genem: implement a generic emptiness check for twa_graph_ptr
* spot/twa/acc.cc, spot/twa/acc.hh (fin_unit, one_fin): New function. * spot/twaalgos/genem.cc, spot/twaalgos/genem.hh: New files. * spot/twaalgos/Makefile.am: Add it. * tests/python/genem.py: New file. * tests/Makefile.am: Add it. * python/spot/impl.i: Add bindings for genem.hh. * NEWS: Mention the new function.
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Alexandre Duret-Lutz
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74dfd73aae
commit
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9 changed files with 514 additions and 0 deletions
222
spot/twaalgos/genem.cc
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222
spot/twaalgos/genem.cc
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// -*- coding: utf-8 -*-
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// Copyright (C) 2017, 2018 Laboratoire de Recherche et Developpement
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// de l'Epita (LRDE).
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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 "config.h"
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#include <spot/twaalgos/genem.hh>
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#include <spot/twaalgos/cleanacc.hh>
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namespace spot
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{
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namespace
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{
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class temporary_acc_set
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{
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twa_graph_ptr aut_;
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acc_cond old_acc_;
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public:
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temporary_acc_set(const const_twa_graph_ptr& aut,
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acc_cond new_acc)
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: aut_(std::const_pointer_cast<twa_graph>(aut)),
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old_acc_(aut->acc())
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{
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set(new_acc);
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}
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void set(acc_cond new_acc)
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{
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aut_->set_acceptance(new_acc);
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}
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~temporary_acc_set()
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{
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aut_->set_acceptance(old_acc_);
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}
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};
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bool scc_split_check(const scc_info& si, unsigned scc,
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acc_cond::mark_t tocut,
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bool (*ec_scc)(const scc_info& si,
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unsigned scc,
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acc_cond::mark_t tocut))
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{
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struct filter_data_t {
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const scc_info& lower_si;
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unsigned lower_scc;
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acc_cond::mark_t cut_sets;
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}
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data = {si, scc, tocut};
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scc_info::edge_filter filter =
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[](const twa_graph::edge_storage_t& e, unsigned dst,
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void* filter_data) -> scc_info::edge_filter_choice
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{
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auto& data = *reinterpret_cast<filter_data_t*>(filter_data);
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if (data.lower_si.scc_of(dst) != data.lower_scc)
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return scc_info::edge_filter_choice::ignore;
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if (data.cut_sets & e.acc)
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return scc_info::edge_filter_choice::cut;
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return scc_info::edge_filter_choice::keep;
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};
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// We want to remove tocut from the acceptance condition right
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// now, because hopefully this will convert the acceptance
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// condition into a Fin-less one, and then we do not have to
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// recurse it.
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acc_cond::mark_t sets = si.acc_sets_of(scc) - tocut;
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auto& autacc = si.get_aut()->acc();
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acc_cond acc = autacc.restrict_to(sets);
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acc = acc.remove(si.common_sets_of(scc), false);
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temporary_acc_set tmp(si.get_aut(), acc);
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scc_info upper_si(si.get_aut(), si.one_state_of(scc), filter, &data,
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scc_info_options::STOP_ON_ACC);
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if (upper_si.one_accepting_scc() >= 0)
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return false;
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if (!acc.uses_fin_acceptance())
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return true;
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unsigned nscc = upper_si.scc_count();
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for (unsigned scc = 0; scc < nscc; ++scc)
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if (!ec_scc(upper_si, scc, tocut))
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return false;
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return true;
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}
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template <bool deal_with_disjunct>
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bool generic_emptiness_check_for_scc_nocopy(const scc_info& si,
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unsigned scc,
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acc_cond::mark_t
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tocut = {})
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{
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if (si.is_rejecting_scc(scc))
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return true;
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acc_cond::mark_t sets = si.acc_sets_of(scc);
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auto& autacc = si.get_aut()->acc();
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acc_cond acc = autacc.restrict_to(sets);
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acc = acc.remove(si.common_sets_of(scc), false);
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if (acc.is_f())
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return true;
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if (acc.is_t())
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return false;
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temporary_acc_set tmp(si.get_aut(), acc);
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if (acc_cond::mark_t fu = acc.fin_unit())
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return scc_split_check
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(si, scc, tocut | fu,
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generic_emptiness_check_for_scc_nocopy<deal_with_disjunct>);
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if (deal_with_disjunct)
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{
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acc_cond::acc_code& code = acc.get_acceptance();
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assert(!code.empty());
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auto pos = &code.back();
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auto start = &code.front();
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assert(pos - pos->sub.size == start);
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if (pos->sub.op == acc_cond::acc_op::Or)
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{
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do
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{
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--pos;
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if (pos->sub.op != acc_cond::acc_op::Inf)
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{
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acc_cond::acc_code one(pos);
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tmp.set(one);
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if (si.get_aut()->acc().uses_fin_acceptance())
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{
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acc_cond::mark_t plus = {};
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if (acc_cond::mark_t fu = one.fin_unit())
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plus = fu;
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if (!scc_split_check
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(si, scc, tocut | plus,
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generic_emptiness_check_for_scc_nocopy
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<deal_with_disjunct>))
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return false;
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}
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}
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pos -= pos->sub.size;
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}
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while (pos > start);
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return true;
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}
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if (pos->sub.op == acc_cond::acc_op::Fin)
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{
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tmp.set(acc_cond::acc_code());
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for (unsigned d: pos[-1].mark.sets())
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if (!scc_split_check
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(si, scc,
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tocut | acc_cond::mark_t({d}),
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generic_emptiness_check_for_scc_nocopy
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<deal_with_disjunct>))
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return false;
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return true;
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}
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}
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int fo = acc.fin_one();
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assert(fo >= 0);
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// Try to accept when Fin(fo) == true
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if (!scc_split_check
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(si, scc, tocut | acc_cond::mark_t({(unsigned) fo}),
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generic_emptiness_check_for_scc_nocopy
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<deal_with_disjunct>))
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return false;
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// Try to accept when Fin(fo) == false
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tmp.set(acc.remove({(unsigned) fo}, false));
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return generic_emptiness_check_for_scc_nocopy
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<deal_with_disjunct>(si, scc, tocut);
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return true;
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}
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template <bool deal_with_disjunct>
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bool generic_emptiness_check_main_nocopy(const twa_graph_ptr& aut)
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{
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cleanup_acceptance_here(aut, false);
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auto& aut_acc = aut->acc();
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if (aut_acc.is_f())
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return true;
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if (!aut->acc().uses_fin_acceptance())
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return aut->is_empty();
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scc_info si(aut, scc_info_options::STOP_ON_ACC
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| scc_info_options::TRACK_STATES);
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if (si.one_accepting_scc() >= 0)
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return false;
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unsigned nscc = si.scc_count();
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for (unsigned scc = 0; scc < nscc; ++scc)
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if (!generic_emptiness_check_for_scc_nocopy
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<deal_with_disjunct>(si, scc))
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return false;
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return true;
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}
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}
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bool generic_emptiness_check(const const_twa_graph_ptr& aut)
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{
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auto aut_ = std::const_pointer_cast<twa_graph>(aut);
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acc_cond old = aut_->acc();
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bool res = generic_emptiness_check_main_nocopy<true>(aut_);
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aut_->set_acceptance(old);
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return res;
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}
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bool generic_emptiness_check_for_scc(const scc_info& si,
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unsigned scc)
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{
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return generic_emptiness_check_for_scc_nocopy<true>(si, scc);
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}
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}
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