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fix axiomatization of str.replace. Fixes issue #703

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-08-20 06:13:52 -07:00
parent 2d8325ed43
commit 879f792125
2 changed files with 7 additions and 2 deletions

View file

@ -144,6 +144,9 @@ zstring zstring::replace(zstring const& src, zstring const& dst) const {
if (length() < src.length()) {
return zstring(*this);
}
if (src.length() == 0) {
return zstring(*this);
}
bool found = false;
for (unsigned i = 0; i < length(); ++i) {
bool eq = !found && i + src.length() <= length();

View file

@ -2903,10 +2903,12 @@ void theory_seq::add_replace_axiom(expr* r) {
expr_ref xsy = mk_concat(x, s, y);
literal cnt = mk_literal(m_util.str.mk_contains(a ,s));
literal a_emp = mk_eq_empty(a);
literal s_emp = mk_eq_empty(s);
add_axiom(~a_emp, mk_seq_eq(r, a));
add_axiom(cnt, mk_seq_eq(r, a));
add_axiom(~cnt, a_emp, mk_seq_eq(a, xsy));
add_axiom(~cnt, a_emp, mk_seq_eq(r, xty));
add_axiom(~s_emp, mk_seq_eq(r, a));
add_axiom(~cnt, a_emp, s_emp, mk_seq_eq(a, xsy));
add_axiom(~cnt, a_emp, s_emp, mk_seq_eq(r, xty));
tightest_prefix(s, x);
}