Root ? Root->contains(V) : false;
835 bool operator==(ImmutableSet RHS) const {
836 return Root && RHS.Root ? Root->isEqual(*RHS.Root) : Root == RHS.Root;
839 bool operator!=(ImmutableSet RHS) const {
840 return Root && RHS.Root ? Root->isNotEqual(*RHS.Root) : Root != RHS.Root;
843 bool isEmpty() const { return !Root; }
845 template <typename Callback>
846 void foreach(Callback& C) { if (Root) Root->foreach(C); }
848 template <typename Callback>
849 void foreach() { if (Root) { Callback C; Root->foreach(C); } }
851 //===--------------------------------------------------===//
853 //===--------------------------------------------------===//
855 void verify() const { if (Root) Root->verify(); }
856 unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
859 } // end namespace llvm