* src/tgbaalgos/bfssteps.hh, src/tgbaalgos/bfssteps.cc: New files.

* src/tgbaalgos/Makefile.am (tgbaalgos_HEADERS,
libtgbaalgos_la_SOURCES): Add them.
* src/tgbaalgos/gv04.cc (gv04::result::accepting_run): Use
the new bfs_steps class.

src/tgbaalgos/bfssteps.cc

@@ -0,0 +1,100 @@
+// Copyright (C) 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
+// et Marie Curie.
+//
+// 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.
+
+#include <map>
+#include <deque>
+#include "bfssteps.hh"
+#include "tgba/tgba.hh"
+
+namespace spot
+{
+
+  bfs_steps::bfs_steps(const tgba* a)
+    : a_(a)
+  {
+  }
+
+  bfs_steps::~bfs_steps()
+  {
+  }
+
+  const state*
+  bfs_steps::search(const state* start, tgba_run::steps& l)
+  {
+    // Records backlinks to parent state during the BFS.
+    // (This also stores the propositions of this link.)
+    std::map<const state*, tgba_run::step,
+      state_ptr_less_than> father;
+    // BFS queue.
+    std::deque<const state*> todo;
+    // Initial state.
+    todo.push_back(start);
+
+    while (!todo.empty())
+      {
+	const state* src = todo.front();
+	todo.pop_front();
+	tgba_succ_iterator* i = a_->succ_iter(src);
+	for (i->first(); !i->done(); i->next())
+	  {
+	    const state* dest = filter(i->current_state());
+
+	    if (!dest)
+	      continue;
+
+	    bdd cond = i->current_condition();
+	    bdd acc = i->current_acceptance_conditions();
+	    tgba_run::step s = { src, cond, acc };
+
+	    if (match(s, dest))
+	      {
+		// Found it!
+
+		tgba_run::steps p;
+		for (;;)
+		  {
+		    tgba_run::step tmp = s;
+		    tmp.s = tmp.s->clone();
+		    p.push_front(tmp);
+		    if (s.s == start)
+		      break;
+		    s = father[s.s];
+		  }
+
+		l.splice(l.end(), p);
+		delete i;
+		return dest;
+	      }
+
+	    // Common case: record backlinks and continue BFS
+	    // for unvisited states.
+	    if (father.find(dest) == father.end())
+	      {
+		todo.push_back(dest);
+		father[dest] = s;
+	      }
+	  }
+	delete i;
+      }
+    return 0;
+  }
+
+}