* LR0.c (new_itemsets): Fix wording in comments: say item index rather

[bison.git] / src / LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index 1e3973244ad38428cddd7a4d6dc403f3efed88ea..689bebcbebf33f81627c7aa3236da32dfec51deb 100644 (file)
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,7 +1,7 @@
 /* Generate the nondeterministic finite state machine for Bison.
 
-   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004 Free
-   Software Foundation, Inc.
+   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004, 2005, 2006, 2007
+   Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -17,13 +17,14 @@
 
    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.  */
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
 
 
 /* See comments in state.h for the data structures that represent it.
    The entry point is generate_states.  */
 
+#include <config.h>
 #include "system.h"
 
 #include <bitset.h>
@@ -66,11 +67,6 @@ 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 +169,10 @@ 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
@@ -183,13 +183,12 @@ new_itemsets (state *s)
   if (trace_flag & trace_automaton)
     fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number);
 
-  for (i = 0; i < nsyms; i++)
-    kernel_size[i] = 0;
+  memset (kernel_size, 0, nsyms * sizeof *kernel_size);
 
   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])
@@ -214,20 +213,20 @@ 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;
 }
 
 /*---------------------------------------------------------------.
@@ -277,11 +276,20 @@ 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.  */
@@ -339,19 +347,16 @@ 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);
@@ -363,10 +368,6 @@ 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 */