The entry point is generate_states. */
#include "system.h"
+#include "symtab.h"
#include "getargs.h"
#include "reader.h"
#include "gram.h"
#include "reduce.h"
int nstates;
-int final_state;
-state_t *first_state = NULL;
-shifts *first_shift = NULL;
+/* Initialize the final state to -1, otherwise, it might be set to 0
+ by default, and since we don't compute the reductions of the final
+ state, we end up not computing the reductions of the initial state,
+ which is of course needed.
+
+ FINAL_STATE is properly set by new_state when it recognizes the
+ accessing symbol: EOF. */
+int final_state = -1;
+static state_t *first_state = NULL;
static state_t *this_state = NULL;
static state_t *last_state = NULL;
-static shifts *last_shift = NULL;
static int nshifts;
static short *shift_symbol = NULL;
int count = 0;
short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals);
- for (i = 0; ritem[i]; ++i)
- if (ritem[i] > 0)
+ for (i = 0; i < nritems; ++i)
+ if (ritem[i] >= 0)
{
count++;
symbol_count[ritem[i]]++;
shiftset = XCALLOC (short, nsyms);
redset = XCALLOC (short, nrules + 1);
state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
+ shift_symbol = XCALLOC (short, nsyms);
}
for (i = 0; i < nsyms; i++)
kernel_size[i] = 0;
- shift_symbol = XCALLOC (short, nsyms);
nshifts = 0;
for (i = 0; i < nitemset; ++i)
{
int symbol = ritem[itemset[i]];
- if (symbol > 0)
+ if (symbol >= 0)
{
if (!kernel_size[symbol])
{
if (trace_flag)
fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
- this_state->number, symbol, tags[symbol]);
+ this_state->number, symbol, symbols[symbol]->tag);
if (nstates >= MAXSHORT)
fatal (_("too many states (max %d)"), MAXSHORT);
last_state = p;
nstates++;
+ /* If this is the eoftoken, then this is the final state. */
+ if (symbol == 0)
+ final_state = p->number;
+
return p;
}
if (trace_flag)
fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
- this_state->number, symbol, tags[symbol]);
+ this_state->number, symbol, symbols[symbol]->tag);
/* Add up the target state's active item numbers to get a hash key.
*/
save_shifts (void)
{
shifts *p = shifts_new (nshifts);
-
- p->number = this_state->number;
-
shortcpy (p->shifts, shiftset, nshifts);
-
- if (last_shift)
- last_shift->next = p;
- else
- first_shift = p;
- last_shift = p;
-}
-
-
-/*------------------------------------------------------------------.
-| Subroutine of augment_automaton. Create the next-to-final state, |
-| to which a shift has already been made in the initial state. |
-| |
-| The task of this state consists in shifting (actually, it's a |
-| goto, but shifts and gotos are both stored in SHIFTS) the start |
-| symbols, hence the name. |
-`------------------------------------------------------------------*/
-
-static void
-insert_start_shifting_state (void)
-{
- state_t *statep;
- shifts *sp;
-
- statep = STATE_ALLOC (0);
- statep->number = nstates;
-
- /* The distinctive feature of this state from the
- eof_shifting_state, is that it is labeled as post-start-symbol
- shifting. I fail to understand why this state, and the
- post-start-start can't be merged into one. But it does fail if
- you try. --akim */
- statep->accessing_symbol = start_symbol;
-
- last_state->next = statep;
- last_state = statep;
-
- /* Make a shift from this state to (what will be) the final state. */
- sp = shifts_new (1);
- sp->number = nstates++;
- sp->shifts[0] = nstates;
-
- last_shift->next = sp;
- last_shift = sp;
-}
-
-
-/*-----------------------------------------------------------------.
-| Subroutine of augment_automaton. Create the final state, which |
-| shifts `0', the end of file. The initial state shifts the start |
-| symbol, and goes to here. |
-`-----------------------------------------------------------------*/
-
-static void
-insert_eof_shifting_state (void)
-{
- state_t *statep;
- shifts *sp;
-
- /* Make the final state--the one that follows a shift from the
- next-to-final state.
- The symbol for that shift is 0 (end-of-file). */
- statep = STATE_ALLOC (0);
- statep->number = nstates;
-
- last_state->next = statep;
- last_state = statep;
-
- /* Make the shift from the final state to the termination state. */
- sp = shifts_new (1);
- sp->number = nstates++;
- sp->shifts[0] = nstates;
-
- last_shift->next = sp;
- last_shift = sp;
-}
-
-
-/*---------------------------------------------------------------.
-| Subroutine of augment_automaton. Create the accepting state. |
-`---------------------------------------------------------------*/
-
-static void
-insert_accepting_state (void)
-{
- state_t *statep;
-
- /* Note that the variable `final_state' refers to what we sometimes
- call the termination state. */
- final_state = nstates;
-
- /* Make the termination state. */
- statep = STATE_ALLOC (0);
- statep->number = nstates++;
- last_state->next = statep;
- last_state = statep;
-}
-
-
-
-
-
-/*------------------------------------------------------------------.
-| Make sure that the initial state has a shift that accepts the |
-| grammar's start symbol and goes to the next-to-final state, which |
-| has a shift going to the final state, which has a shift to the |
-| termination state. Create such states and shifts if they don't |
-| happen to exist already. |
-`------------------------------------------------------------------*/
-
-static void
-augment_automaton (void)
-{
- if (!first_shift->nshifts)
- {
- /* There are no shifts for any state. Make one shift, from the
- initial state to the next-to-final state. */
-
- shifts *sp = shifts_new (1);
- sp->shifts[0] = nstates;
-
- /* Initialize the chain of shifts with sp. */
- first_shift = sp;
- last_shift = sp;
-
- /* Create the next-to-final state, with shift to
- what will be the final state. */
- insert_start_shifting_state ();
- }
- else if (first_shift->number == 0)
- {
- state_t *statep = first_state->next;
- shifts *sp = first_shift;
- shifts *sp1 = NULL;
- /* The states reached by shifts from FIRST_STATE are numbered
- 1..(SP->NSHIFTS). Look for one reached by START_SYMBOL. */
- while (statep->accessing_symbol != start_symbol
- && statep->number < sp->nshifts)
- statep = statep->next;
-
- if (statep->accessing_symbol == start_symbol)
- {
- /* We already have a next-to-final state.
- Make sure it has a shift to what will be the final state. */
- while (sp && sp->number < statep->number)
- {
- sp1 = sp;
- sp = sp->next;
- }
-
- if (sp && sp->number == statep->number)
- {
- int i;
- shifts *sp2 = shifts_new (sp->nshifts + 1);
- sp2->number = statep->number;
- sp2->shifts[0] = nstates;
- for (i = sp->nshifts; i > 0; i--)
- sp2->shifts[i] = sp->shifts[i - 1];
-
- /* Patch sp2 into the chain of shifts in place of sp,
- following sp1. */
- sp2->next = sp->next;
- sp1->next = sp2;
- if (sp == last_shift)
- last_shift = sp2;
- XFREE (sp);
- }
- else
- {
- shifts *sp2 = shifts_new (1);
- sp2->number = statep->number;
- sp2->shifts[0] = nstates;
-
- /* Patch sp2 into the chain of shifts between sp1 and sp. */
- sp2->next = sp;
- sp1->next = sp2;
- if (sp == 0)
- last_shift = sp2;
- }
- }
- else
- {
- int i, k;
- shifts *sp2;
- sp = first_shift;
-
- /* There is no next-to-final state as yet. */
- /* Add one more shift in first_shift,
- going to the next-to-final state (yet to be made). */
- sp2 = shifts_new (sp->nshifts + 1);
-
- /* Stick this shift into the vector at the proper place. */
- statep = first_state->next;
- for (k = 0, i = 0; i < sp->nshifts; k++, i++)
- {
- if (statep->accessing_symbol > start_symbol && i == k)
- sp2->shifts[k++] = nstates;
- sp2->shifts[k] = sp->shifts[i];
- statep = statep->next;
- }
- if (i == k)
- sp2->shifts[k++] = nstates;
-
- /* Patch sp2 into the chain of shifts
- in place of sp, at the beginning. */
- sp2->next = sp->next;
- first_shift = sp2;
- if (last_shift == sp)
- last_shift = sp2;
-
- XFREE (sp);
-
- /* Create the next-to-final state, with shift to
- what will be the final state. */
- insert_start_shifting_state ();
- }
- }
- else
- {
- /* The initial state didn't even have any shifts.
- Give it one shift, to the next-to-final state. */
- shifts *sp = shifts_new (1);
- sp->shifts[0] = nstates;
-
- /* Patch sp into the chain of shifts at the beginning. */
- sp->next = first_shift;
- first_shift = sp;
-
- /* Create the next-to-final state, with shift to
- what will be the final state. */
- insert_start_shifting_state ();
- }
-
- insert_eof_shifting_state ();
- insert_accepting_state ();
+ this_state->shifts = p;
}
static void
save_reductions (void)
{
- int count;
+ int count = 0;
int i;
- /* Find and count the active items that represent ends of rules. */
+ /* If this is the final state, we want it to have no reductions at
+ all, although it has one for `START_SYMBOL EOF .'. */
+ if (this_state->number == final_state)
+ return;
- count = 0;
+ /* Find and count the active items that represent ends of rules. */
for (i = 0; i < nitemset; ++i)
{
int item = ritem[itemset[i]];
}
/* Make a reductions structure and copy the data into it. */
+ this_state->reductions = reductions_new (count);
+ shortcpy (this_state->reductions->rules, redset, count);
+}
- if (count)
- {
- reductions *p = REDUCTIONS_ALLOC (count);
- p->nreds = count;
- shortcpy (p->rules, redset, count);
+\f
+/*---------------.
+| Build STATES. |
+`---------------*/
- this_state->reductions = p;
+static void
+set_states (void)
+{
+ state_t *sp;
+ states = XCALLOC (state_t *, nstates);
+
+ for (sp = first_state; sp; sp = sp->next)
+ {
+ /* Pessimization, but simplification of the code: make sure all
+ the states have a shifts, errs, and reductions, even if
+ reduced to 0. */
+ if (!sp->shifts)
+ sp->shifts = shifts_new (0);
+ if (!sp->errs)
+ sp->errs = errs_new (0);
+ if (!sp->reductions)
+ sp->reductions = reductions_new (0);
+
+ states[sp->number] = sp;
}
}
-\f
/*-------------------------------------------------------------------.
| Compute the nondeterministic finite state machine (see state.h for |
| details) from the grammar. |
generate_states (void)
{
allocate_storage ();
- new_closure (nitems);
+ new_closure (nritems);
new_states ();
while (this_state)
{
if (trace_flag)
fprintf (stderr, "Processing state %d (reached by %s)\n",
- this_state->number, tags[this_state->accessing_symbol]);
+ this_state->number,
+ symbols[this_state->accessing_symbol]->tag);
/* Set up ruleset and itemset for the transitions out of this
state. ruleset gets a 1 bit for each rule that could reduce
now. itemset gets a vector of all the items that could be
free_closure ();
free_storage ();
- /* set up initial and final states as parser wants them */
- augment_automaton ();
+ /* Set up STATES. */
+ set_states ();
}
projects / bison.git / blobdiff