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Diffstat (limited to 'src/gui/painting/qrbtree_p.h')
| -rw-r--r-- | src/gui/painting/qrbtree_p.h | 571 |
1 files changed, 571 insertions, 0 deletions
diff --git a/src/gui/painting/qrbtree_p.h b/src/gui/painting/qrbtree_p.h new file mode 100644 index 0000000000..d3ee23a91c --- /dev/null +++ b/src/gui/painting/qrbtree_p.h @@ -0,0 +1,571 @@ +/**************************************************************************** +** +** Copyright (C) 2016 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtGui module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef QRBTREE_P_H +#define QRBTREE_P_H + +// +// W A R N I N G +// ------------- +// +// This file is not part of the Qt API. It exists purely as an +// implementation detail. This header file may change from version to +// version without notice, or even be removed. +// +// We mean it. +// + +#include <QtGui/private/qtguiglobal_p.h> + +QT_BEGIN_NAMESPACE + +template <class T> +struct QRBTree +{ + struct Node + { + inline Node() : parent(0), left(0), right(0), red(true) { } + inline ~Node() {if (left) delete left; if (right) delete right;} + T data; + Node *parent; + Node *left; + Node *right; + bool red; + }; + + inline QRBTree() : root(0), freeList(0) { } + inline ~QRBTree(); + + inline void clear(); + + void attachBefore(Node *parent, Node *child); + void attachAfter(Node *parent, Node *child); + + inline Node *front(Node *node) const; + inline Node *back(Node *node) const; + Node *next(Node *node) const; + Node *previous(Node *node) const; + + inline void deleteNode(Node *&node); + inline Node *newNode(); + + // Return 1 if 'left' comes after 'right', 0 if equal, and -1 otherwise. + // 'left' and 'right' cannot be null. + int order(Node *left, Node *right); + inline bool validate() const; + +private: + void rotateLeft(Node *node); + void rotateRight(Node *node); + void update(Node *node); + + inline void attachLeft(Node *parent, Node *child); + inline void attachRight(Node *parent, Node *child); + + int blackDepth(Node *top) const; + bool checkRedBlackProperty(Node *top) const; + + void swapNodes(Node *n1, Node *n2); + void detach(Node *node); + + // 'node' must be black. rebalance will reduce the depth of black nodes by one in the sibling tree. + void rebalance(Node *node); + +public: + Node *root; +private: + Node *freeList; +}; + +template <class T> +inline QRBTree<T>::~QRBTree() +{ + clear(); + while (freeList) { + // Avoid recursively calling the destructor, as this list may become large. + Node *next = freeList->right; + freeList->right = 0; + delete freeList; + freeList = next; + } +} + +template <class T> +inline void QRBTree<T>::clear() +{ + if (root) + delete root; + root = 0; +} + +template <class T> +void QRBTree<T>::rotateLeft(Node *node) +{ + // | | // + // N B // + // / \ / \ // + // A B ---> N D // + // / \ / \ // + // C D A C // + + Node *&ref = (node->parent ? (node == node->parent->left ? node->parent->left : node->parent->right) : root); + ref = node->right; + node->right->parent = node->parent; + + // : // + // N // + // / :| // + // A B // + // / \ // + // C D // + + node->right = ref->left; + if (ref->left) + ref->left->parent = node; + + // : | // + // N B // + // / \ : \ // + // A C D // + + ref->left = node; + node->parent = ref; + + // | // + // B // + // / \ // + // N D // + // / \ // + // A C // +} + +template <class T> +void QRBTree<T>::rotateRight(Node *node) +{ + // | | // + // N A // + // / \ / \ // + // A B ---> C N // + // / \ / \ // + // C D D B // + + Node *&ref = (node->parent ? (node == node->parent->left ? node->parent->left : node->parent->right) : root); + ref = node->left; + node->left->parent = node->parent; + + node->left = ref->right; + if (ref->right) + ref->right->parent = node; + + ref->right = node; + node->parent = ref; +} + +template <class T> +void QRBTree<T>::update(Node *node) // call this after inserting a node +{ + for (;;) { + Node *parent = node->parent; + + // if the node is the root, color it black + if (!parent) { + node->red = false; + return; + } + + // if the parent is black, the node can be left red + if (!parent->red) + return; + + // at this point, the parent is red and cannot be the root + Node *grandpa = parent->parent; + Q_ASSERT(grandpa); + + Node *uncle = (parent == grandpa->left ? grandpa->right : grandpa->left); + if (uncle && uncle->red) { + // grandpa's black, parent and uncle are red. + // let parent and uncle be black, grandpa red and recursively update grandpa. + Q_ASSERT(!grandpa->red); + parent->red = false; + uncle->red = false; + grandpa->red = true; + node = grandpa; + continue; + } + + // at this point, uncle is black + if (node == parent->right && parent == grandpa->left) + rotateLeft(node = parent); + else if (node == parent->left && parent == grandpa->right) + rotateRight(node = parent); + parent = node->parent; + + if (parent == grandpa->left) { + rotateRight(grandpa); + parent->red = false; + grandpa->red = true; + } else { + rotateLeft(grandpa); + parent->red = false; + grandpa->red = true; + } + return; + } +} + +template <class T> +inline void QRBTree<T>::attachLeft(Node *parent, Node *child) +{ + Q_ASSERT(!parent->left); + parent->left = child; + child->parent = parent; + update(child); +} + +template <class T> +inline void QRBTree<T>::attachRight(Node *parent, Node *child) +{ + Q_ASSERT(!parent->right); + parent->right = child; + child->parent = parent; + update(child); +} + +template <class T> +void QRBTree<T>::attachBefore(Node *parent, Node *child) +{ + if (!root) + update(root = child); + else if (!parent) + attachRight(back(root), child); + else if (parent->left) + attachRight(back(parent->left), child); + else + attachLeft(parent, child); +} + +template <class T> +void QRBTree<T>::attachAfter(Node *parent, Node *child) +{ + if (!root) + update(root = child); + else if (!parent) + attachLeft(front(root), child); + else if (parent->right) + attachLeft(front(parent->right), child); + else + attachRight(parent, child); +} + +template <class T> +void QRBTree<T>::swapNodes(Node *n1, Node *n2) +{ + // Since iterators must not be invalidated, it is not sufficient to only swap the data. + if (n1->parent == n2) { + n1->parent = n2->parent; + n2->parent = n1; + } else if (n2->parent == n1) { + n2->parent = n1->parent; + n1->parent = n2; + } else { + qSwap(n1->parent, n2->parent); + } + + qSwap(n1->left, n2->left); + qSwap(n1->right, n2->right); + qSwap(n1->red, n2->red); + + if (n1->parent) { + if (n1->parent->left == n2) + n1->parent->left = n1; + else + n1->parent->right = n1; + } else { + root = n1; + } + + if (n2->parent) { + if (n2->parent->left == n1) + n2->parent->left = n2; + else + n2->parent->right = n2; + } else { + root = n2; + } + + if (n1->left) + n1->left->parent = n1; + if (n1->right) + n1->right->parent = n1; + + if (n2->left) + n2->left->parent = n2; + if (n2->right) + n2->right->parent = n2; +} + +template <class T> +void QRBTree<T>::detach(Node *node) // call this before removing a node. +{ + if (node->right) + swapNodes(node, front(node->right)); + + Node *child = (node->left ? node->left : node->right); + + if (!node->red) { + if (child && child->red) + child->red = false; + else + rebalance(node); + } + + Node *&ref = (node->parent ? (node == node->parent->left ? node->parent->left : node->parent->right) : root); + ref = child; + if (child) + child->parent = node->parent; + node->left = node->right = node->parent = 0; +} + +// 'node' must be black. rebalance will reduce the depth of black nodes by one in the sibling tree. +template <class T> +void QRBTree<T>::rebalance(Node *node) +{ + Q_ASSERT(!node->red); + for (;;) { + if (!node->parent) + return; + + // at this point, node is not a parent, it is black, thus it must have a sibling. + Node *sibling = (node == node->parent->left ? node->parent->right : node->parent->left); + Q_ASSERT(sibling); + + if (sibling->red) { + sibling->red = false; + node->parent->red = true; + if (node == node->parent->left) + rotateLeft(node->parent); + else + rotateRight(node->parent); + sibling = (node == node->parent->left ? node->parent->right : node->parent->left); + Q_ASSERT(sibling); + } + + // at this point, the sibling is black. + Q_ASSERT(!sibling->red); + + if ((!sibling->left || !sibling->left->red) && (!sibling->right || !sibling->right->red)) { + bool parentWasRed = node->parent->red; + sibling->red = true; + node->parent->red = false; + if (parentWasRed) + return; + node = node->parent; + continue; + } + + // at this point, at least one of the sibling's children is red. + + if (node == node->parent->left) { + if (!sibling->right || !sibling->right->red) { + Q_ASSERT(sibling->left); + sibling->red = true; + sibling->left->red = false; + rotateRight(sibling); + + sibling = sibling->parent; + Q_ASSERT(sibling); + } + sibling->red = node->parent->red; + node->parent->red = false; + + Q_ASSERT(sibling->right->red); + sibling->right->red = false; + rotateLeft(node->parent); + } else { + if (!sibling->left || !sibling->left->red) { + Q_ASSERT(sibling->right); + sibling->red = true; + sibling->right->red = false; + rotateLeft(sibling); + + sibling = sibling->parent; + Q_ASSERT(sibling); + } + sibling->red = node->parent->red; + node->parent->red = false; + + Q_ASSERT(sibling->left->red); + sibling->left->red = false; + rotateRight(node->parent); + } + return; + } +} + +template <class T> +inline typename QRBTree<T>::Node *QRBTree<T>::front(Node *node) const +{ + while (node->left) + node = node->left; + return node; +} + +template <class T> +inline typename QRBTree<T>::Node *QRBTree<T>::back(Node *node) const +{ + while (node->right) + node = node->right; + return node; +} + +template <class T> +typename QRBTree<T>::Node *QRBTree<T>::next(Node *node) const +{ + if (node->right) + return front(node->right); + while (node->parent && node == node->parent->right) + node = node->parent; + return node->parent; +} + +template <class T> +typename QRBTree<T>::Node *QRBTree<T>::previous(Node *node) const +{ + if (node->left) + return back(node->left); + while (node->parent && node == node->parent->left) + node = node->parent; + return node->parent; +} + +template <class T> +int QRBTree<T>::blackDepth(Node *top) const +{ + if (!top) + return 0; + int leftDepth = blackDepth(top->left); + int rightDepth = blackDepth(top->right); + if (leftDepth != rightDepth) + return -1; + if (!top->red) + ++leftDepth; + return leftDepth; +} + +template <class T> +bool QRBTree<T>::checkRedBlackProperty(Node *top) const +{ + if (!top) + return true; + if (top->left && !checkRedBlackProperty(top->left)) + return false; + if (top->right && !checkRedBlackProperty(top->right)) + return false; + return !(top->red && ((top->left && top->left->red) || (top->right && top->right->red))); +} + +template <class T> +inline bool QRBTree<T>::validate() const +{ + return checkRedBlackProperty(root) && blackDepth(root) != -1; +} + +template <class T> +inline void QRBTree<T>::deleteNode(Node *&node) +{ + Q_ASSERT(node); + detach(node); + node->right = freeList; + freeList = node; + node = 0; +} + +template <class T> +inline typename QRBTree<T>::Node *QRBTree<T>::newNode() +{ + if (freeList) { + Node *node = freeList; + freeList = freeList->right; + node->parent = node->left = node->right = 0; + node->red = true; + return node; + } + return new Node; +} + +// Return 1 if 'left' comes after 'right', 0 if equal, and -1 otherwise. +// 'left' and 'right' cannot be null. +template <class T> +int QRBTree<T>::order(Node *left, Node *right) +{ + Q_ASSERT(left && right); + if (left == right) + return 0; + + QVector<Node *> leftAncestors; + QVector<Node *> rightAncestors; + while (left) { + leftAncestors.push_back(left); + left = left->parent; + } + while (right) { + rightAncestors.push_back(right); + right = right->parent; + } + Q_ASSERT(leftAncestors.back() == root && rightAncestors.back() == root); + + while (!leftAncestors.empty() && !rightAncestors.empty() && leftAncestors.back() == rightAncestors.back()) { + leftAncestors.pop_back(); + rightAncestors.pop_back(); + } + + if (!leftAncestors.empty()) + return (leftAncestors.back() == leftAncestors.back()->parent->left ? -1 : 1); + + if (!rightAncestors.empty()) + return (rightAncestors.back() == rightAncestors.back()->parent->right ? -1 : 1); + + // The code should never reach this point. + Q_ASSERT(!leftAncestors.empty() || !rightAncestors.empty()); + return 0; +} + +QT_END_NAMESPACE + +#endif |