Add trivial() and one_state_of() functions to scc_map.

* src/tgbaalgos/scc.hh, src/tgbaalgos/scc.cc (scc_map::trivial,
scc_map::one_state_of): Two new helper functions.

ChangeLog

+2011-01-04  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Add trivial() and one_state_of() functions to scc_map.
+
+	* src/tgbaalgos/scc.hh, src/tgbaalgos/scc.cc (scc_map::trivial,
+	scc_map::one_state_of): Two new helper functions.
+
 2011-01-04  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	* src/tgba/tgbaunion.hh: Remove one useless include.

src/tgbaalgos/scc.cc

-// Copyright (C) 2008, 2009  Laboratoire de Recherche et Developpement de
-// l'Epita.
+// Copyright (C) 2008, 2009, 2011 Laboratoire de Recherche et
+// Developpement de l'Epita.
 //
 // This file is part of Spot, a model checking library.
 //
@@ -74,6 +74,13 @@ namespace spot
     return scc_map_[n].succ;
   }
 
+  bool
+  scc_map::trivial(unsigned n) const
+  {
+    assert(scc_map_.size() > n);
+    return scc_map_[n].trivial;
+  }
+
   bool
   scc_map::accepting(unsigned n) const
   {
@@ -347,6 +354,12 @@ namespace spot
     return scc_map_[n].states;
   }
 
+  const state* scc_map::one_state_of(unsigned n) const
+  {
+    assert(scc_map_.size() > n);
+    return scc_map_[n].states.front();
+  }
+
   unsigned scc_map::scc_count() const
   {
     return scc_map_.size();

src/tgbaalgos/scc.hh

@@ -105,6 +105,13 @@ namespace spot
     /// \pre This should only be called once build_map() has run.
     const succ_type& succ(unsigned n) const;
 
+    /// \brief Return whether an SCC is trivial.
+    ///
+    /// Trivial SCCs have one state and no self-loop.
+    ///
+    /// \pre This should only be called once build_map() has run.
+    bool trivial(unsigned n) const;
+
     /// \brief Return whether an SCC is accepting.
     ///
     /// \pre This should only be called once build_map() has run.
@@ -150,6 +157,14 @@ namespace spot
     /// \pre This should only be called once build_map() has run.
     const std::list<const state*>& states_of(unsigned n) const;
 
+    /// \brief Return one state of an SCC.
+    ///
+    /// The state in the returned list is still owned by the scc_map
+    /// instance.  It should NOT be deleted by the client code.
+    ///
+    /// \pre This should only be called once build_map() has run.
+    const state* one_state_of(unsigned n) const;
+
     /// \brief Return the number of the SCC a state belongs too.
     ///
     /// \pre This should only be called once build_map() has run.