wehub-resource-sync
94 lines
2.8 KiB
C++
94 lines
2.8 KiB
C++
// Copyright (c) 2023 CINN Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <array>
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#include <functional>
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#include <iostream>
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#include <queue>
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#include <stack>
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#include <unordered_set>
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namespace common {
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// depth-first search visitor
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template <typename NodeType>
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class DfsWalker final {
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public:
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DfsWalker(const DfsWalker&) = delete;
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DfsWalker(DfsWalker&&) = delete;
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using NodeHandlerType = std::function<void(NodeType)>;
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using NodesVisitorType =
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std::function<void(NodeType, const NodeHandlerType&)>;
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DfsWalker(const NodesVisitorType& VisitNextNodes)
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: VisitNextNodes_(VisitNextNodes) {}
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void operator()(NodeType node, const NodeHandlerType& NodeHandler) const {
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std::array<NodeType, 1> nodes{node};
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(*this)(nodes.begin(), nodes.end(), NodeHandler, [&](NodeType) {});
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}
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template <typename NodeIt>
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void operator()(NodeIt begin,
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NodeIt end,
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const NodeHandlerType& NodeHandler) const {
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(*this)(begin, end, NodeHandler, [&](NodeType) {});
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}
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// https://en.wikipedia.org/wiki/Depth-first_search
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template <typename NodeIt>
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void operator()(NodeIt begin,
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NodeIt end,
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const NodeHandlerType& NodeHandlerOnPush,
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const NodeHandlerType& NodeHandlerOnPop) const {
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std::unordered_set<NodeType> discovered;
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struct Neighbours {
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NodeType producer;
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std::queue<NodeType> consumers;
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};
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std::stack<Neighbours> stack;
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const auto& TryPush = [&](NodeType node) {
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if (discovered.count(node) == 0) {
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discovered.insert(node);
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NodeHandlerOnPush(node);
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stack.push(Neighbours{.producer = node});
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VisitNextNodes_(node, [&](NodeType next_node) {
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stack.top().consumers.push(next_node);
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});
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}
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};
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for (NodeIt node_iter = begin; node_iter != end; ++node_iter) {
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TryPush(*node_iter);
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while (!stack.empty()) {
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auto* neighbours = &stack.top();
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if (neighbours->consumers.empty()) {
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NodeHandlerOnPop(neighbours->producer);
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stack.pop();
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} else {
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TryPush(neighbours->consumers.front());
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neighbours->consumers.pop();
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}
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}
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}
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}
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private:
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NodesVisitorType VisitNextNodes_;
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};
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} // namespace common
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