bin: Ignore empty lines on input.

* src/bin/common_finput.cc: Here.
* src/ltltest/ltlfilt.test: Test it.
* NEWS: Mention it.

NEWS

@@ -38,6 +38,8 @@ New in spot 1.1a (not yet released):
     - genltl --gh-r generated the wrong formulas due to a typo.
     - ltlfilt --eventual and --universal were not handled properly.
     - ltlfilt --stutter-invariant would trigger an assert on PSL formulas.
+    - ltl2tgba, ltl2tgta, ltlcross, and ltlfilt, would all choke on empty
+      lines in a file of formulas.  They now ignore empty lines.
 
 New in spot 1.1 (2013-04-28):
 

src/bin/common_finput.cc

 // -*- coding: utf-8 -*-
-// Copyright (C) 2012 Laboratoire de Recherche et Développement de
-// l'Epita (LRDE).
+// Copyright (C) 2012, 2013 Laboratoire de Recherche et Développement
+// de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -114,7 +114,8 @@ job_processor::process_stream(std::istream& is,
   int linenum = 0;
   std::string line;
   while (!abort_run && std::getline(is, line))
-    error |= process_string(line, filename, ++linenum);
+    if (!line.empty())
+      error |= process_string(line, filename, ++linenum);
   return error;
 }
 

src/ltltest/ltlfilt.test

@@ -31,10 +31,12 @@ checkopt()
   diff exp out
 }
 
-
+# The empty lines in the file are meant, we want to make sure that
+# they are ignored.
 cat >formulas <<EOF
 GFa | FGb
 F(GFa | Gb)
+
 F(b W GFa)
 GFa | Gb
 b W GFa
@@ -44,6 +46,7 @@ G(a & Xb)
 Xa
 F(a & !Xa & Xb)
 {a & {b|c} }
+
 EOF
 
 checkopt --eventual <<EOF