Implement Loizou & Thanisch's algorithm for enumerating cycles.

* src/tgbaalgos/cycles.cc, src/tgbaalgos/cycles.hh,
src/tgbatest/cycles.test: New files.
* src/tgbaalgos/Makefile.am, src/tgbatest/Makefile.am: Add them.
* src/tgbatest/ltl2tgba.cc: Add a -KC option for testing.

src/tgbatest/Makefile.am

@@ -108,7 +108,8 @@ TESTS = \
   spotlbtt.test \
   spotlbtt2.test \
   complementation.test \
-  randpsl.test
+  randpsl.test \
+  cycles.test
 
 EXTRA_DIST = $(TESTS)
 

src/tgbatest/cycles.test

@@ -0,0 +1,62 @@
+#!/bin/sh
+# Copyright (C) 2012 Laboratoire de Recherche et Développement
+# de l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Spot; see the file COPYING.  If not, write to the Free
+# Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+# 02111-1307, USA.
+
+# While running some benchmark, Tomáš Babiak found that Spot took too
+# much time (i.e. >1h) to translate those six formulae.  It turns out
+# that the WDBA minimization was performed after the degeneralization
+# algorithm, while this is not necessary (WDBA will produce a BA, so
+# we may as well skip degeneralization).  Translating these formulae
+# in the test-suite ensure that they don't take too much time (the
+# buildfarm will timeout if it does).
+
+. ./defs
+
+set -e
+
+# Fig.1 from Johnson's SIAM J. Comput. 1975 paper.
+
+(
+echo 'acc = ;'
+k=3
+v=`expr $k + 2`
+w=`expr 2 \* $k + 2`
+x=`expr 3 \* $k + 3`
+for i in $(seq 2 `expr $k + 1`); do
+  echo "s1,s$i,,;"
+  echo "s$i,s$v,,;"
+done
+for i in $(seq `expr $k + 2` `expr 2 \* $k`); do
+  echo "s$i,s`expr $i + 1`,,;"
+  echo "s$i,s$w,,;"
+done
+echo "s`expr 2 \* $k + 1`,s$w,,;"
+echo "s`expr 2 \* $k + 1`,s1,,;"
+for i in $(seq `expr 2 \* $k + 3` `expr 3 \* $k + 2`); do
+  echo "s$w,s$i,,;"
+  echo "s$i,s$x,,;"
+done
+echo "s`expr 2 \* $k + 3`,s$v,,;"
+echo "s$x,s$w,,;"
+) > johnson-fig1.tgba
+
+
+run 0 ../ltl2tgba -KC -X johnson-fig1.tgba > out
+test `wc -l < out` -eq 10

src/tgbatest/ltl2tgba.cc

@@ -64,6 +64,7 @@
 #include "tgbaalgos/emptiness_stats.hh"
 #include "tgbaalgos/scc.hh"
 #include "tgbaalgos/isdet.hh"
+#include "tgbaalgos/cycles.hh"
 #include "kripkeparse/public.hh"
 #include "tgbaalgos/simulation.hh"
 
@@ -281,6 +282,7 @@ syntax(char* prog)
 	    << "  -K    dump the graph of SCCs in dot format" << std::endl
 	    << "  -KV   verbosely dump the graph of SCCs in dot format"
 	    << std::endl
+	    << "  -KC   list cycles in automaton" << std::endl
 	    << "  -N    output the never clain for Spin (implies -DS)"
 	    << std::endl
 	    << "  -NN   output the never clain for Spin, with commented states"
@@ -522,6 +524,10 @@ main(int argc, char** argv)
 	{
 	  output = 11;
 	}
+      else if (!strcmp(argv[formula_index], "-KC"))
+	{
+	  output = 15;
+	}
       else if (!strcmp(argv[formula_index], "-l"))
 	{
 	  translation = TransLaCIM;
@@ -1409,6 +1415,20 @@ main(int argc, char** argv)
 	      std::cout << std::endl;
 
 	      break;
+	    case 15:
+	      {
+		spot::scc_map m(a);
+		m.build_map();
+		spot::enumerate_cycles c(a, m);
+		unsigned max = m.scc_count();
+		for (unsigned n = 0; n < max; ++n)
+		  {
+		    std::cout << "Cycles in SCC #" << n << std::endl;
+		    c.run(n);
+		  }
+		break;
+	      }
+
 	    default:
 	      assert(!"unknown output option");
 	    }