NodeAdjacencyTable.h

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <algorithm>
#include <vector>
 
#include "Mesh.h"
#include "Node.h"
 
namespace MeshLib
{
class NodeAdjacencyTable final
{
public:
    explicit NodeAdjacencyTable(Mesh const& mesh) { createTable(mesh); }
 
    std::size_t size() const { return _data.size(); }
 
    std::size_t getNodeDegree(std::size_t const node_id) const
    {
        return _data[node_id].size();
    }
 
    std::vector<std::size_t> const& getAdjacentNodes(
        std::size_t const node_id) const
    {
        return _data[node_id];
    }
 
    void createTable(Mesh const& mesh)
    {
        _data.resize(mesh.getNumberOfNodes());
 
        auto const& connections =
            MeshLib::calculateNodesConnectedByElements(mesh);
        for (auto const node_id : mesh.getNodes() | MeshLib::views::ids)
        {
            auto const& connected_nodes = connections[node_id];
            std::vector<std::size_t>& row = _data[node_id];
            row.reserve(connected_nodes.size());
            std::transform(connected_nodes.cbegin(), connected_nodes.cend(),
                           std::back_inserter(row),
                           [](Node const* const n) { return n->getID(); });
        }
    }
 
private:
    std::vector<std::vector<std::size_t>> _data;
};
 
}  // namespace MeshLib