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clean up suffix/prefix rewriting

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-11-22 11:39:34 -08:00
parent 498fa87993
commit aeb4d1864d
3 changed files with 65 additions and 49 deletions
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108
src/ast/rewriter/seq_rewriter.cpp
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@ -694,7 +694,7 @@ br_status seq_rewriter::mk_seq_contains(expr* a, expr* b, expr_ref& result) {
}
if (as.empty()) {
result = m().mk_eq(b, m_util.str.mk_empty(m().get_sort(b)));
result = m_util.str.mk_is_empty(b);
return BR_REWRITE2;
}
@ -729,7 +729,7 @@ br_status seq_rewriter::mk_seq_contains(expr* a, expr* b, expr_ref& result) {
for (; offs < as.size() && cannot_contain_prefix(as[offs].get(), b0); ++offs) {}
for (; sz > offs && cannot_contain_suffix(as.get(sz-1), bL); --sz) {}
if (offs == sz) {
result = m().mk_eq(b, m_util.str.mk_empty(m().get_sort(b)));
result = m_util.str.mk_is_empty(b);
return BR_REWRITE2;
}
if (offs > 0 || sz < as.size()) {
@ -914,25 +914,23 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
}
}
}
m_util.str.get_concat(a, as);
m_util.str.get_concat(b, bs);
m_util.str.get_concat_units(a, as);
m_util.str.get_concat_units(b, bs);
unsigned i = 0;
expr_ref_vector eqs(m());
for (; i < as.size() && i < bs.size(); ++i) {
expr* a = as[i].get(), *b = bs[i].get();
if (a == b) {
expr* ai = as.get(i), *bi = bs.get(i);
if (m().are_equal(ai, bi)) {
continue;
}
if (m_util.str.is_unit(a) && m_util.str.is_unit(b)) {
eqs.push_back(m().mk_eq(a, b));
continue;
}
if (m().is_value(a) && m().is_value(b) && m_util.str.is_string(a) && m_util.str.is_string(b)) {
TRACE("seq", tout << mk_pp(a, m()) << " != " << mk_pp(b, m()) << "\n";);
if (m().are_distinct(ai, bi)) {
result = m().mk_false();
return BR_DONE;
}
if (m_util.str.is_unit(ai) && m_util.str.is_unit(bi)) {
eqs.push_back(m().mk_eq(ai, bi));
continue;
}
break;
}
if (i == as.size()) {
@ -943,7 +941,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
SASSERT(i < as.size());
if (i == bs.size()) {
for (unsigned j = i; j < as.size(); ++j) {
eqs.push_back(m().mk_eq(m_util.str.mk_empty(m().get_sort(a)), as[j].get()));
eqs.push_back(m_util.str.mk_is_empty(as.get(j)));
}
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
@ -953,13 +951,13 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
SASSERT(i < as.size() && i < bs.size());
a = m_util.str.mk_concat(as.size() - i, as.c_ptr() + i);
b = m_util.str.mk_concat(bs.size() - i, bs.c_ptr() + i);
result = m_util.str.mk_prefix(a, b);
eqs.push_back(m_util.str.mk_prefix(a, b));
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
return BR_DONE;
}
else {
return BR_FAILED;
return BR_REWRITE3;
}
return BR_FAILED;
}
br_status seq_rewriter::mk_seq_suffix(expr* a, expr* b, expr_ref& result) {
@ -973,7 +971,7 @@ br_status seq_rewriter::mk_seq_suffix(expr* a, expr* b, expr_ref& result) {
return BR_DONE;
}
if (m_util.str.is_empty(b)) {
result = m().mk_eq(m_util.str.mk_empty(m().get_sort(a)), a);
result = m_util.str.mk_is_empty(a);
return BR_REWRITE3;
}
@ -1039,36 +1037,48 @@ br_status seq_rewriter::mk_seq_suffix(expr* a, expr* b, expr_ref& result) {
}
}
}
expr_ref_vector as(m()), bs(m());
m_util.str.get_concat(a, as);
m_util.str.get_concat(b, bs);
bool change = false;
while (as.size() > 0 && bs.size() > 0 && as.back() == bs.back()) {
as.pop_back();
bs.pop_back();
change = true;
}
if (as.size() > 0 && bs.size() > 0 && m().is_value(as.back()) && m().is_value(bs.back())) {
result = m().mk_false();
return BR_DONE;
}
if (change) {
// suffix("", bs) <- true
if (as.empty()) {
result = m().mk_true();
expr_ref_vector as(m()), bs(m()), eqs(m());
m_util.str.get_concat_units(a, as);
m_util.str.get_concat_units(b, bs);
unsigned i = 1, sza = as.size(), szb = bs.size();
for (; i <= sza && i <= szb; ++i) {
expr* ai = as.get(sza-i), *bi = bs.get(szb-i);
if (m().are_equal(ai, bi)) {
continue;
}
if (m().are_distinct(ai, bi)) {
result = m().mk_false();
return BR_DONE;
}
// suffix(as, "") iff as = ""
if (bs.empty()) {
for (unsigned j = 0; j < as.size(); ++j) {
bs.push_back(m().mk_eq(m_util.str.mk_empty(m().get_sort(a)), as[j].get()));
}
result = mk_and(bs);
return BR_REWRITE3;
if (m_util.str.is_unit(ai) && m_util.str.is_unit(bi)) {
eqs.push_back(m().mk_eq(ai, bi));
continue;
}
result = m_util.str.mk_suffix(m_util.str.mk_concat(as.size(), as.c_ptr()),
m_util.str.mk_concat(bs.size(), bs.c_ptr()));
return BR_DONE;
break;
}
if (i > sza) {
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
return BR_REWRITE3;
}
if (i > szb) {
for (unsigned j = i; j <= sza; ++j) {
expr* aj = as.get(sza-j);
eqs.push_back(m_util.str.mk_is_empty(aj));
}
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
return BR_REWRITE3;
}
if (i > 1) {
SASSERT(i <= sza && i <= szb);
a = m_util.str.mk_concat(sza - i + 1, as.c_ptr());
b = m_util.str.mk_concat(szb - i + 1, bs.c_ptr());
eqs.push_back(m_util.str.mk_suffix(a, b));
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
return BR_REWRITE3;
}
return BR_FAILED;
@ -1226,7 +1236,7 @@ br_status seq_rewriter::mk_str_in_regexp(expr* a, expr* b, expr_ref& result) {
TRACE("seq", tout << seq << "\n";);
if (seq.empty()) {
result = m().mk_eq(a, m_util.str.mk_empty(m().get_sort(a)));
result = m_util.str.mk_is_empty(a);
}
else {
result = m().mk_eq(a, m_util.str.mk_concat(seq));
@ -1888,7 +1898,7 @@ bool seq_rewriter::reduce_contains(expr* a, expr* b, expr_ref_vector& disj) {
disj.push_back(m_util.str.mk_contains(m_util.str.mk_concat(m_lhs.size() - i, m_lhs.c_ptr() + i), b));
return true;
}
disj.push_back(m().mk_eq(b, m_util.str.mk_empty(m().get_sort(b))));
disj.push_back(m_util.str.mk_is_empty(b));
return true;
}