spot/src/tgbaalgos/sccfilter.cc
Alexandre Duret-Lutz b803a0ee4d get rid of prop_single_acc_set() and set_single_acc_set()
Fixes #64.

* src/tgba/tgba.hh: Here.
* src/tgbaalgos/complete.cc, src/tgbaalgos/degen.cc,
src/tgbaalgos/dtgbacomp.cc, src/tgbaalgos/mask.cc,
src/tgbaalgos/minimize.cc, src/tgbaalgos/remfin.cc,
src/tgbaalgos/sccfilter.cc, src/tgbaalgos/simulation.cc,
src/tgbaalgos/stutter.cc: Adjust.
2015-03-18 21:50:37 +01:00

379 lines
10 KiB
C++

// -*- coding: utf-8 -*-
// Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015 Laboratoire
// de Recherche et Développement de l'Epita (LRDE).
//
// 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 "sccfilter.hh"
#include "reachiter.hh"
#include "sccinfo.hh"
namespace spot
{
namespace
{
// BDD.id -> Acc number
typedef std::map<int, unsigned> accremap_t;
typedef std::vector<accremap_t> remap_table_t;
typedef std::tuple<bool, bdd, acc_cond::mark_t> filtered_trans;
// SCC filters are objects with two methods:
// state(src) return true iff s should be kept
// trans(src, dst, cond, acc) returns a triplet
// (keep, cond2, acc2) where keep is a Boolean stating if the
// transition should be kept, and cond2/acc2
// give replacement values for cond/acc
struct id_filter
{
scc_info* si;
id_filter(scc_info* si)
: si(si)
{
}
// Accept all states
bool state(unsigned)
{
return true;
}
unsigned accsets(unsigned n)
{
return n;
}
// Accept all transitions, unmodified
filtered_trans trans(unsigned, unsigned, bdd cond, acc_cond::mark_t acc)
{
return filtered_trans{true, cond, acc};
}
};
// Remove useless states.
template <class next_filter = id_filter>
struct state_filter: next_filter
{
template<typename... Args>
state_filter(scc_info* si, Args&&... args)
: next_filter(si, std::forward<Args>(args)...)
{
}
bool state(unsigned s)
{
return this->next_filter::state(s) && this->si->is_useful_state(s);
}
};
// Suspension filter, used only by compsusp.cc
template <class next_filter = id_filter>
struct susp_filter: next_filter
{
bdd suspvars;
bdd ignoredvars;
bool early_susp;
template<typename... Args>
susp_filter(scc_info* si,
bdd suspvars, bdd ignoredvars, bool early_susp,
Args&&... args)
: next_filter(si, std::forward<Args>(args)...),
suspvars(suspvars),
ignoredvars(ignoredvars),
early_susp(early_susp)
{
}
filtered_trans trans(unsigned src, unsigned dst,
bdd cond, acc_cond::mark_t acc)
{
bool keep;
std::tie(keep, cond, acc) =
this->next_filter::trans(src, dst, cond, acc);
if (keep)
{
// Always remove ignored variables
cond = bdd_exist(cond, ignoredvars);
// Remove the suspension variables only if
// the destination in not in an accepting SCC,
// or if we are between SCC with early_susp unset.
unsigned u = this->si->scc_of(dst);
if (this->si->is_rejecting_scc(u)
|| (!early_susp && (u != this->si->scc_of(src))))
cond = bdd_exist(cond, suspvars);
}
return filtered_trans(keep, cond, acc);
}
};
// Remove acceptance conditions from all transitions outside of
// non-accepting SCCs.
template <class next_filter = id_filter>
struct acc_filter_all: next_filter
{
template<typename... Args>
acc_filter_all(scc_info* si, Args&&... args)
: next_filter(si, std::forward<Args>(args)...)
{
}
filtered_trans trans(unsigned src, unsigned dst,
bdd cond, acc_cond::mark_t acc)
{
bool keep;
std::tie(keep, cond, acc) =
this->next_filter::trans(src, dst, cond, acc);
if (keep)
{
unsigned u = this->si->scc_of(src);
// If the transition is between two SCCs, or in a
// non-accepting SCC. Remove the acceptance sets.
if (this->si->is_rejecting_scc(u) || u != this->si->scc_of(dst))
acc = 0U;
}
return filtered_trans(keep, cond, acc);
}
};
// Remove acceptance conditions from all transitions whose
// destination is not an accepting SCCs.
template <class next_filter = id_filter>
struct acc_filter_some: next_filter
{
template<typename... Args>
acc_filter_some(scc_info* si, Args&&... args)
: next_filter(si, std::forward<Args>(args)...)
{
}
filtered_trans trans(unsigned src, unsigned dst,
bdd cond, acc_cond::mark_t acc)
{
bool keep;
std::tie(keep, cond, acc) =
this->next_filter::trans(src, dst, cond, acc);
if (this->si->is_rejecting_scc(this->si->scc_of(dst)))
acc = 0U;
return filtered_trans(keep, cond, acc);
}
};
// Simplify redundant acceptance sets used in each SCCs.
template <class next_filter = id_filter>
struct acc_filter_simplify: next_filter
{
// Acceptance sets to strip in each SCC.
std::vector<acc_cond::mark_t> strip_;
template<typename... Args>
acc_filter_simplify(scc_info* si, Args&&... args)
: next_filter(si, std::forward<Args>(args)...)
{
}
unsigned accsets(unsigned n)
{
unsigned scc_count = this->si->scc_count();
auto& acc = this->si->get_aut()->acc();
assert(n == acc.num_sets());
(void) n;
auto used_acc = this->si->used_acc();
assert(used_acc.size() == scc_count);
strip_.resize(scc_count);
std::vector<unsigned> cnt(scc_count); // # of useful sets in each SCC
unsigned max = 0; // Max number of useful sets
for (unsigned n = 0; n < scc_count; ++n)
{
if (this->si->is_rejecting_scc(n))
continue;
strip_[n] = acc.useless(used_acc[n].begin(), used_acc[n].end());
cnt[n] = acc.num_sets() - strip_[n].count();
if (cnt[n] > max)
max = cnt[n];
}
// Now that we know about the max number of acceptance
// conditions, add extra acceptance conditions to those SCC
// that do not have enough.
for (unsigned n = 0; n < scc_count; ++n)
{
if (this->si->is_rejecting_scc(n))
continue;
if (cnt[n] < max)
strip_[n].remove_some(max - cnt[n]);
}
return max;
}
filtered_trans trans(unsigned src, unsigned dst, bdd cond,
acc_cond::mark_t acc)
{
bool keep;
std::tie(keep, cond, acc) =
this->next_filter::trans(src, dst, cond, acc);
if (keep && acc)
{
unsigned u = this->si->scc_of(dst);
if (this->si->is_rejecting_scc(u))
acc = 0U;
else
acc = acc.strip(strip_[u]);
}
return filtered_trans{keep, cond, acc};
}
};
template<class F, typename... Args>
tgba_digraph_ptr scc_filter_apply(const_tgba_digraph_ptr aut,
scc_info* given_si, Args&&... args)
{
if (!aut->acc().is_generalized_buchi())
throw std::runtime_error
("scc_filter() works only with generalized Büchi acceptance");
tgba_digraph_ptr filtered = make_tgba_digraph(aut->get_dict());
unsigned in_n = aut->num_states(); // Number of input states.
if (in_n == 0) // Nothing to filter.
return filtered;
filtered->copy_ap_of(aut);
// Compute scc_info if not supplied.
scc_info* si = given_si;
if (!si)
si = new scc_info(aut);
F filter(si, std::forward<Args>(args)...);
// Renumber all useful states.
unsigned out_n = 0; // Number of output states.
std::vector<unsigned> inout; // Associate old states to new ones.
inout.reserve(in_n);
for (unsigned i = 0; i < in_n; ++i)
if (filter.state(i))
inout.push_back(out_n++);
else
inout.push_back(-1U);
filtered->
set_generalized_buchi(filter.accsets(aut->acc().num_sets()));
filtered->new_states(out_n);
for (unsigned isrc = 0; isrc < in_n; ++isrc)
{
unsigned osrc = inout[isrc];
if (osrc >= out_n)
continue;
for (auto& t: aut->out(isrc))
{
unsigned odst = inout[t.dst];
if (odst >= out_n)
continue;
bool want;
bdd cond;
acc_cond::mark_t acc;
std::tie(want, cond, acc) =
filter.trans(isrc, t.dst, t.cond, t.acc);
if (want)
filtered->new_transition(osrc, odst, cond, acc);
}
}
if (!given_si)
delete si;
// If the initial state has been filtered out, we don't attempt
// to fix it.
auto init = inout[aut->get_init_state_number()];
if (init < out_n)
filtered->set_init_state(init);
return filtered;
}
}
tgba_digraph_ptr
scc_filter_states(const const_tgba_digraph_ptr& aut, scc_info* given_si)
{
auto res = scc_filter_apply<state_filter<>>(aut, given_si);
res->prop_copy(aut, { true, true, true, true });
return res;
}
tgba_digraph_ptr
scc_filter(const const_tgba_digraph_ptr& aut, bool remove_all_useless,
scc_info* given_si)
{
tgba_digraph_ptr res;
if (remove_all_useless)
res = scc_filter_apply<state_filter
<acc_filter_all
<acc_filter_simplify<>>>>(aut, given_si);
else
res = scc_filter_apply<state_filter
<acc_filter_some
<acc_filter_simplify<>>>>(aut, given_si);
res->merge_transitions();
res->prop_copy(aut,
{ false, // state-based acceptance is not preserved
true,
true,
true,
});
return res;
}
tgba_digraph_ptr
scc_filter_susp(const const_tgba_digraph_ptr& aut, bool remove_all_useless,
bdd suspvars, bdd ignoredvars, bool early_susp,
scc_info* given_si)
{
tgba_digraph_ptr res;
if (remove_all_useless)
res = scc_filter_apply<susp_filter
<state_filter
<acc_filter_all
<acc_filter_simplify<>>>>>(aut, given_si,
suspvars,
ignoredvars,
early_susp);
else
res = scc_filter_apply<susp_filter
<state_filter
<acc_filter_some
<acc_filter_simplify<>>>>>(aut, given_si,
suspvars,
ignoredvars,
early_susp);
res->merge_transitions();
res->prop_copy(aut,
{ false, // state-based acceptance is not preserved
true,
false, // determinism may not be preserved
false, // stutter inv. of suspvars probably altered
});
return res;
}
}