introduce count_univbranch_states() and count_univbranch_edges()

Fixes #368, suggested by František Blahoudek.

* spot/twaalgos/isdet.cc, spot/twaalgos/isdet.hh
(count_univbranch_states(), count_univbranch_edges()): New functions.
* bin/common_aoutput.cc, bin/common_aoutput.hh: Add %u and variants.
* NEWS: Mention these.
* tests/core/alternating.test: Test them.

NEWS

@@ -18,6 +18,11 @@ New in spot 2.6.3.dev (not yet released)
   - ltlfilt learned --liveness to match formulas representing liveness
     properties.
 
+  - the --stats= option of tools producing automata learned how to
+    tell if an automaton uses universal branching (%u), or more
+    precisely how many states (%[s]u) or edges (%[e]u) use universal
+    branching.
+
   Python:
 
   - spot.translate() and spot.postprocess() now take an xargs=
@@ -75,6 +80,10 @@ New in spot 2.6.3.dev (not yet released)
     used to check whether a formula or an automaton represents a
     liveness property.
 
+  - Two new functions count_univbranch_states() and
+    count_univbranch_edges() can help measuring the amount of
+    universal branching in alternating automata.
+
   Bugs fixed:
 
   - The pair of acc_cond::mark_t returned by

bin/common_aoutput.cc

@@ -218,6 +218,10 @@ static const argp_option io_options[] =
       "1 if the automaton is complete, 0 otherwise", 0 },
     { "%r", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
       "wall-clock time elapsed in seconds (excluding parsing)", 0 },
+    { "%U, %u, %[LETTER]U, %[LETTER]u", 0, nullptr,
+      OPTION_DOC | OPTION_NO_USAGE,
+      "1 if the automaton contains some universal branching "
+      "(or a number of [s]tates or [e]dges with universal branching)", 0 },
     { "%W, %w", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
       "one word accepted by the automaton", 0 },
     { "%X, %x, %[LETTERS]X, %[LETTERS]x", 0, nullptr,
@@ -272,6 +276,11 @@ static const argp_option o_options[] =
       "or (c) children processes.", 0 },
     { "%n", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
       "number of nondeterministic states in output", 0 },
+    { "%u, %[LETTER]u", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
+      "1 if the automaton contains some universal branching "
+      "(or a number of [s]tates or [e]dges with universal branching)", 0 },
+    { "%u, %[e]u", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
+      "number of states (or [e]dges) with universal branching", 0 },
     { "%d", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
       "1 if the output is deterministic, 0 otherwise", 0 },
     { "%p", 0, nullptr, OPTION_DOC | OPTION_NO_USAGE,
@@ -393,6 +402,7 @@ hoa_stat_printer::hoa_stat_printer(std::ostream& os, const char* format,
       declare('P', &haut_complete_);
       declare('S', &haut_states_);
       declare('T', &haut_trans_);
+      declare('U', &haut_univbranch_);
       declare('W', &haut_word_);
       declare('X', &haut_ap_);
     }
@@ -406,6 +416,7 @@ hoa_stat_printer::hoa_stat_printer(std::ostream& os, const char* format,
     declare('f', &filename_);        // Override the formula printer.
   declare('h', &output_aut_);
   declare('m', &aut_name_);
+  declare('u', &aut_univbranch_);
   declare('w', &aut_word_);
   declare('x', &aut_ap_);
 }
@@ -478,6 +489,8 @@ hoa_stat_printer::print(const spot::const_parsed_aut_ptr& haut,
           // This is more efficient than calling count_nondet_state().
           haut_deterministic_ = is_deterministic(haut->aut);
         }
+      if (has('U'))
+        haut_univbranch_ = haut->aut;
 
       if (has('P'))
         haut_complete_ = is_complete(haut->aut);
@@ -509,6 +522,8 @@ hoa_stat_printer::print(const spot::const_parsed_aut_ptr& haut,
       else
         aut_name_.val().clear();
     }
+  if (has('u'))
+    aut_univbranch_ = aut;
   if (has('w'))
     {
       if (auto word = aut->accepting_word())
@@ -532,6 +547,8 @@ hoa_stat_printer::print(const spot::const_parsed_aut_ptr& haut,
   output_aut_ = nullptr;
   input_aut_ = nullptr;
   haut_scc_.reset();
+  aut_univbranch_ = nullptr;
+  haut_univbranch_ = nullptr;
   aut_ap_.clear();
   haut_ap_.clear();
   return res;
@@ -661,6 +678,26 @@ namespace
   }
 }
 
+void printable_univbranch::print(std::ostream& os, const char* pos) const
+{
+  std::string options = "l";
+  if (pos[0] == '[' && pos[1] != ']')
+    {
+      if (pos[1] == 'e' && pos[2] == ']')
+        {
+          os << spot::count_univbranch_edges(val_);
+          return;
+        }
+      else if (pos[1] == 's' && pos[2] == ']')
+        {
+          os << spot::count_univbranch_states(val_);
+          return;
+        }
+      percent_error(pos, pos + 1);
+    }
+  os << (spot::count_univbranch_edges(val_) ? 1 : 0);
+}
+
 void printable_timer::print(std::ostream& os, const char* pos) const
 {
   double res = 0;

bin/common_aoutput.hh

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2014-2017 Laboratoire de Recherche et Développement
+// Copyright (C) 2014-2018 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -74,6 +74,14 @@ struct printable_automaton final:
   void print(std::ostream& os, const char* pos) const override;
 };
 
+struct printable_univbranch final:
+  public spot::printable_value<spot::const_twa_graph_ptr>
+{
+  using spot::printable_value<spot::const_twa_graph_ptr>::operator=;
+  void print(std::ostream& os, const char* pos) const override;
+};
+
+
 struct printable_timer final: public spot::printable
 {
 protected:
@@ -169,6 +177,8 @@ private:
   spot::printable_value<unsigned> haut_complete_;
   spot::printable_value<const char*> csv_prefix_;
   spot::printable_value<const char*> csv_suffix_;
+  printable_univbranch haut_univbranch_;
+  printable_univbranch aut_univbranch_;
   printable_timer timer_;
   printable_automaton input_aut_;
   printable_automaton output_aut_;

spot/twaalgos/isdet.cc

@@ -310,4 +310,33 @@ namespace spot
     check_semi_determism(aut, true);
   }
 
+  unsigned
+  count_univbranch_states(const const_twa_graph_ptr& aut)
+  {
+    if (aut->is_existential())
+      return 0;
+    unsigned res = 0;
+    unsigned ns = aut->num_states();
+    for (unsigned s = 0; s < ns; ++s)
+      for (auto& e: aut->out(s))
+        if (aut->is_univ_dest(e))
+          {
+            ++res;
+            break;
+          }
+    return res;
+  }
+
+  unsigned
+  count_univbranch_edges(const const_twa_graph_ptr& aut)
+  {
+    if (aut->is_existential())
+      return 0;
+    unsigned res = aut->is_univ_dest(aut->get_init_state_number());
+    for (auto& e: aut->edges())
+      if (aut->is_univ_dest(e))
+        ++res;
+    return res;
+  }
+
 }

spot/twaalgos/isdet.hh

@@ -1,6 +1,6 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2012, 2013, 2014, 2015, 2016, 2017 Laboratoire de Recherche
+// Copyright (C) 2012-2018 Laboratoire de Recherche et Développement
-// et Développement de l'Epita (LRDE).
+// de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -109,4 +109,33 @@ namespace spot
   /// \brief Set the deterministic and semi-deterministic properties
   /// appropriately.
   SPOT_API void check_determinism(twa_graph_ptr aut);
+
+  // \brief Count states with some universal branching.
+  //
+  // This counts the number of states that have edges going to several
+  // destinations at once (as reported by aut->is_univ_dest(...)).
+  //
+  // Note that nondeterministic automata (which include deterministic
+  // automata) have 0 such state, but additionally they also have
+  // "singleton" initial state (which this function does not check).
+  //
+  // \see count_univbranch_edges()
+  SPOT_API unsigned
+  count_univbranch_states(const const_twa_graph_ptr& aut);
+
+  // \brief Count edges with universal branching.
+  //
+  // This counts the number of edges going to several destination at
+  // once (as reported by aut->is_univ_dest(...)).
+  //
+  // If the automaton starts in multiple initial states at once, this
+  // is considered as a universal "initial edge", and adds one to the
+  // total count.
+  //
+  // Nondeterministic automata (which include deterministic automata)
+  // have 0 edges with universal branching.
+  //
+  // \see count_univbranch_states()
+  SPOT_API unsigned
+  count_univbranch_edges(const const_twa_graph_ptr& aut);
 }

tests/core/alternating.test

@@ -53,6 +53,8 @@ State: 6 "t"
 --END--
 EOF
 
+test "1 2 4" = "`autfilt --stats='%u %[s]u %[e]u' alt.hoa`"
+
 autfilt --has-univ-branch --has-exist-branch --dot=bans alt.hoa >alt.dot
 
 cat >expect.dot <<EOF
@@ -986,4 +988,9 @@ State: 2 {0}
 [t] 2&1
 --END--
 EOF
-test '2 0 1 1 1'  = "`autfilt --stats='%[iw]c %[W]c %[c]c %[C]c %[t]c' in`"
+stats='%[iw]c_%[W]c_%[c]c_%[C]c_%[t]c_%U_%[e]U_%[s]U'
+test '2_0_1_1_1_1_3_3' = "`autfilt --stats=$stats in`"
+
+
+autfilt --stats='%[x]U' in 2>stderr && exit2
+grep '%\[x\]U' stderr