/* Generate the nondeterministic finite state machine for bison,
- Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+ Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc.
-This file is part of Bison, the GNU Compiler Compiler.
+ This file is part of Bison, the GNU Compiler Compiler.
-Bison is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+ Bison is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
-Bison is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
+ Bison is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
-You should have received a copy of the GNU General Public License
-along with Bison; see the file COPYING. If not, write to
-the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+ You should have received a copy of the GNU General Public License
+ along with Bison; see the file COPYING. If not, write to
+ the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
/* See comments in state.h for the data structures that represent it.
The entry point is generate_states. */
-#include <stdio.h>
#include "system.h"
-#include "machine.h"
-#include "alloc.h"
+#include "symtab.h"
+#include "getargs.h"
+#include "reader.h"
#include "gram.h"
#include "state.h"
+#include "complain.h"
+#include "closure.h"
+#include "LR0.h"
+#include "lalr.h"
+#include "reduce.h"
+int nstates;
+/* 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.
-extern char *nullable;
-extern short *itemset;
-extern short *itemsetend;
-
+ 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;
-int nstates;
-int final_state;
-core *first_state;
-shifts *first_shift;
-reductions *first_reduction;
-
-int get_state PARAMS((int));
-core *new_state PARAMS((int));
-
-void allocate_itemsets PARAMS((void));
-void allocate_storage PARAMS((void));
-void free_storage PARAMS((void));
-void generate_states PARAMS((void));
-void new_itemsets PARAMS((void));
-void append_states PARAMS((void));
-void initialize_states PARAMS((void));
-void save_shifts PARAMS((void));
-void save_reductions PARAMS((void));
-void augment_automaton PARAMS((void));
-void insert_start_shift PARAMS((void));
-extern void initialize_closure PARAMS((int));
-extern void closure PARAMS((short *, int));
-extern void finalize_closure PARAMS((void));
-extern void toomany PARAMS((char *));
-
-static core *this_state;
-static core *last_state;
-static shifts *last_shift;
-static reductions *last_reduction;
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;
static int nshifts;
-static short *shift_symbol;
+static short *shift_symbol = NULL;
-static short *redset;
-static short *shiftset;
+static short *redset = NULL;
+static short *shiftset = NULL;
-static short **kernel_base;
-static short **kernel_end;
-static short *kernel_items;
+static short **kernel_base = NULL;
+static int *kernel_size = NULL;
+static short *kernel_items = NULL;
/* hash table for states, to recognize equivalent ones. */
-#define STATE_TABLE_SIZE 1009
-static core **state_table;
+#define STATE_HASH_SIZE 1009
+static state_t **state_hash = NULL;
-
-
-void
+\f
+static void
allocate_itemsets (void)
{
- register short *itemp;
- register int symbol;
- register int i;
- register int count;
- register short *symbol_count;
-
- count = 0;
- symbol_count = NEW2(nsyms, short);
-
- itemp = ritem;
- symbol = *itemp++;
- while (symbol)
- {
- if (symbol > 0)
- {
- count++;
- symbol_count[symbol]++;
- }
- symbol = *itemp++;
- }
-
- /* see comments before new_itemsets. All the vectors of items
- live inside kernel_items. The number of active items after
+ int i;
+
+ /* Count the number of occurrences of all the symbols in RITEMS.
+ Note that useless productions (hence useless nonterminals) are
+ browsed too, hence we need to allocate room for _all_ the
+ symbols. */
+ int count = 0;
+ short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals);
+
+ for (i = 0; i < nritems; ++i)
+ if (ritem[i] >= 0)
+ {
+ count++;
+ symbol_count[ritem[i]]++;
+ }
+
+ /* See comments before new_itemsets. All the vectors of items
+ live inside KERNEL_ITEMS. The number of active items after
some symbol cannot be more than the number of times that symbol
appears as an item, which is symbol_count[symbol].
We allocate that much space for each symbol. */
- kernel_base = NEW2(nsyms, short *);
- kernel_items = NEW2(count, short);
+ kernel_base = XCALLOC (short *, nsyms);
+ if (count)
+ kernel_items = XCALLOC (short, count);
count = 0;
for (i = 0; i < nsyms; i++)
count += symbol_count[i];
}
- shift_symbol = symbol_count;
- kernel_end = NEW2(nsyms, short *);
+ free (symbol_count);
+ kernel_size = XCALLOC (int, nsyms);
}
-void
+static void
allocate_storage (void)
{
- allocate_itemsets();
+ allocate_itemsets ();
- shiftset = NEW2(nsyms, short);
- redset = NEW2(nrules + 1, short);
- state_table = NEW2(STATE_TABLE_SIZE, core *);
+ shiftset = XCALLOC (short, nsyms);
+ redset = XCALLOC (short, nrules + 1);
+ state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
+ shift_symbol = XCALLOC (short, nsyms);
}
-void
+static void
free_storage (void)
{
- FREE(shift_symbol);
- FREE(redset);
- FREE(shiftset);
- FREE(kernel_base);
- FREE(kernel_end);
- FREE(kernel_items);
- FREE(state_table);
+ free (shift_symbol);
+ free (redset);
+ free (shiftset);
+ free (kernel_base);
+ free (kernel_size);
+ XFREE (kernel_items);
+ free (state_hash);
}
-/* compute the nondeterministic finite state machine (see state.h for details)
-from the grammar. */
-void
-generate_states (void)
-{
- allocate_storage();
- initialize_closure(nitems);
- initialize_states();
-
- while (this_state)
- {
- /* 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 accepted next. */
- closure(this_state->items, this_state->nitems);
- /* record the reductions allowed out of this state */
- save_reductions();
- /* find the itemsets of the states that shifts can reach */
- new_itemsets();
- /* find or create the core structures for those states */
- append_states();
-
- /* create the shifts structures for the shifts to those states,
- now that the state numbers transitioning to are known */
- if (nshifts > 0)
- save_shifts();
-
- /* states are queued when they are created; process them all */
- this_state = this_state->next;
- }
- /* discard various storage */
- finalize_closure();
- free_storage();
+/*----------------------------------------------------------------.
+| Find which symbols can be shifted in the current state, and for |
+| each one record which items would be active after that shift. |
+| Uses the contents of itemset. |
+| |
+| shift_symbol is set to a vector of the symbols that can be |
+| shifted. For each symbol in the grammar, kernel_base[symbol] |
+| points to a vector of item numbers activated if that symbol is |
+| shifted, and kernel_size[symbol] is their numbers. |
+`----------------------------------------------------------------*/
- /* set up initial and final states as parser wants them */
- augment_automaton();
-}
-
-
-
-/* Find which symbols can be shifted in the current state,
- and for each one record which items would be active after that shift.
- Uses the contents of itemset.
- shift_symbol is set to a vector of the symbols that can be shifted.
- For each symbol in the grammar, kernel_base[symbol] points to
- a vector of item numbers activated if that symbol is shifted,
- and kernel_end[symbol] points after the end of that vector. */
-void
+static void
new_itemsets (void)
{
- register int i;
- register int shiftcount;
- register short *isp;
- register short *ksp;
- register int symbol;
+ int i;
-#ifdef TRACE
- fprintf(stderr, "Entering new_itemsets\n");
-#endif
+ if (trace_flag)
+ fprintf (stderr, "Entering new_itemsets, state = %d\n",
+ this_state->number);
for (i = 0; i < nsyms; i++)
- kernel_end[i] = NULL;
-
- shiftcount = 0;
+ kernel_size[i] = 0;
- isp = itemset;
+ nshifts = 0;
- while (isp < itemsetend)
+ for (i = 0; i < nitemset; ++i)
{
- i = *isp++;
- symbol = ritem[i];
- if (symbol > 0)
+ int symbol = ritem[itemset[i]];
+ if (symbol >= 0)
{
- ksp = kernel_end[symbol];
-
- if (!ksp)
+ if (!kernel_size[symbol])
{
- shift_symbol[shiftcount++] = symbol;
- ksp = kernel_base[symbol];
+ shift_symbol[nshifts] = symbol;
+ nshifts++;
}
- *ksp++ = i + 1;
- kernel_end[symbol] = ksp;
+ kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
+ kernel_size[symbol]++;
}
}
-
- nshifts = shiftcount;
}
-/* Use the information computed by new_itemsets to find the state numbers
- reached by each shift transition from the current state.
+/*-----------------------------------------------------------------.
+| Subroutine of get_state. Create a new state for those items, if |
+| necessary. |
+`-----------------------------------------------------------------*/
- shiftset is set up as a vector of state numbers of those states. */
-void
-append_states (void)
+static state_t *
+new_state (int symbol)
{
- register int i;
- register int j;
- register int symbol;
+ state_t *p;
-#ifdef TRACE
- fprintf(stderr, "Entering append_states\n");
-#endif
+ if (trace_flag)
+ fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
+ this_state->number, symbol, symbols[symbol]->tag);
- /* first sort shift_symbol into increasing order */
+ if (nstates >= MAXSHORT)
+ fatal (_("too many states (max %d)"), MAXSHORT);
- for (i = 1; i < nshifts; i++)
- {
- symbol = shift_symbol[i];
- j = i;
- while (j > 0 && shift_symbol[j - 1] > symbol)
- {
- shift_symbol[j] = shift_symbol[j - 1];
- j--;
- }
- shift_symbol[j] = symbol;
- }
+ p = STATE_ALLOC (kernel_size[symbol]);
+ p->accessing_symbol = symbol;
+ p->number = nstates;
+ p->nitems = kernel_size[symbol];
- for (i = 0; i < nshifts; i++)
- {
- symbol = shift_symbol[i];
- shiftset[i] = get_state(symbol);
- }
-}
+ shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);
+ last_state->next = p;
+ last_state = p;
+ nstates++;
+ /* If this is the eoftoken, then this is the final state. */
+ if (symbol == 0)
+ final_state = p->number;
-/* find the state number for the state we would get to
-(from the current state) by shifting symbol.
-Create a new state if no equivalent one exists already.
-Used by append_states */
+ return p;
+}
-int
-get_state (int symbol)
-{
- register int key;
- register short *isp1;
- register short *isp2;
- register short *iend;
- register core *sp;
- register int found;
- int n;
+/*--------------------------------------------------------------.
+| Find the state number for the state we would get to (from the |
+| current state) by shifting symbol. Create a new state if no |
+| equivalent one exists already. Used by append_states. |
+`--------------------------------------------------------------*/
-#ifdef TRACE
- fprintf(stderr, "Entering get_state, symbol = %d\n", symbol);
-#endif
+static int
+get_state (int symbol)
+{
+ int key;
+ int i;
+ state_t *sp;
- isp1 = kernel_base[symbol];
- iend = kernel_end[symbol];
- n = iend - isp1;
+ if (trace_flag)
+ fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
+ this_state->number, symbol, symbols[symbol]->tag);
- /* add up the target state's active item numbers to get a hash key */
+ /* Add up the target state's active item numbers to get a hash key.
+ */
key = 0;
- while (isp1 < iend)
- key += *isp1++;
-
- key = key % STATE_TABLE_SIZE;
-
- sp = state_table[key];
+ for (i = 0; i < kernel_size[symbol]; ++i)
+ key += kernel_base[symbol][i];
+ key = key % STATE_HASH_SIZE;
+ sp = state_hash[key];
if (sp)
{
- found = 0;
+ int found = 0;
while (!found)
{
- if (sp->nitems == n)
+ if (sp->nitems == kernel_size[symbol])
{
found = 1;
- isp1 = kernel_base[symbol];
- isp2 = sp->items;
-
- while (found && isp1 < iend)
- {
- if (*isp1++ != *isp2++)
- found = 0;
- }
+ for (i = 0; i < kernel_size[symbol]; ++i)
+ if (kernel_base[symbol][i] != sp->items[i])
+ found = 0;
}
if (!found)
{
sp = sp->link;
}
- else /* bucket exhausted and no match */
+ else /* bucket exhausted and no match */
{
- sp = sp->link = new_state(symbol);
+ sp = sp->link = new_state (symbol);
found = 1;
}
}
}
}
- else /* bucket is empty */
+ else /* bucket is empty */
{
- state_table[key] = sp = new_state(symbol);
+ state_hash[key] = sp = new_state (symbol);
}
- return (sp->number);
-}
-
+ if (trace_flag)
+ fprintf (stderr, "Exiting get_state => %d\n", sp->number);
+ return sp->number;
+}
-/* subroutine of get_state. create a new state for those items, if necessary. */
+/*------------------------------------------------------------------.
+| Use the information computed by new_itemsets to find the state |
+| numbers reached by each shift transition from the current state. |
+| |
+| shiftset is set up as a vector of state numbers of those states. |
+`------------------------------------------------------------------*/
-core *
-new_state (int symbol)
+static void
+append_states (void)
{
- register int n;
- register core *p;
- register short *isp1;
- register short *isp2;
- register short *iend;
-
-#ifdef TRACE
- fprintf(stderr, "Entering new_state, symbol = %d\n", symbol);
-#endif
-
- if (nstates >= MAXSHORT)
- toomany("states");
+ int i;
+ int j;
+ int symbol;
- isp1 = kernel_base[symbol];
- iend = kernel_end[symbol];
- n = iend - isp1;
+ if (trace_flag)
+ fprintf (stderr, "Entering append_states, state = %d\n",
+ this_state->number);
- p = (core *) xmalloc((unsigned) (sizeof(core) + (n - 1) * sizeof(short)));
- p->accessing_symbol = symbol;
- p->number = nstates;
- p->nitems = n;
-
- isp2 = p->items;
- while (isp1 < iend)
- *isp2++ = *isp1++;
-
- last_state->next = p;
- last_state = p;
+ /* first sort shift_symbol into increasing order */
- nstates++;
+ for (i = 1; i < nshifts; i++)
+ {
+ symbol = shift_symbol[i];
+ j = i;
+ while (j > 0 && shift_symbol[j - 1] > symbol)
+ {
+ shift_symbol[j] = shift_symbol[j - 1];
+ j--;
+ }
+ shift_symbol[j] = symbol;
+ }
- return (p);
+ for (i = 0; i < nshifts; i++)
+ shiftset[i] = get_state (shift_symbol[i]);
}
-void
-initialize_states (void)
+static void
+new_states (void)
{
- register core *p;
-/* register unsigned *rp1; JF unused */
-/* register unsigned *rp2; JF unused */
-/* register unsigned *rend; JF unused */
-
- p = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
- first_state = last_state = this_state = p;
+ first_state = last_state = this_state = STATE_ALLOC (0);
nstates = 1;
}
-void
+/*------------------------------------------------------------.
+| Save the NSHIFTS of SHIFTSET into the current linked list. |
+`------------------------------------------------------------*/
+
+static void
save_shifts (void)
{
- register shifts *p;
- register short *sp1;
- register short *sp2;
- register short *send;
-
- p = (shifts *) xmalloc((unsigned) (sizeof(shifts) +
- (nshifts - 1) * sizeof(short)));
-
- p->number = this_state->number;
- p->nshifts = nshifts;
-
- sp1 = shiftset;
- sp2 = p->shifts;
- send = shiftset + nshifts;
-
- while (sp1 < send)
- *sp2++ = *sp1++;
-
- if (last_shift)
- {
- last_shift->next = p;
- last_shift = p;
- }
- else
- {
- first_shift = p;
- last_shift = p;
- }
+ shifts *p = shifts_new (nshifts);
+ shortcpy (p->shifts, shiftset, nshifts);
+ this_state->shifts = p;
}
+/*----------------------------------------------------------------.
+| Find which rules can be used for reduction transitions from the |
+| current state and make a reductions structure for the state to |
+| record their rule numbers. |
+`----------------------------------------------------------------*/
-/* find which rules can be used for reduction transitions from the current state
- and make a reductions structure for the state to record their rule numbers. */
-void
+static void
save_reductions (void)
{
- register short *isp;
- register short *rp1;
- register short *rp2;
- register int item;
- register int count;
- register reductions *p;
+ int count = 0;
+ int i;
- short *rend;
+ /* 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;
- /* find and count the active items that represent ends of rules */
-
- count = 0;
- for (isp = itemset; isp < itemsetend; isp++)
+ /* Find and count the active items that represent ends of rules. */
+ for (i = 0; i < nitemset; ++i)
{
- item = ritem[*isp];
+ int item = ritem[itemset[i]];
if (item < 0)
- {
- redset[count++] = -item;
- }
+ redset[count++] = -item;
}
- /* make a reductions structure and copy the data into it. */
-
- if (count)
- {
- p = (reductions *) xmalloc((unsigned) (sizeof(reductions) +
- (count - 1) * sizeof(short)));
-
- p->number = this_state->number;
- p->nreds = count;
-
- rp1 = redset;
- rp2 = p->rules;
- rend = rp1 + count;
-
- while (rp1 < rend)
- *rp2++ = *rp1++;
-
- if (last_reduction)
- {
- last_reduction->next = p;
- last_reduction = p;
- }
- else
- {
- first_reduction = p;
- last_reduction = p;
- }
- }
+ /* Make a reductions structure and copy the data into it. */
+ this_state->reductions = reductions_new (count);
+ shortcpy (this_state->reductions->rules, redset, count);
}
+\f
+/*---------------.
+| Build STATES. |
+`---------------*/
-
-/* 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. */
-void
-augment_automaton (void)
+static void
+set_states (void)
{
- register int i;
- register int k;
-/* register int found; JF unused */
- register core *statep;
- register shifts *sp;
- register shifts *sp2;
- register shifts *sp1 = NULL;
-
- sp = first_shift;
+ state_t *sp;
+ states = XCALLOC (state_t *, nstates);
- if (sp)
+ for (sp = first_state; sp; sp = sp->next)
{
- if (sp->number == 0)
- {
- k = sp->nshifts;
- statep = first_state->next;
-
- /* The states reached by shifts from first_state are numbered 1...K.
- Look for one reached by start_symbol. */
- while (statep->accessing_symbol < start_symbol
- && statep->number < k)
- 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. */
- k = statep->number;
-
- while (sp && sp->number < k)
- {
- sp1 = sp;
- sp = sp->next;
- }
-
- if (sp && sp->number == k)
- {
- sp2 = (shifts *) xmalloc((unsigned) (sizeof(shifts)
- + sp->nshifts * sizeof(short)));
- sp2->number = k;
- sp2->nshifts = sp->nshifts + 1;
- 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;
- FREE(sp);
- }
- else
- {
- sp2 = NEW(shifts);
- sp2->number = k;
- sp2->nshifts = 1;
- 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
- {
- /* 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). */
- sp = first_shift;
-
- sp2 = (shifts *) xmalloc(sizeof(shifts)
- + sp->nshifts * sizeof(short));
- sp2->nshifts = 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;
-
- FREE(sp);
-
- /* Create the next-to-final state, with shift to
- what will be the final state. */
- insert_start_shift();
- }
- }
- else
- {
- /* The initial state didn't even have any shifts.
- Give it one shift, to the next-to-final state. */
- sp = NEW(shifts);
- sp->nshifts = 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_shift();
- }
+ /* 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;
}
- else
- {
- /* There are no shifts for any state.
- Make one shift, from the initial state to the next-to-final state. */
-
- sp = NEW(shifts);
- sp->nshifts = 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_shift();
- }
-
- /* 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 = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
- statep->number = nstates;
- last_state->next = statep;
- last_state = statep;
-
- /* Make the shift from the final state to the termination state. */
- sp = NEW(shifts);
- sp->number = nstates++;
- sp->nshifts = 1;
- sp->shifts[0] = nstates;
- last_shift->next = sp;
- last_shift = sp;
-
- /* Note that the variable `final_state' refers to what we sometimes call
- the termination state. */
- final_state = nstates;
-
- /* Make the termination state. */
- statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
- statep->number = nstates++;
- last_state->next = statep;
- last_state = statep;
}
+/*-------------------------------------------------------------------.
+| Compute the nondeterministic finite state machine (see state.h for |
+| details) from the grammar. |
+`-------------------------------------------------------------------*/
-/* subroutine of augment_automaton.
- Create the next-to-final state, to which a shift has already been made in
- the initial state. */
void
-insert_start_shift (void)
+generate_states (void)
{
- register core *statep;
- register shifts *sp;
+ allocate_storage ();
+ new_closure (nritems);
+ new_states ();
+
+ while (this_state)
+ {
+ if (trace_flag)
+ fprintf (stderr, "Processing state %d (reached by %s)\n",
+ 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
+ accepted next. */
+ closure (this_state->items, this_state->nitems);
+ /* record the reductions allowed out of this state */
+ save_reductions ();
+ /* find the itemsets of the states that shifts can reach */
+ new_itemsets ();
+ /* find or create the core structures for those states */
+ append_states ();
- statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
- statep->number = nstates;
- statep->accessing_symbol = start_symbol;
+ /* create the shifts structures for the shifts to those states,
+ now that the state numbers transitioning to are known */
+ save_shifts ();
- last_state->next = statep;
- last_state = statep;
+ /* states are queued when they are created; process them all */
+ this_state = this_state->next;
+ }
- /* Make a shift from this state to (what will be) the final state. */
- sp = NEW(shifts);
- sp->number = nstates++;
- sp->nshifts = 1;
- sp->shifts[0] = nstates;
+ /* discard various storage */
+ free_closure ();
+ free_storage ();
- last_shift->next = sp;
- last_shift = sp;
+ /* Set up STATES. */
+ set_states ();
}
projects / bison.git / blobdiff