X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0fb669f9d648dfdd7a39478a6b658511455ae966..5422d56a718805a2470558808355e04182a12d65:/src/LR0.c
diff --git a/src/LR0.c b/src/LR0.c
index 43030fc5..b357e2db 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,29 +1,28 @@
-/* Generate the nondeterministic finite state machine for Bison.
+/* Generate the LR(0) parser states for Bison.
- Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004 Free
+ Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2007, 2009-2011 Free
Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
- Bison is free software; you can redistribute it and/or modify
+ This program 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.
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
- Bison is distributed in the hope that it will be useful,
+ This program 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., 51 Franklin Street, Fifth Floor,
- Boston, MA 02110-1301, USA. */
+ along with this program. If not, see . */
/* See comments in state.h for the data structures that represent it.
The entry point is generate_states. */
+#include
#include "system.h"
#include
@@ -66,11 +65,6 @@ state_list_append (symbol_number sym, size_t core_size, item_number *core)
fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n",
nstates, sym, symbols[sym]->tag);
- /* If this is the endtoken, and this is not the initial state, then
- this is the final state. */
- if (sym == 0 && first_state)
- final_state = s;
-
node->next = NULL;
node->state = s;
@@ -173,6 +167,10 @@ free_storage (void)
| 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. |
+| |
+| itemset is sorted on item index in ritem, which is sorted on |
+| rule number. Compute each kernel_base[symbol] with the same |
+| sort. |
`---------------------------------------------------------------*/
static void
@@ -187,8 +185,8 @@ new_itemsets (state *s)
nshifts = 0;
- for (i = 0; i < nritemset; ++i)
- if (ritem[itemset[i]] >= 0)
+ for (i = 0; i < nitemset; ++i)
+ if (item_number_is_symbol_number (ritem[itemset[i]]))
{
symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]);
if (!kernel_size[sym])
@@ -213,20 +211,20 @@ new_itemsets (state *s)
static state *
get_state (symbol_number sym, size_t core_size, item_number *core)
{
- state *sp;
+ state *s;
if (trace_flag & trace_automaton)
fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
sym, symbols[sym]->tag);
- sp = state_hash_lookup (core_size, core);
- if (!sp)
- sp = state_list_append (sym, core_size, core);
+ s = state_hash_lookup (core_size, core);
+ if (!s)
+ s = state_list_append (sym, core_size, core);
if (trace_flag & trace_automaton)
- fprintf (stderr, "Exiting get_state => %d\n", sp->number);
+ fprintf (stderr, "Exiting get_state => %d\n", s->number);
- return sp;
+ return s;
}
/*---------------------------------------------------------------.
@@ -276,11 +274,20 @@ save_reductions (state *s)
size_t i;
/* Find and count the active items that represent ends of rules. */
- for (i = 0; i < nritemset; ++i)
+ for (i = 0; i < nitemset; ++i)
{
- int item = ritem[itemset[i]];
- if (item < 0)
- redset[count++] = &rules[item_number_as_rule_number (item)];
+ item_number item = ritem[itemset[i]];
+ if (item_number_is_rule_number (item))
+ {
+ rule_number r = item_number_as_rule_number (item);
+ redset[count++] = &rules[r];
+ if (r == 0)
+ {
+ /* This is "reduce 0", i.e., accept. */
+ aver (!final_state);
+ final_state = s;
+ }
+ }
}
/* Make a reductions structure and copy the data into it. */
@@ -322,8 +329,8 @@ set_states (void)
/*-------------------------------------------------------------------.
-| Compute the nondeterministic finite state machine (see state.h for |
-| details) from the grammar. |
+| Compute the LR(0) parser states (see state.h for details) from the |
+| grammar. |
`-------------------------------------------------------------------*/
void
@@ -338,19 +345,16 @@ generate_states (void)
item of this initial rule. */
state_list_append (0, 1, &initial_core);
- list = first_state;
-
- while (list)
+ /* States are queued when they are created; process them all. */
+ for (list = first_state; list; list = list->next)
{
state *s = list->state;
if (trace_flag & trace_automaton)
fprintf (stderr, "Processing state %d (reached by %s)\n",
s->number,
symbols[s->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. */
+ /* Set up itemset for the transitions out of this state. itemset gets a
+ vector of all the items that could be accepted next. */
closure (s->items, s->nitems);
/* Record the reductions allowed out of this state. */
save_reductions (s);
@@ -362,10 +366,6 @@ generate_states (void)
/* Create the shifts structures for the shifts to those states,
now that the state numbers transitioning to are known. */
state_transitions_set (s, nshifts, shiftset);
-
- /* states are queued when they are created; process them all.
- */
- list = list->next;
}
/* discard various storage */