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https://github.com/Z3Prover/z3
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seq
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
30580a012a
commit
5eb23e1e7a
17 changed files with 287 additions and 141 deletions
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@ -74,7 +74,8 @@ br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * con
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case OP_SEQ_INDEX:
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if (num_args == 2) {
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expr_ref arg3(m_autil.mk_int(0), m());
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return mk_seq_index(args[0], args[1], arg3, result);
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result = m_util.str.mk_index(args[0], args[1], arg3);
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return BR_REWRITE1;
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}
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SASSERT(num_args == 3);
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return mk_seq_index(args[0], args[1], args[2], result);
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@ -202,19 +203,19 @@ br_status seq_rewriter::mk_seq_extract(expr* a, expr* b, expr* c, expr_ref& resu
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br_status seq_rewriter::mk_seq_contains(expr* a, expr* b, expr_ref& result) {
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std::string c, d;
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if (m_util.str.is_string(a, c) && m_util.str.is_string(b, d)) {
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result = m().mk_bool_val(0 != strstr(d.c_str(), c.c_str()));
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result = m().mk_bool_val(0 != strstr(c.c_str(), d.c_str()));
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return BR_DONE;
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}
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// check if subsequence of a is in b.
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// check if subsequence of b is in a.
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ptr_vector<expr> as, bs;
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m_util.str.get_concat(a, as);
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m_util.str.get_concat(b, bs);
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bool found = false;
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for (unsigned i = 0; !found && i < bs.size(); ++i) {
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if (as.size() > bs.size() - i) break;
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for (unsigned i = 0; !found && i < as.size(); ++i) {
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if (bs.size() > as.size() - i) break;
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unsigned j = 0;
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for (; j < as.size() && as[j] == bs[i+j]; ++j) {};
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found = j == as.size();
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for (; j < bs.size() && as[j] == bs[i+j]; ++j) {};
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found = j == bs.size();
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}
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if (found) {
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result = m().mk_true();
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@ -260,7 +261,7 @@ br_status seq_rewriter::mk_seq_index(expr* a, expr* b, expr* c, expr_ref& result
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return BR_DONE;
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}
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if (m_util.str.is_empty(b)) {
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if (m_util.str.is_empty(b) && m_autil.is_numeral(c, r) && r.is_zero()) {
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result = c;
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return BR_DONE;
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}
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@ -380,6 +381,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
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return BR_REWRITE3;
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}
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if (i > 0) {
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SASSERT(i < as.size() && i < bs.size());
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a = m_util.str.mk_concat(as.size() - i, as.c_ptr() + i);
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b = m_util.str.mk_concat(bs.size() - i, bs.c_ptr() + i);
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result = m_util.str.mk_prefix(a, b);
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@ -657,54 +659,127 @@ bool seq_rewriter::reduce_eq(expr* l, expr* r, expr_ref_vector& lhs, expr_ref_ve
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}
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bool is_sat;
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if (!change) {
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if (is_subsequence(m_lhs.size(), m_lhs.c_ptr(), m_rhs.size(), m_rhs.c_ptr(), lhs, rhs, is_sat)) {
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return is_sat;
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}
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unsigned szl = m_lhs.size() - head1, szr = m_rhs.size() - head2;
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expr* const* ls = m_lhs.c_ptr() + head1, * const*rs = m_rhs.c_ptr() + head2;
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if (length_constrained(szl, ls, szr, rs, lhs, rhs, is_sat)) {
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return is_sat;
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}
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if (is_subsequence(szl, ls, szr, rs, lhs, rhs, is_sat)) {
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return is_sat;
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}
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if (szl == 0 && szr == 0) {
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return true;
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}
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else if (!change) {
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lhs.push_back(l);
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rhs.push_back(r);
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}
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else if (head1 == m_lhs.size() && head2 == m_rhs.size()) {
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// skip
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}
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else if (head1 == m_lhs.size()) {
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return set_empty(m_rhs.size() - head2, m_rhs.c_ptr() + head2, lhs, rhs);
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}
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else if (head2 == m_rhs.size()) {
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return set_empty(m_lhs.size() - head1, m_lhs.c_ptr() + head1, lhs, rhs);
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}
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else { // could solve if either side is fixed size.
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SASSERT(head1 < m_lhs.size() && head2 < m_rhs.size());
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if (is_subsequence(m_lhs.size() - head1, m_lhs.c_ptr() + head1,
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m_rhs.size() - head2, m_rhs.c_ptr() + head2, lhs, rhs, is_sat)) {
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return is_sat;
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}
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else {
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// could solve if either side is fixed size.
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SASSERT(szl > 0 && szr > 0);
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lhs.push_back(m_util.str.mk_concat(m_lhs.size() - head1, m_lhs.c_ptr() + head1));
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rhs.push_back(m_util.str.mk_concat(m_rhs.size() - head2, m_rhs.c_ptr() + head2));
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lhs.push_back(m_util.str.mk_concat(szl, ls));
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rhs.push_back(m_util.str.mk_concat(szr, rs));
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}
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return true;
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}
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bool seq_rewriter::set_empty(unsigned sz, expr* const* es, expr_ref_vector& lhs, expr_ref_vector& rhs) {
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expr* seq_rewriter::concat_non_empty(unsigned n, expr* const* as) {
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SASSERT(n > 0);
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ptr_vector<expr> bs;
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for (unsigned i = 0; i < n; ++i) {
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if (m_util.str.is_unit(as[i]) ||
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m_util.str.is_string(as[i])) {
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bs.push_back(as[i]);
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}
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}
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if (bs.empty()) {
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return m_util.str.mk_empty(m().get_sort(as[0]));
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}
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else {
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return m_util.str.mk_concat(bs.size(), bs.c_ptr());
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}
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}
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bool seq_rewriter::set_empty(unsigned sz, expr* const* es, bool all, expr_ref_vector& lhs, expr_ref_vector& rhs) {
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std::string s;
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for (unsigned i = 0; i < sz; ++i) {
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if (m_util.str.is_unit(es[i])) {
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return false;
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if (all) return false;
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}
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if (m_util.str.is_empty(es[i])) {
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else if (m_util.str.is_empty(es[i])) {
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continue;
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}
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if (m_util.str.is_string(es[i], s)) {
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SASSERT(s.length() > 0);
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return false;
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else if (m_util.str.is_string(es[i], s)) {
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if (all) {
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SASSERT(s.length() > 0);
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return false;
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}
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}
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else {
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lhs.push_back(m_util.str.mk_empty(m().get_sort(es[i])));
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rhs.push_back(es[i]);
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}
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lhs.push_back(m_util.str.mk_empty(m().get_sort(es[i])));
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rhs.push_back(es[i]);
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}
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return true;
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}
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bool seq_rewriter::min_length(unsigned n, expr* const* es, size_t& len) {
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std::string s;
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bool bounded = true;
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len = 0;
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for (unsigned i = 0; i < n; ++i) {
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if (m_util.str.is_unit(es[i])) {
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++len;
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}
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else if (m_util.str.is_empty(es[i])) {
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continue;
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}
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else if (m_util.str.is_string(es[i], s)) {
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len += s.length();
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}
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else {
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bounded = false;
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}
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}
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return bounded;
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}
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bool seq_rewriter::length_constrained(unsigned szl, expr* const* l, unsigned szr, expr* const* r,
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expr_ref_vector& lhs, expr_ref_vector& rhs, bool& is_sat) {
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is_sat = true;
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size_t len1 = 0, len2 = 0;
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bool bounded1 = min_length(szl, l, len1);
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bool bounded2 = min_length(szr, r, len2);
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if (bounded1 && len1 < len2) {
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is_sat = false;
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return true;
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}
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if (bounded2 && len2 < len1) {
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is_sat = false;
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return true;
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}
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if (bounded1 && len1 == len2 && len1 > 0) {
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is_sat = set_empty(szr, r, false, lhs, rhs);
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if (is_sat) {
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lhs.push_back(concat_non_empty(szl, l));
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rhs.push_back(concat_non_empty(szr, r));
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}
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return true;
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}
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if (bounded2 && len1 == len2 && len1 > 0) {
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is_sat = set_empty(szl, l, false, lhs, rhs);
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if (is_sat) {
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lhs.push_back(concat_non_empty(szl, l));
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rhs.push_back(concat_non_empty(szr, r));
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}
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return true;
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}
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return false;
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}
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bool seq_rewriter::is_subsequence(unsigned szl, expr* const* l, unsigned szr, expr* const* r,
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expr_ref_vector& lhs, expr_ref_vector& rhs, bool& is_sat) {
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is_sat = true;
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@ -733,13 +808,15 @@ bool seq_rewriter::is_subsequence(unsigned szl, expr* const* l, unsigned szr, ex
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if (rpos.contains(j)) {
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rs.push_back(r[j]);
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}
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else if (!set_empty(1, r + j, lhs, rhs)) {
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else if (!set_empty(1, r + j, true, lhs, rhs)) {
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is_sat = false;
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return true;
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}
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}
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SASSERT(szl == rs.size());
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lhs.push_back(m_util.str.mk_concat(szl, l));
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rhs.push_back(m_util.str.mk_concat(szl, rs.c_ptr()));
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if (szl > 0) {
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lhs.push_back(m_util.str.mk_concat(szl, l));
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rhs.push_back(m_util.str.mk_concat(szl, rs.c_ptr()));
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}
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return true;
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}
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