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safra: Edges to accepting SCC are accepting

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*  src/twaalgos/safra.cc, src/twaalgos/safra.hh: Implement optimisation.
Update function calls with new API.
* src/tests/safra.cc, src/tests/safra.test: Use new API.
This commit is contained in:
Alexandre Lewkowicz 2015-09-22 08:33:48 +02:00 • committed by Alexandre Duret-Lutz
parent f29de22b8a
commit e8c428d0a3
4 changed files with 120 additions and 49 deletions
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78
src/twaalgos/safra.cc
View file

@ -24,6 +24,7 @@
#include "safra.hh"
#include "twaalgos/degen.hh"
#include "twaalgos/sccinfo.hh"
#include "twaalgos/simulation.hh"
namespace spot
@ -141,7 +142,7 @@ namespace spot
{
assert(max_acc < 32);
unsigned mask = (1 << max_acc) - 1;
for (auto& t: aut->transitions())
for (auto& t: aut->edges())
{
t.acc &= mask;
}
@ -166,26 +167,30 @@ namespace spot
}
}
auto
void
safra_state::compute_succs(const const_twa_graph_ptr& aut,
const std::vector<unsigned>& bddnums,
std::unordered_map<bdd,
std::pair<unsigned, unsigned>,
bdd_hash>& deltas) const -> succs_t
bdd_hash>& deltas,
succs_t& res) const
{
succs_t res;
// Given a bdd returns index of associated safra_state in res
std::map<unsigned, unsigned> bdd2num;
for (auto& node: nodes_)
{
for (auto& t: aut->out(node.first))
{
// deltas precalculate all transitions in edge t
auto p = deltas[t.cond];
for (unsigned j = p.first; j < p.second; ++j)
{
auto i = bdd2num.insert(std::make_pair(bddnums[j], res.size()));
unsigned idx;
if (!i.second)
// No new state added, so get pre-existing state whichi is an
// index in the vector of safra states (res)
idx = i.first->second;
else
{
@ -203,9 +208,17 @@ namespace spot
for (auto& s: res)
{
safra_state& tmp = s.first;
tmp.ungreenify_last_brace();
s.first.color_ = tmp.finalize_construction();
}
return res;
}
void safra_state::ungreenify_last_brace()
{
// Step A4: For a brace to emit green it must surround other braces.
// Hence, the last brace cannot emit green as it is the most inside brace.
for (auto& n: nodes_)
is_green_[n.second.back()] = false;
}
unsigned safra_state::finalize_construction()
@ -218,7 +231,7 @@ namespace spot
{
if (nb_braces_[i] == 0)
{
// It is impossible to emit red == -1 as those transitions would
// It is impossible to emit red == -1 as those edges would
// lead us in a sink states which are not created here.
assert(i >= 1);
red = std::min(red, 2 * i - 1);
@ -301,12 +314,10 @@ namespace spot
unsigned dst, const acc_cond::mark_t acc)
{
std::vector<node_helper::brace_t> copy = braces;
// TODO handle multiple accepting sets
if (acc.count())
{
assert(acc.has(0) && acc.count() == 1 &&
"Only one TBA are accepted at the moment");
// Accepting transition generate new braces: step A1
assert(acc.has(0) && acc.count() == 1 && "Only one TBA are accepted");
// Accepting edge generate new braces: step A1
copy.emplace_back(nb_braces_.size());
// nb_braces_ gets updated later so put 0 for now
nb_braces_.emplace_back(0);
@ -333,9 +344,6 @@ namespace spot
// After inserting new node, update the brace count per node
for (auto b: i.first->second)
++nb_braces_[b];
// Step A4: For a brace to emit green it must surround other braces.
// Hence, the last brace cannot emit green as it is the most inside brace.
is_green_[i.first->second.back()] = false;
}
// Called only to initialize first state
@ -367,16 +375,32 @@ namespace spot
return nodes_ < other.nodes_;
}
// All edge going into an accepting SCC are marked as accepting
// This helps safra make fewer trees as we immediately see the accepting
// edge and don't create useless states
void
emit_accepting_scc(twa_graph_ptr& aut, scc_info& scc)
{
for (auto& e: aut->edges())
{
unsigned src_scc = scc.scc_of(e.src);
unsigned dst_scc = scc.scc_of(e.dst);
if (src_scc == dst_scc)
continue;
if (scc.is_accepting_scc(dst_scc))
e.acc |= 1;
}
}
twa_graph_ptr
tgba_determinisation(const const_twa_graph_ptr& a, bool bisimulation,
bool pretty_print)
bool pretty_print, bool emit_scc)
{
// Degeneralize
const_twa_graph_ptr aut;
if (a->acc().is_generalized_buchi())
aut = spot::degeneralize_tba(a);
else
aut = a;
twa_graph_ptr aut = spot::degeneralize_tba(a);
scc_info scc = scc_info(aut);
if (emit_scc)
emit_accepting_scc(aut, scc);
bdd allap = bddtrue;
@ -384,7 +408,7 @@ namespace spot
typedef std::set<bdd, bdd_less_than> sup_map;
sup_map sup;
// Record occurrences of all guards
for (auto& t: aut->transitions())
for (auto& t: aut->edges())
sup.emplace(t.cond);
for (auto& i: sup)
allap &= bdd_support(i);
@ -398,7 +422,7 @@ namespace spot
// Used to convert large bdd to indexes
std::unordered_map<bdd, std::pair<unsigned, unsigned>, bdd_hash> deltas;
std::vector<unsigned> bddnums;
for (auto& t: aut->transitions())
for (auto& t: aut->edges())
{
auto it = deltas.find(t.cond);
if (it == deltas.end())
@ -428,7 +452,7 @@ namespace spot
});
// Given a safra_state get its associated state in output automata.
// Required to create new transitions from 2 safra-state
// Required to create new edges from 2 safra-state
power_set seen;
safra_state init(aut->get_init_state_number(), true);
unsigned num = res->new_state();
@ -437,13 +461,14 @@ namespace spot
std::deque<safra_state> todo;
todo.push_back(init);
unsigned sets = 0;
using succs_t = safra_state::succs_t;
succs_t succs;
while (!todo.empty())
{
using succs_t = safra_state::succs_t;
safra_state curr = todo.front();
unsigned src_num = seen.find(curr)->second;
todo.pop_front();
succs_t succs = curr.compute_succs(aut, bddnums, deltas);
curr.compute_succs(aut, bddnums, deltas, succs);
for (auto s: succs)
{
auto i = seen.find(s.first);
@ -461,15 +486,16 @@ namespace spot
}
if (s.first.color_ != -1U)
{
res->new_transition(src_num, dst_num, num2bdd[s.second],
res->new_edge(src_num, dst_num, num2bdd[s.second],
{s.first.color_});
// We only care about green acc
if (s.first.color_ % 2 == 0)
sets = std::max(s.first.color_ + 1, sets);
}
else
res->new_transition(src_num, dst_num, num2bdd[s.second]);
res->new_edge(src_num, dst_num, num2bdd[s.second]);
}
succs.clear();
}
remove_dead_acc(res, sets);
res->set_acceptance(sets, acc_cond::acc_code::parity(false, false, sets));