//
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// Copyright (C) 2010 The Android Open Source Project
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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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//
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#ifndef UPDATE_ENGINE_PAYLOAD_GENERATOR_TARJAN_H_
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#define UPDATE_ENGINE_PAYLOAD_GENERATOR_TARJAN_H_
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// This is an implementation of Tarjan's algorithm which finds all
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// Strongly Connected Components in a graph.
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// Note: a true Tarjan algorithm would find all strongly connected components
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// in the graph. This implementation will only find the strongly connected
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// component containing the vertex passed in.
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#include <vector>
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#include "update_engine/payload_generator/graph_types.h"
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namespace chromeos_update_engine {
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class TarjanAlgorithm {
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public:
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TarjanAlgorithm() : index_(0), required_vertex_(0) {}
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// 'out' is set to the result if there is one, otherwise it's untouched.
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void Execute(Vertex::Index vertex,
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Graph* graph,
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std::vector<Vertex::Index>* out);
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private:
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void Tarjan(Vertex::Index vertex, Graph* graph);
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Vertex::Index index_;
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Vertex::Index required_vertex_;
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std::vector<Vertex::Index> stack_;
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std::vector<std::vector<Vertex::Index>> components_;
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};
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} // namespace chromeos_update_engine
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#endif // UPDATE_ENGINE_PAYLOAD_GENERATOR_TARJAN_H_
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