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;
+/* 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;
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.
*/
}
-/*------------------------------------------------------------------.
-| 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);
- statep->shifts = sp;
- sp->shifts[0] = nstates;
-}
-
-
-/*-----------------------------------------------------------------.
-| 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);
- statep->shifts = sp;
- sp->shifts[0] = nstates;
-}
-
-
-/*---------------------------------------------------------------.
-| 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_state->shifts->nshifts)
- {
- /* The first state has no shifts. Make one shift, from the
- initial state to the next-to-final state. */
-
- shifts *sp = shifts_new (1);
- first_state->shifts = sp;
- sp->shifts[0] = nstates;
-
- /* Create the next-to-final state, with shift to
- what will be the final state. */
- insert_start_shifting_state ();
- }
- else
- {
- state_t *statep = first_state->next;
- /* The states reached by shifts from FIRST_STATE are numbered
- 1..(SP->NSHIFTS). Look for one reached by START_SYMBOL.
- This is typical of `start: start ... ;': there is a state
- with the item `start: start . ...'. We want to add a `shift
- on EOF to eof-shifting state here. */
- while (statep->accessing_symbol != start_symbol
- && statep->number < first_state->shifts->nshifts)
- statep = statep->next;
-
- if (statep->accessing_symbol == start_symbol)
- {
- /* We already have STATEP, a next-to-final state for `start:
- start . ...'. Make sure it has a shift to what will be
- the final state. */
- int i;
-
- /* Find the shift of the inital state that leads to STATEP. */
- shifts *sp = statep->shifts;
-
- shifts *sp1 = shifts_new (sp->nshifts + 1);
- statep->shifts = sp1;
- sp1->shifts[0] = nstates;
- for (i = sp->nshifts; i > 0; i--)
- sp1->shifts[i] = sp->shifts[i - 1];
-
- XFREE (sp);
-
- insert_eof_shifting_state ();
- }
- else
- {
- /* There is no state for `start: start . ...'. */
- int i, k;
- shifts *sp = first_state->shifts;
- shifts *sp1 = NULL;
-
- /* Add one more shift to the initial state, going to the
- next-to-final state (yet to be made). */
- sp1 = shifts_new (sp->nshifts + 1);
- first_state->shifts = sp1;
- /* 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)
- sp1->shifts[k++] = nstates;
- sp1->shifts[k] = sp->shifts[i];
- statep = statep->next;
- }
- if (i == k)
- sp1->shifts[k++] = nstates;
-
- XFREE (sp);
-
- /* Create the next-to-final state, with shift to what will
- be the final state. Corresponds to `start: start . ...'. */
- insert_start_shifting_state ();
- }
- }
-
- insert_accepting_state ();
-}
-
-
/*----------------------------------------------------------------.
| Find which rules can be used for reduction transitions from the |
| current state and make a reductions structure for the state to |
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]];
\f
/*--------------------.
-| Build STATE_TABLE. |
+| Build STATES. |
`--------------------*/
static void
-set_state_table (void)
+set_states (void)
{
state_t *sp;
- state_table = XCALLOC (state_t *, nstates);
+ states = XCALLOC (state_t *, nstates);
for (sp = first_state; sp; sp = sp->next)
{
if (!sp->reductions)
sp->reductions = reductions_new (0);
- state_table[sp->number] = sp;
+ states[sp->number] = sp;
}
}
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 STATE_TABLE. */
- set_state_table ();
+ /* Set up STATES. */
+ set_states ();
}
projects / bison.git / blobdiff