new partial_degeneralize() algorithm

* spot/twaalgos/degen.hh, spot/twaalgos/degen.cc: Implement it.
* tests/python/pdegen.py: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention the new function.

tests/python/pdegen.py

@@ -0,0 +1,98 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2019 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/>.
+
+# Test that the spot.gen package works, in particular, we want
+# to make sure that the objects created from spot.gen methods
+# are usable with methods from the spot package.
+
+
+import spot
+
+a, b, d = spot.automata("""
+HOA: v1
+States: 2
+Start: 0
+AP: 1 "p0"
+Acceptance: 3 Inf(0)&Inf(1)|Fin(2)
+--BODY--
+State: 0
+[0] 1 {1 2}
+State: 1
+[0] 0 {0}
+--END--
+HOA: v1
+States: 3
+Start: 2
+AP: 1 "p0"
+Acceptance: 3 Inf(0)&Inf(1)|Fin(2)
+--BODY--
+State: 0
+[0] 1 {1 2}
+State: 1
+[0] 0 {0}
+State: 2
+[0] 0 {0}
+[0] 0 {1}
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 1 "p0"
+Acceptance: 1 Fin(0)
+--BODY--
+State: 0
+[0] 0 {0}
+--END--
+""")
+
+da = spot.partial_degeneralize(a, [0, 1])
+assert da.equivalent_to(a)
+assert da.num_states() == 2
+
+db = spot.partial_degeneralize(b, [0, 1])
+assert db.equivalent_to(b)
+assert db.num_states() == 3
+
+db.copy_state_names_from(b)
+dbhoa = db.to_str('hoa')
+assert dbhoa == """HOA: v1
+States: 3
+Start: 0
+AP: 1 "p0"
+acc-name: Streett 1
+Acceptance: 2 Fin(0) | Inf(1)
+properties: trans-labels explicit-labels state-acc deterministic
+--BODY--
+State: 0 "2#0"
+[0] 2
+State: 1 "1#0"
+[0] 2
+State: 2 "0#1" {0 1}
+[0] 1
+--END--"""
+
+c = spot.automaton("randaut -A'(Fin(0)&Inf(1)&Inf(2))|Fin(2)' 1 |")
+dc = spot.partial_degeneralize(c, [1, 2])
+assert dc.equivalent_to(c)
+assert str(dc.get_acceptance()) == '(Fin(0) & Inf(2)) | Fin(1)'
+
+dd = spot.partial_degeneralize(d, [])
+assert dd.equivalent_to(d)
+assert dd.num_states() == 1
+assert str(dd.get_acceptance()) == 'Inf(1) & Fin(0)'