spot/src/twaalgos/remfin.cc
2015-04-28 18:25:10 +02:00

340 lines
8.7 KiB
C++

// -*- coding: utf-8 -*-
// Copyright (C) 2015 Laboratoire de Recherche et
// Développement de l'Epita.
//
// 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 "remfin.hh"
#include "sccinfo.hh"
#include <iostream>
#include "cleanacc.hh"
//#define TRACE
#ifdef TRACE
#define trace std::cerr
#else
#define trace while (0) std::cerr
#endif
namespace spot
{
namespace
{
// If the DNF is
// Fin(1)&Inf(2)&Inf(4) | Fin(2)&Fin(3)&Inf(1) |
// Inf(1)&Inf(3) | Inf(1)&Inf(2) | Fin(4)
// this returns the following map:
// {1} => Inf(2)&Inf(4)
// {2,3} => Inf(1)
// {} => Inf(1)&Inf(3) | Inf(1)&Inf(2)
// {4} => t
static std::map<acc_cond::mark_t, acc_cond::acc_code>
split_dnf_acc_by_fin(const acc_cond::acc_code& acc)
{
std::map<acc_cond::mark_t, acc_cond::acc_code> res;
auto pos = &acc.back();
if (pos->op == acc_cond::acc_op::Or)
--pos;
auto start = &acc.front();
while (pos > start)
{
if (pos->op == acc_cond::acc_op::Fin)
{
// We have only a Fin term, without Inf. In this case
// only, the Fin() may encode a disjunction of sets.
for (auto s: pos[-1].mark.sets())
{
acc_cond::mark_t fin = 0U;
fin.set(s);
res[fin] = acc_cond::acc_code{};
}
pos -= pos->size + 1;
}
else
{
// We have a conjunction of Fin and Inf sets.
auto end = pos - pos->size - 1;
acc_cond::mark_t fin = 0U;
acc_cond::mark_t inf = 0U;
while (pos > end)
{
switch (pos->op)
{
case acc_cond::acc_op::And:
--pos;
break;
case acc_cond::acc_op::Fin:
fin |= pos[-1].mark;
assert(pos[-1].mark.count() == 1);
pos -= 2;
break;
case acc_cond::acc_op::Inf:
inf |= pos[-1].mark;
pos -= 2;
break;
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
case acc_cond::acc_op::Or:
SPOT_UNREACHABLE();
break;
}
}
assert(pos == end);
acc_cond::acc_word w[2];
w[0].mark = inf;
w[1].op = acc_cond::acc_op::Inf;
w[1].size = 1;
acc_cond::acc_code c;
c.insert(c.end(), w, w + 2);
auto p = res.emplace(fin, c);
if (!p.second)
p.first->second.append_or(std::move(c));
}
}
return res;
}
}
twa_graph_ptr remove_fin(const const_twa_graph_ptr& aut)
{
if (!aut->acc().uses_fin_acceptance())
return std::const_pointer_cast<twa_graph>(aut);
std::vector<acc_cond::acc_code> code;
std::vector<acc_cond::mark_t> rem;
std::vector<acc_cond::mark_t> keep;
std::vector<acc_cond::mark_t> add;
bool has_true_term = false;
acc_cond::mark_t allinf = 0U;
acc_cond::mark_t allfin = 0U;
{
auto acccode = aut->get_acceptance();
if (!acccode.is_dnf())
acccode = acccode.to_dnf();
auto split = split_dnf_acc_by_fin(acccode);
auto sz = split.size();
assert(sz > 0);
rem.reserve(sz);
code.reserve(sz);
keep.reserve(sz);
add.reserve(sz);
for (auto p: split)
{
// The empty Fin should always come first
assert(p.first != 0U || rem.empty());
rem.push_back(p.first);
allfin |= p.first;
acc_cond::mark_t inf = 0U;
if (!p.second.empty())
{
auto pos = &p.second.back();
auto end = &p.second.front();
while (pos > end)
{
switch (pos->op)
{
case acc_cond::acc_op::And:
case acc_cond::acc_op::Or:
--pos;
break;
case acc_cond::acc_op::Inf:
inf |= pos[-1].mark;
pos -= 2;
break;
case acc_cond::acc_op::Fin:
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
SPOT_UNREACHABLE();
break;
}
}
}
if (inf == 0U)
{
has_true_term = true;
}
code.push_back(std::move(p.second));
keep.push_back(inf);
allinf |= inf;
add.push_back(0U);
}
}
assert(add.size() > 0);
acc_cond acc = aut->acc();
unsigned extra_sets = 0;
// Do we have common sets between the acceptance terms?
// If so, we need extra sets to distinguish the terms.
bool interference = false;
{
auto sz = keep.size();
acc_cond::mark_t sofar = 0U;
for (unsigned i = 0; i < sz; ++i)
{
auto k = keep[i];
if (k & sofar)
{
interference = true;
break;
}
sofar |= k;
}
if (interference)
{
trace << "We have interferences\n";
// We need extra set, but we will try
// to reuse the Fin number if they are
// not used as Inf as well.
std::vector<int> exs(acc.num_sets());
for (auto f: allfin.sets())
{
if (allinf.has(f)) // Already used as Inf
{
exs[f] = acc.add_set();
++extra_sets;
}
else
{
exs[f] = f;
}
}
for (unsigned i = 0; i < sz; ++i)
{
acc_cond::mark_t m = 0U;
for (auto f: rem[i].sets())
m.set(exs[f]);
trace << "rem[" << i << "] = " << rem[i]
<< " m = " << m << '\n';
add[i] = m;
code[i].append_and(acc.inf(m));
trace << "code[" << i << "] = " << code[i] << '\n';
}
}
else if (has_true_term)
{
trace << "We have a true term\n";
unsigned one = acc.add_sets(1);
extra_sets += 1;
auto m = acc.marks({one});
auto c = acc.inf(m);
for (unsigned i = 0; i < sz; ++i)
{
if (!code[i].is_true())
continue;
add[i] = m;
code[i].append_and(c);
c = acc.fin(0U); // Use false for the other terms.
trace << "code[" << i << "] = " << code[i] << '\n';
}
}
}
acc_cond::acc_code new_code = aut->acc().fin(0U);
for (auto c: code)
new_code.append_or(std::move(c));
unsigned cs = code.size();
for (unsigned i = 0; i < cs; ++i)
trace << i << " Rem " << rem[i] << " Code " << code[i]
<< " Keep " << keep[i] << '\n';
scc_info si(aut);
unsigned nst = aut->num_states();
auto res = make_twa_graph(aut->get_dict());
res->copy_ap_of(aut);
res->prop_copy(aut, { false, false, false, true });
res->new_states(nst);
res->set_acceptance(aut->acc().num_sets() + extra_sets, new_code);
res->set_init_state(aut->get_init_state_number());
unsigned nscc = si.scc_count();
std::vector<unsigned> state_map(nst);
for (unsigned n = 0; n < nscc; ++n)
{
auto m = si.acc(n);
auto states = si.states_of(n);
trace << "SCC #" << n << " uses " << m << '\n';
// What to keep and add into the main copy
acc_cond::mark_t main_sets = 0U;
acc_cond::mark_t main_add = 0U;
for (unsigned i = 0; i < cs; ++i)
if (!(m & rem[i]))
{
main_sets |= keep[i];
main_add |= add[i];
}
trace << "main_sets " << main_sets << "\nmain_add " << main_add << '\n';
// Create the main copy
for (auto s: states)
for (auto& t: aut->out(s))
res->new_transition(s, t.dst, t.cond,
(t.acc & main_sets) | main_add);
if (si.is_rejecting_scc(n))
continue;
// Create clones
for (unsigned i = 0; i < cs; ++i)
if (m & rem[i])
{
auto r = rem[i];
trace << "rem[" << i << "] = " << r << " requires a copy\n";
unsigned base = res->new_states(states.size());
for (auto s: states)
state_map[s] = base++;
auto k = keep[i];
auto a = add[i];
for (auto s: states)
{
auto ns = state_map[s];
for (auto& t: aut->out(s))
{
if ((t.acc & r) || si.scc_of(t.dst) != n)
continue;
auto nd = state_map[t.dst];
res->new_transition(ns, nd, t.cond, (t.acc & k) | a);
// We need only one non-deterministic jump per
// cycle. As an approximation, we only do
// them on back-links.
//
// The acceptance marks on these transition
// are useless, but we keep them to preserve
// state-based acceptance if any.
if (t.dst <= s)
res->new_transition(s, nd, t.cond,
(t.acc & main_sets) | main_add);
}
}
}
}
res->purge_dead_states();
trace << "before cleanup: " << res->get_acceptance() << '\n';
cleanup_acceptance_here(res);
trace << "after cleanup: " << res->get_acceptance() << '\n';
return res;
}
}