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Greatly simplify move_from_uci()

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Use a reverse logic: among the list of generated legal moves
transformed in UCI coordinate notation find the one that
matches the given string.

It is a bit slower, but here is not performance critical and
is much more simplified then before.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-01-08 16:00:22 +01:00
parent 82d5386435
commit 6b49d509a1
1 changed files with 12 additions and 66 deletions
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78
src/san.cpp
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@ -60,7 +60,7 @@ namespace {
const std::string move_to_uci(Move m, bool chess960) {
std::string str;
std::string promotion;
Square from = move_from(m);
Square to = move_to(m);
@ -76,80 +76,26 @@ const std::string move_to_uci(Move m, bool chess960) {
if (move_is_long_castle(m) && !chess960)
return from == SQ_E1 ? "e1c1" : "e8c8";
str = square_to_string(from) + square_to_string(to);
if (move_is_promotion(m))
str += char(tolower(piece_type_to_char(move_promotion_piece(m))));
promotion = char(tolower(piece_type_to_char(move_promotion_piece(m))));
return str;
return square_to_string(from) + square_to_string(to) + promotion;
}
/// move_from_uci() takes a position and a string as input, and attempts to
/// convert the string to a move, using simple coordinate notation (g1f3,
/// a7a8q, etc.). This function is not robust, and expects that the input
/// move is legal and correctly formatted.
/// move_from_uci() takes a position and a string representing a move in
/// simple coordinate notation and returns an equivalent Move.
Move move_from_uci(const Position& pos, const std::string& str) {
Square from, to;
Piece piece;
Color us = pos.side_to_move();
MoveStack mlist[MOVES_MAX];
MoveStack* last = generate<MV_LEGAL>(pos, mlist);
if (str.length() < 4)
return MOVE_NONE;
for (MoveStack* cur = mlist; cur != last; cur++)
if (str == move_to_uci(cur->move, pos.is_chess960()))
return cur->move;
// Read the from and to squares
from = make_square(file_from_char(str[0]), rank_from_char(str[1]));
to = make_square(file_from_char(str[2]), rank_from_char(str[3]));
// Find the moving piece
piece = pos.piece_on(from);
// If the string has more than 4 characters, try to interpret the 5th
// character as a promotion.
if (str.length() > 4 && piece == piece_of_color_and_type(us, PAWN))
{
switch (tolower(str[4])) {
case 'n':
return make_promotion_move(from, to, KNIGHT);
case 'b':
return make_promotion_move(from, to, BISHOP);
case 'r':
return make_promotion_move(from, to, ROOK);
case 'q':
return make_promotion_move(from, to, QUEEN);
}
}
// En passant move? We assume that a pawn move is an en passant move
// if the destination square is epSquare.
if (to == pos.ep_square() && piece == piece_of_color_and_type(us, PAWN))
return make_ep_move(from, to);
// Is this a castling move? A king move is assumed to be a castling move
// if the destination square is occupied by a friendly rook, or if the
// distance between the source and destination squares is more than 1.
if (piece == piece_of_color_and_type(us, KING))
{
if (pos.piece_on(to) == piece_of_color_and_type(us, ROOK))
return make_castle_move(from, to);
if (square_distance(from, to) > 1)
{
// This is a castling move, but we have to translate it to the
// internal "king captures rook" representation.
SquareDelta delta = (to > from ? DELTA_E : DELTA_W);
Square s = from;
do s += delta;
while ( pos.piece_on(s) != piece_of_color_and_type(us, ROOK)
&& relative_rank(us, s) == RANK_1);
return relative_rank(us, s) == RANK_1 ? make_castle_move(from, s) : MOVE_NONE;
}
}
return make_move(from, to);
return MOVE_NONE;
}