11-fyi-axiom-rule.patch

[Akim Demaille]

Index: ChangeLog
from  Akim Demaille  <address@hidden>

        * src/LR0.c (new_state): Display `nstates' as the name of the
        newly created state.
        Adjust to initialize first_state and last_state if needed.
        Be sure to distinguish the initial from the final state.
        (new_states): Create the itemset of the initial state, and use
        new_state.
        * src/closure.c (closure): Now that the initial state has its
        items properly set, there is no need for a special case when
        creating `ruleset'.

        As a result, now the rule 0, reducing to $axiom, is visible in the
        outputs.  Adjust the test suite.

        * tests/conflicts.at (Solved SR Conflicts)
        (Unresolved SR Conflicts): Adjust.
        * tests/regression.at (Web2c Report, Rule Line Numbers): Idem.
        * tests/conflicts.at (S/R in initial): New.

Index: NEWS
--- NEWS Mon, 25 Mar 2002 20:34:56 +0100 akim
+++ NEWS Wed, 03 Apr 2002 22:06:40 +0200 akim
@@ -3,6 +3,11 @@

 Changes in version 1.49a:

+* The initial rule is explicit.
+  Bison used to play hacks with the initial rule, which the user does
+  not write.  It is now explicit, and visible in the reports and
+  graphs as rule 0.
+
 * Useless rules are actually removed.
   Before, Bison reported the useless rules, but, although not used,
   included them in the parsers.
Index: src/LR0.c
--- src/LR0.c Sat, 30 Mar 2002 00:05:55 +0100 akim
+++ src/LR0.c Wed, 03 Apr 2002 22:05:07 +0200 akim
@@ -35,7 +35,7 @@
 #include "lalr.h"
 #include "reduce.h"

-unsigned int nstates;
+unsigned int nstates = 0;
 /* Initialize the final state to -1, otherwise, it might be set to 0
    by default, and since we don't compute the reductions of the final
    state, we end up not computing the reductions of the initial state,
@@ -190,7 +190,7 @@

   if (trace_flag)
     fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
-            this_state->number, symbol, symbols[symbol]->tag);
+            nstates, symbol, symbols[symbol]->tag);

   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
@@ -202,13 +202,18 @@

   shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);

-  last_state->next = p;
+  /* If this is the eoftoken, and this is not the initial state, then
+     this is the final state.  */
+  if (symbol == 0 && first_state)
+    final_state = p->number;
+
+  if (!first_state)
+    first_state = p;
+  if (last_state)
+    last_state->next = p;
   last_state = p;
-  nstates++;

-  /* If this is the eoftoken, then this is the final state. */
-  if (symbol == 0)
-    final_state = p->number;
+  nstates++;

   return p;
 }
@@ -317,8 +322,10 @@
 static void
 new_states (void)
 {
-  first_state = last_state = this_state = STATE_ALLOC (0);
-  nstates = 1;
+  /* The 0 at the lhs is the index of the item of this initial rule.  */
+  kernel_base[0][0] = 0;
+  kernel_size[0] = 1;
+  this_state = new_state (0);
 }


Index: src/closure.c
--- src/closure.c Sat, 23 Mar 2002 13:51:12 +0100 akim
+++ src/closure.c Wed, 03 Apr 2002 20:21:28 +0200 akim
@@ -244,18 +244,11 @@
   if (trace_flag)
     print_closure ("input", core, n);

-  if (n == 0)
-    {
-      bitset_copy (ruleset, FDERIVES (start_symbol));
-    }
-  else
-    {
-      bitset_zero (ruleset);
+  bitset_zero (ruleset);

-      for (c = 0; c < n; ++c)
-       if (ISVAR (ritem[core[c]]))
-         bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]]));
-    }
+  for (c = 0; c < n; ++c)
+    if (ISVAR (ritem[core[c]]))
+      bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]]));

   nitemset = 0;
   c = 0;
Index: tests/Makefile.am
--- tests/Makefile.am Sat, 16 Mar 2002 13:28:35 +0100 akim
+++ tests/Makefile.am Wed, 03 Apr 2002 22:00:10 +0200 akim
@@ -55,7 +55,7 @@
 TESTSUITE = $(srcdir)/testsuite

 AUTOTEST = $(AUTOM4TE) --language=autotest
-$(srcdir)/$(TESTSUITE): package.m4 $(TESTSUITE_AT)
+$(TESTSUITE): package.m4 $(TESTSUITE_AT)
        $(AUTOTEST) -I $(srcdir) testsuite.at -o address@hidden
        mv address@hidden $@

Index: tests/conflicts.at
--- tests/conflicts.at Sat, 16 Mar 2002 13:10:21 +0100 akim
+++ tests/conflicts.at Wed, 03 Apr 2002 21:57:45 +0200 akim
@@ -1,5 +1,5 @@
 # Exercising Bison on conflicts.                         -*- Autotest -*-
-# Copyright 2002 Free Software Foundation, Inc.
+# Copyright (C) 2002 Free Software Foundation, Inc.

 # 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
@@ -19,6 +19,28 @@
 AT_BANNER([[Conflicts.]])


+## ---------------- ##
+## S/R in initial.  ##
+## ---------------- ##
+
+# I once hacked Bison in such a way that it lost its reductions on the
+# initial state (because it was confusing it with the last state).  It
+# took me a while to strip down my failures to this simple case.  So
+# make sure it finds the s/r conflict below.
+
+AT_SETUP([S/R in initial])
+
+AT_DATA([[input.y]],
+[[%expect 1
+%%
+exp: e 'e';
+e: 'e' | /* Nothing. */;
+]])
+
+AT_CHECK([bison input.y -o input.c])
+
+AT_CLEANUP
+
 ## ------------------- ##
 ## %nonassoc and eof.  ##
 ## ------------------- ##
@@ -143,6 +165,8 @@ exp: exp OP exp | NUM;

 state 0

+    $axiom  ->  . exp $   (rule 0)
+
     NUM        shift, and go to state 1

     exp        go to state 2
@@ -246,6 +270,8 @@ exp: exp OP exp | NUM;


 state 0
+
+    $axiom  ->  . exp $   (rule 0)

     NUM        shift, and go to state 1

Index: tests/regression.at
--- tests/regression.at Sat, 16 Mar 2002 13:10:21 +0100 akim
+++ tests/regression.at Wed, 03 Apr 2002 20:38:14 +0200 akim
@@ -139,6 +139,8 @@ expr:

 state 0

+    $axiom  ->  . expr $   (rule 0)
+
     'a'        shift, and go to state 1

     $default   reduce using rule 3 (@2)
@@ -348,6 +350,7 @@ input.y:2: fatal error: no input grammar
 @1 (11)
     on left: 4, on right: 5
 state 0
+    $axiom  ->  . CONST_DEC_PART $   (rule 0)
     $default   reduce using rule 4 (@1)
     CONST_DEC_PART     go to state 1
     CONST_DEC_LIST     go to state 2