| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef GrRedBlackTree_DEFINED |
| #define GrRedBlackTree_DEFINED |
| |
| #include "SkTypes.h" |
| |
| template <typename T> |
| class GrLess { |
| public: |
| bool operator()(const T& a, const T& b) const { return a < b; } |
| }; |
| |
| template <typename T> |
| class GrLess<T*> { |
| public: |
| bool operator()(const T* a, const T* b) const { return *a < *b; } |
| }; |
| |
| /** |
| * In debug build this will cause full traversals of the tree when the validate |
| * is called on insert and remove. Useful for debugging but very slow. |
| */ |
| #define DEEP_VALIDATE 0 |
| |
| /** |
| * A sorted tree that uses the red-black tree algorithm. Allows duplicate |
| * entries. Data is of type T and is compared using functor C. A single C object |
| * will be created and used for all comparisons. |
| */ |
| template <typename T, typename C = GrLess<T> > |
| class GrRedBlackTree : public SkNoncopyable { |
| public: |
| /** |
| * Creates an empty tree. |
| */ |
| GrRedBlackTree(); |
| virtual ~GrRedBlackTree(); |
| |
| /** |
| * Class used to iterater through the tree. The valid range of the tree |
| * is given by [begin(), end()). It is legal to dereference begin() but not |
| * end(). The iterator has preincrement and predecrement operators, it is |
| * legal to decerement end() if the tree is not empty to get the last |
| * element. However, a last() helper is provided. |
| */ |
| class Iter; |
| |
| /** |
| * Add an element to the tree. Duplicates are allowed. |
| * @param t the item to add. |
| * @return an iterator to the item. |
| */ |
| Iter insert(const T& t); |
| |
| /** |
| * Removes all items in the tree. |
| */ |
| void reset(); |
| |
| /** |
| * @return true if there are no items in the tree, false otherwise. |
| */ |
| bool empty() const {return 0 == fCount;} |
| |
| /** |
| * @return the number of items in the tree. |
| */ |
| int count() const {return fCount;} |
| |
| /** |
| * @return an iterator to the first item in sorted order, or end() if empty |
| */ |
| Iter begin(); |
| /** |
| * Gets the last valid iterator. This is always valid, even on an empty. |
| * However, it can never be dereferenced. Useful as a loop terminator. |
| * @return an iterator that is just beyond the last item in sorted order. |
| */ |
| Iter end(); |
| /** |
| * @return an iterator that to the last item in sorted order, or end() if |
| * empty. |
| */ |
| Iter last(); |
| |
| /** |
| * Finds an occurrence of an item. |
| * @param t the item to find. |
| * @return an iterator to a tree element equal to t or end() if none exists. |
| */ |
| Iter find(const T& t); |
| /** |
| * Finds the first of an item in iterator order. |
| * @param t the item to find. |
| * @return an iterator to the first element equal to t or end() if |
| * none exists. |
| */ |
| Iter findFirst(const T& t); |
| /** |
| * Finds the last of an item in iterator order. |
| * @param t the item to find. |
| * @return an iterator to the last element equal to t or end() if |
| * none exists. |
| */ |
| Iter findLast(const T& t); |
| /** |
| * Gets the number of items in the tree equal to t. |
| * @param t the item to count. |
| * @return number of items equal to t in the tree |
| */ |
| int countOf(const T& t) const; |
| |
| /** |
| * Removes the item indicated by an iterator. The iterator will not be valid |
| * afterwards. |
| * |
| * @param iter iterator of item to remove. Must be valid (not end()). |
| */ |
| void remove(const Iter& iter) { deleteAtNode(iter.fN); } |
| |
| static void UnitTest(); |
| |
| private: |
| enum Color { |
| kRed_Color, |
| kBlack_Color |
| }; |
| |
| enum Child { |
| kLeft_Child = 0, |
| kRight_Child = 1 |
| }; |
| |
| struct Node { |
| T fItem; |
| Color fColor; |
| |
| Node* fParent; |
| Node* fChildren[2]; |
| }; |
| |
| void rotateRight(Node* n); |
| void rotateLeft(Node* n); |
| |
| static Node* SuccessorNode(Node* x); |
| static Node* PredecessorNode(Node* x); |
| |
| void deleteAtNode(Node* x); |
| static void RecursiveDelete(Node* x); |
| |
| int onCountOf(const Node* n, const T& t) const; |
| |
| #ifdef SK_DEBUG |
| void validate() const; |
| int checkNode(Node* n, int* blackHeight) const; |
| // checks relationship between a node and its children. allowRedRed means |
| // node may be in an intermediate state where a red parent has a red child. |
| bool validateChildRelations(const Node* n, bool allowRedRed) const; |
| // place to stick break point if validateChildRelations is failing. |
| bool validateChildRelationsFailed() const { return false; } |
| #else |
| void validate() const {} |
| #endif |
| |
| int fCount; |
| Node* fRoot; |
| Node* fFirst; |
| Node* fLast; |
| |
| const C fComp; |
| }; |
| |
| template <typename T, typename C> |
| class GrRedBlackTree<T,C>::Iter { |
| public: |
| Iter() {}; |
| Iter(const Iter& i) {fN = i.fN; fTree = i.fTree;} |
| Iter& operator =(const Iter& i) { |
| fN = i.fN; |
| fTree = i.fTree; |
| return *this; |
| } |
| // altering the sort value of the item using this method will cause |
| // errors. |
| T& operator *() const { return fN->fItem; } |
| bool operator ==(const Iter& i) const { |
| return fN == i.fN && fTree == i.fTree; |
| } |
| bool operator !=(const Iter& i) const { return !(*this == i); } |
| Iter& operator ++() { |
| SkASSERT(*this != fTree->end()); |
| fN = SuccessorNode(fN); |
| return *this; |
| } |
| Iter& operator --() { |
| SkASSERT(*this != fTree->begin()); |
| if (NULL != fN) { |
| fN = PredecessorNode(fN); |
| } else { |
| *this = fTree->last(); |
| } |
| return *this; |
| } |
| |
| private: |
| friend class GrRedBlackTree; |
| explicit Iter(Node* n, GrRedBlackTree* tree) { |
| fN = n; |
| fTree = tree; |
| } |
| Node* fN; |
| GrRedBlackTree* fTree; |
| }; |
| |
| template <typename T, typename C> |
| GrRedBlackTree<T,C>::GrRedBlackTree() : fComp() { |
| fRoot = NULL; |
| fFirst = NULL; |
| fLast = NULL; |
| fCount = 0; |
| validate(); |
| } |
| |
| template <typename T, typename C> |
| GrRedBlackTree<T,C>::~GrRedBlackTree() { |
| RecursiveDelete(fRoot); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::begin() { |
| return Iter(fFirst, this); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::end() { |
| return Iter(NULL, this); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::last() { |
| return Iter(fLast, this); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::find(const T& t) { |
| Node* n = fRoot; |
| while (NULL != n) { |
| if (fComp(t, n->fItem)) { |
| n = n->fChildren[kLeft_Child]; |
| } else { |
| if (!fComp(n->fItem, t)) { |
| return Iter(n, this); |
| } |
| n = n->fChildren[kRight_Child]; |
| } |
| } |
| return end(); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::findFirst(const T& t) { |
| Node* n = fRoot; |
| Node* leftMost = NULL; |
| while (NULL != n) { |
| if (fComp(t, n->fItem)) { |
| n = n->fChildren[kLeft_Child]; |
| } else { |
| if (!fComp(n->fItem, t)) { |
| // found one. check if another in left subtree. |
| leftMost = n; |
| n = n->fChildren[kLeft_Child]; |
| } else { |
| n = n->fChildren[kRight_Child]; |
| } |
| } |
| } |
| return Iter(leftMost, this); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::findLast(const T& t) { |
| Node* n = fRoot; |
| Node* rightMost = NULL; |
| while (NULL != n) { |
| if (fComp(t, n->fItem)) { |
| n = n->fChildren[kLeft_Child]; |
| } else { |
| if (!fComp(n->fItem, t)) { |
| // found one. check if another in right subtree. |
| rightMost = n; |
| } |
| n = n->fChildren[kRight_Child]; |
| } |
| } |
| return Iter(rightMost, this); |
| } |
| |
| template <typename T, typename C> |
| int GrRedBlackTree<T,C>::countOf(const T& t) const { |
| return onCountOf(fRoot, t); |
| } |
| |
| template <typename T, typename C> |
| int GrRedBlackTree<T,C>::onCountOf(const Node* n, const T& t) const { |
| // this is count*log(n) :( |
| while (NULL != n) { |
| if (fComp(t, n->fItem)) { |
| n = n->fChildren[kLeft_Child]; |
| } else { |
| if (!fComp(n->fItem, t)) { |
| int count = 1; |
| count += onCountOf(n->fChildren[kLeft_Child], t); |
| count += onCountOf(n->fChildren[kRight_Child], t); |
| return count; |
| } |
| n = n->fChildren[kRight_Child]; |
| } |
| } |
| return 0; |
| |
| } |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::reset() { |
| RecursiveDelete(fRoot); |
| fRoot = NULL; |
| fFirst = NULL; |
| fLast = NULL; |
| fCount = 0; |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Iter GrRedBlackTree<T,C>::insert(const T& t) { |
| validate(); |
| |
| ++fCount; |
| |
| Node* x = SkNEW(Node); |
| x->fChildren[kLeft_Child] = NULL; |
| x->fChildren[kRight_Child] = NULL; |
| x->fItem = t; |
| |
| Node* returnNode = x; |
| |
| Node* gp = NULL; |
| Node* p = NULL; |
| Node* n = fRoot; |
| Child pc = kLeft_Child; // suppress uninit warning |
| Child gpc = kLeft_Child; |
| |
| bool first = true; |
| bool last = true; |
| while (NULL != n) { |
| gpc = pc; |
| pc = fComp(x->fItem, n->fItem) ? kLeft_Child : kRight_Child; |
| first = first && kLeft_Child == pc; |
| last = last && kRight_Child == pc; |
| gp = p; |
| p = n; |
| n = p->fChildren[pc]; |
| } |
| if (last) { |
| fLast = x; |
| } |
| if (first) { |
| fFirst = x; |
| } |
| |
| if (NULL == p) { |
| fRoot = x; |
| x->fColor = kBlack_Color; |
| x->fParent = NULL; |
| SkASSERT(1 == fCount); |
| return Iter(returnNode, this); |
| } |
| p->fChildren[pc] = x; |
| x->fColor = kRed_Color; |
| x->fParent = p; |
| |
| do { |
| // assumptions at loop start. |
| SkASSERT(NULL != x); |
| SkASSERT(kRed_Color == x->fColor); |
| // can't have a grandparent but no parent. |
| SkASSERT(!(NULL != gp && NULL == p)); |
| // make sure pc and gpc are correct |
| SkASSERT(NULL == p || p->fChildren[pc] == x); |
| SkASSERT(NULL == gp || gp->fChildren[gpc] == p); |
| |
| // if x's parent is black then we didn't violate any of the |
| // red/black properties when we added x as red. |
| if (kBlack_Color == p->fColor) { |
| return Iter(returnNode, this); |
| } |
| // gp must be valid because if p was the root then it is black |
| SkASSERT(NULL != gp); |
| // gp must be black since it's child, p, is red. |
| SkASSERT(kBlack_Color == gp->fColor); |
| |
| |
| // x and its parent are red, violating red-black property. |
| Node* u = gp->fChildren[1-gpc]; |
| // if x's uncle (p's sibling) is also red then we can flip |
| // p and u to black and make gp red. But then we have to recurse |
| // up to gp since it's parent may also be red. |
| if (NULL != u && kRed_Color == u->fColor) { |
| p->fColor = kBlack_Color; |
| u->fColor = kBlack_Color; |
| gp->fColor = kRed_Color; |
| x = gp; |
| p = x->fParent; |
| if (NULL == p) { |
| // x (prev gp) is the root, color it black and be done. |
| SkASSERT(fRoot == x); |
| x->fColor = kBlack_Color; |
| validate(); |
| return Iter(returnNode, this); |
| } |
| gp = p->fParent; |
| pc = (p->fChildren[kLeft_Child] == x) ? kLeft_Child : |
| kRight_Child; |
| if (NULL != gp) { |
| gpc = (gp->fChildren[kLeft_Child] == p) ? kLeft_Child : |
| kRight_Child; |
| } |
| continue; |
| } break; |
| } while (true); |
| // Here p is red but u is black and we still have to resolve the fact |
| // that x and p are both red. |
| SkASSERT(NULL == gp->fChildren[1-gpc] || kBlack_Color == gp->fChildren[1-gpc]->fColor); |
| SkASSERT(kRed_Color == x->fColor); |
| SkASSERT(kRed_Color == p->fColor); |
| SkASSERT(kBlack_Color == gp->fColor); |
| |
| // make x be on the same side of p as p is of gp. If it isn't already |
| // the case then rotate x up to p and swap their labels. |
| if (pc != gpc) { |
| if (kRight_Child == pc) { |
| rotateLeft(p); |
| Node* temp = p; |
| p = x; |
| x = temp; |
| pc = kLeft_Child; |
| } else { |
| rotateRight(p); |
| Node* temp = p; |
| p = x; |
| x = temp; |
| pc = kRight_Child; |
| } |
| } |
| // we now rotate gp down, pulling up p to be it's new parent. |
| // gp's child, u, that is not affected we know to be black. gp's new |
| // child is p's previous child (x's pre-rotation sibling) which must be |
| // black since p is red. |
| SkASSERT(NULL == p->fChildren[1-pc] || |
| kBlack_Color == p->fChildren[1-pc]->fColor); |
| // Since gp's two children are black it can become red if p is made |
| // black. This leaves the black-height of both of p's new subtrees |
| // preserved and removes the red/red parent child relationship. |
| p->fColor = kBlack_Color; |
| gp->fColor = kRed_Color; |
| if (kLeft_Child == pc) { |
| rotateRight(gp); |
| } else { |
| rotateLeft(gp); |
| } |
| validate(); |
| return Iter(returnNode, this); |
| } |
| |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::rotateRight(Node* n) { |
| /* d? d? |
| * / / |
| * n s |
| * / \ ---> / \ |
| * s a? c? n |
| * / \ / \ |
| * c? b? b? a? |
| */ |
| Node* d = n->fParent; |
| Node* s = n->fChildren[kLeft_Child]; |
| SkASSERT(NULL != s); |
| Node* b = s->fChildren[kRight_Child]; |
| |
| if (NULL != d) { |
| Child c = d->fChildren[kLeft_Child] == n ? kLeft_Child : |
| kRight_Child; |
| d->fChildren[c] = s; |
| } else { |
| SkASSERT(fRoot == n); |
| fRoot = s; |
| } |
| s->fParent = d; |
| s->fChildren[kRight_Child] = n; |
| n->fParent = s; |
| n->fChildren[kLeft_Child] = b; |
| if (NULL != b) { |
| b->fParent = n; |
| } |
| |
| GR_DEBUGASSERT(validateChildRelations(d, true)); |
| GR_DEBUGASSERT(validateChildRelations(s, true)); |
| GR_DEBUGASSERT(validateChildRelations(n, false)); |
| GR_DEBUGASSERT(validateChildRelations(n->fChildren[kRight_Child], true)); |
| GR_DEBUGASSERT(validateChildRelations(b, true)); |
| GR_DEBUGASSERT(validateChildRelations(s->fChildren[kLeft_Child], true)); |
| } |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::rotateLeft(Node* n) { |
| |
| Node* d = n->fParent; |
| Node* s = n->fChildren[kRight_Child]; |
| SkASSERT(NULL != s); |
| Node* b = s->fChildren[kLeft_Child]; |
| |
| if (NULL != d) { |
| Child c = d->fChildren[kRight_Child] == n ? kRight_Child : |
| kLeft_Child; |
| d->fChildren[c] = s; |
| } else { |
| SkASSERT(fRoot == n); |
| fRoot = s; |
| } |
| s->fParent = d; |
| s->fChildren[kLeft_Child] = n; |
| n->fParent = s; |
| n->fChildren[kRight_Child] = b; |
| if (NULL != b) { |
| b->fParent = n; |
| } |
| |
| GR_DEBUGASSERT(validateChildRelations(d, true)); |
| GR_DEBUGASSERT(validateChildRelations(s, true)); |
| GR_DEBUGASSERT(validateChildRelations(n, true)); |
| GR_DEBUGASSERT(validateChildRelations(n->fChildren[kLeft_Child], true)); |
| GR_DEBUGASSERT(validateChildRelations(b, true)); |
| GR_DEBUGASSERT(validateChildRelations(s->fChildren[kRight_Child], true)); |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Node* GrRedBlackTree<T,C>::SuccessorNode(Node* x) { |
| SkASSERT(NULL != x); |
| if (NULL != x->fChildren[kRight_Child]) { |
| x = x->fChildren[kRight_Child]; |
| while (NULL != x->fChildren[kLeft_Child]) { |
| x = x->fChildren[kLeft_Child]; |
| } |
| return x; |
| } |
| while (NULL != x->fParent && x == x->fParent->fChildren[kRight_Child]) { |
| x = x->fParent; |
| } |
| return x->fParent; |
| } |
| |
| template <typename T, typename C> |
| typename GrRedBlackTree<T,C>::Node* GrRedBlackTree<T,C>::PredecessorNode(Node* x) { |
| SkASSERT(NULL != x); |
| if (NULL != x->fChildren[kLeft_Child]) { |
| x = x->fChildren[kLeft_Child]; |
| while (NULL != x->fChildren[kRight_Child]) { |
| x = x->fChildren[kRight_Child]; |
| } |
| return x; |
| } |
| while (NULL != x->fParent && x == x->fParent->fChildren[kLeft_Child]) { |
| x = x->fParent; |
| } |
| return x->fParent; |
| } |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::deleteAtNode(Node* x) { |
| SkASSERT(NULL != x); |
| validate(); |
| --fCount; |
| |
| bool hasLeft = NULL != x->fChildren[kLeft_Child]; |
| bool hasRight = NULL != x->fChildren[kRight_Child]; |
| Child c = hasLeft ? kLeft_Child : kRight_Child; |
| |
| if (hasLeft && hasRight) { |
| // first and last can't have two children. |
| SkASSERT(fFirst != x); |
| SkASSERT(fLast != x); |
| // if x is an interior node then we find it's successor |
| // and swap them. |
| Node* s = x->fChildren[kRight_Child]; |
| while (NULL != s->fChildren[kLeft_Child]) { |
| s = s->fChildren[kLeft_Child]; |
| } |
| SkASSERT(NULL != s); |
| // this might be expensive relative to swapping node ptrs around. |
| // depends on T. |
| x->fItem = s->fItem; |
| x = s; |
| c = kRight_Child; |
| } else if (NULL == x->fParent) { |
| // if x was the root we just replace it with its child and make |
| // the new root (if the tree is not empty) black. |
| SkASSERT(fRoot == x); |
| fRoot = x->fChildren[c]; |
| if (NULL != fRoot) { |
| fRoot->fParent = NULL; |
| fRoot->fColor = kBlack_Color; |
| if (x == fLast) { |
| SkASSERT(c == kLeft_Child); |
| fLast = fRoot; |
| } else if (x == fFirst) { |
| SkASSERT(c == kRight_Child); |
| fFirst = fRoot; |
| } |
| } else { |
| SkASSERT(fFirst == fLast && x == fFirst); |
| fFirst = NULL; |
| fLast = NULL; |
| SkASSERT(0 == fCount); |
| } |
| delete x; |
| validate(); |
| return; |
| } |
| |
| Child pc; |
| Node* p = x->fParent; |
| pc = p->fChildren[kLeft_Child] == x ? kLeft_Child : kRight_Child; |
| |
| if (NULL == x->fChildren[c]) { |
| if (fLast == x) { |
| fLast = p; |
| SkASSERT(p == PredecessorNode(x)); |
| } else if (fFirst == x) { |
| fFirst = p; |
| SkASSERT(p == SuccessorNode(x)); |
| } |
| // x has two implicit black children. |
| Color xcolor = x->fColor; |
| p->fChildren[pc] = NULL; |
| delete x; |
| x = NULL; |
| // when x is red it can be with an implicit black leaf without |
| // violating any of the red-black tree properties. |
| if (kRed_Color == xcolor) { |
| validate(); |
| return; |
| } |
| // s is p's other child (x's sibling) |
| Node* s = p->fChildren[1-pc]; |
| |
| //s cannot be an implicit black node because the original |
| // black-height at x was >= 2 and s's black-height must equal the |
| // initial black height of x. |
| SkASSERT(NULL != s); |
| SkASSERT(p == s->fParent); |
| |
| // assigned in loop |
| Node* sl; |
| Node* sr; |
| bool slRed; |
| bool srRed; |
| |
| do { |
| // When we start this loop x may already be deleted it is/was |
| // p's child on its pc side. x's children are/were black. The |
| // first time through the loop they are implict children. |
| // On later passes we will be walking up the tree and they will |
| // be real nodes. |
| // The x side of p has a black-height that is one less than the |
| // s side. It must be rebalanced. |
| SkASSERT(NULL != s); |
| SkASSERT(p == s->fParent); |
| SkASSERT(NULL == x || x->fParent == p); |
| |
| //sl and sr are s's children, which may be implicit. |
| sl = s->fChildren[kLeft_Child]; |
| sr = s->fChildren[kRight_Child]; |
| |
| // if the s is red we will rotate s and p, swap their colors so |
| // that x's new sibling is black |
| if (kRed_Color == s->fColor) { |
| // if s is red then it's parent must be black. |
| SkASSERT(kBlack_Color == p->fColor); |
| // s's children must also be black since s is red. They can't |
| // be implicit since s is red and it's black-height is >= 2. |
| SkASSERT(NULL != sl && kBlack_Color == sl->fColor); |
| SkASSERT(NULL != sr && kBlack_Color == sr->fColor); |
| p->fColor = kRed_Color; |
| s->fColor = kBlack_Color; |
| if (kLeft_Child == pc) { |
| rotateLeft(p); |
| s = sl; |
| } else { |
| rotateRight(p); |
| s = sr; |
| } |
| sl = s->fChildren[kLeft_Child]; |
| sr = s->fChildren[kRight_Child]; |
| } |
| // x and s are now both black. |
| SkASSERT(kBlack_Color == s->fColor); |
| SkASSERT(NULL == x || kBlack_Color == x->fColor); |
| SkASSERT(p == s->fParent); |
| SkASSERT(NULL == x || p == x->fParent); |
| |
| // when x is deleted its subtree will have reduced black-height. |
| slRed = (NULL != sl && kRed_Color == sl->fColor); |
| srRed = (NULL != sr && kRed_Color == sr->fColor); |
| if (!slRed && !srRed) { |
| // if s can be made red that will balance out x's removal |
| // to make both subtrees of p have the same black-height. |
| if (kBlack_Color == p->fColor) { |
| s->fColor = kRed_Color; |
| // now subtree at p has black-height of one less than |
| // p's parent's other child's subtree. We move x up to |
| // p and go through the loop again. At the top of loop |
| // we assumed x and x's children are black, which holds |
| // by above ifs. |
| // if p is the root there is no other subtree to balance |
| // against. |
| x = p; |
| p = x->fParent; |
| if (NULL == p) { |
| SkASSERT(fRoot == x); |
| validate(); |
| return; |
| } else { |
| pc = p->fChildren[kLeft_Child] == x ? kLeft_Child : |
| kRight_Child; |
| |
| } |
| s = p->fChildren[1-pc]; |
| SkASSERT(NULL != s); |
| SkASSERT(p == s->fParent); |
| continue; |
| } else if (kRed_Color == p->fColor) { |
| // we can make p black and s red. This balance out p's |
| // two subtrees and keep the same black-height as it was |
| // before the delete. |
| s->fColor = kRed_Color; |
| p->fColor = kBlack_Color; |
| validate(); |
| return; |
| } |
| } |
| break; |
| } while (true); |
| // if we made it here one or both of sl and sr is red. |
| // s and x are black. We make sure that a red child is on |
| // the same side of s as s is of p. |
| SkASSERT(slRed || srRed); |
| if (kLeft_Child == pc && !srRed) { |
| s->fColor = kRed_Color; |
| sl->fColor = kBlack_Color; |
| rotateRight(s); |
| sr = s; |
| s = sl; |
| //sl = s->fChildren[kLeft_Child]; don't need this |
| } else if (kRight_Child == pc && !slRed) { |
| s->fColor = kRed_Color; |
| sr->fColor = kBlack_Color; |
| rotateLeft(s); |
| sl = s; |
| s = sr; |
| //sr = s->fChildren[kRight_Child]; don't need this |
| } |
| // now p is either red or black, x and s are red and s's 1-pc |
| // child is red. |
| // We rotate p towards x, pulling s up to replace p. We make |
| // p be black and s takes p's old color. |
| // Whether p was red or black, we've increased its pc subtree |
| // rooted at x by 1 (balancing the imbalance at the start) and |
| // we've also its subtree rooted at s's black-height by 1. This |
| // can be balanced by making s's red child be black. |
| s->fColor = p->fColor; |
| p->fColor = kBlack_Color; |
| if (kLeft_Child == pc) { |
| SkASSERT(NULL != sr && kRed_Color == sr->fColor); |
| sr->fColor = kBlack_Color; |
| rotateLeft(p); |
| } else { |
| SkASSERT(NULL != sl && kRed_Color == sl->fColor); |
| sl->fColor = kBlack_Color; |
| rotateRight(p); |
| } |
| } |
| else { |
| // x has exactly one implicit black child. x cannot be red. |
| // Proof by contradiction: Assume X is red. Let c0 be x's implicit |
| // child and c1 be its non-implicit child. c1 must be black because |
| // red nodes always have two black children. Then the two subtrees |
| // of x rooted at c0 and c1 will have different black-heights. |
| SkASSERT(kBlack_Color == x->fColor); |
| // So we know x is black and has one implicit black child, c0. c1 |
| // must be red, otherwise the subtree at c1 will have a different |
| // black-height than the subtree rooted at c0. |
| SkASSERT(kRed_Color == x->fChildren[c]->fColor); |
| // replace x with c1, making c1 black, preserves all red-black tree |
| // props. |
| Node* c1 = x->fChildren[c]; |
| if (x == fFirst) { |
| SkASSERT(c == kRight_Child); |
| fFirst = c1; |
| while (NULL != fFirst->fChildren[kLeft_Child]) { |
| fFirst = fFirst->fChildren[kLeft_Child]; |
| } |
| SkASSERT(fFirst == SuccessorNode(x)); |
| } else if (x == fLast) { |
| SkASSERT(c == kLeft_Child); |
| fLast = c1; |
| while (NULL != fLast->fChildren[kRight_Child]) { |
| fLast = fLast->fChildren[kRight_Child]; |
| } |
| SkASSERT(fLast == PredecessorNode(x)); |
| } |
| c1->fParent = p; |
| p->fChildren[pc] = c1; |
| c1->fColor = kBlack_Color; |
| delete x; |
| validate(); |
| } |
| validate(); |
| } |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::RecursiveDelete(Node* x) { |
| if (NULL != x) { |
| RecursiveDelete(x->fChildren[kLeft_Child]); |
| RecursiveDelete(x->fChildren[kRight_Child]); |
| delete x; |
| } |
| } |
| |
| #ifdef SK_DEBUG |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::validate() const { |
| if (fCount) { |
| SkASSERT(NULL == fRoot->fParent); |
| SkASSERT(NULL != fFirst); |
| SkASSERT(NULL != fLast); |
| |
| SkASSERT(kBlack_Color == fRoot->fColor); |
| if (1 == fCount) { |
| SkASSERT(fFirst == fRoot); |
| SkASSERT(fLast == fRoot); |
| SkASSERT(0 == fRoot->fChildren[kLeft_Child]); |
| SkASSERT(0 == fRoot->fChildren[kRight_Child]); |
| } |
| } else { |
| SkASSERT(NULL == fRoot); |
| SkASSERT(NULL == fFirst); |
| SkASSERT(NULL == fLast); |
| } |
| #if DEEP_VALIDATE |
| int bh; |
| int count = checkNode(fRoot, &bh); |
| SkASSERT(count == fCount); |
| #endif |
| } |
| |
| template <typename T, typename C> |
| int GrRedBlackTree<T,C>::checkNode(Node* n, int* bh) const { |
| if (NULL != n) { |
| SkASSERT(validateChildRelations(n, false)); |
| if (kBlack_Color == n->fColor) { |
| *bh += 1; |
| } |
| SkASSERT(!fComp(n->fItem, fFirst->fItem)); |
| SkASSERT(!fComp(fLast->fItem, n->fItem)); |
| int leftBh = *bh; |
| int rightBh = *bh; |
| int cl = checkNode(n->fChildren[kLeft_Child], &leftBh); |
| int cr = checkNode(n->fChildren[kRight_Child], &rightBh); |
| SkASSERT(leftBh == rightBh); |
| *bh = leftBh; |
| return 1 + cl + cr; |
| } |
| return 0; |
| } |
| |
| template <typename T, typename C> |
| bool GrRedBlackTree<T,C>::validateChildRelations(const Node* n, |
| bool allowRedRed) const { |
| if (NULL != n) { |
| if (NULL != n->fChildren[kLeft_Child] || |
| NULL != n->fChildren[kRight_Child]) { |
| if (n->fChildren[kLeft_Child] == n->fChildren[kRight_Child]) { |
| return validateChildRelationsFailed(); |
| } |
| if (n->fChildren[kLeft_Child] == n->fParent && |
| NULL != n->fParent) { |
| return validateChildRelationsFailed(); |
| } |
| if (n->fChildren[kRight_Child] == n->fParent && |
| NULL != n->fParent) { |
| return validateChildRelationsFailed(); |
| } |
| if (NULL != n->fChildren[kLeft_Child]) { |
| if (!allowRedRed && |
| kRed_Color == n->fChildren[kLeft_Child]->fColor && |
| kRed_Color == n->fColor) { |
| return validateChildRelationsFailed(); |
| } |
| if (n->fChildren[kLeft_Child]->fParent != n) { |
| return validateChildRelationsFailed(); |
| } |
| if (!(fComp(n->fChildren[kLeft_Child]->fItem, n->fItem) || |
| (!fComp(n->fChildren[kLeft_Child]->fItem, n->fItem) && |
| !fComp(n->fItem, n->fChildren[kLeft_Child]->fItem)))) { |
| return validateChildRelationsFailed(); |
| } |
| } |
| if (NULL != n->fChildren[kRight_Child]) { |
| if (!allowRedRed && |
| kRed_Color == n->fChildren[kRight_Child]->fColor && |
| kRed_Color == n->fColor) { |
| return validateChildRelationsFailed(); |
| } |
| if (n->fChildren[kRight_Child]->fParent != n) { |
| return validateChildRelationsFailed(); |
| } |
| if (!(fComp(n->fItem, n->fChildren[kRight_Child]->fItem) || |
| (!fComp(n->fChildren[kRight_Child]->fItem, n->fItem) && |
| !fComp(n->fItem, n->fChildren[kRight_Child]->fItem)))) { |
| return validateChildRelationsFailed(); |
| } |
| } |
| } |
| } |
| return true; |
| } |
| #endif |
| |
| #include "SkRandom.h" |
| |
| template <typename T, typename C> |
| void GrRedBlackTree<T,C>::UnitTest() { |
| GrRedBlackTree<int> tree; |
| |
| SkRandom r; |
| |
| int count[100] = {0}; |
| // add 10K ints |
| for (int i = 0; i < 10000; ++i) { |
| int x = r.nextU()%100; |
| SkDEBUGCODE(Iter xi = ) tree.insert(x); |
| SkASSERT(*xi == x); |
| ++count[x]; |
| } |
| |
| tree.insert(0); |
| ++count[0]; |
| tree.insert(99); |
| ++count[99]; |
| SkASSERT(*tree.begin() == 0); |
| SkASSERT(*tree.last() == 99); |
| SkASSERT(--(++tree.begin()) == tree.begin()); |
| SkASSERT(--tree.end() == tree.last()); |
| SkASSERT(tree.count() == 10002); |
| |
| int c = 0; |
| // check that we iterate through the correct number of |
| // elements and they are properly sorted. |
| for (Iter a = tree.begin(); tree.end() != a; ++a) { |
| Iter b = a; |
| ++b; |
| ++c; |
| SkASSERT(b == tree.end() || *a <= *b); |
| } |
| SkASSERT(c == tree.count()); |
| |
| // check that the tree reports the correct number of each int |
| // and that we can iterate through them correctly both forward |
| // and backward. |
| for (int i = 0; i < 100; ++i) { |
| int c; |
| c = tree.countOf(i); |
| SkASSERT(c == count[i]); |
| c = 0; |
| Iter iter = tree.findFirst(i); |
| while (iter != tree.end() && *iter == i) { |
| ++c; |
| ++iter; |
| } |
| SkASSERT(count[i] == c); |
| c = 0; |
| iter = tree.findLast(i); |
| if (iter != tree.end()) { |
| do { |
| if (*iter == i) { |
| ++c; |
| } else { |
| break; |
| } |
| if (iter != tree.begin()) { |
| --iter; |
| } else { |
| break; |
| } |
| } while (true); |
| } |
| SkASSERT(c == count[i]); |
| } |
| // remove all the ints between 25 and 74. Randomly chose to remove |
| // the first, last, or any entry for each. |
| for (int i = 25; i < 75; ++i) { |
| while (0 != tree.countOf(i)) { |
| --count[i]; |
| int x = r.nextU() % 3; |
| Iter iter; |
| switch (x) { |
| case 0: |
| iter = tree.findFirst(i); |
| break; |
| case 1: |
| iter = tree.findLast(i); |
| break; |
| case 2: |
| default: |
| iter = tree.find(i); |
| break; |
| } |
| tree.remove(iter); |
| } |
| SkASSERT(0 == count[i]); |
| SkASSERT(tree.findFirst(i) == tree.end()); |
| SkASSERT(tree.findLast(i) == tree.end()); |
| SkASSERT(tree.find(i) == tree.end()); |
| } |
| // remove all of the 0 entries. (tests removing begin()) |
| SkASSERT(*tree.begin() == 0); |
| SkASSERT(*(--tree.end()) == 99); |
| while (0 != tree.countOf(0)) { |
| --count[0]; |
| tree.remove(tree.find(0)); |
| } |
| SkASSERT(0 == count[0]); |
| SkASSERT(tree.findFirst(0) == tree.end()); |
| SkASSERT(tree.findLast(0) == tree.end()); |
| SkASSERT(tree.find(0) == tree.end()); |
| SkASSERT(0 < *tree.begin()); |
| |
| // remove all the 99 entries (tests removing last()). |
| while (0 != tree.countOf(99)) { |
| --count[99]; |
| tree.remove(tree.find(99)); |
| } |
| SkASSERT(0 == count[99]); |
| SkASSERT(tree.findFirst(99) == tree.end()); |
| SkASSERT(tree.findLast(99) == tree.end()); |
| SkASSERT(tree.find(99) == tree.end()); |
| SkASSERT(99 > *(--tree.end())); |
| SkASSERT(tree.last() == --tree.end()); |
| |
| // Make sure iteration still goes through correct number of entries |
| // and is still sorted correctly. |
| c = 0; |
| for (Iter a = tree.begin(); tree.end() != a; ++a) { |
| Iter b = a; |
| ++b; |
| ++c; |
| SkASSERT(b == tree.end() || *a <= *b); |
| } |
| SkASSERT(c == tree.count()); |
| |
| // repeat check that correct number of each entry is in the tree |
| // and iterates correctly both forward and backward. |
| for (int i = 0; i < 100; ++i) { |
| SkASSERT(tree.countOf(i) == count[i]); |
| int c = 0; |
| Iter iter = tree.findFirst(i); |
| while (iter != tree.end() && *iter == i) { |
| ++c; |
| ++iter; |
| } |
| SkASSERT(count[i] == c); |
| c = 0; |
| iter = tree.findLast(i); |
| if (iter != tree.end()) { |
| do { |
| if (*iter == i) { |
| ++c; |
| } else { |
| break; |
| } |
| if (iter != tree.begin()) { |
| --iter; |
| } else { |
| break; |
| } |
| } while (true); |
| } |
| SkASSERT(count[i] == c); |
| } |
| |
| // remove all entries |
| while (!tree.empty()) { |
| tree.remove(tree.begin()); |
| } |
| |
| // test reset on empty tree. |
| tree.reset(); |
| } |
| |
| #endif |
