trival: new class for tri-valued logic

* spot/misc/trival.hh: New file.
* spot/misc/Makefile.am: Add it.
* python/spot_impl.i: Add Python bindings.
* tests/core/trival.cc, tests/core/trival.test,
tests/python/trival.py: New files, testing it.
* tests/Makefile.am: Add them.

python/spot_impl.i

 // -*- coding: utf-8 -*-
-// Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015  Laboratoire de
-// Recherche et Développement de l'Epita (LRDE).
+// Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016
+// Laboratoire de Recherche et Développement de l'Epita (LRDE).
 // Copyright (C) 2003, 2004, 2005, 2006  Laboratoire d'Informatique
 // de Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
 // Université Pierre et Marie Curie.
@@ -81,6 +81,7 @@
 #include <spot/misc/optionmap.hh>
 #include <spot/misc/random.hh>
 #include <spot/misc/escape.hh>
+#include <spot/misc/trival.hh>
 
 #include <spot/tl/formula.hh>
 
@@ -331,6 +332,9 @@ namespace swig
 %include <spot/misc/random.hh>
 %include <spot/misc/escape.hh>
 
+%implicitconv spot::trival;
+%include <spot/misc/trival.hh>
+
 %implicitconv std::vector<spot::formula>;
 
 %include <spot/tl/formula.hh>
@@ -439,7 +443,36 @@ namespace std {
 %include <spot/taalgos/minimize.hh>
 
 
-#undef ltl
+%extend spot::trival {
+  std::string __repr__()
+  {
+    std::ostringstream os;
+    os << *self;
+    return os.str();
+  }
+
+  std::string __str__()
+  {
+    std::ostringstream os;
+    os << *self;
+    return os.str();
+  }
+
+  spot::trival __neg__()
+  {
+    return !*self;
+  }
+
+  spot::trival __and__(spot::trival other)
+  {
+    return *self && other;
+  }
+
+  spot::trival __or__(spot::trival other)
+  {
+    return *self || other;
+  }
+}
 
 %exception spot::formula::__getitem__ {
   try {

spot/misc/Makefile.am

 ## -*- coding: utf-8 -*-
-## Copyright (C) 2011, 2012, 2013, 2014 Laboratoire de Recherche et
-## Développement de l'Epita (LRDE).
+## Copyright (C) 2011, 2012, 2013, 2014, 2016 Laboratoire de Recherche
+## et Développement de l'Epita (LRDE).
 ## Copyright (C) 2003, 2004, 2005, 2006 Laboratoire d'Informatique de
 ## Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
 ## Université Pierre et Marie Curie.
@@ -53,6 +53,7 @@ misc_HEADERS = \
   satsolver.hh \
   timer.hh \
   tmpfile.hh \
+  trival.hh \
   version.hh
 
 noinst_LTLIBRARIES = libmisc.la

spot/misc/trival.hh

+// -*- coding: utf-8 -*-
+// Copyright (C) 2016 Laboratoire de Recherche et Developpement 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <iostream>
+
+namespace spot
+{
+
+  /// \ingroup misc_tools
+  /// @{
+
+  /// \brief A class implementing Kleene's three-valued logic.
+  ///
+  /// https://en.wikipedia.org/wiki/Three-valued_logic#Kleene_and_Priest_logics
+  class trival
+  {
+  public:
+    // We use repr_t instead of value_t in bitfields to avoid a warning from gcc
+    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51242
+    typedef signed char repr_t;
+    enum value_t : repr_t { no_value = -1, maybe_value = 0, yes_value = 1 };
+  private:
+    value_t val_;
+  public:
+    constexpr trival()
+      : val_(maybe_value)
+    {
+    }
+
+    constexpr trival(bool v)
+      : val_(v ? yes_value : no_value)
+    {
+    }
+
+    trival(repr_t v)
+    {
+      val_ = static_cast<value_t>(v);
+    }
+
+    constexpr trival(value_t v)
+      : val_(v)
+    {
+    }
+
+    static constexpr trival maybe()
+    {
+      return trival();
+    }
+
+    /// Is true or false, but not maybe.
+    constexpr bool is_known() const
+    {
+      return val_ != maybe_value;
+    }
+
+    constexpr bool is_maybe() const
+    {
+      return val_ == maybe_value;
+    }
+
+    constexpr bool is_true() const
+    {
+      return val_ == yes_value;
+    }
+
+    constexpr bool is_false() const
+    {
+      return val_ == no_value;
+    }
+
+    constexpr bool operator==(trival o) const
+    {
+      return val_ == o.val_;
+    }
+
+    constexpr bool operator!=(trival o) const
+    {
+      return val_ != o.val_;
+    }
+
+    constexpr value_t val() const
+    {
+      return val_;
+    }
+
+#ifndef SWIG
+    // constexpr explicit only supported in SWIG >= 3.0.4
+    constexpr
+#endif
+    explicit operator bool() const
+    {
+      return val_ == yes_value;
+    }
+
+    constexpr trival operator!() const
+    {
+      return trival((val_ == yes_value) ? no_value :
+		    (val_ == no_value) ? yes_value :
+		    maybe_value);
+    }
+  };
+
+  constexpr bool operator==(bool a, trival b)
+  {
+    return b == trival(a);
+  }
+
+  constexpr bool operator!=(bool a, trival b)
+  {
+    return b != trival(a);
+  }
+
+  constexpr trival operator&&(trival a, trival b)
+  {
+    return
+      (a.val() == trival::no_value || b.val() == trival::no_value)
+      ? trival(false)
+      : (a.val() == trival::maybe_value || b.val() == trival::maybe_value)
+      ? trival::maybe()
+      : trival(true);
+  }
+
+  constexpr trival operator&&(bool a, trival b)
+  {
+    return trival(a) && b;
+  }
+
+  constexpr trival operator&&(trival a, bool b)
+  {
+    return a && trival(b);
+  }
+
+  constexpr trival operator||(trival a, trival b)
+  {
+    return
+      (a.val() == trival::yes_value || b.val() == trival::yes_value)
+      ? trival(true)
+      : (a.val() == trival::maybe_value || b.val() == trival::maybe_value)
+      ? trival::maybe()
+      : trival(false);
+  }
+
+  constexpr trival operator||(bool a, trival b)
+  {
+    return trival(a) || b;
+  }
+
+  constexpr trival operator||(trival a, bool b)
+  {
+    return a || trival(b);
+  }
+
+  inline std::ostream& operator<<(std::ostream& os, trival v)
+  {
+    return os << ((v.val() == trival::no_value) ? "no"
+		  : (v.val() == trival::maybe_value) ? "maybe"
+		  : "yes");
+  }
+
+  /// @}
+}

tests/Makefile.am

@@ -36,8 +36,8 @@ check_SCRIPTS = run
 
 # We try to keep this somehow by strength.  Test basic things first,
 # because such failures will be easier to diagnose and fix.
-TESTS = $(TESTS_sanity) $(TESTS_tl) $(TESTS_graph) $(TESTS_kripke) \
-  $(TESTS_twa) $(TESTS_python) $(TESTS_ltsmin)
+TESTS = $(TESTS_sanity) $(TESTS_misc) $(TESTS_tl) $(TESTS_graph) \
+  $(TESTS_kripke) $(TESTS_twa) $(TESTS_python) $(TESTS_ltsmin)
 
 distclean-local:
 	find . -name '*.dir' -type d -print | xargs rm -rf
@@ -85,6 +85,7 @@ check_PROGRAMS = \
   core/reductaustr \
   core/syntimpl \
   core/taatgba \
+  core/trival \
   core/tgbagraph \
   core/tostring \
   core/tunabbrev \
@@ -131,6 +132,7 @@ core_reductaustr_SOURCES = core/equalsf.cc
 core_reductaustr_CPPFLAGS = $(AM_CPPFLAGS) -DREDUC_TAUSTR
 core_syntimpl_SOURCES = core/syntimpl.cc
 core_tostring_SOURCES = core/tostring.cc
+core_trival_SOURCES = core/trival.cc
 core_tunabbrev_SOURCES = core/equalsf.cc
 core_tunabbrev_CPPFLAGS = $(AM_CPPFLAGS) -DUNABBREV='"^ieFG"'
 core_tunenoform_SOURCES = core/equalsf.cc
@@ -180,11 +182,14 @@ TESTS_graph = \
 TESTS_kripke = \
   core/kripke.test
 
+TESTS_misc = \
+  core/bitvect.test \
+  core/intvcomp.test \
+  core/trival.test
+
 TESTS_twa = \
   core/acc.test \
   core/acc2.test \
-  core/intvcomp.test \
-  core/bitvect.test \
   core/ltlcross3.test \
   core/taatgba.test \
   core/renault.test \
@@ -299,7 +304,8 @@ TESTS_python = \
   python/remfin.py \
   python/satmin.py \
   python/setxor.py \
-  python/testingaut.ipynb
+  python/testingaut.ipynb \
+  python/trival.py
 endif
 
 SUFFIXES = .ipynb .html

tests/core/.gitignore

@@ -65,6 +65,7 @@ tgbagraph
 tgbaread
 tostring
 tripprod
+trival
 tunabbrev
 tunenoform
 unabbrevwm

tests/core/trival.cc

+// -*- coding: utf-8 -*-
+// Copyright (C) 2016 Laboratoire de Recherche et Developpement 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#undef NDEBUG
+#include <spot/misc/trival.hh>
+#include <cassert>
+
+int main()
+{
+  spot::trival v1;
+  spot::trival v2(false);
+  spot::trival v3(true);
+  spot::trival v4 = spot::trival::maybe();
+  assert(v1 != v2);
+  assert(v1 != v3);
+  assert(v2 != v3);
+  assert(v4 != v2);
+  assert(v4 != v3);
+  assert(v2 == false);
+  assert(true == v3);
+  assert(v4 == spot::trival::maybe());
+  assert(v3);
+  assert(!v2);
+  assert(!(bool)!v1);
+  assert(!(bool)v1);
+  assert(!(bool)!v3);
+
+  for (auto u : {v2, v1, v3})
+    for (auto v : {v2, v1, v3})
+      std::cout << u << " && " << v << " == " << (u && v) << '\n';
+  for (auto u : {v2, v1, v3})
+    for (auto v : {v2, v1, v3})
+      std::cout << u << " || " << v << " == " << (u || v) << '\n';
+}

tests/core/trival.test

+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2016 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# 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
+
+run 0 ../trival > trival.out
+
+cat > expected <<EOF
+no && no == no
+no && maybe == no
+no && yes == no
+maybe && no == no
+maybe && maybe == maybe
+maybe && yes == maybe
+yes && no == no
+yes && maybe == maybe
+yes && yes == yes
+no || no == no
+no || maybe == maybe
+no || yes == yes
+maybe || no == maybe
+maybe || maybe == maybe
+maybe || yes == yes
+yes || no == yes
+yes || maybe == yes
+yes || yes == yes
+EOF
+
+diff trival.out expected

tests/python/trival.py

+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2016  Laboratoire de Recherche et Développement
+# de l'Epita
+#
+# 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import spot
+
+v1 = spot.trival()
+v2 = spot.trival(False)
+v3 = spot.trival(True)
+v4 = spot.trival_maybe()
+assert v1 != v2
+assert v1 != v3
+assert v2 != v3
+assert v4 != v2
+assert v4 != v3
+assert v2 == False
+assert True == v3
+assert v4 == spot.trival_maybe()
+assert v3
+assert -v2
+assert not -v1
+assert not v1;
+assert not -v3
+
+for u in (v1, v2, v3):
+  for v in (v1, v2, v3):
+      assert (u & v) == -(-u | -v)