mirror of
https://github.com/classilla/tenfourfox.git
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157 lines
3.7 KiB
C++
157 lines
3.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set sw=2 ts=8 et tw=80 : */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_layers_TreeTraversal_h
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#define mozilla_layers_TreeTraversal_h
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#include <queue>
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#include <stack>
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namespace mozilla {
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namespace layers {
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/*
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* Returned by |aAction| in ForEachNode. If the action returns
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* TraversalFlag::Skip, the node's children are not added to the traverrsal
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* stack. Otherwise, a return value of TraversalFlag::Continue indicates that
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* ForEachNode should traverse each of the node's children.
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*/
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enum class TraversalFlag { Skip, Continue };
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/*
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* Do a breadth-first search of the tree rooted at |aRoot|, and return the
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* first visited node that satisfies |aCondition|, or nullptr if no such node
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* was found.
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*
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* |Node| should have methods GetLastChild() and GetPrevSibling().
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*/
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template <typename Node, typename Condition>
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Node* BreadthFirstSearch(Node* aRoot, const Condition& aCondition)
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{
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if (!aRoot) {
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return nullptr;
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}
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std::queue<Node*> queue;
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queue.push(aRoot);
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while (!queue.empty()) {
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Node* node = queue.front();
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queue.pop();
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if (aCondition(node)) {
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return node;
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}
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for (Node* child = node->GetLastChild();
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child;
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child = child->GetPrevSibling()) {
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queue.push(child);
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}
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}
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return nullptr;
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}
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/*
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* Do a depth-first search of the tree rooted at |aRoot|, and return the
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* first visited node that satisfies |aCondition|, or nullptr if no such node
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* was found.
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*
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* |Node| should have methods GetLastChild() and GetPrevSibling().
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*/
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template <typename Node, typename Condition>
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Node* DepthFirstSearch(Node* aRoot, const Condition& aCondition)
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{
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if (!aRoot) {
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return nullptr;
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}
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std::stack<Node*> stack;
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stack.push(aRoot);
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while (!stack.empty()) {
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Node* node = stack.top();
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stack.pop();
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if (aCondition(node)) {
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return node;
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}
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for (Node* child = node->GetLastChild();
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child;
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child = child->GetPrevSibling()) {
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stack.push(child);
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}
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}
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return nullptr;
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}
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/*
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* Do a depth-first traversal of the tree rooted at |aRoot|, performing
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* |aAction| for each node. |aAction| can return a TraversalFlag to determine
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* whether or not to omit the children of a particular node.
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*
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* If |aAction| does not return a TraversalFlag, it must return nothing. There
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* is no ForEachNode instance handling types other than void or TraversalFlag.
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*/
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template <typename Node, typename Action>
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auto ForEachNode(Node* aRoot, const Action& aAction) ->
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typename EnableIf<IsSame<decltype(aAction(aRoot)), TraversalFlag>::value, void>::Type
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{
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if (!aRoot) {
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return;
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}
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std::stack<Node*> stack;
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stack.push(aRoot);
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while (!stack.empty()) {
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Node* node = stack.top();
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stack.pop();
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TraversalFlag result = aAction(node);
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if (result == TraversalFlag::Continue) {
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for (Node* child = node->GetLastChild();
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child;
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child = child->GetPrevSibling()) {
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stack.push(child);
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}
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}
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}
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}
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template <typename Node, typename Action>
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auto ForEachNode(Node* aRoot, const Action& aAction) ->
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typename EnableIf<IsSame<decltype(aAction(aRoot)), void>::value, void>::Type
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{
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if (!aRoot) {
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return;
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}
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std::stack<Node*> stack;
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stack.push(aRoot);
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while (!stack.empty()) {
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Node* node = stack.top();
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stack.pop();
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aAction(node);
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for (Node* child = node->GetLastChild();
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child;
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child = child->GetPrevSibling()) {
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stack.push(child);
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}
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}
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}
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}
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}
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#endif // mozilla_layers_TreeTraversal_h
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