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add simplification for equalities between itos and constant strings, Issue #589

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-07-08 11:50:39 -07:00
parent bdbf1c9bf4
commit d5ee7e24bc
4 changed files with 60 additions and 11 deletions
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55
src/ast/rewriter/seq_rewriter.cpp
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@ -1515,6 +1515,11 @@ bool seq_rewriter::reduce_eq(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_
unsigned szl = ls.size() - head1, szr = rs.size() - head2;
expr* const* _ls = ls.c_ptr() + head1, * const* _rs = rs.c_ptr() + head2;
if (solve_itos(szl, _ls, szr, _rs, lhs, rhs, is_sat)) {
ls.reset(); rs.reset();
change = true;
return is_sat;
}
if (length_constrained(szl, _ls, szr, _rs, lhs, rhs, is_sat)) {
ls.reset(); rs.reset();
@ -1679,6 +1684,56 @@ bool seq_rewriter::min_length(unsigned n, expr* const* es, unsigned& len) {
return bounded;
}
bool seq_rewriter::is_string(unsigned n, expr* const* es, zstring& s) const {
zstring s1;
expr* e;
bv_util bv(m());
rational val;
unsigned sz;
for (unsigned i = 0; i < n; ++i) {
if (m_util.str.is_string(es[i], s1)) {
s = s + s1;
}
else if (m_util.str.is_unit(es[i], e) && bv.is_numeral(e, val, sz)) {
s = s + zstring(val.get_unsigned());
}
else {
return false;
}
}
return true;
}
bool seq_rewriter::solve_itos(unsigned szl, expr* const* ls, unsigned szr, expr* const* rs,
expr_ref_vector& lhs, expr_ref_vector& rhs, bool& is_sat) {
expr* l, *r;
if (szl == 1 && m_util.str.is_itos(ls[0], l)) {
if (szr == 1 && m_util.str.is_itos(rs[0], r)) {
lhs.push_back(l);
rhs.push_back(r);
is_sat = true;
return true;
}
zstring s;
if (is_string(szr, rs, s)) {
std::string s1 = s.encode();
rational r(s1.c_str());
if (s1 == r.to_string()) {
lhs.push_back(l);
rhs.push_back(m_autil.mk_numeral(r, true));
return true;
}
}
}
if (szr == 1 && m_util.str.is_itos(rs[0], r)) {
return solve_itos(szr, rs, szl, ls, rhs, lhs, is_sat);
}
return false;
}
bool seq_rewriter::length_constrained(unsigned szl, expr* const* l, unsigned szr, expr* const* r,
expr_ref_vector& lhs, expr_ref_vector& rhs, bool& is_sat) {
is_sat = true;