X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/fb9c0b3360928887038a296c338025ced68e2d8c..728c4be290a95081c272ca917c54987135cde7e3:/src/state.c

diff --git a/src/state.c b/src/state.c
index 8030811a..3ba592bf 100644
--- a/src/state.c
+++ b/src/state.c
@@ -1,6 +1,7 @@
 /* Type definitions for nondeterministic finite state machine for Bison.
 
-   Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software
+   Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -19,7 +20,7 @@
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.  */
 
-
+#include <config.h>
 #include "system.h"
 
 #include <hash.h>
@@ -58,10 +59,12 @@ state *
 transitions_to (transitions *shifts, symbol_number sym)
 {
   int j;
-  for (j = 0; j < shifts->num; j++)
-    if (TRANSITION_SYMBOL (shifts, j) == sym)
-      return shifts->states[j];
-  abort ();
+  for (j = 0; ; j++)
+    {
+      aver (j < shifts->num);
+      if (TRANSITION_SYMBOL (shifts, j) == sym)
+	return shifts->states[j];
+    }
 }
 
 
@@ -102,7 +105,7 @@ reductions_new (int num, rule **reds)
   size_t rules_size = num * sizeof *reds;
   reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
   res->num = num;
-  res->look_ahead_tokens = NULL;
+  res->lookahead_tokens = NULL;
   memcpy (res->rules, reds, rules_size);
   return res;
 }
@@ -132,8 +135,7 @@ state_new (symbol_number accessing_symbol,
   state *res;
   size_t items_size = nitems * sizeof *core;
 
-  if (STATE_NUMBER_MAXIMUM <= nstates)
-    abort ();
+  aver (nstates < STATE_NUMBER_MAXIMUM);
 
   res = xmalloc (offsetof (state, items) + items_size);
   res->number = nstates++;
@@ -174,8 +176,7 @@ state_free (state *s)
 void
 state_transitions_set (state *s, int num, state **trans)
 {
-  if (s->transitions)
-    abort ();
+  aver (!s->transitions);
   s->transitions = transitions_new (num, trans);
 }
 
@@ -187,8 +188,7 @@ state_transitions_set (state *s, int num, state **trans)
 void
 state_reductions_set (state *s, int num, rule **reds)
 {
-  if (s->reductions)
-    abort ();
+  aver (!s->reductions);
   s->reductions = reductions_new (num, reds);
 }
 
@@ -212,45 +212,44 @@ state_reduction_find (state *s, rule *r)
 void
 state_errs_set (state *s, int num, symbol **tokens)
 {
-  if (s->errs)
-    abort ();
+  aver (!s->errs);
   s->errs = errs_new (num, tokens);
 }
 
 
 
-/*---------------------------------------------------.
-| Print on OUT all the look-ahead tokens such that S |
-| wants to reduce R.                                 |
-`---------------------------------------------------*/
+/*--------------------------------------------------.
+| Print on OUT all the lookahead tokens such that S |
+| wants to reduce R.                                |
+`--------------------------------------------------*/
 
 void
-state_rule_look_ahead_tokens_print (state *s, rule *r, FILE *out)
+state_rule_lookahead_tokens_print (state *s, rule *r, FILE *out)
 {
   /* Find the reduction we are handling.  */
   reductions *reds = s->reductions;
   int red = state_reduction_find (s, r);
 
   /* Print them if there are.  */
-  if (reds->look_ahead_tokens && red != -1)
+  if (reds->lookahead_tokens && red != -1)
     {
       bitset_iterator biter;
       int k;
       char const *sep = "";
-      fputs ("  [", out);
-      BITSET_FOR_EACH (biter, reds->look_ahead_tokens[red], k, 0)
+      fprintf (out, "  [");
+      BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
 	{
 	  fprintf (out, "%s%s", sep, symbols[k]->tag);
 	  sep = ", ";
 	}
-      fputc (']', out);
+      fprintf (out, "]");
     }
 }
 
 
-/*----------------------.
+/*---------------------.
 | A state hash table.  |
-`----------------------*/
+`---------------------*/
 
 /* Initial capacity of states hash table.  */
 #define HT_INITIAL_CAPACITY 257
@@ -353,6 +352,52 @@ state_hash_lookup (size_t nitems, item_number *core)
   return entry;
 }
 
+
+/*--------------------------------------------------------.
+| Record S and all states reachable from S in REACHABLE.  |
+`--------------------------------------------------------*/
+
+static void
+state_record_reachable_states (state *s, bitset reachable)
+{
+  if (bitset_test (reachable, s->number))
+    return;
+  bitset_set (reachable, s->number);
+  {
+    int i;
+    for (i = 0; i < s->transitions->num; ++i)
+      if (!TRANSITION_IS_DISABLED (s->transitions, i))
+        state_record_reachable_states (s->transitions->states[i], reachable);
+  }
+}
+
+void
+state_remove_unreachable_states (state_number old_to_new[])
+{
+  state_number nstates_reachable = 0;
+  bitset reachable = bitset_create (nstates, BITSET_FIXED);
+  state_record_reachable_states (states[0], reachable);
+  {
+    state_number i;
+    for (i = 0; i < nstates; ++i)
+      {
+        if (bitset_test (reachable, states[i]->number))
+          {
+            states[nstates_reachable] = states[i];
+            states[nstates_reachable]->number = nstates_reachable;
+            old_to_new[i] = nstates_reachable++;
+          }
+        else
+          {
+            state_free (states[i]);
+            old_to_new[i] = nstates;
+          }
+      }
+  }
+  nstates = nstates_reachable;
+  bitset_free (reachable);
+}
+
 /* All the decorated states, indexed by the state number.  */
 state **states = NULL;