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twa_graph: add a method to merge states with same outgoing edges

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* spot/twa/twagraph.hh, spot/twa/twagraph.cc: here
* NEWS: document it
* tests/core/twagraph.cc, tests/core/tgbagraph.test: test it
This commit is contained in:
Maximilien Colange 2018-05-25 10:26:03 +02:00
parent 5b9088006c
commit 5a819e0c93
5 changed files with 89 additions and 1 deletions
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42
spot/twa/twagraph.cc
View file

@ -231,6 +231,48 @@ namespace spot
g_.chain_edges_();
}
void twa_graph::merge_states()
{
if (!is_existential())
throw std::runtime_error(
"twa_graph::merge_states() does not work on alternating automata");
const unsigned nb_states = num_states();
std::vector<unsigned> remap(nb_states, -1U);
for (unsigned i = 0; i != nb_states; ++i)
{
auto out1 = out(i);
for (unsigned j = 0; j != i; ++j)
{
auto out2 = out(j);
if (std::equal(out1.begin(), out1.end(), out2.begin(), out2.end(),
[](const edge_storage_t& a,
const edge_storage_t& b)
{ return a.dst == b.dst && a.data() == b.data(); }))
{
remap[i] = j;
break;
}
}
}
for (auto& e: edges())
if (remap[e.dst] != -1U)
e.dst = remap[e.dst];
if (remap[get_init_state_number()] != -1U)
set_init_state(remap[get_init_state_number()]);
unsigned st = 0;
for (auto& s: remap)
if (s == -1U)
s = st++;
else
s = -1U;
defrag_states(std::move(remap), st);
}
void twa_graph::purge_unreachable_states(shift_action* f, void* action_data)
{
unsigned num_states = g_.num_states();

8
spot/twa/twagraph.hh
View file

@ -553,6 +553,14 @@ namespace spot
/// This is already called by merge_edges().
void merge_univ_dests();
/// \brief Merge states that can be merged.
///
/// This merges states that have the exact same outgoing edges. This method
/// compares the successors of states in the order in which they are stored.
/// Therefore, it is better to call it when you know that the edges are
/// stored, e.g. after a call to merge_edges().
void merge_states();
/// \brief Remove all dead states
///
/// Dead states are all the states that cannot be part of