05-fyi-flush-reduce.patch

[Akim Demaille]

Index: ChangeLog
from  Akim Demaille  <address@hidden>
        * src/conflicts.c (flush_shift): Also adjust lookaheadset.
        (flush_reduce): New.
        (resolve_sr_conflict): Adjust.
        
        
Index: src/conflicts.c
--- src/conflicts.c Sun, 16 Dec 2001 11:51:05 +0100 akim
+++ src/conflicts.c Sun, 16 Dec 2001 17:07:36 +0100 akim
@@ -60,12 +60,26 @@
   shifts *shiftp = state_table[state]->shifts;
   int i;
 
+  RESETBIT (lookaheadset, token);
   for (i = 0; i < shiftp->nshifts; i++)
     if (!SHIFT_IS_DISABLED (shiftp, i) && SHIFT_SYMBOL (shiftp, i) == token)
       SHIFT_DISABLE (shiftp, i);
 }
 
 
+/*-------------------------------------------------------------------.
+| Turn off the reduce recorded for the specified token for the       |
+| specified lookahead.  Used when we resolve a shift-reduce conflict |
+| in favor of the shift.                                             |
+`-------------------------------------------------------------------*/
+
+static void
+flush_reduce (int lookahead, int token)
+{
+  RESETBIT (LA (lookahead), token);
+}
+
+
 /*------------------------------------------------------------------.
 | Attempt to resolve shift-reduce conflict for one rule by means of |
 | precedence declarations.  It has already been checked that the    |
@@ -74,74 +88,58 @@
 `------------------------------------------------------------------*/
 
 static void
-resolve_sr_conflict (int state, int lookaheadnum)
+resolve_sr_conflict (int state, int lookahead)
 {
   int i;
   /* find the rule to reduce by to get precedence of reduction  */
-  int redprec = rule_table[LAruleno[lookaheadnum]].prec;
+  int redprec = rule_table[LAruleno[lookahead]].prec;
   errs *errp = ERRS_ALLOC (ntokens + 1);
   short *errtokens = errp->errs;
 
   for (i = 0; i < ntokens; i++)
-    if (BITISSET (LA (lookaheadnum), i)
+    if (BITISSET (LA (lookahead), i)
        && BITISSET (lookaheadset, i)
        && sprec[i])
-      /* Shift-reduce conflict occurs for token number i
-        and it has a precedence.
-        The precedence of shifting is that of token i.  */
       {
+       /* Shift-reduce conflict occurs for token number i
+          and it has a precedence.
+          The precedence of shifting is that of token i.  */
        if (sprec[i] < redprec)
          {
-           log_resolution (state, lookaheadnum, i, _("reduce"));
-           /* flush the shift for this token */
-           RESETBIT (lookaheadset, i);
+           log_resolution (state, lookahead, i, _("reduce"));
            flush_shift (state, i);
          }
        else if (sprec[i] > redprec)
          {
-           log_resolution (state, lookaheadnum, i, _("shift"));
-           /* flush the reduce for this token */
-           RESETBIT (LA (lookaheadnum), i);
+           log_resolution (state, lookahead, i, _("shift"));
+           flush_reduce (lookahead, i);
          }
        else
-         {
-           /* Matching precedence levels.
-              For left association, keep only the reduction.
-              For right association, keep only the shift.
-              For nonassociation, keep neither.  */
-
-           switch (sassoc[i])
-             {
-             case right_assoc:
-               log_resolution (state, lookaheadnum, i, _("shift"));
-               break;
-
-             case left_assoc:
-               log_resolution (state, lookaheadnum, i, _("reduce"));
-               break;
-
-             case non_assoc:
-               log_resolution (state, lookaheadnum, i, _("an error"));
-               break;
-             }
-
-           if (sassoc[i] != right_assoc)
-             {
-               /* flush the shift for this token */
-               RESETBIT (lookaheadset, i);
-               flush_shift (state, i);
-             }
-           if (sassoc[i] != left_assoc)
-             {
-               /* flush the reduce for this token */
-               RESETBIT (LA (lookaheadnum), i);
-             }
-           if (sassoc[i] == non_assoc)
-             {
-               /* Record an explicit error for this token.  */
-               *errtokens++ = i;
-             }
-         }
+         /* Matching precedence levels.
+            For left association, keep only the reduction.
+            For right association, keep only the shift.
+            For nonassociation, keep neither.  */
+
+         switch (sassoc[i])
+           {
+           case right_assoc:
+             log_resolution (state, lookahead, i, _("shift"));
+             flush_reduce (lookahead, i);
+             break;
+
+           case left_assoc:
+             log_resolution (state, lookahead, i, _("reduce"));
+             flush_shift (state, i);
+             break;
+
+           case non_assoc:
+             log_resolution (state, lookahead, i, _("an error"));
+             flush_shift (state, i);
+             flush_reduce (lookahead, i);
+             /* Record an explicit error for this token.  */
+             *errtokens++ = i;
+             break;
+           }
       }
 
   errp->nerrs = errtokens - errp->errs;