allowe parsing / disambiguation of SAN moves like Xe4 in certain situations

This patch allows parsing / disambiguation of SAN moves like Xe4, if there
is only one wild-card piece X on the board. Moves with wild-card pieces
are now considered illegal if they leave the King in check by a piece of
known gait.

diff --git a/moves.c b/moves.c
index 59700b7..2a017c3 100644 (file)
--- a/moves.c
+++ b/moves.c
@@ -680,6 +680,14 @@ void GenPseudoLegal(board, flags, epfile, callback, closure)
                     }
                  }
              break;
+           case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
+           case BlackFalcon:
+           case WhiteCobra:
+           case BlackCobra:
+           case WhiteLance:
+           case BlackLance:
+             callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
+             break;
 
          }
       }
@@ -1053,7 +1061,7 @@ ChessMove LegalityTest(board, flags, epfile, castlingRights, rf, ff, rt, ft, pro
     if(piece == WhiteFalcon || piece == BlackFalcon ||
        piece == WhiteCobra  || piece == BlackCobra  ||
        piece == WhiteLance  || piece == BlackLance)
-        return NormalMove;
+        return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
 
     cl.rf = rf;
     cl.ff = ff;
@@ -1195,6 +1203,13 @@ void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
      VOIDSTAR closure;
 {
     register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
+    int wildCard = FALSE; ChessSquare piece = board[rf][ff];
+
+    // [HGM] wild: for wild-card pieces rt and rf are dummies
+    if(piece == WhiteFalcon || piece == BlackFalcon ||
+       piece == WhiteCobra  || piece == BlackCobra  ||
+       piece == WhiteLance  || piece == BlackLance)
+        wildCard = TRUE;
 
     if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
          || PieceToChar(board[rf][ff]) == '~'
@@ -1202,15 +1217,15 @@ void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
                                                                       ) &&
        (cl->rfIn == -1 || cl->rfIn == rf) &&
        (cl->ffIn == -1 || cl->ffIn == ff) &&
-       (cl->rtIn == -1 || cl->rtIn == rt) &&
-       (cl->ftIn == -1 || cl->ftIn == ft)) {
+       (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
+       (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
 
        cl->count++;
         cl->piece = board[rf][ff];
        cl->rf = rf;
        cl->ff = ff;
-       cl->rt = rt;
-       cl->ft = ft;
+       cl->rt = wildCard ? cl->rtIn : rt;
+       cl->ft = wildCard ? cl->ftIn : ft;
        cl->kind = kind;
     }
 }
@@ -1221,6 +1236,7 @@ void Disambiguate(board, flags, epfile, closure)
      DisambiguateClosure *closure;
 {
     int illegal = 0; char c = closure->promoCharIn;
+
     closure->count = 0;
     closure->rf = closure->ff = closure->rt = closure->ft = 0;
     closure->kind = ImpossibleMove;