} goto_list_t;
-rule_t **LArule = NULL;
-bitsetv LA = NULL;
+/* LA is a LR by NTOKENS matrix of bits. LA[l, i] is 1 if the rule
+ LArule[l] is applicable in the appropriate state when the next
+ token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j,
+ it is a conflict. */
+
+static bitsetv LA = NULL;
size_t nLA;
-static void
-initialize_LA (void)
-{
- state_number_t i;
- int j;
- rule_t **np;
-
- /* Avoid having to special case 0. */
- if (!nLA)
- nLA = 1;
-
- LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
- LArule = XCALLOC (rule_t *, nLA);
- lookback = XCALLOC (goto_list_t *, nLA);
-
- np = LArule;
- for (i = 0; i < nstates; i++)
- if (!states[i]->consistent)
- for (j = 0; j < states[i]->reductions->num; j++)
- *np++ = states[i]->reductions->rules[j];
-}
-
-
static void
set_goto_map (void)
{
int i;
for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i)
{
- if (ngotos == GOTO_NUMBER_MAX)
- fatal (_("too many gotos (max %d)"), GOTO_NUMBER_MAX);
-
+ assert (ngotos < GOTO_NUMBER_MAX);
ngotos++;
goto_map[TRANSITION_SYMBOL (sp, i)]++;
}
static void
-add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono)
+add_lookback_edge (state_t *state, rule_t *rule, int gotono)
{
- int i;
- goto_list_t *sp;
-
- for (i = 0; i < state->nlookaheads; ++i)
- if (state->lookaheads_rule[i]->number == ruleno)
- break;
-
- assert (state->lookaheads_rule[i]->number == ruleno);
-
- sp = XCALLOC (goto_list_t, 1);
- sp->next = lookback[(state->lookaheads - LA) + i];
+ int r = state_reduction_find (state, rule);
+ goto_list_t *sp = XCALLOC (goto_list_t, 1);
+ sp->next = lookback[(state->reductions->lookaheads - LA) + r];
sp->value = gotono;
- lookback[(state->lookaheads - LA) + i] = sp;
+ lookback[(state->reductions->lookaheads - LA) + r] = sp;
}
{
int nedges = 0;
symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol;
- rule_number_t *rulep;
+ rule_t **rulep;
- for (rulep = derives[symbol1]; *rulep >= 0; rulep++)
+ for (rulep = derives[symbol1]; *rulep; rulep++)
{
int done;
int length = 1;
state_t *state = states[from_state[i]];
states1[0] = state->number;
- for (rp = rules[*rulep].rhs; *rp >= 0; rp++)
+ for (rp = (*rulep)->rhs; *rp >= 0; rp++)
{
state = transitions_to (state->transitions,
item_number_as_symbol_number (*rp));
}
-/*-------------------------------------------------------------.
-| Count the number of lookaheads required for each state |
-| (NLOOKAHEADS member). Compute the total number of LA, NLA. |
-`-------------------------------------------------------------*/
+/*---------------------------------------------------------------.
+| Count the number of lookaheads required for STATE (NLOOKAHEADS |
+| member). |
+`---------------------------------------------------------------*/
-static void
-states_lookaheads_count (void)
+static int
+state_lookaheads_count (state_t *state)
{
- state_number_t i;
- nLA = 0;
-
- /* Count */
- for (i = 0; i < nstates; i++)
- {
- int k;
- int nlookaheads = 0;
- reductions_t *rp = states[i]->reductions;
- transitions_t *sp = states[i]->transitions;
-
- /* We need a lookahead either to distinguish different
- reductions (i.e., there are two or more), or to distinguish a
- reduction from a shift. Otherwise, it is straightforward,
- and the state is `consistent'. */
- if (rp->num > 1
- || (rp->num == 1 && sp->num &&
- !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
- nlookaheads += rp->num;
- else
- states[i]->consistent = 1;
-
- for (k = 0; k < sp->num; k++)
- if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
- {
- states[i]->consistent = 0;
- break;
- }
+ int k;
+ int nlookaheads = 0;
+ reductions_t *rp = state->reductions;
+ transitions_t *sp = state->transitions;
+
+ /* We need a lookahead either to distinguish different
+ reductions (i.e., there are two or more), or to distinguish a
+ reduction from a shift. Otherwise, it is straightforward,
+ and the state is `consistent'. */
+ if (rp->num > 1
+ || (rp->num == 1 && sp->num &&
+ !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0)))
+ nlookaheads += rp->num;
+ else
+ state->consistent = 1;
+
+ for (k = 0; k < sp->num; k++)
+ if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k))
+ {
+ state->consistent = 0;
+ break;
+ }
- states[i]->nlookaheads = nlookaheads;
- nLA += nlookaheads;
- }
+ return nlookaheads;
}
-/*--------------------------------------.
-| Initializing the lookaheads members. |
-`--------------------------------------*/
+/*----------------------------------------------.
+| Compute LA, NLA, and the lookaheads members. |
+`----------------------------------------------*/
static void
-states_lookaheads_initialize (void)
+initialize_LA (void)
{
state_number_t i;
- bitsetv pLA = LA;
- rule_t **pLArule = LArule;
+ bitsetv pLA;
+
+ /* Compute the total number of reductions requiring a lookahead. */
+ nLA = 0;
+ for (i = 0; i < nstates; i++)
+ nLA += state_lookaheads_count (states[i]);
+ /* Avoid having to special case 0. */
+ if (!nLA)
+ nLA = 1;
- /* Initialize the members LOOKAHEADS and LOOKAHEADS_RULE for each
- state. */
+ pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED);
+ lookback = XCALLOC (goto_list_t *, nLA);
+
+ /* Initialize the members LOOKAHEADS for each state which reductions
+ require lookaheads. */
for (i = 0; i < nstates; i++)
{
- states[i]->lookaheads = pLA;
- states[i]->lookaheads_rule = pLArule;
- pLA += states[i]->nlookaheads;
- pLArule += states[i]->nlookaheads;
+ int count = state_lookaheads_count (states[i]);
+ if (count)
+ {
+ states[i]->reductions->lookaheads = pLA;
+ pLA += count;
+ }
}
}
fprintf (out, "Lookaheads: BEGIN\n");
for (i = 0; i < nstates; ++i)
{
+ reductions_t *reds = states[i]->reductions;
bitset_iterator iter;
+ int nlookaheads = 0;
+
+ if (reds->lookaheads)
+ for (k = 0; k < reds->num; ++k)
+ if (reds->lookaheads[k])
+ ++nlookaheads;
fprintf (out, "State %d: %d lookaheads\n",
- i, states[i]->nlookaheads);
+ i, nlookaheads);
- for (j = 0; j < states[i]->nlookaheads; ++j)
- BITSET_FOR_EACH (iter, states[i]->lookaheads[j], k, 0)
- {
- fprintf (out, " on %d (%s) -> rule %d\n",
- k, symbols[k]->tag,
- states[i]->lookaheads_rule[j]->number);
- };
+ if (reds->lookaheads)
+ for (j = 0; j < reds->num; ++j)
+ BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0)
+ {
+ fprintf (out, " on %d (%s) -> rule %d\n",
+ k, symbols[k]->tag,
+ reds->rules[j]->number);
+ };
}
fprintf (out, "Lookaheads: END\n");
}
void
lalr (void)
{
- states_lookaheads_count ();
initialize_LA ();
- states_lookaheads_initialize ();
set_goto_map ();
initialize_F ();
build_relations ();
if (trace_flag & trace_sets)
lookaheads_print (stderr);
}
+
+
+void
+lalr_free (void)
+{
+ state_number_t s;
+ for (s = 0; s < nstates; ++s)
+ states[s]->reductions->lookaheads = NULL;
+ bitsetv_free (LA);
+}
projects / bison.git / blobdiff