all_arrangements.hpp

/*********************************************************************
 *
 * Linear Arrangement Library - A library that implements a collection
 * algorithms for linear arrangments of graphs.
 *
 * Copyright (C) 2019 - 2023
 *
 * This file is part of Linear Arrangement Library. The full code is available
 * at:
 *      https://github.com/LAL-project/linear-arrangement-library.git
 *
 * Linear Arrangement Library is free software: you can redistribute it
 * and/or modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * Linear Arrangement Library is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Linear Arrangement Library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Contact:
 *
 *     Lluís Alemany Puig (lalemany@cs.upc.edu)
 *         LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/lalemany/
 *
 *     Ramon Ferrer i Cancho (rferrericancho@cs.upc.edu)
 *         LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Office S124, Omega building
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/rferrericancho/
 *
 ********************************************************************/
 
#pragma once
 
// C++ includes
#include <algorithm>
#include <numeric>
 
// lal includes
#include <lal/graphs/graph.hpp>
#include <lal/linear_arrangement.hpp>
 
namespace lal {
namespace generate {
 
class all_arrangements {
public:
    all_arrangements(const lal::graphs::graph& g) noexcept
        : all_arrangements(g.get_num_nodes())
    { }
 
    all_arrangements(uint64_t n) noexcept
        : m_n(n),
          m_arr(lal::linear_arrangement(m_n))
    {
        reset();
    }
 
    const linear_arrangement& get_arrangement() const noexcept
    { return m_arr; }
 
    bool end() const noexcept { return m_reached_end; }
 
    void next() noexcept {
        m_reached_end =
            not std::next_permutation(m_arr.begin_direct(), m_arr.end_direct());
        m_arr.update_inverse();
    }
 
    void reset() noexcept {
        m_reached_end = false;
        m_arr.identity();
    }
 
    linear_arrangement yield_arrangement() noexcept {
        // yes, a copy...
        const linear_arrangement arr = get_arrangement();
        next();
        return arr;
    }
 
private:
    const uint64_t m_n;
    linear_arrangement m_arr;
    bool m_reached_end = false;
};
 
} // -- namespace generate
} // -- namespace lal