The neverclaim output by spin -f '([]a && XXXX!a)' was not

understood by Spot.

* src/neverparse/neverclaimparse.yy: Support "if :: false fi;"
instructions.  Spin sometimes output these on dead states.
Also rewrite the "transitions" rule as a left recursion.
* src/tgbatest/neverclaimread.test: Adjust output because
of the right->left recursion change, and add two more formula
to submit to Spin to test its output.

ChangeLog

+2011-01-06  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	The neverclaim output by spin -f '([]a && XXXX!a)' was not
+	understood by Spot.
+
+	* src/neverparse/neverclaimparse.yy: Support "if :: false fi;"
+	instructions.  Spin sometimes output these on dead states.
+	Also rewrite the "transitions" rule as a left recursion.
+	* src/tgbatest/neverclaimread.test: Adjust output because
+	of the right->left recursion change, and add two more formula
+	to submit to Spin to test its output.
+
 2011-01-06  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	Speed up computation of non_final states for minimize_wdba.

src/neverparse/neverclaimparse.yy

-/* Copyright (C) 2010 Laboratoire de Recherche et Dveloppement
+/* Copyright (C) 2010, 2011 Laboratoire de Recherche et Dveloppement
 ** de l'Epita (LRDE).
 **
 ** This file is part of Spot, a model checking library.
@@ -71,7 +71,7 @@ using namespace spot::ltl;
 %token FALSE "false"
 %token <str> FORMULA "boolean formula"
 %token <str> IDENT "identifier"
-%type <str> formula
+%type <str> formula opt_dest
 %type <p> transition
 %type <list> transitions
 %type <str> ident_list
@@ -88,7 +88,11 @@ using namespace spot::ltl;
   }
   delete $$;
   } <list>
-%printer { debug_stream() << *$$; } <str>
+  %printer {
+    if ($$)
+      debug_stream() << *$$;
+    else
+      debug_stream() << "\"\""; } <str>
 
 %%
 neverclaim:
@@ -101,7 +105,7 @@ states:
   | states ';' state
   | states ';'
 
-ident_list: 
+ident_list:
     IDENT ':'
     {
       $$ = $1;
@@ -119,7 +123,7 @@ state:
       spot::tgba_explicit::transition* t = result->create_transition(*$1, *$1);
       bool acc = !strncmp("accept", $1->c_str(), 6);
       if (acc)
-	result->add_acceptance_condition(t, 
+	result->add_acceptance_condition(t,
 					 spot::ltl::constant::true_instance());
       delete $1;
     }
@@ -133,7 +137,7 @@ state:
       {
 	spot::tgba_explicit::transition* t =
 	  result->create_transition(*$1,*it->second);
-	      
+
 	result->add_condition(t, it->first);
 	if (acc)
 	  result
@@ -150,35 +154,60 @@ state:
 
 transitions:
   /* empty */ { $$ = new std::list<pair>; }
-  | transition transitions
+  | transitions transition
     {
-      $2->push_back(*$1);
-      delete $1;
-      $$ = $2;
+      if ($2)
+	{
+	  $1->push_back(*$2);
+	  delete $2;
+	}
+      $$ = $1;
     }
 
 
 formula: FORMULA | "false" { $$ = new std::string("0"); }
-   
+
+opt_dest:
+  /* empty */
+    {
+      $$ = 0;
+    }
+  | "->" "goto" IDENT
+    {
+      $$ = $3;
+    }
+
 transition:
-  ':' ':' formula  "->" "goto" IDENT
+  ':' ':' formula opt_dest
     {
-      spot::ltl::parse_error_list pel;
-      spot::ltl::formula* f = spot::ltl::parse(*$3, pel);
-      delete $3;
-      for(spot::ltl::parse_error_list::const_iterator i = pel.begin();
-	  i != pel.end(); ++i)
+      // If there is no destination, do ignore the transition.
+      // This happens for instance with
+      //   if
+      //   :: false
+      //   fi
+      if (!$4)
 	{
-	  // Adjust the diagnostic to the current position.
-	  location here = @3;
-	  here.end.line = here.begin.line + i->first.end.line - 1;
-	  here.end.column = here.begin.column + i->first.end.column -1;
-	  here.begin.line += i->first.begin.line - 1;
-	  here.begin.column += i->first.begin.column - 1;
-	  error(here, i->second);
+	  delete $3;
+	  $$ = 0;
+	}
+      else
+	{
+	  spot::ltl::parse_error_list pel;
+	  spot::ltl::formula* f = spot::ltl::parse(*$3, pel);
+	  delete $3;
+	  for(spot::ltl::parse_error_list::const_iterator i = pel.begin();
+	  i != pel.end(); ++i)
+	    {
+	      // Adjust the diagnostic to the current position.
+	      location here = @3;
+	      here.end.line = here.begin.line + i->first.end.line - 1;
+	      here.end.column = here.begin.column + i->first.end.column -1;
+	      here.begin.line += i->first.begin.line - 1;
+	      here.begin.column += i->first.begin.column - 1;
+	      error(here, i->second);
+	    }
+	  $$ = new pair(f, $4);
 	}
-
-      $$ = new pair(f, $6);
     }
 %%
 

src/tgbatest/neverclaimread.test

 #!/bin/sh
-# Copyright (C) 2010 Laboratoire de Recherche et Dveloppement
+# Copyright (C) 2010, 2011 Laboratoire de Recherche et Dveloppement
 # de l'Epita (LRDE).
 #
 # This file is part of Spot, a model checking library.
@@ -48,11 +48,11 @@ digraph G {
   0 [label="", style=invis, height=0]
   0 -> 1
   1 [label="T2_init"]
-  1 -> 2 [label="p0 & p1\n"]
   1 -> 1 [label="1\n"]
+  1 -> 2 [label="p0 & p1\n"]
   2 [label="T1"]
-  2 -> 2 [label="p1\n"]
   2 -> 3 [label="p1 & !p0\n"]
+  2 -> 2 [label="p1\n"]
   3 [label="accept_all"]
   3 -> 3 [label="1\n{Acc[1]}"]
 }
@@ -101,6 +101,8 @@ a
 X false
 ([] a) U X b
 (a U b) U (c U d)
+true
+([]a && XXXX!a)
 EOF
 while read f
 do