58b349d3ca
* spot/twaalgos/sbacc.cc (sbacc): Define the original-states property on the created automaton. * spot/twaalgos/sbacc.hh: Improve documentation. * tests/python/sbacc.py: Update test cases.
208 lines
7.5 KiB
C++
208 lines
7.5 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2015-2018, 2021 Laboratoire de Recherche et Développement
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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 <vector>
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#include <map>
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#include <utility>
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#include <spot/twaalgos/sbacc.hh>
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#include <spot/twaalgos/sccinfo.hh>
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#include <spot/twaalgos/stripacc.hh>
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namespace spot
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{
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twa_graph_ptr sbacc(twa_graph_ptr old)
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{
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if (old->prop_state_acc())
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return old;
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// We will need a mark that is rejecting to mark rejecting states.
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// If no such mark exist, our work is actually quite simple: we
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// just have to copy the automaton and give it "t" as acceptance
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// condition.
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auto unsat_mark = old->acc().unsat_mark();
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if (!unsat_mark.first)
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{
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auto res = make_twa_graph(old, twa::prop_set::all());
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strip_acceptance_here(res);
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return res;
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}
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scc_info si(old, scc_info_options::NONE);
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unsigned ns = old->num_states();
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acc_cond::mark_t all = old->acc().all_sets();
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// Marks that are common to all ingoing or outgoing transitions.
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std::vector<acc_cond::mark_t> common_in(ns, all);
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std::vector<acc_cond::mark_t> common_out(ns, all);
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// Marks that label one incoming transition from the same SCC.
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std::vector<acc_cond::mark_t> one_in(ns, acc_cond::mark_t({}));
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std::vector<bool> true_state(ns, false);
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acc_cond::mark_t true_state_acc = {};
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// Do not initialize true_state_last, but prevent GCC from warning
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// about a possible uninitialized use later.
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unsigned true_state_last = unsigned();
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for (auto& e: old->edges())
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for (unsigned d: old->univ_dests(e.dst))
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if (si.scc_of(e.src) == si.scc_of(d))
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{
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common_in[d] &= e.acc;
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common_out[e.src] &= e.acc;
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// Any state with an accepting edge labeled by true is a
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// "true state". We will merge all true states, and
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// ignore other outgoing edges. See issue #276 for an
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// example.
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if (e.src == e.dst && e.cond == bddtrue
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&& old->acc().accepting(e.acc))
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{
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true_state[d] = true;
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true_state_acc = e.acc;
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true_state_last = e.src;
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}
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}
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for (unsigned s = 0; s < ns; ++s)
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common_out[s] |= common_in[s];
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for (auto& e: old->edges())
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for (unsigned d: old->univ_dests(e.dst))
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if (si.scc_of(e.src) == si.scc_of(d))
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one_in[d] = e.acc - common_out[e.src];
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auto res = make_twa_graph(old->get_dict());
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res->copy_ap_of(old);
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res->copy_acceptance_of(old);
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res->prop_copy(old, {false, true, true, true, true, true});
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res->prop_state_acc(true);
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typedef std::pair<unsigned, acc_cond::mark_t> pair_t;
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std::map<pair_t, unsigned> s2n;
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std::vector<std::pair<pair_t, unsigned>> todo;
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auto* origin = new std::vector<unsigned>;
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origin->reserve(ns);
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res->set_named_prop("original-states", origin);
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auto new_state =
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[&](unsigned state, acc_cond::mark_t m) -> unsigned
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{
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bool ts = true_state[state];
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if (ts) // Merge all true states.
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{
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// g++ 10.2 is afraid true_state_last might be
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// uninitialized, however if ts==true, it means some true
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// state were found, and the last true state is known.
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state = true_state_last;
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m = {};
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}
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pair_t x(state, m);
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auto p = s2n.emplace(x, 0);
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if (p.second) // This is a new state
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{
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unsigned s = res->new_state();
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assert(origin->size() == s);
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origin->push_back(state);
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p.first->second = s;
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if (ts)
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{
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res->new_edge(s, s, bddtrue, true_state_acc);
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// As we do not process all outgoing transition of
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// STATE, it is possible that a non-deterministic
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// automaton becomes deterministic.
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if (res->prop_universal().is_false())
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res->prop_universal(trival::maybe());
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}
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else
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todo.emplace_back(x, s);
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}
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return p.first->second;
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};
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std::vector<unsigned> old_init;
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for (unsigned d: old->univ_dests(old->get_init_state_number()))
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old_init.push_back(d);
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std::vector<unsigned> old_st;
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internal::univ_dest_mapper<twa_graph::graph_t> uniq(res->get_graph());
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for (unsigned s: old_init)
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{
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acc_cond::mark_t init_acc = {};
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if (!si.is_rejecting_scc(si.scc_of(s)))
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// Use any edge going into the initial state to set the first
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// acceptance mark.
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init_acc = one_in[s] | common_out[s];
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old_st.push_back(new_state(s, init_acc));
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}
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res->set_init_state(uniq.new_univ_dests(old_st.begin(), old_st.end()));
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while (!todo.empty())
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{
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auto one = todo.back();
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todo.pop_back();
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unsigned scc_src = si.scc_of(one.first.first);
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bool maybe_accepting = !si.is_rejecting_scc(scc_src);
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for (auto& t: old->out(one.first.first))
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{
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std::vector<unsigned> dests;
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for (unsigned d: old->univ_dests(t.dst))
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{
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unsigned scc_dst = si.scc_of(d);
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acc_cond::mark_t acc = {};
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bool dst_acc = !si.is_rejecting_scc(scc_dst);
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if (maybe_accepting && scc_src == scc_dst)
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acc = t.acc - common_out[t.src];
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else if (dst_acc)
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// We enter a new accepting SCC. Use any edge going into
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// t.dst from this SCC to set the initial acceptance mark.
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acc = one_in[d];
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if (dst_acc)
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acc |= common_out[d];
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else
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acc = unsat_mark.second;
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dests.push_back(new_state(d, acc));
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}
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res->new_edge(one.second,
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uniq.new_univ_dests(dests.begin(), dests.end()),
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t.cond, one.first.second);
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}
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}
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res->merge_edges();
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// Compose original-states with the any previously existing one.
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if (auto old_orig_states =
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old->get_named_prop<std::vector<unsigned>>("original-states"))
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for (auto& s: *origin)
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s = (*old_orig_states)[s];
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// If the automaton was marked as not complete or not universal,
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// and we have ignored some unreachable state, then it is possible
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// that the result becomes complete or universal.
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if (res->prop_complete().is_false() || res->prop_universal().is_false())
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for (unsigned i = 0; i < ns; ++i)
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if (!si.reachable_state(i))
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{
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if (res->prop_complete().is_false())
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res->prop_complete(trival::maybe());
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if (res->prop_universal().is_false())
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res->prop_universal(trival::maybe());
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break;
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}
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return res;
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}
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}
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