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Regex range bug fix (#5601)

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* added a missing derivative case for nonground range

* further missing cases and a bug fix in re.to_str
This commit is contained in:
Margus Veanes 2021-10-15 15:30:55 -07:00 • committed by GitHub
parent 6302b864c8
commit cb120c93f4
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2 changed files with 50 additions and 22 deletions
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44
src/ast/rewriter/seq_rewriter.cpp
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@ -3126,21 +3126,49 @@ void seq_rewriter::mk_antimirov_deriv_rec(expr* e, expr* r, expr* path, expr_ref
}
else if (re().is_range(r, r1, r2)) {
expr_ref range(m());
expr_ref psi(m());
expr_ref psi(m().mk_false(), m());
if (str().is_unit_string(r1, c1) && str().is_unit_string(r2, c2)) {
SASSERT(u().is_char(c1));
SASSERT(u().is_char(c2));
// range represents c1 <= e <= c2
// case: c1 <= e <= c2
range = simplify_path(m().mk_and(u().mk_le(c1, e), u().mk_le(e, c2)));
psi = simplify_path(m().mk_and(path, range));
if (m().is_false(psi))
result = nothing();
else
// D(e,c1..c2) = if (c1<=e<=c2) then () else []
result = re().mk_ite_simplify(range, epsilon(), nothing());
}
else
else if (!str().is_string(r1) && str().is_unit_string(r2, c2)) {
SASSERT(u().is_char(c2));
// r1 nonground: |r1|=1 & r1[0] <= e <= c2
expr_ref one(m_autil.mk_int(1), m());
expr_ref zero(m_autil.mk_int(0), m());
expr_ref r1_length_eq_one(m().mk_eq(str().mk_length(r1), one), m());
expr_ref r1_0(str().mk_nth_i(r1, zero), m());
range = simplify_path(m().mk_and(r1_length_eq_one, m().mk_and(u().mk_le(r1_0, e), u().mk_le(e, c2))));
psi = simplify_path(m().mk_and(path, range));
}
else if (!str().is_string(r2) && str().is_unit_string(r1, c1)) {
SASSERT(u().is_char(c1));
// r2 nonground: |r2|=1 & c1 <= e <= r2_0
expr_ref one(m_autil.mk_int(1), m());
expr_ref zero(m_autil.mk_int(0), m());
expr_ref r2_length_eq_one(m().mk_eq(str().mk_length(r2), one), m());
expr_ref r2_0(str().mk_nth_i(r2, zero), m());
range = simplify_path(m().mk_and(r2_length_eq_one, m().mk_and(u().mk_le(c1, e), u().mk_le(e, r2_0))));
psi = simplify_path(m().mk_and(path, range));
}
else if (!str().is_string(r1) && !str().is_string(r2)) {
// both r1 and r2 nonground: |r1|=1 & |r2|=1 & r1[0] <= e <= r2[0]
expr_ref one(m_autil.mk_int(1), m());
expr_ref zero(m_autil.mk_int(0), m());
expr_ref r1_length_eq_one(m().mk_eq(str().mk_length(r1), one), m());
expr_ref r1_0(str().mk_nth_i(r1, zero), m());
expr_ref r2_length_eq_one(m().mk_eq(str().mk_length(r2), one), m());
expr_ref r2_0(str().mk_nth_i(r2, zero), m());
range = simplify_path(m().mk_and(r1_length_eq_one, m().mk_and(r2_length_eq_one, m().mk_and(u().mk_le(r1_0, e), u().mk_le(e, r2_0)))));
psi = simplify_path(m().mk_and(path, range));
}
if (m().is_false(psi))
result = nothing();
else
result = re().mk_ite_simplify(range, epsilon(), nothing());
}
else if (re().is_union(r, r1, r2))
result = mk_antimirov_deriv_union(mk_antimirov_deriv(e, r1, path), mk_antimirov_deriv(e, r2, path));