/* Find and resolve or report look-ahead conflicts for bison,
- Copyright 1984, 1989, 1992, 2000, 2001, 2002 Free Software Foundation, Inc.
+ Copyright (C) 1984, 1989, 1992, 2000, 2001, 2002
+ Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
/* -1 stands for not specified. */
int expected_conflicts = -1;
static char *conflicts = NULL;
+struct obstack solved_conflicts_obstack;
static bitset shiftset;
static bitset lookaheadset;
+
\f
+enum conflict_resolution_e
+ {
+ shift_resolution,
+ reduce_resolution,
+ left_resolution,
+ right_resolution,
+ nonassoc_resolution
+ };
+
+
+/*----------------------------------------------------------------.
+| Explain how an SR conflict between TOKEN and RULE was resolved: |
+| RESOLUTION. |
+`----------------------------------------------------------------*/
+
static inline void
-log_resolution (state_t *state, int LAno, int token, char *resolution)
+log_resolution (rule_t *rule, int token,
+ enum conflict_resolution_e resolution)
{
- if (verbose_flag)
- obstack_fgrow4 (&output_obstack,
- _("\
-Conflict in state %d between rule %d and token %s resolved as %s.\n"),
- state->number, LAruleno[LAno], symbols[token]->tag,
- resolution);
+ if (report_flag & report_solved_conflicts)
+ {
+ /* The description of the resolution. */
+ switch (resolution)
+ {
+ case shift_resolution:
+ case left_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as shift"),
+ rule->number,
+ symbols[token]->tag);
+ break;
+ case reduce_resolution:
+ case right_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as reduce"),
+ rule->number,
+ symbols[token]->tag);
+ break;
+ case nonassoc_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as an error"),
+ rule->number,
+ symbols[token]->tag);
+ break;
+ }
+
+ /* The reason. */
+ switch (resolution)
+ {
+ case shift_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ " (%s < %s)",
+ rule->prec->tag,
+ symbols[token]->tag);
+ break;
+
+ case reduce_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ " (%s < %s)",
+ symbols[token]->tag,
+ rule->prec->tag);
+ break;
+
+ case left_resolution:
+ obstack_fgrow1 (&solved_conflicts_obstack,
+ " (%%left %s)",
+ symbols[token]->tag);
+ break;
+
+ case right_resolution:
+ obstack_fgrow1 (&solved_conflicts_obstack,
+ " (%%right %s)",
+ symbols[token]->tag);
+ break;
+ case nonassoc_resolution:
+ obstack_fgrow1 (&solved_conflicts_obstack,
+ " (%%nonassoc %s)",
+ symbols[token]->tag);
+ break;
+ }
+ obstack_sgrow (&solved_conflicts_obstack, ".\n");
+ }
}
`-------------------------------------------------------------------*/
static void
-flush_reduce (int lookahead, int token)
+flush_reduce (bitset lookaheads, int token)
{
- bitset_reset (LA[lookahead], token);
+ bitset_reset (lookaheads, token);
}
| precedence declarations. It has already been checked that the |
| rule has a precedence. A conflict is resolved by modifying the |
| shift or reduce tables so that there is no longer a conflict. |
+| |
+| LOOKAHEAD is the number of the lookahead bitset to consider. |
`------------------------------------------------------------------*/
static void
resolve_sr_conflict (state_t *state, int lookahead)
{
int i;
- /* find the rule to reduce by to get precedence of reduction */
- int redprec = rules[LAruleno[lookahead]].prec;
+ /* Find the rule to reduce by to get precedence of reduction. */
+ rule_t *redrule = state->lookaheads_rule[lookahead];
+ int redprec = redrule->prec->prec;
+ bitset lookaheads = state->lookaheads[lookahead];
errs *errp = errs_new (ntokens + 1);
errp->nerrs = 0;
for (i = 0; i < ntokens; i++)
- if (bitset_test (LA[lookahead], i)
+ if (bitset_test (lookaheads, i)
&& bitset_test (lookaheadset, i)
&& symbols[i]->prec)
{
The precedence of shifting is that of token i. */
if (symbols[i]->prec < redprec)
{
- log_resolution (state, lookahead, i, _("reduce"));
+ log_resolution (redrule, i, reduce_resolution);
flush_shift (state, i);
}
else if (symbols[i]->prec > redprec)
{
- log_resolution (state, lookahead, i, _("shift"));
- flush_reduce (lookahead, i);
+ log_resolution (redrule, i, shift_resolution);
+ flush_reduce (lookaheads, i);
}
else
/* Matching precedence levels.
switch (symbols[i]->assoc)
{
case right_assoc:
- log_resolution (state, lookahead, i, _("shift"));
- flush_reduce (lookahead, i);
+ log_resolution (redrule, i, right_resolution);
+ flush_reduce (lookaheads, i);
break;
case left_assoc:
- log_resolution (state, lookahead, i, _("reduce"));
+ log_resolution (redrule, i, left_resolution);
flush_shift (state, i);
break;
case non_assoc:
- log_resolution (state, lookahead, i, _("an error"));
+ log_resolution (redrule, i, nonassoc_resolution);
flush_shift (state, i);
- flush_reduce (lookahead, i);
+ flush_reduce (lookaheads, i);
/* Record an explicit error for this token. */
errp->errs[errp->nerrs++] = i;
break;
+
+ case undef_assoc:
+ assert (symbols[i]->assoc != undef_assoc);
+ break;
}
}
permanent errs structure for this state, to record them. */
state->errs = errs_dup (errp);
free (errp);
+
+ if (obstack_object_size (&solved_conflicts_obstack))
+ {
+ obstack_1grow (&solved_conflicts_obstack, '\0');
+ state->solved_conflicts = obstack_finish (&solved_conflicts_obstack);
+ }
}
static void
set_conflicts (state_t *state)
{
- int i, j;
+ int i;
shifts *shiftp;
if (state->consistent)
/* Loop over all rules which require lookahead in this state. First
check for shift-reduce conflict, and try to resolve using
- precedence */
+ precedence. */
for (i = 0; i < state->nlookaheads; ++i)
- if (rules[LAruleno[state->lookaheadsp + i]].prec)
- for (j = 0; j < ntokens; ++j)
- if (bitset_test (LA[state->lookaheadsp + i], j)
- && bitset_test (lookaheadset, j))
- {
- resolve_sr_conflict (state, state->lookaheadsp + i);
- break;
- }
-
+ if (state->lookaheads_rule[i]->prec
+ && state->lookaheads_rule[i]->prec->prec
+ && !bitset_disjoint_p (state->lookaheads[i], lookaheadset))
+ {
+ resolve_sr_conflict (state, i);
+ break;
+ }
/* Loop over all rules which require lookahead in this state. Check
for conflicts not resolved above. */
for (i = 0; i < state->nlookaheads; ++i)
{
- for (j = 0; j < ntokens; ++j)
- if (bitset_test (LA[state->lookaheadsp + i], j)
- && bitset_test (lookaheadset, j))
- conflicts[state->number] = 1;
-
- for (j = 0; j < ntokens; ++j)
- if (bitset_test (LA[state->lookaheadsp + i], j))
- bitset_set (lookaheadset, j);
+ if (!bitset_disjoint_p (state->lookaheads[i], lookaheadset))
+ conflicts[state->number] = 1;
+
+ bitset_or (lookaheadset, lookaheadset, state->lookaheads[i]);
}
}
void
-solve_conflicts (void)
+conflicts_solve (void)
{
size_t i;
conflicts = XCALLOC (char, nstates);
shiftset = bitset_create (ntokens, BITSET_FIXED);
- bitset_zero (shiftset);
lookaheadset = bitset_create (ntokens, BITSET_FIXED);
- bitset_zero (lookaheadset);
+ obstack_init (&solved_conflicts_obstack);
for (i = 0; i < nstates; i++)
set_conflicts (states[i]);
static int
count_sr_conflicts (state_t *state)
{
- int i, k;
+ int i;
int src_count = 0;
shifts *shiftp = state->shifts;
bitset_set (shiftset, SHIFT_SYMBOL (shiftp, i));
for (i = 0; i < state->nlookaheads; ++i)
- for (k = 0; k < ntokens; ++k)
- if (bitset_test (LA[state->lookaheadsp + i], k))
- bitset_set (lookaheadset, k);
+ bitset_or (lookaheadset, lookaheadset, state->lookaheads[i]);
bitset_and (lookaheadset, lookaheadset, shiftset);
- for (i = 0; i < ntokens; i++)
- if (bitset_test (lookaheadset, i))
- src_count++;
+ src_count = bitset_count (lookaheadset);
return src_count;
}
int count = 0;
int j;
for (j = 0; j < state->nlookaheads; ++j)
- if (bitset_test (LA[state->lookaheadsp + j], i))
+ if (bitset_test (state->lookaheads[j], i))
count++;
if (count >= 2)
void
-free_conflicts (void)
+conflicts_free (void)
{
XFREE (conflicts);
bitset_free (shiftset);
bitset_free (lookaheadset);
+ obstack_free (&solved_conflicts_obstack, NULL);
}
projects / bison.git / blobdiff