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67 lines
2.2 KiB
C++
67 lines
2.2 KiB
C++
#pragma once
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#include <unordered_map>
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namespace vcpkg::Graphs
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{
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enum class ExplorationStatus
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{
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// We have not visited this vertex
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NOT_EXPLORED,
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// We have visited this vertex but haven't visited all vertices in its subtree
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PARTIALLY_EXPLORED,
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// We have visited this vertex and all vertices in its subtree
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FULLY_EXPLORED
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};
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template<class V, class U>
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__interface AdjacencyProvider
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{
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std::vector<V> adjacency_list(const U& vertex) const;
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U load_vertex_data(const V& vertex) const;
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};
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template<class V, class U>
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static void topological_sort_internal(const V& vertex,
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const AdjacencyProvider<V, U>& f,
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std::unordered_map<V, ExplorationStatus>& exploration_status,
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std::vector<U>& sorted)
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{
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ExplorationStatus& status = exploration_status[vertex];
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switch (status)
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{
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case ExplorationStatus::FULLY_EXPLORED: return;
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case ExplorationStatus::PARTIALLY_EXPLORED: Checks::exit_with_message(VCPKG_LINE_INFO, "cycle in graph");
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case ExplorationStatus::NOT_EXPLORED:
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{
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status = ExplorationStatus::PARTIALLY_EXPLORED;
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U vertex_data = f.load_vertex_data(vertex);
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for (const V& neighbour : f.adjacency_list(vertex_data))
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topological_sort_internal(neighbour, f, exploration_status, sorted);
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sorted.push_back(std::move(vertex_data));
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status = ExplorationStatus::FULLY_EXPLORED;
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return;
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}
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default: Checks::unreachable(VCPKG_LINE_INFO);
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}
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}
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template<class V, class U>
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std::vector<U> topological_sort(const std::vector<V>& starting_vertices, const AdjacencyProvider<V, U>& f)
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{
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std::vector<U> sorted;
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std::unordered_map<V, ExplorationStatus> exploration_status;
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for (auto& vertex : starting_vertices)
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{
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topological_sort_internal(vertex, f, exploration_status, sorted);
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}
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return sorted;
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}
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}
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