Commit a12d676b authored by Thomas Medioni's avatar Thomas Medioni

introduce spot::simplify_acceptance()

Simplify some automata where some marks are identical,
or complementary to another. Fixes #216.

* NEWS: mention the new function.
* spot/twaalgos/cleanacc.cc, spot/twaalgos/cleanacc.hh: Implement
  the function.
* tests/Makefile.am, tests/python/merge.py: Test this implementation.
parent 22620e18
......@@ -104,6 +104,10 @@ New in spot 2.3.4.dev (not yet released)
automaton. This parameter is defaulted to true, in order to
keep this modification backward-compatible.
- The new function spot::simplify_acceptance() is able to perform
some simplifications on an acceptance condition, and might lead
to the removal of some acceptance sets.
Python:
- The 'spot.gen' package exports the functions from libspotgen.
......
......@@ -73,5 +73,224 @@ namespace spot
twa::prop_set::all()));
}
namespace
{
twa_graph_ptr merge_identical_marks_here(twa_graph_ptr aut)
{
// always cleanup before proceeding, otherwise if some mark appears in the
// acceptance condition, but not in the automaton the result is undefined.
cleanup_acceptance_here(aut, false);
auto& acc = aut->acc();
auto& c = acc.get_acceptance();
acc_cond::mark_t used_in_cond = c.used_sets();
if (!used_in_cond)
return aut;
unsigned num_sets = acc.num_sets();
std::vector<acc_cond::mark_t> always_together(num_sets);
for (unsigned i = 0; i < num_sets; ++i)
if (used_in_cond.has(i))
always_together[i] = used_in_cond;
else
always_together[i] = acc_cond::mark_t({i});
acc_cond::mark_t previous_a = 0U;
for (auto& t: aut->edges())
{
acc_cond::mark_t a = t.acc & used_in_cond;
if (a == previous_a)
continue;
previous_a = a;
for (unsigned m: a.sets())
{
acc_cond::mark_t at = always_together[m];
acc_cond::mark_t newm = at & a;
for (unsigned rem: (at - newm).sets())
always_together[rem] -= newm;
always_together[m] = newm;
}
}
acc_cond::mark_t to_remove = 0U;
for (unsigned i = 0; i < num_sets; ++i)
{
auto oldm = always_together[i];
if (oldm == acc_cond::mark_t({i}))
continue;
acc_cond::mark_t newm = oldm.lowest();
to_remove |= oldm - newm;
always_together[i] = newm;
}
for (auto& t: aut->edges())
t.acc -= to_remove;
// Replace the marks in the acceptance condition
auto pos = &c.back();
auto end = &c.front();
while (pos > end)
{
switch (pos->sub.op)
{
case acc_cond::acc_op::And:
case acc_cond::acc_op::Or:
--pos;
break;
case acc_cond::acc_op::Fin:
case acc_cond::acc_op::Inf:
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
acc_cond::mark_t replace = pos[-1].mark & to_remove;
pos[-1].mark -= replace;
for (unsigned m: replace.sets())
pos[-1].mark |= always_together[m];
pos -= 2;
break;
}
}
return aut;
}
// Eventually remove complementary marks from the acceptance condition.
acc_cond::acc_code remove_compl_rec(const acc_cond::acc_word* pos,
const std::vector<acc_cond::mark_t>&
complement)
{
auto start = pos - pos->sub.size;
switch (pos->sub.op)
{
case acc_cond::acc_op::And:
{
--pos;
auto res = acc_cond::acc_code::t();
acc_cond::mark_t seen_fin = 0U;
auto inf = acc_cond::acc_code::inf(0U);
do
{
auto tmp = remove_compl_rec(pos, complement);
if (tmp.back().sub.op == acc_cond::acc_op::Fin
&& tmp.front().mark.count() == 1)
seen_fin |= tmp.front().mark;
if (tmp.back().sub.op == acc_cond::acc_op::Inf)
{
inf &= std::move(tmp);
pos -= pos->sub.size + 1;
continue;
}
tmp &= std::move(res);
std::swap(tmp, res);
pos -= pos->sub.size + 1;
}
while (pos > start);
for (auto m: seen_fin.sets())
inf.front().mark -= complement[m];
res &= inf;
return res;
}
case acc_cond::acc_op::Or:
{
--pos;
auto res = acc_cond::acc_code::f();
acc_cond::mark_t seen_inf = 0U;
auto fin = acc_cond::acc_code::f();
do
{
auto tmp = remove_compl_rec(pos, complement);
if (tmp.back().sub.op == acc_cond::acc_op::Inf
&& tmp.front().mark.count() == 1)
seen_inf |= tmp.front().mark;
if (tmp.back().sub.op == acc_cond::acc_op::Fin)
{
fin |= std::move(tmp);
pos -= pos->sub.size + 1;
continue;
}
tmp |= std::move(res);
std::swap(tmp, res);
pos -= pos->sub.size + 1;
}
while (pos > start);
for (auto m: seen_inf.sets())
fin.front().mark -= complement[m];
res |= fin;
return res;
}
case acc_cond::acc_op::Fin:
return acc_cond::acc_code::fin(pos[-1].mark);
case acc_cond::acc_op::Inf:
return acc_cond::acc_code::inf(pos[-1].mark);
case acc_cond::acc_op::FinNeg:
case acc_cond::acc_op::InfNeg:
SPOT_UNREACHABLE();
};
SPOT_UNREACHABLE();
return {};
}
// Always cleanup_acceptance_here with stripping after calling this function
// As complementary marks might be simplified in the acceptance condition.
twa_graph_ptr simplify_complementary_marks_here(twa_graph_ptr aut)
{
auto& acc = aut->acc();
auto c = acc.get_acceptance();
acc_cond::mark_t used_in_cond = c.used_sets();
if (!used_in_cond)
return aut;
unsigned num_sets = acc.num_sets();
std::vector<acc_cond::mark_t> complement(num_sets);
for (unsigned i = 0; i < num_sets; ++i)
if (used_in_cond.has(i))
complement[i] = used_in_cond - acc_cond::mark_t({i});
acc_cond::mark_t previous_a = 0U;
for (auto& t: aut->edges())
{
if (t.acc == previous_a)
continue;
previous_a = t.acc;
for (unsigned m: used_in_cond.sets())
{
if (t.acc.has(m))
complement[m] -= t.acc;
else
complement[m] &= t.acc;
}
}
aut->set_acceptance(num_sets,
remove_compl_rec(&acc.get_acceptance().back(),
complement));
return aut;
}
}
twa_graph_ptr simplify_acceptance_here(twa_graph_ptr aut)
{
cleanup_acceptance_here(aut, false);
merge_identical_marks_here(aut);
simplify_complementary_marks_here(aut);
cleanup_acceptance_here(aut, true);
return aut;
}
twa_graph_ptr simplify_acceptance(const_twa_graph_ptr aut)
{
return simplify_acceptance_here(make_twa_graph(aut, twa::prop_set::all()));
}
}
......@@ -34,4 +34,17 @@ namespace spot
/// \brief Remove useless acceptance sets
SPOT_API twa_graph_ptr
cleanup_acceptance(const_twa_graph_ptr aut);
/// \brief Simplify an acceptance condition
///
/// Remove useless acceptance sets.
/// Merge identical sets.
/// If some sets are complement to each other, might result in the
/// simplification of some clause in the acceptance condition.
SPOT_API twa_graph_ptr
simplify_acceptance_here(twa_graph_ptr aut);
/// \brief Simplify an acceptance condition
SPOT_API twa_graph_ptr
simplify_acceptance(const_twa_graph_ptr aut);
}
......@@ -348,6 +348,7 @@ TESTS_python = \
python/ltlf.py \
python/ltlparse.py \
python/ltlsimple.py \
python/merge.py \
python/minato.py \
python/misc-ec.py \
python/optionmap.py \
......
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