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prune dead states from automata

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-08-31 07:33:55 -07:00
parent e8198bbbe3
commit 059bad909a
5 changed files with 70 additions and 22 deletions
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72
src/math/automata/automaton.h
View file

@ -25,6 +25,7 @@ Revision History:
#include "util/util.h"
#include "util/vector.h"
#include "util/uint_set.h"
#include "util/trace.h"
template<class T>
class default_value_manager {
@ -383,12 +384,12 @@ public:
else if (1 == in_degree(dst) && (!is_final_state(dst) || is_final_state(src)) && init() != dst) {
moves const& mvs = m_delta[dst];
moves mvs1;
for (unsigned k = 0; k < mvs.size(); ++k) {
mvs1.push_back(move(m, src, mvs[k].dst(), mvs[k].t()));
for (move const& mv : mvs) {
mvs1.push_back(move(m, src, mv.dst(), mv.t()));
}
for (unsigned k = 0; k < mvs1.size(); ++k) {
remove(dst, mvs1[k].dst(), mvs1[k].t());
add(mvs1[k]);
for (move const& mv : mvs1) {
remove(dst, mv.dst(), mv.t());
add(mv);
}
}
//
@ -401,13 +402,13 @@ public:
unsigned_vector src0s;
moves const& mvs = m_delta_inv[dst];
moves mvs1;
for (unsigned k = 0; k < mvs.size(); ++k) {
SASSERT(mvs[k].is_epsilon());
mvs1.push_back(move(m, mvs[k].src(), dst1, t));
for (move const& mv1 : mvs) {
SASSERT(mv1.is_epsilon());
mvs1.push_back(move(m, mv1.src(), dst1, t));
}
for (unsigned k = 0; k < mvs1.size(); ++k) {
remove(mvs1[k].src(), dst, 0);
add(mvs1[k]);
for (move const& mv1 : mvs1) {
remove(mv1.src(), dst, 0);
add(mv1);
}
remove(dst, dst1, t);
--j;
@ -419,12 +420,12 @@ public:
else if (1 == out_degree(src) && init() != src && (!is_final_state(src) || is_final_state(dst))) {
moves const& mvs = m_delta_inv[src];
moves mvs1;
for (unsigned k = 0; k < mvs.size(); ++k) {
mvs1.push_back(move(m, mvs[k].src(), dst, mvs[k].t()));
for (move const& mv : mvs) {
mvs1.push_back(move(m, mv.src(), dst, mv.t()));
}
for (unsigned k = 0; k < mvs1.size(); ++k) {
remove(mvs1[k].src(), src, mvs1[k].t());
add(mvs1[k]);
for (move const& mv : mvs1) {
remove(mv.src(), src, mv.t());
add(mv);
}
}
else {
@ -447,6 +448,7 @@ public:
break;
}
}
sinkify_dead_states();
}
bool is_sequence(unsigned& length) const {
@ -564,6 +566,40 @@ public:
}
private:
void sinkify_dead_states() {
uint_set dead_states;
for (unsigned i = 0; i < m_delta.size(); ++i) {
if (!m_final_states.contains(i)) {
dead_states.insert(i);
}
}
bool change = true;
unsigned_vector to_remove;
while (change) {
change = false;
to_remove.reset();
for (unsigned s : dead_states) {
moves const& mvs = m_delta[s];
for (move const& mv : mvs) {
if (!dead_states.contains(mv.dst())) {
to_remove.push_back(s);
break;
}
}
}
change = !to_remove.empty();
for (unsigned s : to_remove) {
dead_states.remove(s);
}
to_remove.reset();
}
TRACE("seq", tout << "remove: " << dead_states << "\n";);
for (unsigned s : dead_states) {
CTRACE("seq", !m_delta[s].empty(), tout << "live state " << s << "\n";);
m_delta[s].reset();
}
}
void remove_dead_states() {
unsigned_vector remap;
for (unsigned i = 0; i < m_delta.size(); ++i) {
@ -669,8 +705,8 @@ private:
}
static void append_final(unsigned offset, automaton const& a, unsigned_vector& final) {
for (unsigned i = 0; i < a.m_final_states.size(); ++i) {
final.push_back(a.m_final_states[i]+offset);
for (unsigned s : a.m_final_states) {
final.push_back(s+offset);
}
}