scc_info: make it possible to ignore or cut edges

* spot/twaalgos/sccinfo.hh, spot/twaalgos/sccinfo.cc: Take
a filter function as optional argument.
* tests/core/sccif.cc, tests/core/sccif.test: New files.
* tests/Makefile.am, tests/core/.gitignore: Adjust.
* NEWS: Mention the new feature.

tests/core/.gitignore

@@ -58,6 +58,7 @@ reductau
 reductaustr
 reduccmp
 reductgba
+sccif
 stdout
 spotlbtt
 syntimpl

tests/core/sccif.cc

@@ -0,0 +1,101 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2017 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/>.
+
+
+#include <iostream>
+#include <spot/twa/twagraph.hh>
+#include <spot/twaalgos/sccinfo.hh>
+#include <spot/twaalgos/hoa.hh>
+
+static void display(spot::scc_info& si)
+{
+  unsigned ns = si.scc_count();
+  for (unsigned n = 0; n < ns; ++n)
+    {
+      std::cout << "SCC#" << n << "\n  states:";
+      for (unsigned s: si.states_of(n))
+        std::cout << ' ' << s;
+      std::cout << '\n';
+      std::cout << "  edges:";
+      for (auto& e: si.inner_edges_of(n))
+        std::cout << ' ' << e.src << "->" << e.dst;
+      std::cout << '\n';
+      std::cout << "  succs:";
+      for (unsigned s: si.succ(n))
+        std::cout << ' ' << s;
+      std::cout << '\n';
+    }
+  std::cout << '\n';
+}
+
+int main()
+{
+  auto d = spot::make_bdd_dict();
+  auto tg = make_twa_graph(d);
+  bdd p1 = bdd_ithvar(tg->register_ap("p1"));
+  bdd p2 = bdd_ithvar(tg->register_ap("p2"));
+  tg->set_generalized_buchi(2);
+
+  auto s1 = tg->new_state();
+  auto s2 = tg->new_state();
+  auto s3 = tg->new_state();
+  tg->set_init_state(s1);
+  tg->new_edge(s1, s1, bddfalse);
+  tg->new_edge(s1, s2, p1);
+  tg->new_edge(s1, s3, p2, {1});
+  tg->new_edge(s2, s3, p1 & p2, {0});
+  tg->new_edge(s3, s1, p1 | p2, {0, 1});
+  tg->new_edge(s3, s2, p1 >> p2);
+  tg->new_edge(s3, s3, bddtrue, {0, 1});
+
+  spot::print_hoa(std::cout, tg) << '\n';
+
+  {
+    std::cout << "** default\n";
+    spot::scc_info si(tg);
+    display(si);
+  }
+  {
+    std::cout << "** ignore edges to 2\n";
+    auto filter = [](const spot::twa_graph::edge_storage_t&,
+                     unsigned dst, void*)
+      {
+        if (dst == 2)
+          return spot::scc_info::edge_filter_choice::ignore;
+        else
+          return spot::scc_info::edge_filter_choice::keep;
+      };
+    spot::scc_info si(tg, s1, filter, nullptr);
+    display(si);
+  }
+  {
+    std::cout << "** cut edges to 2\n";
+    auto filter = [](const spot::twa_graph::edge_storage_t&,
+                     unsigned dst, void* val)
+      {
+        if (dst == *static_cast<unsigned*>(val))
+          return spot::scc_info::edge_filter_choice::cut;
+        else
+          return spot::scc_info::edge_filter_choice::keep;
+      };
+    unsigned ignore = 2;
+    spot::scc_info si(tg, s1, filter, &ignore);
+    display(si);
+  }
+}

tests/core/sccif.test

@@ -0,0 +1,87 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2017 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 ../sccif > stdout
+
+cat >expected <<EOF
+HOA: v1
+States: 3
+Start: 0
+AP: 2 "p1" "p2"
+acc-name: generalized-Buchi 2
+Acceptance: 2 Inf(0)&Inf(1)
+properties: trans-labels explicit-labels trans-acc
+--BODY--
+State: 0
+[f] 0
+[0] 1
+[1] 2 {1}
+State: 1
+[0&1] 2 {0}
+State: 2
+[0 | 1] 0 {0 1}
+[!0 | 1] 1
+[t] 2 {0 1}
+--END--
+** default
+SCC#0
+  states: 0 1 2
+  edges: 0->0 0->1 0->2 1->2 2->0 2->1 2->2
+  succs:
+
+** ignore edges to 2
+SCC#0
+  states: 1
+  edges:
+  succs:
+SCC#1
+  states: 0
+  edges: 0->0
+  succs: 0
+
+** cut edges to 2
+SCC#0
+  states: 1
+  edges:
+  succs:
+SCC#1
+  states: 0
+  edges: 0->0
+  succs: 0
+SCC#2
+  states: 2
+  edges: 2->2
+  succs: 0 1
+
+EOF
+
+diff expected stdout