558 lines
15 KiB
C++
558 lines
15 KiB
C++
// -*- coding: utf-8 -*-
|
|
// Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014 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, bdd> filtered_trans;
|
|
typedef std::pair<bdd, bdd> acc_pair;
|
|
|
|
|
|
// 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;
|
|
}
|
|
|
|
acc_pair accsets(bdd all, bdd all_neg)
|
|
{
|
|
return acc_pair(all, all_neg);
|
|
}
|
|
|
|
// Accept all transitions, unmodified
|
|
filtered_trans trans(unsigned, unsigned, bdd cond, bdd 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, bdd 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_accepting_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, bdd 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_accepting_scc(u) || u != this->si->scc_of(dst))
|
|
acc = bddfalse;
|
|
}
|
|
|
|
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, bdd acc)
|
|
{
|
|
bool keep;
|
|
std::tie(keep, cond, acc) =
|
|
this->next_filter::trans(src, dst, cond, acc);
|
|
|
|
if (!this->si->is_accepting_scc(this->si->scc_of(dst)))
|
|
acc = bddfalse;
|
|
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
|
|
{
|
|
std::vector<bdd> acc_;
|
|
typedef std::map<int, bdd> map_t;
|
|
typedef std::vector<map_t> remap_t;
|
|
remap_t remap_;
|
|
|
|
template<typename... Args>
|
|
acc_filter_simplify(scc_info* si, Args&&... args)
|
|
: next_filter(si, std::forward<Args>(args)...)
|
|
{
|
|
}
|
|
|
|
acc_pair accsets(bdd in_all, bdd in_all_neg)
|
|
{
|
|
std::tie(in_all, in_all_neg) =
|
|
this->next_filter::accsets(in_all, in_all_neg);
|
|
|
|
unsigned scc_count = this->si->scc_count();
|
|
remap_table_t remap_table(scc_count);
|
|
std::vector<unsigned> max_table(scc_count);
|
|
std::vector<bdd> useful_table(scc_count);
|
|
std::vector<bdd> useless_table(scc_count);
|
|
unsigned max_num = 1;
|
|
const_tgba_digraph_ptr aut = this->si->get_aut();
|
|
|
|
std::vector<bdd> used_acc = this->si->used_acc();
|
|
|
|
for (unsigned n = 0; n < scc_count; ++n)
|
|
{
|
|
if (!this->si->is_accepting_scc(n))
|
|
continue;
|
|
bdd all = used_acc[n];
|
|
|
|
//std::cerr << "SCC #" << n << "; used = " << all << std::endl;
|
|
|
|
// Compute a set of useless acceptance sets.
|
|
// If the acceptance combinations occurring in
|
|
// the automata are { a, ab, abc, bd }, then
|
|
// ALL contains (a&!b&!c&!d)|(a&b&!c&!d)|(a&b&c&!d)|(!a&b&!c&d)
|
|
// and we want to find that 'a' and 'b' are useless because
|
|
// they always occur with 'c'.
|
|
// The way we check if 'a' is useless is to look whether ALL
|
|
// implications (x -> a) for some other acceptance set x.
|
|
//
|
|
// The two while() loops in the code perform the equivalent of
|
|
// for all a in allconds_a:
|
|
// for all x in allconds_x:
|
|
// check whether x -> a
|
|
// ...
|
|
//
|
|
// Initially allconds_a = allconds_x contains all acceptance
|
|
// sets. However when an acceptance set 'a' is determined to
|
|
// be useless, it can be removed from allconds_x from future
|
|
// iterations.
|
|
bdd allconds_a = bdd_support(in_all_neg);
|
|
bdd allconds_x = allconds_a;
|
|
bdd useless = bddtrue;
|
|
while (allconds_a != bddtrue)
|
|
{
|
|
// Speed-up the computation of implied acceptance sets by
|
|
// removing those that are always present. We detect
|
|
// those that appear as conjunction of positive variables
|
|
// at the start of ALL.
|
|
bdd prefix = bdd_satprefix(all);
|
|
if (prefix != bddtrue)
|
|
{
|
|
assert(prefix == bdd_support(prefix));
|
|
allconds_a = bdd_exist(allconds_a, prefix);
|
|
if (allconds_a != bddtrue)
|
|
{
|
|
useless &= prefix;
|
|
}
|
|
else
|
|
{
|
|
// Never erase all conditions: at least keep one.
|
|
useless &= bdd_high(prefix);
|
|
break;
|
|
}
|
|
allconds_x = bdd_exist(allconds_x, prefix);
|
|
}
|
|
|
|
// Pick an acceptance set 'a'.
|
|
bdd a = bdd_ithvar(bdd_var(allconds_a));
|
|
// For all acceptance sets 'x' that are not already
|
|
// useless...
|
|
bdd others = allconds_x;
|
|
while (others != bddtrue)
|
|
{
|
|
bdd x = bdd_ithvar(bdd_var(others));
|
|
// ... check whether 'x' always implies 'a'.
|
|
if (x != a && bdd_implies(all, x >> a))
|
|
{
|
|
// If so, 'a' is useless.
|
|
all = bdd_exist(all, a);
|
|
useless &= a;
|
|
allconds_x = bdd_exist(allconds_x, a);
|
|
break;
|
|
}
|
|
others = bdd_high(others);
|
|
}
|
|
allconds_a = bdd_high(allconds_a);
|
|
}
|
|
|
|
// We never remove ALL acceptance marks.
|
|
assert(in_all_neg == bddtrue || useless != bdd_support(in_all_neg));
|
|
|
|
useless_table[n] = useless;
|
|
bdd useful = bdd_exist(in_all_neg, useless);
|
|
|
|
//std::cerr << "SCC #" << n << "; useful = " << useful << std::endl;
|
|
|
|
// Go over all useful sets of acceptance marks, and give them
|
|
// a number.
|
|
unsigned num = 1;
|
|
// First compute the number of acceptance conditions used.
|
|
for (BDD c = useful.id(); c != 1; c = bdd_low(c))
|
|
++num;
|
|
max_table[n] = num;
|
|
if (num > max_num)
|
|
max_num = num;
|
|
|
|
useful_table[n] = useful;
|
|
}
|
|
|
|
// 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_accepting_scc(n))
|
|
continue;
|
|
//std::cerr << "SCC " << n << '\n';
|
|
bdd useful = useful_table[n];
|
|
|
|
int missing = max_num - max_table[n];
|
|
bdd useless = useless_table[n];
|
|
while (missing--)
|
|
{
|
|
//std::cerr << useful << " : " << useless << std::endl;
|
|
useful &= bdd_nithvar(bdd_var(useless));
|
|
useless = bdd_high(useless);
|
|
}
|
|
int num = max_num;
|
|
// Then number all of these acceptance conditions in the
|
|
// reverse order. This makes sure that the associated number
|
|
// varies in the same direction as the bdd variables, which in
|
|
// turn makes sure we preserve the acceptance condition
|
|
// ordering (which matters for degeneralization).
|
|
for (BDD c = useful.id(); c != 1; c = bdd_low(c))
|
|
remap_table[n].emplace(bdd_var(c), --num);
|
|
|
|
max_table[n] = max_num;
|
|
}
|
|
|
|
acc_.resize(max_num);
|
|
acc_[0] = bddfalse;
|
|
bdd tmp = in_all;
|
|
assert(aut->number_of_acceptance_conditions() >= max_num - 1);
|
|
|
|
bdd all = bddfalse;
|
|
bdd all_neg = bddtrue;
|
|
|
|
if (tmp != bddfalse)
|
|
{
|
|
for (unsigned n = max_num - 1; n > 0; --n)
|
|
{
|
|
assert(tmp != bddfalse);
|
|
int v = bdd_var(tmp);
|
|
bdd vn = bdd_nithvar(v);
|
|
all = (all & vn) | (all_neg & bdd_ithvar(v));
|
|
all_neg &= vn;
|
|
tmp = bdd_low(tmp);
|
|
}
|
|
tmp = in_all;
|
|
for (unsigned n = max_num - 1; n > 0; --n)
|
|
{
|
|
int v = bdd_var(tmp);
|
|
acc_[n] = bdd_compose(all_neg, bdd_nithvar(v), v);
|
|
tmp = bdd_low(tmp);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
assert(max_num == 1);
|
|
}
|
|
|
|
remap_.resize(scc_count);
|
|
bdd all_orig_neg = in_all_neg;
|
|
bdd all_sup = bdd_support(all_orig_neg);
|
|
|
|
for (unsigned n = 0; n < scc_count; ++n)
|
|
{
|
|
//std::cerr << "SCC #" << n << '\n';
|
|
if (!this->si->is_accepting_scc(n))
|
|
continue;
|
|
|
|
bdd all = used_acc[n];
|
|
while (all != bddfalse)
|
|
{
|
|
bdd one = bdd_satoneset(all, all_sup, bddtrue);
|
|
all -= one;
|
|
bdd res = bddfalse;
|
|
bdd resacc = bddfalse;
|
|
while (one != bddtrue)
|
|
{
|
|
if (bdd_high(one) == bddfalse)
|
|
{
|
|
one = bdd_low(one);
|
|
continue;
|
|
}
|
|
int vn = bdd_var(one);
|
|
bdd v = bdd_ithvar(vn);
|
|
resacc |= bdd_exist(all_orig_neg, v) & v;
|
|
res |= acc_[remap_table[n][vn]];
|
|
one = bdd_high(one);
|
|
}
|
|
int id = resacc.id();
|
|
//std::cerr << resacc << " -> " << res << '\n';
|
|
remap_[n][id] = res;
|
|
}
|
|
}
|
|
return acc_pair{all, all_neg};
|
|
}
|
|
|
|
filtered_trans trans(unsigned src, unsigned dst, bdd cond, bdd acc)
|
|
{
|
|
bool keep;
|
|
std::tie(keep, cond, acc) =
|
|
this->next_filter::trans(src, dst, cond, acc);
|
|
|
|
if (keep && acc != bddfalse)
|
|
{
|
|
unsigned u = this->si->scc_of(dst);
|
|
|
|
auto i = remap_[u].find(acc.id());
|
|
if (i != remap_[u].end())
|
|
acc = i->second;
|
|
else
|
|
acc = bddfalse;
|
|
}
|
|
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)
|
|
{
|
|
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);
|
|
|
|
{
|
|
bdd all = aut->all_acceptance_conditions();
|
|
bdd neg = aut->neg_acceptance_conditions();
|
|
filtered->set_acceptance_conditions(filter.accsets(all, neg).first);
|
|
}
|
|
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;
|
|
bdd 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,
|
|
true,
|
|
false); // determinism may not be preserved
|
|
return res;
|
|
}
|
|
|
|
}
|