X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/b7c49edf135cea5dc2bd0942b42d28e6c84cf71f..e7b8bef1b1fa6eae346c4a3ee00e897a4d6f9058:/src/reader.c

diff --git a/src/reader.c b/src/reader.c
index c5f3b11e..bebbc153 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -71,6 +71,7 @@ static int lastprec;
 static bucket *errtoken = NULL;
 static bucket *undeftoken = NULL;
 static bucket *eoftoken = NULL;
+static bucket *axiom = NULL;
 
 static symbol_list *
 symbol_list_new (bucket *sym)
@@ -1450,12 +1451,8 @@ readgram (void)
 	t = lex ();
       }
 
-
   /* grammar has been read.  Do some checking */
 
-  if (nsyms > MAXSHORT)
-    fatal (_("too many symbols (tokens plus nonterminals); maximum %d"),
-	   MAXSHORT);
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 
@@ -1471,6 +1468,25 @@ readgram (void)
 	bp->value = nvars++;
       }
 
+  /* Insert the initial rule, which line is that of the first rule
+     (not that of the start symbol):
+
+     axiom: %start EOF.  */
+  p = symbol_list_new (axiom);
+  p->line = grammar->line;
+  p->next = symbol_list_new (startval);
+  p->next->next = symbol_list_new (eoftoken);
+  p->next->next->next = symbol_list_new (NULL);
+  p->next->next->next->next = grammar;
+  nrules += 1;
+  nitems += 3;
+  grammar = p;
+  startval = axiom;
+
+  if (nsyms > MAXSHORT)
+    fatal (_("too many symbols (tokens plus nonterminals); maximum %d"),
+	   MAXSHORT);
+
   ntokens = nsyms - nvars;
 }
 
@@ -1764,6 +1780,8 @@ packgram (void)
     }
 
   ritem[itemno] = 0;
+  nritems = itemno;
+  assert (nritems == nitems);
 
   if (trace_flag)
     ritem_print (stderr);
@@ -1805,6 +1823,11 @@ reader (void)
   /* Initialize the symbol table.  */
   tabinit ();
 
+  /* Construct the axiom symbol. */
+  axiom = getsym ("$axiom");
+  axiom->class = nterm_sym;
+  axiom->value = nvars++;
+
   /* Construct the error token */
   errtoken = getsym ("error");
   errtoken->class = token_sym;