hoa: better support for aliases on output

Part of issue #497.

* doc/org/concepts.org: Declare a new "aliases" named property.
* spot/parseaut/parseaut.yy: Fill the aliases named property.
* spot/twa/twa.cc (copy_named_properties_of): Copy it.
* spot/twaalgos/hoa.cc: Use "aliases" while encoding BDDs for
output.
* spot/twaalgos/hoa.hh: Add helper function to set/get aliases.
* python/spot/impl.i: Create a type for aliases.
* tests/core/parseaut.test: Adjust test case.
* tests/python/aliases.py: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention this change.

tests/Makefile.am

@@ -1,5 +1,5 @@
 ## -*- coding: utf-8 -*-
-## Copyright (C) 2009-2021 Laboratoire de Recherche et Développement
+## Copyright (C) 2009-2022 Laboratoire de Recherche et Développement
 ## de l'Epita (LRDE).
 ## Copyright (C) 2003-2006 Laboratoire d'Informatique de Paris 6
 ## (LIP6), département Systèmes Répartis Coopératifs (SRC), Université
@@ -388,6 +388,7 @@ TESTS_python = \
   python/_aux.ipynb \
   python/accparse2.py \
   python/alarm.py \
+  python/aliases.py \
   python/aiger.py \
   python/alternating.py \
   python/bdddict.py \

tests/core/parseaut.test

@@ -630,12 +630,14 @@ acc-name: generalized-Buchi 2
 Acceptance: 2 Inf(0)&Inf(1)
 properties: trans-labels explicit-labels trans-acc complete
 properties: deterministic
+Alias: @a 0
+Alias: @b.c 1&2
 --BODY--
 State: 0
-[!0&!1 | !0&!2] 0
-[0&!1 | 0&!2] 0 {0}
-[!0&1&2] 0 {1}
-[0&1&2] 0 {0 1}
+[!@a&!@b.c] 0
+[@a&!@b.c] 0 {0}
+[@b.c&!@a] 0 {1}
+[@b.c&@a] 0 {0 1}
 --END--
 HOA: v1
 name: "GFa & GF(b & c)"
@@ -646,12 +648,14 @@ acc-name: generalized-Buchi 2
 Acceptance: 2 Inf(0)&Inf(1)
 properties: trans-labels explicit-labels trans-acc complete
 properties: deterministic
+Alias: @b.c 1&2
+Alias: @a 0
 --BODY--
 State: 0
-[!0&!1 | !0&!2] 0
-[0&!1 | 0&!2] 0 {0}
-[!0&1&2] 0 {1}
-[0&1&2] 0 {0 1}
+[!@a&!@b.c] 0
+[@a&!@b.c] 0 {0}
+[!@a&@b.c] 0 {1}
+[@a&@b.c] 0 {0 1}
 --END--
 HOA: v1
 States: 2

tests/python/aliases.py

@@ -0,0 +1,152 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2020, 2022 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 for parts of Issue #497.
+
+import spot
+
+aut = spot.automaton("""
+HOA: v1
+States: 1
+Start: 0
+acc-name: who cares
+Acceptance: 0 t
+properties: very-weak
+AP: 3 "x" "y" "z"
+Alias: @p0 0
+Alias: @p1 1
+Alias: @a !@p0&!@p1
+Alias: @b !@p0&@p1
+Alias: @c @p0&!@p1
+--BODY--
+State: 0
+[@p0] 0
+[!@p0] 0
+[@p1] 0
+[!@p1] 0
+[@a] 0
+[!@a] 0
+[@b] 0
+[!@b] 0
+[@c] 0
+[!@c] 0
+[@a|@b] 0
+[@a|@c] 0
+[@b|@c] 0
+[@a|@b|@c] 0
+[!@a|!@b] 0
+[!@a|!@c] 0
+[!@b|!@c] 0
+[@p0&@p1] 0
+[!@a&!@b] 0
+[!@a&!@c] 0
+[!@b&!@c] 0
+[!@b&!@c&2] 0
+[@a&2] 0
+[!@a&2] 0
+--END--""")
+s = aut.to_str('hoa')
+aut2 = spot.automaton(s)
+assert aut.equivalent_to(aut2)
+s2 = aut.to_str('hoa')
+assert s == s2
+
+assert s == """HOA: v1
+States: 1
+Start: 0
+AP: 3 "x" "y" "z"
+acc-name: all
+Acceptance: 0 t
+properties: trans-labels explicit-labels state-acc complete very-weak
+Alias: @p0 0
+Alias: @p1 1
+Alias: @a !@p1&!@p0
+Alias: @b @p1&!@p0
+Alias: @c !@p1&@p0
+--BODY--
+State: 0
+[@p0] 0
+[!@p0] 0
+[@p1] 0
+[!@p1] 0
+[@a] 0
+[!@a] 0
+[@b] 0
+[!@b] 0
+[@c] 0
+[!@c] 0
+[!@p0] 0
+[!@p1] 0
+[@c | @b] 0
+[@c | @b | @a] 0
+[t] 0
+[t] 0
+[t] 0
+[@p1&@p0] 0
+[@p0] 0
+[@p1] 0
+[!@c&!@b] 0
+[@a&2 | @p1&@p0&2] 0
+[@a&2] 0
+[@p0&2 | @p1&2] 0
+--END--"""
+
+# Check what happens to aliases when an AP has been removed, but
+# the aliases have been preserved...
+rem = spot.remove_ap()
+rem.add_ap("x")
+aut3 = rem.strip(aut)
+spot.set_aliases(aut3, spot.get_aliases(aut))
+s2 = aut3.to_str('hoa')
+# Aliases based on "x" should have disappeared.
+assert(s2 == """HOA: v1
+States: 1
+Start: 0
+AP: 2 "y" "z"
+acc-name: all
+Acceptance: 0 t
+properties: trans-labels explicit-labels state-acc complete very-weak
+Alias: @p1 0
+--BODY--
+State: 0
+[t] 0
+[t] 0
+[@p1] 0
+[!@p1] 0
+[!@p1] 0
+[t] 0
+[@p1] 0
+[t] 0
+[!@p1] 0
+[t] 0
+[t] 0
+[!@p1] 0
+[t] 0
+[t] 0
+[t] 0
+[t] 0
+[t] 0
+[@p1] 0
+[t] 0
+[@p1] 0
+[t] 0
+[1] 0
+[!@p1&1] 0
+[1] 0
+--END--""")