X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/55a91a8242d818dd4869e0de4333d7cf4d557beb..89ff1b5e71a6d8aa34b3578282528adb43b198cd:/src/LR0.c
diff --git a/src/LR0.c b/src/LR0.c
index aeb597d8..f6a9537e 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,40 +1,37 @@
-/* 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
- Software Foundation, Inc.
+ Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2013 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., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, 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
-#include
#include "LR0.h"
#include "closure.h"
#include "complain.h"
#include "getargs.h"
#include "gram.h"
-#include "gram.h"
#include "lalr.h"
#include "reader.h"
#include "reduce.h"
@@ -64,12 +61,7 @@ state_list_append (symbol_number sym, size_t core_size, item_number *core)
if (trace_flag & trace_automaton)
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;
+ nstates, sym, symbols[sym]->tag);
node->next = NULL;
node->state = s;
@@ -107,13 +99,13 @@ allocate_itemsets (void)
symbols. */
size_t count = 0;
size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals,
- sizeof *symbol_count);
+ sizeof *symbol_count);
for (r = 0; r < nrules; ++r)
for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
{
- count++;
- symbol_count[*rhsp]++;
+ count++;
+ symbol_count[*rhsp]++;
}
/* See comments before new_itemsets. All the vectors of items
@@ -173,6 +165,10 @@ 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
@@ -187,18 +183,18 @@ 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])
- {
- shift_symbol[nshifts] = sym;
- nshifts++;
- }
-
- kernel_base[sym][kernel_size[sym]] = itemset[i] + 1;
- kernel_size[sym]++;
+ symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]);
+ if (!kernel_size[sym])
+ {
+ shift_symbol[nshifts] = sym;
+ nshifts++;
+ }
+
+ kernel_base[sym][kernel_size[sym]] = itemset[i] + 1;
+ kernel_size[sym]++;
}
}
@@ -213,25 +209,25 @@ 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);
+ 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;
}
/*---------------------------------------------------------------.
| Use the information computed by new_itemsets to find the state |
-| numbers reached by each shift transition from S. |
+| numbers reached by each shift transition from S. |
| |
| SHIFTSET is set up as a vector of those states. |
`---------------------------------------------------------------*/
@@ -251,7 +247,7 @@ append_states (state *s)
symbol_number sym = shift_symbol[i];
int j;
for (j = i; 0 < j && sym < shift_symbol[j - 1]; j--)
- shift_symbol[j] = shift_symbol[j - 1];
+ shift_symbol[j] = shift_symbol[j - 1];
shift_symbol[j] = sym;
}
@@ -276,11 +272,20 @@ 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. */
@@ -302,14 +307,14 @@ set_states (void)
state_list *this = first_state;
/* Pessimization, but simplification of the code: make sure all
- the states have valid transitions and reductions members,
- even if reduced to 0. It is too soon for errs, which are
- computed later, but set_conflicts. */
+ the states have valid transitions and reductions members,
+ even if reduced to 0. It is too soon for errs, which are
+ computed later, but set_conflicts. */
state *s = this->state;
if (!s->transitions)
- state_transitions_set (s, 0, 0);
+ state_transitions_set (s, 0, 0);
if (!s->reductions)
- state_reductions_set (s, 0, 0);
+ state_reductions_set (s, 0, 0);
states[s->number] = s;
@@ -322,8 +327,8 @@ 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 +343,16 @@ 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. */
+ fprintf (stderr, "Processing state %d (reached by %s)\n",
+ s->number,
+ symbols[s->accessing_symbol]->tag);
+ /* 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);
@@ -360,12 +362,8 @@ generate_states (void)
append_states (s);
/* Create the shifts structures for the shifts to those states,
- now that the state numbers transitioning to are known. */
+ 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 */