74e20a6ec4
* src/tgbaalgos/complete.cc, src/tgbaalgos/complete.hh (tgba_complete_here): New method for tgba_digraph. (tgba_complete): Rewrite using dupexp and the above.
113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2013, 2014 Laboratoire de Recherche et Développement
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// de l'Epita.
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//
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// This file is part of Spot, a model checking library.
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//
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// Spot is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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//
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// Spot is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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// License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#include "complete.hh"
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#include "ltlast/constant.hh"
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#include "dupexp.hh"
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namespace spot
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{
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unsigned tgba_complete_here(tgba_digraph* aut)
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{
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unsigned n = aut->num_states();
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unsigned sink = -1U;
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bdd allacc = aut->all_acceptance_conditions();
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if (allacc == bddfalse)
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{
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// We cannot safely complete an automaton if it has no
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// acceptance set as the added sink would become accepting.
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// In this case, add an acceptance set to all transitions.
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const ltl::formula* t = ltl::constant::true_instance();
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int v = aut->get_dict()->register_acceptance_variable(t, aut);
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allacc = bdd_ithvar(v);
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aut->set_acceptance_conditions(allacc);
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for (auto& t: aut->transitions())
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t.acc = allacc;
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}
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else
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{
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// If some acceptance sets were used, loop over the states and
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// seek a state that has only self loops, and that is not
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// accepting. This will be our sink state.
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for (unsigned i = 0; i < n; ++i)
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{
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bool selfloop = true;
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bdd accsum = bddfalse;
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for (auto& t: aut->out(i))
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{
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if (t.dst != i) // Not a self-loop
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{
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selfloop = false;
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break;
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}
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accsum |= t.acc;
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}
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if (selfloop && accsum != allacc) // We have found a sink!
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{
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sink = i;
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break;
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}
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}
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}
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// If we haven't found any sink, simply add one.
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if (sink == -1U)
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{
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sink = aut->new_state();
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++n;
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}
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// Now complete all states (including the sink).
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for (unsigned i = 0; i < n; ++i)
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{
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bdd missingcond = bddtrue;
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bdd acc = bddfalse;
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for (auto& t: aut->out(i))
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{
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missingcond -= t.cond;
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// FIXME: This is ugly.
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//
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// In case the automaton uses state-based acceptance, we
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// need to put the new transition in the same set as all
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// the other.
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//
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// In case the automaton uses transition-based acceptance,
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// it does not matter what acceptance set we put the new
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// transition into.
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//
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// So in both cases, we put the transition in the same
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// acceptance sets as the last outgoing transition of the
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// state.
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acc = t.acc;
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}
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// In case the automaton use state-based acceptance, propagate
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// the acceptance of the first transition to the one we add.
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if (missingcond != bddfalse)
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aut->new_transition(i, sink, missingcond, acc);
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}
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return sink;
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}
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tgba_digraph* tgba_complete(const tgba* aut)
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{
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tgba_digraph* res = tgba_dupexp_dfs(aut);
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tgba_complete_here(res);
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return res;
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}
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}
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