/* Find and resolve or report look-ahead conflicts for bison,
- Copyright 1984, 1989, 1992, 2000, 2001 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.
02111-1307, USA. */
#include "system.h"
+
+#include <bitset.h>
+
+#include "LR0.h"
#include "complain.h"
-#include "getargs.h"
+#include "conflicts.h"
#include "files.h"
+#include "getargs.h"
#include "gram.h"
-#include "state.h"
#include "lalr.h"
-#include "conflicts.h"
#include "reader.h"
-#include "LR0.h"
+#include "state.h"
+#include "symtab.h"
/* -1 stands for not specified. */
int expected_conflicts = -1;
static char *conflicts = NULL;
+struct obstack solved_conflicts_obstack;
+
+static bitset shiftset;
+static bitset lookaheadset;
-static unsigned *shiftset = NULL;
-static unsigned *lookaheadset = NULL;
\f
+enum conflict_resolution
+ {
+ 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 (int state, int LAno, int token, char *resolution)
+log_resolution (rule *r, symbol_number token,
+ enum conflict_resolution resolution)
{
- if (verbose_flag)
- obstack_fgrow4 (&output_obstack,
- _("\
-Conflict in state %d between rule %d and token %s resolved as %s.\n"),
- state, LAruleno[LAno], tags[token], resolution);
+ if (report_flag & report_solved_conflicts)
+ {
+ /* The description of the resolution. */
+ switch (resolution)
+ {
+ case shift_resolution:
+ case right_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as shift"),
+ r->number,
+ symbols[token]->tag);
+ break;
+ case reduce_resolution:
+ case left_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as reduce"),
+ r->number,
+ symbols[token]->tag);
+ break;
+ case nonassoc_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ _("\
+ Conflict between rule %d and token %s resolved as an error"),
+ r->number,
+ symbols[token]->tag);
+ break;
+ }
+
+ /* The reason. */
+ switch (resolution)
+ {
+ case shift_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ " (%s < %s)",
+ r->prec->tag,
+ symbols[token]->tag);
+ break;
+
+ case reduce_resolution:
+ obstack_fgrow2 (&solved_conflicts_obstack,
+ " (%s < %s)",
+ symbols[token]->tag,
+ r->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_shift (int state, int token)
+flush_shift (state *s, int token)
{
- shifts *shiftp = state_table[state]->shifts;
+ transitions *trans = s->transitions;
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);
+ bitset_reset (lookaheadset, token);
+ for (i = 0; i < trans->num; i++)
+ if (!TRANSITION_IS_DISABLED (trans, i)
+ && TRANSITION_SYMBOL (trans, i) == token)
+ TRANSITION_DISABLE (trans, i);
}
`-------------------------------------------------------------------*/
static void
-flush_reduce (int lookahead, int token)
+flush_reduce (bitset lookaheads, int token)
{
- RESETBIT (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. |
+| |
+| ERRORS can be used to store discovered explicit errors. |
`------------------------------------------------------------------*/
static void
-resolve_sr_conflict (int state, int lookahead)
+resolve_sr_conflict (state *s, int ruleno, symbol **errors)
{
- int i;
- /* find the rule to reduce by to get precedence of reduction */
- int redprec = rule_table[LAruleno[lookahead]].prec;
- errs *errp = ERRS_ALLOC (ntokens + 1);
- short *errtokens = errp->errs;
+ symbol_number i;
+ reductions *reds = s->reductions;
+ /* Find the rule to reduce by to get precedence of reduction. */
+ rule *redrule = reds->rules[ruleno];
+ int redprec = redrule->prec->prec;
+ bitset lookaheads = reds->lookaheads[ruleno];
+ int nerrs = 0;
for (i = 0; i < ntokens; i++)
- if (BITISSET (LA (lookahead), i)
- && BITISSET (lookaheadset, i)
- && sprec[i])
+ if (bitset_test (lookaheads, i)
+ && bitset_test (lookaheadset, i)
+ && symbols[i]->prec)
{
/* 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)
+ if (symbols[i]->prec < redprec)
{
- log_resolution (state, lookahead, i, _("reduce"));
- flush_shift (state, i);
+ log_resolution (redrule, i, reduce_resolution);
+ flush_shift (s, i);
}
- else if (sprec[i] > redprec)
+ 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.
For right association, keep only the shift.
For nonassociation, keep neither. */
- switch (sassoc[i])
+ 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"));
- flush_shift (state, i);
+ log_resolution (redrule, i, left_resolution);
+ flush_shift (s, i);
break;
case non_assoc:
- log_resolution (state, lookahead, i, _("an error"));
- flush_shift (state, i);
- flush_reduce (lookahead, i);
+ log_resolution (redrule, i, nonassoc_resolution);
+ flush_shift (s, i);
+ flush_reduce (lookaheads, i);
/* Record an explicit error for this token. */
- *errtokens++ = i;
+ errors[nerrs++] = symbols[i];
break;
+
+ case undef_assoc:
+ abort ();
}
}
- errp->nerrs = errtokens - errp->errs;
/* Some tokens have been explicitly made errors. Allocate a
permanent errs structure for this state, to record them. */
- i = (char *) errtokens - (char *) errp;
- state_table[state]->errs = ERRS_ALLOC (i + 1);
- memcpy (state_table[state]->errs, errp, i);
- free (errp);
+ state_errs_set (s, nerrs, errors);
+
+ if (obstack_object_size (&solved_conflicts_obstack))
+ {
+ obstack_1grow (&solved_conflicts_obstack, '\0');
+ s->solved_conflicts = obstack_finish (&solved_conflicts_obstack);
+ }
}
+/*-------------------------------------------------------------------.
+| Solve the S/R conflicts of state S using the |
+| precedence/associativity, and flag it inconsistent if it still has |
+| conflicts. ERRORS can be used as storage to compute the list of |
+| lookaheads on which S raises a syntax error (%nonassoc). |
+`-------------------------------------------------------------------*/
+
static void
-set_conflicts (int state)
+set_conflicts (state *s, symbol **errors)
{
- int i, j;
- shifts *shiftp;
+ int i;
+ transitions *trans = s->transitions;
+ reductions *reds = s->reductions;
- if (state_table[state]->consistent)
+ if (s->consistent)
return;
- for (i = 0; i < tokensetsize; i++)
- lookaheadset[i] = 0;
+ bitset_zero (lookaheadset);
- shiftp = state_table[state]->shifts;
- for (i = 0; i < shiftp->nshifts && SHIFT_IS_SHIFT (shiftp, i); i++)
- if (!SHIFT_IS_DISABLED (shiftp, i))
- SETBIT (lookaheadset, SHIFT_SYMBOL (shiftp, i));
+ FOR_EACH_SHIFT (trans, i)
+ bitset_set (lookaheadset, TRANSITION_SYMBOL (trans, i));
/* Loop over all rules which require lookahead in this state. First
check for shift-reduce conflict, and try to resolve using
- precedence */
- for (i = state_table[state]->lookaheads;
- i < state_table[state + 1]->lookaheads;
- ++i)
- if (rule_table[LAruleno[i]].prec)
- for (j = 0; j < tokensetsize; ++j)
- if (LA (i)[j] & lookaheadset[j])
- {
- resolve_sr_conflict (state, i);
- break;
- }
-
+ precedence. */
+ for (i = 0; i < reds->num; ++i)
+ if (reds->rules[i]->prec && reds->rules[i]->prec->prec
+ && !bitset_disjoint_p (reds->lookaheads[i], lookaheadset))
+ {
+ resolve_sr_conflict (s, i, errors);
+ break;
+ }
/* Loop over all rules which require lookahead in this state. Check
for conflicts not resolved above. */
- for (i = state_table[state]->lookaheads;
- i < state_table[state + 1]->lookaheads;
- ++i)
+ for (i = 0; i < reds->num; ++i)
{
- for (j = 0; j < tokensetsize; ++j)
- if (LA (i)[j] & lookaheadset[j])
- conflicts[state] = 1;
+ if (!bitset_disjoint_p (reds->lookaheads[i], lookaheadset))
+ conflicts[s->number] = 1;
- for (j = 0; j < tokensetsize; ++j)
- lookaheadset[j] |= LA (i)[j];
+ bitset_or (lookaheadset, lookaheadset, reds->lookaheads[i]);
}
}
+
+/*----------------------------------------------------------------.
+| Solve all the S/R conflicts using the precedence/associativity, |
+| and flag as inconsistent the states that still have conflicts. |
+`----------------------------------------------------------------*/
+
void
-solve_conflicts (void)
+conflicts_solve (void)
{
- int i;
+ state_number i;
+ /* List of lookaheads on which we explicitly raise a syntax error. */
+ symbol **errors = XMALLOC (symbol *, ntokens + 1);
conflicts = XCALLOC (char, nstates);
- shiftset = XCALLOC (unsigned, tokensetsize);
- lookaheadset = XCALLOC (unsigned, tokensetsize);
+ shiftset = bitset_create (ntokens, BITSET_FIXED);
+ lookaheadset = bitset_create (ntokens, BITSET_FIXED);
+ obstack_init (&solved_conflicts_obstack);
for (i = 0; i < nstates; i++)
- set_conflicts (i);
+ {
+ set_conflicts (states[i], errors);
+
+ /* For uniformity of the code, make sure all the states have a valid
+ `errs' member. */
+ if (!states[i]->errs)
+ states[i]->errs = errs_new (0, 0);
+ }
+
+ free (errors);
}
`---------------------------------------------*/
static int
-count_sr_conflicts (int state)
+count_sr_conflicts (state *s)
{
- int i, k;
+ int i;
int src_count = 0;
- shifts *shiftp = state_table[state]->shifts;
+ transitions *trans = s->transitions;
+ reductions *reds = s->reductions;
- if (!shiftp)
+ if (!trans)
return 0;
- for (i = 0; i < tokensetsize; i++)
- {
- shiftset[i] = 0;
- lookaheadset[i] = 0;
- }
+ bitset_zero (lookaheadset);
+ bitset_zero (shiftset);
- for (i = 0; i < shiftp->nshifts && SHIFT_IS_SHIFT (shiftp, i); i++)
- if (!SHIFT_IS_DISABLED (shiftp, i))
- SETBIT (shiftset, SHIFT_SYMBOL (shiftp, i));
+ FOR_EACH_SHIFT (trans, i)
+ bitset_set (shiftset, TRANSITION_SYMBOL (trans, i));
- for (i = state_table[state]->lookaheads;
- i < state_table[state + 1]->lookaheads;
- ++i)
- for (k = 0; k < tokensetsize; ++k)
- lookaheadset[k] |= LA (i)[k];
+ for (i = 0; i < reds->num; ++i)
+ bitset_or (lookaheadset, lookaheadset, reds->lookaheads[i]);
- for (k = 0; k < tokensetsize; ++k)
- lookaheadset[k] &= shiftset[k];
+ bitset_and (lookaheadset, lookaheadset, shiftset);
- for (i = 0; i < ntokens; i++)
- if (BITISSET (lookaheadset, i))
- src_count++;
+ src_count = bitset_count (lookaheadset);
return src_count;
}
-/*----------------------------------------------.
-| Count the number of reduce/reduce conflicts. |
-`----------------------------------------------*/
+/*----------------------------------------------------------------.
+| Count the number of reduce/reduce conflicts. If ONE_PER_TOKEN, |
+| count one conflict for each token that has any reduce/reduce |
+| conflicts. Otherwise, count one conflict for each pair of |
+| conflicting reductions. |
++`----------------------------------------------------------------*/
static int
-count_rr_conflicts (int state)
+count_rr_conflicts (state *s, int one_per_token)
{
int i;
+ reductions *reds = s->reductions;
int rrc_count = 0;
- int m = state_table[state]->lookaheads;
- int n = state_table[state + 1]->lookaheads;
-
- if (n - m < 2)
- return 0;
-
for (i = 0; i < ntokens; i++)
{
int count = 0;
int j;
- for (j = m; j < n; j++)
- if (BITISSET (LA (m), j))
+ for (j = 0; j < reds->num; ++j)
+ if (bitset_test (reds->lookaheads[j], i))
count++;
if (count >= 2)
- rrc_count++;
+ rrc_count += one_per_token ? 1 : count-1;
}
return rrc_count;
}
+
/*--------------------------------------------------------------.
| Return a human readable string which reports shift/reduce and |
| reduce/reduce conflict numbers (SRC_NUM, RRC_NUM). |
cp += strlen (cp);
}
- *cp++ = '.';
- *cp++ = '\n';
*cp++ = '\0';
return res;
}
+/*----------------------------------------------------------------.
+| Same as above, but report the number of conflicts a` la POSIX. |
+`----------------------------------------------------------------*/
+
+static void
+conflict_report_yacc (int src_num, int rrc_num)
+{
+ /* If invoked with `--yacc', use the output format specified by
+ POSIX. */
+ fprintf (stderr, _("conflicts: "));
+ if (src_num > 0)
+ fprintf (stderr, _(" %d shift/reduce"), src_num);
+ if (src_num > 0 && rrc_num > 0)
+ fprintf (stderr, ",");
+ if (rrc_num > 0)
+ fprintf (stderr, _(" %d reduce/reduce"), rrc_num);
+ putc ('\n', stderr);
+}
+
+
/*-----------------------------------------------------------.
| Output the detailed description of states with conflicts. |
`-----------------------------------------------------------*/
void
conflicts_output (FILE *out)
{
- bool printed_sth = FALSE;
- int i;
+ bool printed_sth = false;
+ state_number i;
+ for (i = 0; i < nstates; i++)
+ {
+ state *s = states[i];
+ if (conflicts[i])
+ {
+ fprintf (out, _("State %d contains "), i);
+ fprintf (out, "%s.\n",
+ conflict_report (count_sr_conflicts (s),
+ count_rr_conflicts (s, true)));
+ printed_sth = true;
+ }
+ }
+ if (printed_sth)
+ fputs ("\n\n", out);
+}
+
+/*--------------------------------------------------------.
+| Total the number of S/R and R/R conflicts. Unlike the |
+| code in conflicts_output, however, count EACH pair of |
+| reductions for the same state and lookahead as one |
+| conflict. |
+`--------------------------------------------------------*/
+
+int
+conflicts_total_count (void)
+{
+ state_number i;
+ int count;
+
+ /* Conflicts by state. */
+ count = 0;
for (i = 0; i < nstates; i++)
if (conflicts[i])
{
- fprintf (out, _("State %d contains "), i);
- fputs (conflict_report (count_sr_conflicts (i),
- count_rr_conflicts (i)), out);
- printed_sth = TRUE;
+ count += count_sr_conflicts (states[i]);
+ count += count_rr_conflicts (states[i], false);
}
- if (printed_sth)
- fputs ("\n\n", out);
+ return count;
}
void
conflicts_print (void)
{
- int i;
-
/* Is the number of SR conflicts OK? Either EXPECTED_CONFLICTS is
not set, and then we want 0 SR, or else it is specified, in which
case we want equality. */
int rrc_total = 0;
/* Conflicts by state. */
- for (i = 0; i < nstates; i++)
- if (conflicts[i])
- {
- src_total += count_sr_conflicts (i);
- rrc_total += count_rr_conflicts (i);
- }
+ {
+ state_number i;
+
+ for (i = 0; i < nstates; i++)
+ if (conflicts[i])
+ {
+ src_total += count_sr_conflicts (states[i]);
+ rrc_total += count_rr_conflicts (states[i], true);
+ }
+ }
src_ok = src_total == (expected_conflicts == -1 ? 0 : expected_conflicts);
/* Report the total number of conflicts on STDERR. */
if (yacc_flag)
- {
- /* If invoked with `--yacc', use the output format specified by
- POSIX. */
- fprintf (stderr, _("conflicts: "));
- if (src_total > 0)
- fprintf (stderr, _(" %d shift/reduce"), src_total);
- if (src_total > 0 && rrc_total > 0)
- fprintf (stderr, ",");
- if (rrc_total > 0)
- fprintf (stderr, _(" %d reduce/reduce"), rrc_total);
- putc ('\n', stderr);
- }
+ conflict_report_yacc (src_total, rrc_total);
else
- {
- fprintf (stderr, _("%s contains "), infile);
- fputs (conflict_report (src_total, rrc_total), stderr);
- }
+ warn ("%s", conflict_report (src_total, rrc_total));
if (expected_conflicts != -1 && !src_ok)
- {
- complain_message_count++;
- fprintf (stderr, ngettext ("expected %d shift/reduce conflict\n",
- "expected %d shift/reduce conflicts\n",
- expected_conflicts),
- expected_conflicts);
- }
-}
-
-
-void
-print_reductions (FILE *out, int state)
-{
- int i;
- int j;
- int m = state_table[state]->lookaheads;
- int n = state_table[state + 1]->lookaheads;
- shifts *shiftp = state_table[state]->shifts;
- errs *errp = state_table[state]->errs;
- int nodefault = 0;
-
- for (i = 0; i < tokensetsize; i++)
- shiftset[i] = 0;
-
- for (i = 0; i < shiftp->nshifts && SHIFT_IS_SHIFT (shiftp, i); i++)
- if (!SHIFT_IS_DISABLED (shiftp, i))
- {
- /* if this state has a shift for the error token, don't use a
- default rule. */
- if (SHIFT_IS_ERROR (shiftp, i))
- nodefault = 1;
- SETBIT (shiftset, SHIFT_SYMBOL (shiftp, i));
- }
-
- if (errp)
- for (i = 0; i < errp->nerrs; i++)
- if (errp->errs[i])
- SETBIT (shiftset, errp->errs[i]);
-
- if (n - m == 1 && !nodefault)
- {
- int k;
- int default_rule = LAruleno[m];
-
- for (k = 0; k < tokensetsize; ++k)
- lookaheadset[k] = LA (m)[k] & shiftset[k];
-
- for (i = 0; i < ntokens; i++)
- if (BITISSET (lookaheadset, i))
- fprintf (out, _(" %-4s\t[reduce using rule %d (%s)]\n"),
- tags[i], default_rule,
- tags[rule_table[default_rule].lhs]);
-
- fprintf (out, _(" $default\treduce using rule %d (%s)\n\n"),
- default_rule, tags[rule_table[default_rule].lhs]);
- }
- else if (n - m >= 1)
- {
- int k;
-
- int cmax = 0;
- int default_LA = -1;
- int default_rule = 0;
-
- if (!nodefault)
- for (i = m; i < n; i++)
- {
- int count = 0;
-
- for (k = 0; k < tokensetsize; ++k)
- lookaheadset[k] = LA (i)[k] & ~shiftset[k];
-
- for (j = 0; j < ntokens; j++)
- if (BITISSET (lookaheadset, j))
- count++;
-
- if (count > cmax)
- {
- cmax = count;
- default_LA = i;
- default_rule = LAruleno[i];
- }
-
- for (k = 0; k < tokensetsize; ++k)
- shiftset[k] |= lookaheadset[k];
- }
-
- for (i = 0; i < tokensetsize; i++)
- shiftset[i] = 0;
-
- for (i = 0; i < shiftp->nshifts && SHIFT_IS_SHIFT (shiftp, i); i++)
- if (!SHIFT_IS_DISABLED (shiftp, i))
- SETBIT (shiftset, SHIFT_SYMBOL (shiftp, i));
-
- for (i = 0; i < ntokens; i++)
- {
- int defaulted = 0;
- int count = BITISSET (shiftset, i);
-
- for (j = m; j < n; j++)
- {
- if (BITISSET (LA (m), j))
- {
- if (count == 0)
- {
- if (j != default_LA)
- fprintf (out,
- _(" %-4s\treduce using rule %d (%s)\n"),
- tags[i],
- LAruleno[j],
- tags[rule_table[LAruleno[j]].lhs]);
- else
- defaulted = 1;
-
- count++;
- }
- else
- {
- if (defaulted)
- fprintf (out,
- _(" %-4s\treduce using rule %d (%s)\n"),
- tags[i],
- LAruleno[default_LA],
- tags[rule_table[LAruleno[default_LA]].lhs]);
- defaulted = 0;
- fprintf (out,
- _(" %-4s\t[reduce using rule %d (%s)]\n"),
- tags[i],
- LAruleno[j],
- tags[rule_table[LAruleno[j]].lhs]);
- }
- }
- }
- }
-
- if (default_LA >= 0)
- fprintf (out, _(" $default\treduce using rule %d (%s)\n"),
- default_rule, tags[rule_table[default_rule].lhs]);
- }
+ complain (ngettext ("expected %d shift/reduce conflict",
+ "expected %d shift/reduce conflicts",
+ expected_conflicts),
+ expected_conflicts);
}
void
-free_conflicts (void)
+conflicts_free (void)
{
XFREE (conflicts);
- XFREE (shiftset);
- XFREE (lookaheadset);
+ bitset_free (shiftset);
+ bitset_free (lookaheadset);
+ obstack_free (&solved_conflicts_obstack, NULL);
}
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