acc: recognize parity acceptance

It has two modes: strict or not.  In strict mode (tested in
hoaparse.test), the acceptance formula has to match exactly the one
given in the HOA spec.  In non-strict mode (tested in accparse2.py)
any equivalent formula is accepted.

* src/twa/acc.cc, src/twa/acc.hh (acc_cond::is_parity): New method.
* src/twaalgos/hoa.cc: Use it.
* src/tests/hoaparse.test: Test it.
* wrap/python/spot_impl.i: Bind it.
* wrap/python/tests/accparse2.py: New file.
* wrap/python/tests/Makefile.am: Add it.

src/tests/hoaparse.test

@@ -1789,6 +1789,54 @@ State: 0
 [!0&1] 0 {2}
 [0&1] 0 {}
 --END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Inf(0)|Fin(1)&Inf(2) /* min even 4 */
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0 {}
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Inf(3)|Fin(2)&Inf(1) /* max odd 4 */
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0 {}
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Fin(3) & (Inf(2) | (Fin(1) & Inf(0))) /* max even 4 */
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0 {}
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Inf(0) | (Fin(1) & Inf(2)) /* min even 4 (reorderd) */
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0 {}
+--END--
 EOF
 
 expectok input <<EOF
@@ -1853,6 +1901,66 @@ State: 0
 [!0&1] 0 {2}
 [0&1] 0
 --END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+acc-name: parity min even 4
+Acceptance: 4 Inf(0) | (Fin(1) & Inf(2))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+acc-name: parity max odd 4
+Acceptance: 4 Inf(3) | (Fin(2) & Inf(1))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+acc-name: parity max even 4
+Acceptance: 4 Fin(3) & (Inf(2) | (Fin(1) & Inf(0)))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+acc-name: parity min even 4
+Acceptance: 4 Inf(0) | (Fin(1) & Inf(2))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
 EOF
 
 # The complements are Streett and Rabin, but the acceptance set are
@@ -1917,4 +2025,60 @@ State: 0
 [!0&1] 0 {2}
 [0&1] 0
 --END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Fin(0) & (Inf(1) | Fin(2))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Fin(3) & (Inf(2) | Fin(1))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Inf(3) | (Fin(2) & (Inf(1) | Fin(0)))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 4 Fin(0) & (Inf(1) | Fin(2))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 1}
+[0&!1] 0 {1}
+[!0&1] 0 {2}
+[0&1] 0
+--END--
 EOF

src/twa/acc.cc

@@ -526,6 +526,76 @@ namespace spot
       SPOT_UNREACHABLE();
       return bddfalse;
     }
+
+    static bool
+    equiv_codes(const acc_cond::acc_code& lhs,
+		const acc_cond::acc_code& rhs)
+    {
+      auto used = lhs.used_sets() | rhs.used_sets();
+
+      unsigned c = used.count();
+      unsigned umax = used.max_set();
+
+      bdd_allocator ba;
+      int base = ba.allocate_variables(c);
+      assert(base == 0);
+      std::vector<bdd> r;
+      for (unsigned i = 0; r.size() < umax; ++i)
+	if (used.has(i))
+	  r.push_back(bdd_ithvar(base++));
+	else
+	  r.push_back(bddfalse);
+      return to_bdd_rec(&lhs.back(), &r[0]) == to_bdd_rec(&rhs.back(), &r[0]);
+    }
+  }
+
+  bool acc_cond::is_parity(bool& max, bool& odd, bool equiv) const
+  {
+    unsigned sets = num_;
+    if (sets == 0)
+      {
+	max = false;
+	odd = false;
+	return is_false();
+      }
+    if (is_true())
+      return false;
+    acc_cond::mark_t u_inf;
+    acc_cond::mark_t u_fin;
+    std::tie(u_inf, u_fin) = code_.used_inf_fin_sets();
+
+    odd = !u_inf.has(0);
+    for (auto s: u_inf.sets())
+      if ((s & 1) != odd)
+	return false;
+
+    auto max_code = acc_code::parity(true, odd, sets);
+    if (max_code == code_)
+      {
+	max = true;
+	return true;
+      }
+    auto min_code = acc_code::parity(false, odd, sets);
+    if (min_code == code_)
+      {
+	max = false;
+	return true;
+      }
+
+    if (!equiv)
+      return false;
+
+    if (equiv_codes(code_, max_code))
+      {
+	max = true;
+	return true;
+      }
+    if (equiv_codes(code_, min_code))
+      {
+	max = false;
+	return true;
+      }
+    return false;
   }
 
   acc_cond::acc_code acc_cond::acc_code::to_dnf() const

src/twa/acc.hh

@@ -905,6 +905,13 @@ namespace spot
     // Return the number of Inf in each pair.
     bool is_generalized_rabin(std::vector<unsigned>& pairs) const;
 
+    // If EQUIV is false, this return true iff the acceptance
+    // condition is a parity condition written in the canonical way
+    // given in the HOA specifications.  If EQUIV is true, then we
+    // check whether the condition is logically equivalent to some
+    // parity acceptance condition.
+    bool is_parity(bool& max, bool& odd, bool equiv = false) const;
+
     static acc_code generalized_buchi(unsigned n)
     {
       mark_t m((1U << n) - 1);

src/twaalgos/hoa.cc

@@ -328,6 +328,16 @@ namespace spot
 		      os << ' ' << p;
 		    os << nl;
 		  }
+		else
+		  {
+		    bool max = false;
+		    bool odd = false;
+		    if (aut->acc().is_parity(max, odd))
+		      os << "acc-name: parity "
+			 << (max ? "max " : "min ")
+			 << (odd ? "odd " : "even ")
+			 << num_acc << nl;
+		  }
 	      }
 	  }
       }

wrap/python/spot_impl.i

@@ -33,6 +33,7 @@
 %include "std_list.i"
 %include "std_set.i"
 %include "exception.i"
+%include "typemaps.i"
 
  // git grep 'typedef.*std::shared_ptr' | grep -v const |
  //   sed 's/.*<\(.*\)>.*/%shared_ptr(spot::\1)/g'
@@ -234,6 +235,7 @@ using namespace spot;
 %include "twa/fwd.hh"
 %feature("flatnested") spot::acc_cond::mark_t;
 %feature("flatnested") spot::acc_cond::acc_code;
+%apply bool* OUTPUT {bool& max, bool& odd};
 %include "twa/acc.hh"
 %include "twa/twa.hh"
 

wrap/python/tests/Makefile.am

@@ -32,6 +32,7 @@ check_SCRIPTS = run
 
 TESTS = \
   accparse.ipynb \
+  accparse2.py \
   alarm.py \
   automata.ipynb \
   automata-io.ipynb \

wrap/python/tests/accparse2.py

@@ -0,0 +1,33 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2015  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
+
+a = spot.acc_cond(5)
+a.set_acceptance(spot.parse_acc_code('parity min odd 5'))
+assert(a.is_parity() == [True, False, True])
+a.set_acceptance(spot.parse_acc_code('parity max even 5'))
+assert(a.is_parity() == [True, True, False])
+a.set_acceptance(spot.parse_acc_code('generalized-Buchi 5'))
+assert(a.is_parity() == [False, False, False])
+assert(a.is_parity(True) == [False, False, False])
+a.set_acceptance(spot.parse_acc_code(
+    'Inf(4) | (Fin(3)&Inf(2)) | (Fin(3)&Fin(1)&Inf(0))'))
+assert(a.is_parity() == [False, False, False])
+assert(a.is_parity(True) == [True, True, False])