tokens they accept. */
#include "system.h"
+#include "reader.h"
#include "types.h"
#include "LR0.h"
+#include "symtab.h"
#include "gram.h"
#include "complain.h"
#include "lalr.h"
#include "derives.h"
#include "getargs.h"
-/* All the decorated states, indexed by the state number. Warning:
- there is a state_TABLE in LR0.c, but it is different and static.
- */
-state_t *state_table = NULL;
+/* All the decorated states, indexed by the state number. */
+state_t **states = NULL;
int tokensetsize;
short *LAruleno;
unsigned *LA;
+size_t nLA;
static int ngotos;
short *goto_map;
break;
for (k = 0; k < size; ++k)
- F (i)[k] = F (j)[k];
+ F (j)[k] = F (i)[k];
}
}
}
-/*--------------------.
-| Build STATE_TABLE. |
-`--------------------*/
-
-static void
-set_state_table (void)
-{
- /* NSTATES + 1 because lookahead for the pseudo state number NSTATES
- might be used (see conflicts.c). It is too opaque for me to
- provide a probably less hacky implementation. --akim */
- state_table = XCALLOC (state_t, nstates + 1);
-
- {
- core *sp;
- for (sp = first_state; sp; sp = sp->next)
- {
- state_table[sp->number].state = sp;
- state_table[sp->number].accessing_symbol = sp->accessing_symbol;
- }
- }
-
- {
- shifts *sp;
- for (sp = first_shift; sp; sp = sp->next)
- state_table[sp->number].shifts = sp;
- }
-
- {
- reductions *rp;
- for (rp = first_reduction; rp; rp = rp->next)
- state_table[rp->number].reductions = rp;
- }
-
- /* Pessimization, but simplification of the code: make sense all the
- states have a shifts, even if reduced to 0 shifts. */
- {
- int i;
- for (i = 0; i < nstates; i++)
- if (!state_table[i].shifts)
- state_table[i].shifts = shifts_new (0);
- }
-
- /* Initializing the lookaheads members. Please note that it must be
- performed after having set some of the other members which are
- used below. Change with extreme caution. */
- {
- int i;
- int count = 0;
- for (i = 0; i < nstates; i++)
- {
- int k;
- reductions *rp = state_table[i].reductions;
- shifts *sp = state_table[i].shifts;
-
- state_table[i].lookaheads = count;
-
- if (rp
- && (rp->nreds > 1 || (sp->nshifts && SHIFT_IS_SHIFT (sp, 0))))
- count += rp->nreds;
- else
- state_table[i].consistent = 1;
-
- for (k = 0; k < sp->nshifts; k++)
- if (SHIFT_IS_ERROR (sp, k))
- {
- state_table[i].consistent = 0;
- break;
- }
- }
- state_table[nstates].lookaheads = count;
- }
-}
-
-
static void
initialize_LA (void)
{
int i;
int j;
short *np;
- reductions *rp;
- size_t nLA = state_table[nstates].lookaheads;
+ /* Avoid having to special case 0. */
if (!nLA)
nLA = 1;
np = LAruleno;
for (i = 0; i < nstates; i++)
- if (!state_table[i].consistent)
- if ((rp = state_table[i].reductions))
- for (j = 0; j < rp->nreds; j++)
- *np++ = rp->rules[j];
+ if (!states[i]->consistent)
+ for (j = 0; j < states[i]->reductions->nreds; j++)
+ *np++ = states[i]->reductions->rules[j];
}
static void
set_goto_map (void)
{
- shifts *sp;
- int i;
- int symbol;
- int k;
+ int state, i;
short *temp_map;
- int state2;
- int state1;
goto_map = XCALLOC (short, nvars + 1) - ntokens;
temp_map = XCALLOC (short, nvars + 1) - ntokens;
ngotos = 0;
- for (sp = first_shift; sp; sp = sp->next)
- for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
- {
- symbol = state_table[sp->shifts[i]].accessing_symbol;
+ for (state = 0; state < nstates; ++state)
+ {
+ shifts *sp = states[state]->shifts;
+ for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
+ {
+ if (ngotos == MAXSHORT)
+ fatal (_("too many gotos (max %d)"), MAXSHORT);
- if (ngotos == MAXSHORT)
- fatal (_("too many gotos (max %d)"), MAXSHORT);
+ ngotos++;
+ goto_map[SHIFT_SYMBOL (sp, i)]++;
+ }
+ }
- ngotos++;
- goto_map[symbol]++;
+ {
+ int k = 0;
+ for (i = ntokens; i < nsyms; i++)
+ {
+ temp_map[i] = k;
+ k += goto_map[i];
}
- k = 0;
- for (i = ntokens; i < nsyms; i++)
- {
- temp_map[i] = k;
- k += goto_map[i];
- }
-
- for (i = ntokens; i < nsyms; i++)
- goto_map[i] = temp_map[i];
+ for (i = ntokens; i < nsyms; i++)
+ goto_map[i] = temp_map[i];
- goto_map[nsyms] = ngotos;
- temp_map[nsyms] = ngotos;
+ goto_map[nsyms] = ngotos;
+ temp_map[nsyms] = ngotos;
+ }
from_state = XCALLOC (short, ngotos);
to_state = XCALLOC (short, ngotos);
- for (sp = first_shift; sp; sp = sp->next)
+ for (state = 0; state < nstates; ++state)
{
- state1 = sp->number;
+ shifts *sp = states[state]->shifts;
for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
{
- state2 = sp->shifts[i];
- symbol = state_table[state2].accessing_symbol;
-
- k = temp_map[symbol]++;
- from_state[k] = state1;
- to_state[k] = state2;
+ int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
+ from_state[k] = state;
+ to_state[k] = sp->shifts[i];
}
}
for (i = 0; i < ngotos; i++)
{
int stateno = to_state[i];
- shifts *sp = state_table[stateno].shifts;
+ shifts *sp = states[stateno]->shifts;
int j;
for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
- {
- int symbol = state_table[sp->shifts[j]].accessing_symbol;
- SETBIT (F (i), symbol);
- }
+ SETBIT (F (i), SHIFT_SYMBOL (sp, j));
for (; j < sp->nshifts; j++)
{
- int symbol = state_table[sp->shifts[j]].accessing_symbol;
+ int symbol = SHIFT_SYMBOL (sp, j);
if (nullable[symbol])
edge[nedges++] = map_goto (stateno, symbol);
}
static void
-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state_t *state, int ruleno, int gotono)
{
int i;
- int k;
- int found;
shorts *sp;
- i = state_table[stateno].lookaheads;
- k = state_table[stateno + 1].lookaheads;
- found = 0;
- while (!found && i < k)
- {
- if (LAruleno[i] == ruleno)
- found = 1;
- else
- i++;
- }
+ for (i = 0; i < state->nlookaheads; ++i)
+ if (LAruleno[state->lookaheadsp + i] == ruleno)
+ break;
- assert (found);
+ assert (LAruleno[state->lookaheadsp + i] == ruleno);
sp = XCALLOC (shorts, 1);
- sp->next = lookback[i];
+ sp->next = lookback[state->lookaheadsp + i];
sp->value = gotono;
- lookback[i] = sp;
+ lookback[state->lookaheadsp + i] = sp;
}
build_relations (void)
{
short *edge = XCALLOC (short, ngotos + 1);
- short *states = XCALLOC (short, ritem_longest_rhs () + 1);
+ short *states1 = XCALLOC (short, ritem_longest_rhs () + 1);
int i;
includes = XCALLOC (short *, ngotos);
for (i = 0; i < ngotos; i++)
{
int nedges = 0;
- int state1 = from_state[i];
- int symbol1 = state_table[to_state[i]].accessing_symbol;
+ int symbol1 = states[to_state[i]]->accessing_symbol;
short *rulep;
for (rulep = derives[symbol1]; *rulep > 0; rulep++)
{
int done;
int length = 1;
- int stateno = state1;
short *rp;
- states[0] = state1;
+ state_t *state = states[from_state[i]];
+ states1[0] = state->number;
- for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++)
+ for (rp = &ritem[rules[*rulep].rhs]; *rp >= 0; rp++)
{
- shifts *sp = state_table[stateno].shifts;
+ shifts *sp = state->shifts;
int j;
for (j = 0; j < sp->nshifts; j++)
{
- stateno = sp->shifts[j];
- if (state_table[stateno].accessing_symbol == *rp)
+ state = states[sp->shifts[j]];
+ if (state->accessing_symbol == *rp)
break;
}
- states[length++] = stateno;
+ states1[length++] = state->number;
}
- if (!state_table[stateno].consistent)
- add_lookback_edge (stateno, *rulep, i);
+ if (!state->consistent)
+ add_lookback_edge (state, *rulep, i);
length--;
done = 0;
/* JF added rp>=ritem && I hope to god its right! */
if (rp >= ritem && ISVAR (*rp))
{
- stateno = states[--length];
- edge[nedges++] = map_goto (stateno, *rp);
+ edge[nedges++] = map_goto (states1[--length], *rp);
if (nullable[*rp])
done = 0;
}
}
XFREE (edge);
- XFREE (states);
+ XFREE (states1);
includes = transpose (includes, ngotos);
}
static void
compute_lookaheads (void)
{
- int i;
+ size_t i;
shorts *sp;
- for (i = 0; i < state_table[nstates].lookaheads; i++)
+ for (i = 0; i < nLA; i++)
for (sp = lookback[i]; sp; sp = sp->next)
{
int size = LA (i + 1) - LA (i);
}
/* Free LOOKBACK. */
- for (i = 0; i < state_table[nstates].lookaheads; i++)
+ for (i = 0; i < nLA; i++)
LIST_FREE (shorts, lookback[i]);
XFREE (lookback);
}
+/*--------------------------------------.
+| Initializing the lookaheads members. |
+`--------------------------------------*/
+
+static void
+initialize_lookaheads (void)
+{
+ int i;
+ nLA = 0;
+ for (i = 0; i < nstates; i++)
+ {
+ int k;
+ int nlookaheads = 0;
+ reductions *rp = states[i]->reductions;
+ shifts *sp = states[i]->shifts;
+
+ /* 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->nreds > 1
+ || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))
+ nlookaheads += rp->nreds;
+ else
+ states[i]->consistent = 1;
+
+ for (k = 0; k < sp->nshifts; k++)
+ if (SHIFT_IS_ERROR (sp, k))
+ {
+ states[i]->consistent = 0;
+ break;
+ }
+
+ states[i]->nlookaheads = nlookaheads;
+ states[i]->lookaheadsp = nLA;
+ nLA += nlookaheads;
+ }
+}
+
+
+/*---------------------------------------.
+| Output the lookaheads for each state. |
+`---------------------------------------*/
+
+static void
+lookaheads_print (FILE *out)
+{
+ int i, j, k;
+ fprintf (out, "Lookaheads: BEGIN\n");
+ for (i = 0; i < nstates; ++i)
+ {
+ fprintf (out, "State %d: %d lookaheads\n",
+ i, states[i]->nlookaheads);
+
+ for (j = 0; j < states[i]->nlookaheads; ++j)
+ for (k = 0; k < ntokens; ++k)
+ if (BITISSET (LA (states[i]->lookaheadsp + j), j))
+ fprintf (out, " on %d (%s) -> rule %d\n",
+ k, symbols[k]->tag,
+ -LAruleno[states[i]->lookaheadsp + j] - 1);
+ }
+ fprintf (out, "Lookaheads: END\n");
+}
+
void
lalr (void)
{
tokensetsize = WORDSIZE (ntokens);
- set_state_table ();
+ initialize_lookaheads ();
initialize_LA ();
set_goto_map ();
initialize_F ();
build_relations ();
compute_FOLLOWS ();
compute_lookaheads ();
+
+ if (trace_flag)
+ lookaheads_print (stderr);
}
projects / bison.git / blobdiff