353 lines
11 KiB
C++
353 lines
11 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2012-2015, 2018, 2019 Laboratoire de Recherche et
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// Développement 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/compsusp.hh>
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#include <spot/twaalgos/sccfilter.hh>
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#include <spot/twaalgos/sccinfo.hh>
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#include <spot/twa/twagraph.hh>
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#include <spot/twaalgos/ltl2tgba_fm.hh>
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#include <spot/twaalgos/minimize.hh>
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#include <spot/twaalgos/simulation.hh>
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#include <spot/twaalgos/strength.hh>
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#include <spot/tl/print.hh>
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#include <queue>
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#include <sstream>
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#include <spot/tl/environment.hh>
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namespace spot
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{
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namespace
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{
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typedef std::map<formula, bdd> formula_bdd_map;
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typedef std::vector<formula> vec;
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// Rewrite the suspendable subformulae "s" of an LTL formula in
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// the form Gg where "g" is an atomic proposition representing
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// "s". At the same time, populate maps that associate "s" to "g"
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// and vice-versa.
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class ltl_suspender_visitor final
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{
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public:
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typedef std::map<formula, formula> fmap_t;
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ltl_suspender_visitor(fmap_t& g2s, fmap_t& a2o, bool oblig)
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: g2s_(g2s), a2o_(a2o), oblig_(oblig)
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{
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}
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formula
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visit(formula f)
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{
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switch (op o = f.kind())
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{
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case op::Or:
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case op::And:
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{
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vec res;
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vec oblig;
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vec susp;
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unsigned mos = f.size();
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for (unsigned i = 0; i < mos; ++i)
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{
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formula c = f[i];
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if (c.is_boolean())
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res.emplace_back(c);
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else if (oblig_ && c.is_syntactic_obligation())
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oblig.emplace_back(c);
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else if (c.is_eventual() && c.is_universal())
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susp.emplace_back(c);
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else
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res.emplace_back(recurse(c));
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}
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if (!oblig.empty())
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{
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res.emplace_back(recurse(formula::multop(o, oblig)));
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}
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if (!susp.empty())
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{
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formula x = formula::multop(o, susp);
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// Rewrite 'x' as 'G"x"'
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formula g = recurse(x);
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if (o == op::And)
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{
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res.emplace_back(g);
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}
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else
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{
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// res || susp -> (res && G![susp]) || G[susp])
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auto r = formula::multop(o, res);
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auto gn = formula::G(formula::Not(g[0]));
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return formula::Or({formula::And({r, gn}), g});
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}
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}
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return formula::multop(o, res);
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}
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break;
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default:
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return f.map([this](formula f)
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{
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return this->recurse(f);
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});
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}
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}
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formula
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recurse(formula f)
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{
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formula res;
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if (f.is_boolean())
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return f;
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if (oblig_ && f.is_syntactic_obligation())
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{
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fmap_t::const_iterator i = assoc_.find(f);
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if (i != assoc_.end())
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return i->second;
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std::ostringstream s;
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print_psl(s << "〈", f) << "〉";
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res = formula::ap(s.str());
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a2o_[res] = f;
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assoc_[f] = res;
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return res;
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}
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if (f.is_eventual() && f.is_universal())
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{
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fmap_t::const_iterator i = assoc_.find(f);
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if (i != assoc_.end())
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return formula::G(i->second);
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std::ostringstream s;
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print_psl(s << '[', f) << "]$";
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res = formula::ap(s.str());
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g2s_[res] = f;
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assoc_[f] = res;
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return formula::G(res);
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}
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return visit(f);
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}
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private:
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fmap_t& g2s_;
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fmap_t assoc_; // This one is only needed by the visitor.
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fmap_t& a2o_;
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bool oblig_;
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};
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typedef std::pair<const state*, const state*> state_pair;
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typedef std::map<state_pair, unsigned> pair_map;
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typedef std::deque<state_pair> pair_queue;
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static
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twa_graph_ptr
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susp_prod(const const_twa_ptr& left, formula f, bdd v)
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{
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bdd_dict_ptr dict = left->get_dict();
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auto right =
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iterated_simulations(scc_filter(ltl_to_tgba_fm(f, dict, true, true),
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false));
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twa_graph_ptr res = make_twa_graph(dict);
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{
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// Copy all atomic propositions, except the one corresponding
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// to the variable v used for synchronization.
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int vn = bdd_var(v);
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assert(dict->bdd_map[vn].type == bdd_dict::var);
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formula vf = dict->bdd_map[vn].f;
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for (auto a: left->ap())
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if (a != vf)
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res->register_ap(a);
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for (auto a: right->ap())
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if (a != vf)
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res->register_ap(a);
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}
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unsigned lsets = left->num_sets();
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res->set_generalized_buchi(lsets + right->num_sets());
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acc_cond::mark_t radd = right->acc().all_sets();
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pair_map seen;
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pair_queue todo;
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state_pair p(left->get_init_state(), nullptr);
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const state* ris = right->get_init_state();
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p.second = ris;
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unsigned i = res->new_state();
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seen[p] = i;
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todo.emplace_back(p);
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res->set_init_state(i);
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while (!todo.empty())
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{
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p = todo.front();
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todo.pop_front();
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const state* ls = p.first;
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const state* rs = p.second;
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int src = seen[p];
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for (auto li: left->succ(ls))
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{
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state_pair d(li->dst(), ris);
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bdd lc = li->cond();
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twa_succ_iterator* ri = nullptr;
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// Should we reset the right automaton?
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if ((lc & v) == lc)
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{
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// No.
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ri = right->succ_iter(rs);
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ri->first();
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}
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// Yes. Reset the right automaton.
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else
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{
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p.second = ris;
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}
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// This loops over all the right edges
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// if RI is defined. Otherwise this just makes
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// one iteration as if the right automaton was
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// looping in state 0 with "true".
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while (!ri || !ri->done())
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{
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bdd cond = lc;
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acc_cond::mark_t racc = radd;
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if (ri)
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{
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cond = lc & ri->cond();
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// Skip incompatible edges.
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if (cond == bddfalse)
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{
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ri->next();
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continue;
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}
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d.second = ri->dst();
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racc = ri->acc();
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}
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int dest;
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pair_map::const_iterator i = seen.find(d);
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if (i != seen.end()) // Is this an existing state?
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{
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dest = i->second;
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}
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else
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{
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dest = res->new_state();
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seen[d] = dest;
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todo.emplace_back(d);
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}
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acc_cond::mark_t a = li->acc() | (racc << lsets);
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res->new_edge(src, dest, bdd_exist(cond, v), a);
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if (ri)
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ri->next();
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else
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break;
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}
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if (ri)
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right->release_iter(ri);
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}
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}
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return res;
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}
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}
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twa_graph_ptr
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compsusp(formula f, const bdd_dict_ptr& dict,
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bool no_wdba, bool no_simulation,
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bool early_susp, bool no_susp_product, bool wdba_smaller,
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bool oblig)
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{
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ltl_suspender_visitor::fmap_t g2s;
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ltl_suspender_visitor::fmap_t a2o;
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ltl_suspender_visitor v(g2s, a2o, oblig);
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formula g = v.recurse(f);
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// Translate the patched formula, and remove useless SCCs.
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twa_graph_ptr res =
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scc_filter(ltl_to_tgba_fm(g, dict, true, true, false, false,
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nullptr, nullptr),
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false);
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if (!no_wdba)
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{
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twa_graph_ptr min = minimize_obligation(res, g,
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nullptr, wdba_smaller);
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if (min != res)
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{
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res = min;
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no_simulation = true;
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}
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}
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if (!no_simulation)
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res = iterated_simulations(res);
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// Create a map of suspended formulae to BDD variables.
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spot::formula_bdd_map susp;
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for (auto& it: g2s)
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{
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auto j = dict->var_map.find(it.first);
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// If no BDD variable of this suspended formula exist in the
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// BDD dict, it means the suspended subformulae was never
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// actually used in the automaton. Just skip it. FIXME: It
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// would be better if we had a way to check that the variable
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// is used in this automaton, and not in some automaton
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// (sharing the same dictionary.)
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if (j != dict->var_map.end())
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susp[it.second] = bdd_ithvar(j->second);
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}
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// Remove suspendable formulae from non-accepting SCCs.
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bdd suspvars = bddtrue;
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for (formula_bdd_map::const_iterator i = susp.begin();
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i != susp.end(); ++i)
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suspvars &= i->second;
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bdd allaccap = bddtrue; // set of atomic prop used in accepting SCCs.
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{
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scc_info si(res);
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// Restrict suspvars to the set of suspension labels that occur
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// in accepting SCC.
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unsigned sn = si.scc_count();
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for (unsigned n = 0; n < sn; n++)
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if (si.is_accepting_scc(n))
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allaccap &= si.scc_ap_support(n);
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bdd ignored = bdd_exist(suspvars, allaccap);
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suspvars = bdd_existcomp(suspvars, allaccap);
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res = scc_filter_susp(res, false, suspvars, ignored, early_susp, &si);
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}
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// Do we need to synchronize any suspended formula?
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if (!susp.empty() && !no_susp_product)
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for (formula_bdd_map::const_iterator i = susp.begin();
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i != susp.end(); ++i)
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if ((allaccap & i->second) == allaccap)
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res = susp_prod(res, i->first, i->second);
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return res;
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}
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}
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