pbook.h

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/*
 * Copyright (C) 1999-2000  Shane Hudson
 * Copyright (C) 2017  Fulvio Benini

 * This file is part of Scid (Shane's Chess Information Database).
 *
 * Scid is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.
 *
 * Scid 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Scid.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef SCID_PBOOK_H
#define SCID_PBOOK_H

#include "common.h"
#include "misc.h"
#include <algorithm>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>
class Position;

/**
 * A PBook is a collection of chess positions, each with the corresponding ECO
 * code, a mnemonic name, and the list of moves to reach the position.
 */
class PBook {
    struct bookDataT {
        std::unique_ptr<char[]> compactStr;
        std::unique_ptr<char[]> comment;

        bookDataT(char* compact, char* comm)
            : compactStr(compact), comment(comm) {}
    };
    std::unordered_multimap<unsigned, bookDataT> pos_;
    std::vector<const char*> comments_;
    unsigned LineCount = 0;
    unsigned LeastMaterial = 32; // The smallest amount of material in any
                                 // position in the book. In the range 0..32.
public:
    /**
     * Read a file with a list of ECO codes and creates a PBook object.
     * The file is composed of lines like this:
     * C50a "Italian Game"  1.e4 e5 2.Nf3 Nc6 3.Bc4 *
     * @param FileName: the name of the file to be read.
     * @returns
     * - on success, a @e std::pair containing OK and the pointer to the newly
     *   created object.
     * - on failure, a @e std::pair containing an error code and nullptr.
     */
    static std::pair<errorT, std::unique_ptr<PBook> >
    ReadEcoFile(const char* FileName);

    /**
     * Retrieve an ECO string containing the ECO code and the mnemonic name.
     * @param pos: the position to search for.
     * @returns
     * - if the position is found, a @e std::pair with the range iterators for
     *   the string (string_view).
     * - a @e std::pair containing nullptr otherwise.
     */
    std::pair<const char*, const char*> findECOstr(Position* pos) const;

    /**
     * Retrieve the ECO code of a position.
     * @param pos: the position to search for.
     * @returns the corresponding ECO code or ECO_None if not found.
     */
    ecoT findECO(Position* pos) const {
        auto it = findECOstr(pos);
        if (!it.first)
            return ECO_None;

        char buf[7] = {0};
        std::copy_n(it.first,
                    std::min(ptrdiff_t(6), std::distance(it.first, it.second)),
                    buf);
        return eco_FromString(buf);
    }

    std::string EcoSummary(const char* ecoPrefix) const;

    unsigned GetLineNumber() const { return LineCount; }
    unsigned FewestPieces() const { return LeastMaterial; }
    size_t Size() const { return pos_.size(); }
};

#endif // SCID_PBOOK_H