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seq

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-01-01 09:00:21 -08:00
parent 6c6d1d92c4
commit 876fd1f7ba
5 changed files with 140 additions and 37 deletions
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45
src/ast/rewriter/seq_rewriter.cpp
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@ -520,20 +520,10 @@ br_status seq_rewriter::mk_seq_suffix(expr* a, expr* b, expr_ref& result) {
result = m().mk_eq(m_util.str.mk_empty(m().get_sort(a)), a);
return BR_REWRITE3;
}
// TBD concatenation is right-associative
expr* a1, *a2, *b1, *b2;
if (m_util.str.is_concat(a, a1, a2) &&
m_util.str.is_concat(b, b1, b2) && a2 == b2) {
result = m_util.str.mk_suffix(a1, b1);
return BR_REWRITE1;
}
if (m_util.str.is_concat(b, b1, b2) && b2 == a) {
result = m().mk_true();
return BR_DONE;
}
bool isc1 = false;
bool isc2 = false;
expr* a1, *a2, *b1, *b2;
if (m_util.str.is_concat(a, a1, a2) && m_util.str.is_string(a2, s1)) {
isc1 = true;
}
@ -593,6 +583,37 @@ 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();
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;
}
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;
}
return BR_FAILED;
}