AdjacencyList.h

/*
 * Copyright 2022 Adobe. All rights reserved.
 * This file is licensed to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. You may obtain a copy
 * of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under
 * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
 * OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
#pragma once
 
#include <vector>
 
#include <lagrange/utils/assert.h>
#include <lagrange/utils/span.h>
 
namespace lagrange {
 
 
template <typename Index>
class AdjacencyList
{
public:
    using ValueArray = std::vector<Index>;
    using IndexArray = std::vector<size_t>;
 
public:
    AdjacencyList(ValueArray data, IndexArray indices)
        : m_data(std::move(data))
        , m_indices(std::move(indices))
    {}
 
    [[nodiscard]] size_t get_num_entries() const { return m_indices.size() - 1; }
 
    [[nodiscard]] span<const Index> get_neighbors(size_t i) const
    {
        la_runtime_assert(
            i + 1 < m_indices.size(),
            "Invalid index, perhaps adjacency list is uninitialized?");
        return {m_data.data() + m_indices[i], m_indices[i + 1] - m_indices[i]};
    }
 
    [[nodiscard]] size_t get_num_neighbors(size_t i) const
    {
        la_runtime_assert(
            i + 1 < m_indices.size(),
            "Invalid index, perhaps adjacency list is uninitialized?");
        return m_indices[i + 1] - m_indices[i];
    }
 
private:
    ValueArray m_data;
    IndexArray m_indices;
};
 
 
} // namespace lagrange