autfilt: add highlighting options for nondeterminism

Fixes #123.

* bin/autfilt.cc: Add options --highlight-nondet-states=NUM,
 --highlight-nondet-edges=NUM, and  --highlight-nondet=NUM.
* spot/twaalgos/isdet.cc,
spot/twaalgos/isdet.hh (highlight_nondet_states,
highlight_nondet_edges): New functions.
* tests/core/det.test: Add test cases.
* NEWS: Mention them.

spot/twaalgos/isdet.cc

@@ -73,6 +73,53 @@ namespace spot
     return !count_nondet_states_aux<false>(aut);
   }
 
+  void
+  highlight_nondet_states(twa_graph_ptr& aut, unsigned color)
+  {
+    if (aut->prop_deterministic())
+      return;
+    unsigned ns = aut->num_states();
+    auto* highlight = new std::map<unsigned, unsigned>;
+    for (unsigned src = 0; src < ns; ++src)
+      {
+        bdd available = bddtrue;
+        for (auto& t: aut->out(src))
+          if (!bdd_implies(t.cond, available))
+            highlight->emplace(src, color);
+          else
+            available -= t.cond;
+      }
+    aut->prop_deterministic(highlight->empty());
+    aut->set_named_prop("highlight-states", highlight);
+  }
+
+  void
+  highlight_nondet_edges(twa_graph_ptr& aut, unsigned color)
+  {
+    if (aut->prop_deterministic())
+      return;
+    unsigned ns = aut->num_states();
+    auto* highlight = new std::map<unsigned, unsigned>;
+    for (unsigned src = 0; src < ns; ++src)
+      {
+        // Make a first pass to gather non-deterministic labels
+        bdd available = bddtrue;
+        bdd extra = bddfalse;
+        for (auto& t: aut->out(src))
+          if (!bdd_implies(t.cond, available))
+            extra |= (t.cond - available);
+          else
+            available -= t.cond;
+        // Second pass to gather the relevant edges.
+        if (extra != bddfalse)
+          for (auto& t: aut->out(src))
+            if ((t.cond & extra) != bddfalse)
+              highlight->emplace(aut->get_graph().index_of_edge(t), color);
+      }
+    aut->prop_deterministic(highlight->empty());
+    aut->set_named_prop("highlight-edges", highlight);
+  }
+
   bool
   is_complete(const const_twa_graph_ptr& aut)
   {

spot/twaalgos/isdet.hh

@@ -46,12 +46,32 @@ namespace spot
   SPOT_API bool
   is_deterministic(const const_twa_graph_ptr& aut);
 
+  /// \brief Highlight nondeterministic states
+  ///
+  /// A state is nondeterministic if it has two outgoing edges whose
+  /// labels are not incompatibles.
+  ///
+  /// \param aut the automaton to process
+  /// \param color the color to give to nondeterministic states.
+  SPOT_API void
+  highlight_nondet_states(twa_graph_ptr& aut, unsigned color);
+
+  /// \brief Highlight nondeterministic edges
+  ///
+  /// An edge is nondeterministic if there exist another edge leaving
+  /// the same source state, with a compatible label (i.e., the
+  /// conjunction of the two labels is not false).
+  ///
+  /// \param aut the automaton to process
+  /// \param color the color to give to nondeterministic edges.
+  SPOT_API void
+  highlight_nondet_edges(twa_graph_ptr& aut, unsigned color);
+  /// @}
+
   /// \brief Return true iff \a aut is complete.
   ///
   /// An automaton is complete if its translation relation is total,
   /// i.e., each state as a successor for any possible configuration.
   SPOT_API bool
   is_complete(const const_twa_graph_ptr& aut);
-
-  /// @}
 }