Function constructDBKey

Rapfi/database/dbclient.cpp:333–390

namespace Database {

DBKey constructDBKey(const Board &board, Rule rule, TransformType *transType)
{
    DBKey    key[TRANS_NB];
    StonePos whiteStones[TRANS_NB][MAX_MOVES];
    for (int trans = IDENTITY; trans < TRANS_NB; trans++) {
        key[trans].rule           = rule;
        key[trans].boardWidth     = board.size();
        key[trans].boardHeight    = board.size();
        key[trans].sideToMove     = board.sideToMove();
        key[trans].numBlackStones = 0;
        key[trans].numWhiteStones = 0;
    }

    for (int ply = 0; ply < board.ply(); ply++) {
        Pos move = board.getHistoryMove(ply);
        if (move == Pos::PASS)
            continue;

        Color c = board.cell(move).piece;
        if (c == BLACK) {
            for (int trans = IDENTITY; trans < TRANS_NB; trans++) {
                Pos transformedPos = applyTransform(move, board.size(), (TransformType)trans);
                key[trans].stones[key[trans].numBlackStones++] = {transformedPos.x(),
                                                                  transformedPos.y()};
            }
        }
        else if (c == WHITE) {
            for (int trans = IDENTITY; trans < TRANS_NB; trans++) {
                Pos transformedPos = applyTransform(move, board.size(), (TransformType)trans);
                whiteStones[trans][key[trans].numWhiteStones++] = {transformedPos.x(),
                                                                   transformedPos.y()};
            }
        }
    }

    // Construct 8 symmetry database keys, and find the smallest one
    int smallestIndex = 0;

    for (int trans = IDENTITY; trans < TRANS_NB; trans++) {
        std::sort(key[trans].stones,
                  key[trans].stones + key[trans].numBlackStones,
                  std::less<StonePos>());
        std::copy(whiteStones[trans],
                  whiteStones[trans] + key[trans].numWhiteStones,
                  key[trans].stones + key[trans].numBlackStones);
        std::sort(key[trans].stones + key[trans].numBlackStones,
                  key[trans].stones + key[trans].numBlackStones + key[trans].numWhiteStones,
                  std::less<StonePos>());

        if (trans != smallestIndex && key[trans] < key[smallestIndex])
            smallestIndex = trans;
    }

    if (transType)
        *transType = static_cast<TransformType>(smallestIndex);

    return key[smallestIndex];
}