Move uci move parsing under san.cpp

This partially reverts 1e7aaed8bc keeping the conversion
functions from/to move to uci string in the same file.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/san.cpp

@@ -53,6 +53,106 @@ namespace {
 //// Functions
 ////
 
+/// move_to_uci() converts a move to a string in coordinate notation
+/// (g1f3, a7a8q, etc.). The only special case is castling moves, where we
+/// print in the e1g1 notation in normal chess mode, and in e1h1 notation in
+/// Chess960 mode.
+
+const std::string move_to_uci(Move m, bool chess960) {
+
+  std::string str;
+  Square from = move_from(m);
+  Square to = move_to(m);
+
+  if (m == MOVE_NONE)
+      return "(none)";
+
+  if (m == MOVE_NULL)
+      return "0000";
+
+  if (move_is_short_castle(m) && !chess960)
+      return from == SQ_E1 ? "e1g1" : "e8g8";
+
+  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))));
+
+  return str;
+}
+
+/// 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 move_from_uci(const Position& pos, const std::string& str) {
+
+  Square from, to;
+  Piece piece;
+  Color us = pos.side_to_move();
+
+  if (str.length() < 4)
+      return MOVE_NONE;
+
+  // 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);
+}
+
+
 /// move_to_san() takes a position and a move as input, where it is assumed
 /// that the move is a legal move from the position. The return value is
 /// a string containing the move in short algebraic notation.