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Make the backtracking look like a standard Prolog box.

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This commit is contained in:
Bruno Haible
2003-02-25 12:01:50 +00:00
parent ee424350d0
commit ea37cea17b
1 changed files with 51 additions and 32 deletions
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31
src/search.cc
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@@ -993,6 +993,16 @@ Search::find_asso_values ()
} }
} }
/* Backtracking according to the standard Prolog call pattern:
+------------------+
-------CALL------>| |-------RETURN------>
| |
<------FAIL-------| |<------REDO---------
+------------------+
A CALL and RETURN increase the stack pointer, FAIL and REDO decrease it.
*/
{ {
/* Current stack pointer. */ /* Current stack pointer. */
StackEntry *sp = &stack[0]; StackEntry *sp = &stack[0];
@@ -1014,7 +1024,8 @@ Search::find_asso_values ()
/* Remaining number of iterations. */ /* Remaining number of iterations. */
int iter; int iter;
STARTOUTERLOOP: /* ==== CALL ==== */
CALL:
/* Next keyword from the list. */ /* Next keyword from the list. */
curr = sp->_curr; curr = sp->_curr;
@@ -1092,7 +1103,7 @@ Search::find_asso_values ()
fflush (stderr); fflush (stderr);
} }
goto RECURSE_COLLISION; goto RECURSE_COLLISION;
BACKTRACK_COLLISION: ; BACKTRACK_COLLISION:
if (option[DEBUG]) if (option[DEBUG])
{ {
fprintf (stderr, "back to collision on keyword #%d, prior = \"%.*s\", curr = \"%.*s\" hash = %d\n", fprintf (stderr, "back to collision on keyword #%d, prior = \"%.*s\", curr = \"%.*s\" hash = %d\n",
@@ -1126,11 +1137,19 @@ Search::find_asso_values ()
iterations); iterations);
fflush (stderr); fflush (stderr);
} }
}
else
{
/* Nothing to do, just recurse. */
goto RECURSE_NO_COLLISION;
BACKTRACK_NO_COLLISION: ;
}
BACKTRACK_NO_COLLISION: /* ==== FAIL ==== */
if (sp != stack) if (sp != stack)
{ {
sp--; sp--;
/* ==== REDO ==== */
curr = sp->_curr; curr = sp->_curr;
prior = sp->_prior; prior = sp->_prior;
if (prior == NULL) if (prior == NULL)
@@ -1154,8 +1173,7 @@ Search::find_asso_values ()
else else
fprintf (stderr, "try options -m or -r.\n\n"); fprintf (stderr, "try options -m or -r.\n\n");
exit (1); exit (1);
}
goto RECURSE_NO_COLLISION;
RECURSE_COLLISION: RECURSE_COLLISION:
/*sp->_union_set = union_set;*/ // redundant /*sp->_union_set = union_set;*/ // redundant
sp->_union_set_length = union_set_length; sp->_union_set_length = union_set_length;
@@ -1166,9 +1184,10 @@ Search::find_asso_values ()
RECURSE_NO_COLLISION: RECURSE_NO_COLLISION:
/*sp->_curr = curr;*/ // redundant /*sp->_curr = curr;*/ // redundant
sp->_prior = prior; sp->_prior = prior;
/* ==== RETURN ==== */
sp++; sp++;
if (sp - stack < _list_len) if (sp - stack < _list_len)
goto STARTOUTERLOOP; goto CALL;
} }
/* Deallocate stack. */ /* Deallocate stack. */