Pay attention to hint move in walking pobder PV

When requesting to walk the PV of a pondering engine, it would only
work if that engine had printed the ponder move (in parentheses) as
first move of the PV. But the recommended mode in CECP would have
provided the ponder move in a 'Hint:' command, and start the PV after it.
So that the PV would always start with an invalid move (for the other
player). Backing up to the previous position such as would have to be
done when walking an old PV after the engine has moved, does not solve
this; we have to go one position forward rather than backward. Now
we first try to put the hint move before the PV, if the engine supplying
the PV provided the hint, and pondering is on, before we try to back up.

diff --git a/backend.c b/backend.c
index da93d18..ddb8894 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -442,7 +442,7 @@ char *currentDebugFile; // [HGM] debug split: to remember name
 */
 
 char cmailMove[CMAIL_MAX_GAMES][MOVE_LEN], cmailMsg[MSG_SIZ];
-char bookOutput[MSG_SIZ*10], thinkOutput[MSG_SIZ*10], lastHint[MSG_SIZ];
+char bookOutput[MSG_SIZ*10], thinkOutput[MSG_SIZ*10], lastHint[MSG_SIZ], hintSrc;
 char thinkOutput1[MSG_SIZ*10];
 char promoRestrict[MSG_SIZ];
 
@@ -5678,7 +5678,7 @@ Boolean pushed = FALSE;
 char *lastParseAttempt;
 
 void
-ParsePV (char *pv, Boolean storeComments, Boolean atEnd)
+ParsePV (char *pv, Boolean storeComments, Boolean atEnd, int engine)
 { // Parse a string of PV moves, and append to current game, behind forwardMostMove
   int fromX, fromY, toX, toY; char promoChar;
   ChessMove moveType;
@@ -5696,10 +5696,15 @@ ParsePV (char *pv, Boolean storeComments, Boolean atEnd)
     if(nr == 0 && !storeComments && *pv == '(') pv++; // first (ponder) move can be in parentheses
     lastParseAttempt = pv;
     valid = ParseOneMove(pv, endPV, &moveType, &fromX, &fromY, &toX, &toY, &promoChar);
-    if(!valid && nr == 0 &&
-       ParseOneMove(pv, endPV-1, &moveType, &fromX, &fromY, &toX, &toY, &promoChar)){
-        nr++; moveType = Comment; // First move has been played; kludge to make sure we continue
-        // Hande case where played move is different from leading PV move
+    if(!valid && nr == 0) {
+       if(engine == hintSrc && *lastHint && appData.ponderNextMove &&
+                 ParseOneMove(lastHint, endPV, &moveType, &fromX, &fromY, &toX, &toY, &promoChar)){
+        // first PV move is invalid, but the engine provided hint and is probably pondering on it
+        valid++; goto append_move; // use this hint as first move
+       }
+       if(ParseOneMove(pv, endPV-1, &moveType, &fromX, &fromY, &toX, &toY, &promoChar)){
+        nr++; moveType = Comment; // PV was for previous position; kludge to make sure we continue
+        // Handle case where played move is different from leading PV move
         CopyBoard(boards[endPV+1], boards[endPV-1]); // tentatively unplay last game move
         CopyBoard(boards[endPV+2], boards[endPV-1]); // and play first move of PV
         ApplyMove(fromX, fromY, toX, toY, promoChar, boards[endPV+2]);
@@ -5712,7 +5717,8 @@ ParsePV (char *pv, Boolean storeComments, Boolean atEnd)
           parseList[endPV-1][0] = NULLCHAR;
           safeStrCpy(moveList[endPV-2], "_0_0", sizeof(moveList[endPV-2])/sizeof(moveList[endPV-2][0])); // suppress premove highlight on takeback move
         }
-      }
+       }
+    }
     pv = strstr(pv, yy_textstr) + strlen(yy_textstr); // skip what we parsed
     if(nr == 0 && !storeComments && *pv == ')') pv++; // closing parenthesis of ponder move;
     if(moveType == Comment && storeComments) AppendComment(endPV, yy_textstr, FALSE);
@@ -5720,6 +5726,7 @@ ParsePV (char *pv, Boolean storeComments, Boolean atEnd)
        valid++; // allow comments in PV
        continue;
     }
+  append_move:
     nr++;
     if(endPV+1 > framePtr) break; // no space, truncate
     if(!valid) break;
@@ -5798,7 +5805,7 @@ LoadMultiPV (int x, int y, char *buf, int index, int *start, int *end, int pane)
                Collapse(origIndex - lineStart);
                return FALSE;
        }
-       ParsePV(buf+startPV, FALSE, gameMode != AnalyzeMode);
+       ParsePV(buf+startPV, FALSE, gameMode != AnalyzeMode, pane+1);
        *start = startPV; *end = index-1;
        extendGame = (gameMode == AnalyzeMode && appData.autoExtend && origIndex - startPV < 5);
        return TRUE;
@@ -5811,7 +5818,7 @@ PvToSAN (char *pv)
        int i, k=0, savedEnd=endPV, saveFMM = forwardMostMove;
        *buf = NULLCHAR;
        if(forwardMostMove < endPV) PushInner(forwardMostMove, endPV); // shelve PV of PV-walk
-       ParsePV(pv, FALSE, 2); // this appends PV to game, suppressing any display of it
+       ParsePV(pv, FALSE, 2, 0); // this appends PV to game, suppressing any display of it
        for(i = forwardMostMove; i<endPV; i++){
            if(i&1) snprintf(buf+k, 10*MSG_SIZ-k, "%s ", parseList[i]);
            else    snprintf(buf+k, 10*MSG_SIZ-k, "%d. %s ", i/2 + 1, parseList[i]);
@@ -5829,7 +5836,7 @@ LoadPV (int x, int y)
 { // called on right mouse click to load PV
   int which = gameMode == TwoMachinesPlay && (WhiteOnMove(forwardMostMove) == (second.twoMachinesColor[0] == 'w'));
   lastX = x; lastY = y;
-  ParsePV(lastPV[which], FALSE, TRUE); // load the PV of the thinking engine in the boards array.
+  ParsePV(lastPV[which], FALSE, TRUE, 0); // load the PV of the thinking engine in the boards array.
   extendGame = FALSE;
   return TRUE;
 }
@@ -9129,7 +9136,7 @@ FakeBookMove: // [HGM] book: we jump here to simulate machine moves after book h
            }
         }
        hintRequested = FALSE;
-       lastHint[0] = NULLCHAR;
+       lastHint[0] = NULLCHAR; hintSrc = 0;
        bookRequested = FALSE;
        /* Program may be pondering now */
        cps->maybeThinking = TRUE;
@@ -9692,7 +9699,7 @@ FakeBookMove: // [HGM] book: we jump here to simulate machine moves after book h
                DisplayError(buf2, 0);
            }
        } else {
-         safeStrCpy(lastHint, buf1, sizeof(lastHint)/sizeof(lastHint[0]));
+         safeStrCpy(lastHint, buf1, sizeof(lastHint)/sizeof(lastHint[0])); hintSrc = (cps != &first) + 1;
        }
        return;
     }
@@ -12300,7 +12307,7 @@ Reset (int redraw, int init)
     first.bookSuspend = FALSE; // [HGM] book
     second.bookSuspend = FALSE;
     thinkOutput[0] = NULLCHAR;
-    lastHint[0] = NULLCHAR;
+    lastHint[0] = NULLCHAR; hintSrc = 0;
     ClearGameInfo(&gameInfo);
     gameInfo.variant = StringToVariant(appData.variant);
     if(gameInfo.variant == VariantNormal && strcmp(appData.variant, "normal")) {
@@ -19362,7 +19369,7 @@ LoadVariation (int index, char *text)
        PushTail(currentMove, forwardMostMove); // shelve main variation. This truncates game
        // kludge: use ParsePV() to append variation to game
        move = currentMove;
-       ParsePV(start, TRUE, TRUE);
+       ParsePV(start, TRUE, TRUE, 0);
        forwardMostMove = endPV; endPV = -1; currentMove = move; // cleanup what ParsePV did
        ClearPremoveHighlights();
        CommentPopDown();