The Tor Browser: gfx/skia/trunk/src/gpu/GrRedBlackTree.h@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrRedBlackTree.h@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrRedBlackTree.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  * 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 "GrConfig.h"
 #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; }
 };
 class GrStrLess {
 public:
     bool operator()(const char* a, const char* b) const { return strcmp(a,b) < 0; }
 };
 /**
  * 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); }
 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
 #endif

The Tor Browser / annotate

gfx/skia/trunk/src/gpu/GrRedBlackTree.h@6474c204b198 (annotated)

gfx/skia/trunk/src/gpu/GrRedBlackTree.h