X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/ed8e1f68e9743c391f4aba148968ea1e5e960973..ead9e56eb214ad082ef4689afb8600d3e9d24727:/src/nullable.c

diff --git a/src/nullable.c b/src/nullable.c
index bbd8e319..d65c4f2b 100644
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -1,5 +1,7 @@
-/* Part of the bison parser generator,
-   Copyright 1984, 1989, 2000, 2001 Free Software Foundation, Inc.
+/* Calculate which nonterminals can expand into the null string for Bison.
+
+   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2003, 2004 Free
+   Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -24,14 +26,21 @@
    do so.  */
 
 #include "system.h"
+
 #include "getargs.h"
-#include "reader.h"
-#include "types.h"
 #include "gram.h"
-#include "reduce.h"
 #include "nullable.h"
+#include "reduce.h"
+#include "symtab.h"
 
-char *nullable = NULL;
+/* Linked list of rules.  */
+typedef struct rule_list
+{
+  struct rule_list *next;
+  rule *value;
+} rule_list;
+
+bool *nullable = NULL;
 
 static void
 nullable_print (FILE *out)
@@ -39,92 +48,96 @@ nullable_print (FILE *out)
   int i;
   fputs ("NULLABLE\n", out);
   for (i = ntokens; i < nsyms; i++)
-    fprintf (out, "\t%s: %s\n", tags[i], nullable[i] ? "yes" : "no");
+    fprintf (out, "\t%s: %s\n", symbols[i]->tag,
+	     nullable[i - ntokens] ? "yes" : "no");
   fputs ("\n\n", out);
 }
 
 void
-set_nullable (void)
+nullable_compute (void)
 {
-  int ruleno;
-  short *s1;
-  short *s2;
-  shorts *p;
+  rule_number ruleno;
+  symbol_number *s1;
+  symbol_number *s2;
+  rule_list *p;
 
-  short *squeue = XCALLOC (short, nvars);
-  short *rcount = XCALLOC (short, nrules + 1);
+  symbol_number *squeue = CALLOC (squeue, nvars);
+  short int *rcount = CALLOC (rcount, nrules);
   /* RITEM contains all the rules, including useless productions.
      Hence we must allocate room for useless nonterminals too.  */
-  shorts **rsets = XCALLOC (shorts *, nvars) - ntokens;
+  rule_list **rsets = CALLOC (rsets, nvars);
   /* This is said to be more elements than we actually use.
-     Supposedly nitems - nrules is enough.  But why take the risk?  */
-  shorts *relts = XCALLOC (shorts, nitems + nvars + 1);
-
-  if (trace_flag)
-    fprintf (stderr, "Entering set_nullable\n");
+     Supposedly NRITEMS - NRULES is enough.  But why take the risk?  */
+  rule_list *relts = CALLOC (relts, nritems + nvars + 1);
 
-  nullable = XCALLOC (char, nvars) - ntokens;
+  CALLOC (nullable, nvars);
 
   s1 = s2 = squeue;
   p = relts;
 
-  for (ruleno = 1; ruleno < nrules + 1; ++ruleno)
-    if (ritem[rule_table[ruleno].rhs] > 0)
+  for (ruleno = 0; ruleno < nrules; ++ruleno)
+    if (rules[ruleno].useful)
       {
-	/* This rule has a non empty RHS. */
-	short *r;
-	int any_tokens = 0;
-	for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
-	  if (ISTOKEN (*r))
-	    any_tokens = 1;
-
-	/* This rule has only nonterminals: schedule it for the second
-	   pass.  */
-	if (!any_tokens)
-	  for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
-	    {
-	      rcount[ruleno]++;
-	      p->next = rsets[*r];
-	      p->value = ruleno;
-	      rsets[*r] = p;
-	      p++;
-	    }
-      }
-    else
-      {
-	/* This rule has an empty RHS. */
-	assert (ritem[rule_table[ruleno].rhs] == -ruleno);
-	if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
+	rule *rules_ruleno = &rules[ruleno];
+	if (rules_ruleno->rhs[0] >= 0)
+	  {
+	    /* This rule has a non empty RHS. */
+	    item_number *rp = NULL;
+	    bool any_tokens = false;
+	    for (rp = rules_ruleno->rhs; *rp >= 0; ++rp)
+	      if (ISTOKEN (*rp))
+		any_tokens = true;
+
+	    /* This rule has only nonterminals: schedule it for the second
+	       pass.  */
+	    if (!any_tokens)
+	      for (rp = rules_ruleno->rhs; *rp >= 0; ++rp)
+		{
+		  rcount[ruleno]++;
+		  p->next = rsets[*rp - ntokens];
+		  p->value = rules_ruleno;
+		  rsets[*rp - ntokens] = p;
+		  p++;
+		}
+	  }
+	else
 	  {
-	    nullable[rule_table[ruleno].lhs] = 1;
-	    *s2++ = rule_table[ruleno].lhs;
+	    /* This rule has an empty RHS. */
+	    if (item_number_as_rule_number (rules_ruleno->rhs[0]) != ruleno)
+	      abort ();
+	    if (rules_ruleno->useful
+		&& ! nullable[rules_ruleno->lhs->number - ntokens])
+	      {
+		nullable[rules_ruleno->lhs->number - ntokens] = true;
+		*s2++ = rules_ruleno->lhs->number;
+	      }
 	  }
       }
 
   while (s1 < s2)
-    for (p = rsets[*s1++]; p; p = p->next)
+    for (p = rsets[*s1++ - ntokens]; p; p = p->next)
       {
-	ruleno = p->value;
-	if (--rcount[ruleno] == 0)
-	  if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
+	rule *r = p->value;
+	if (--rcount[r->number] == 0)
+	  if (r->useful && ! nullable[r->lhs->number - ntokens])
 	    {
-	      nullable[rule_table[ruleno].lhs] = 1;
-	      *s2++ = rule_table[ruleno].lhs;
+	      nullable[r->lhs->number - ntokens] = true;
+	      *s2++ = r->lhs->number;
 	    }
       }
 
   XFREE (squeue);
   XFREE (rcount);
-  XFREE (rsets + ntokens);
+  XFREE (rsets);
   XFREE (relts);
 
-  if (trace_flag)
+  if (trace_flag & trace_sets)
     nullable_print (stderr);
 }
 
 
 void
-free_nullable (void)
+nullable_free (void)
 {
-  XFREE (nullable + ntokens);
+  XFREE (nullable);
 }