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https://github.com/Z3Prover/z3
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zero-length automaton solution fix
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Murphy Berzish
parent
dbb15f65b5
commit
5727950a3c
1 changed files with 100 additions and 48 deletions
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@ -9811,33 +9811,85 @@ namespace smt {
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continue;
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}
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if (exact_length_value.is_zero()) {
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// shortcut
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expr_ref lhs(ctx.mk_eq_atom(mk_strlen(str), m_autil.mk_numeral(rational::zero(), true)), m);
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expr_ref rhs(ctx.mk_eq_atom(str, mk_string("")), m);
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assert_implication(lhs, rhs);
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} else {
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// find a consistent automaton for this term
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bool found = false;
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regex_automaton_under_assumptions assumption;
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if (regex_automaton_assumptions.contains(re) &&
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!regex_automaton_assumptions[re].empty()){
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for (svector<regex_automaton_under_assumptions>::iterator it = regex_automaton_assumptions[re].begin();
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it != regex_automaton_assumptions[re].end(); ++it) {
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regex_automaton_under_assumptions autA = *it;
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rational assumed_upper_bound, assumed_lower_bound;
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bool assumes_upper_bound = autA.get_upper_bound(assumed_upper_bound);
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bool assumes_lower_bound = autA.get_lower_bound(assumed_lower_bound);
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if (!assumes_upper_bound && !assumes_lower_bound) {
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// automaton with no assumptions is always usable
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assumption = autA;
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found = true;
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break;
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// find a consistent automaton for this term
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bool found = false;
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regex_automaton_under_assumptions assumption;
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if (regex_automaton_assumptions.contains(re) &&
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!regex_automaton_assumptions[re].empty()){
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for (svector<regex_automaton_under_assumptions>::iterator it = regex_automaton_assumptions[re].begin();
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it != regex_automaton_assumptions[re].end(); ++it) {
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regex_automaton_under_assumptions autA = *it;
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rational assumed_upper_bound, assumed_lower_bound;
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bool assumes_upper_bound = autA.get_upper_bound(assumed_upper_bound);
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bool assumes_lower_bound = autA.get_lower_bound(assumed_lower_bound);
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if (!assumes_upper_bound && !assumes_lower_bound) {
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// automaton with no assumptions is always usable
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assumption = autA;
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found = true;
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break;
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}
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// check consistency of bounds assumptions
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} // foreach(a in regex_automaton_assumptions)
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}
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if (found) {
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if (exact_length_value.is_zero()) {
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// check consistency of 0-length solution with automaton
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eautomaton * aut = assumption.get_automaton();
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bool zero_solution = false;
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unsigned initial_state = aut->init();
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if (aut->is_final_state(initial_state)) {
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zero_solution = true;
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} else {
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unsigned_vector eps_states;
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aut->get_epsilon_closure(initial_state, eps_states);
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for (unsigned_vector::iterator it = eps_states.begin(); it != eps_states.end(); ++it) {
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unsigned state = *it;
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if (aut->is_final_state(state)) {
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zero_solution = true;
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break;
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}
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}
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// check consistency of bounds assumptions
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} // foreach(a in regex_automaton_assumptions)
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}
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if (found) {
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}
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// now check polarity of automaton wrt. original term
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if ( (current_assignment == l_true && !assumption.get_polarity())
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|| (current_assignment == l_false && assumption.get_polarity())) {
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// invert sense
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NOT_IMPLEMENTED_YET();
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}
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if (zero_solution) {
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TRACE("str", tout << "zero-length solution OK -- asserting empty path constraint" << std::endl;);
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expr_ref_vector lhs_terms(m);
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if (current_assignment == l_true) {
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lhs_terms.push_back(str_in_re);
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} else {
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lhs_terms.push_back(m.mk_not(str_in_re));
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}
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lhs_terms.push_back(ctx.mk_eq_atom(mk_strlen(str), m_autil.mk_numeral(exact_length_value, true)));
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expr_ref lhs(mk_and(lhs_terms), m);
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expr_ref rhs(ctx.mk_eq_atom(str, mk_string("")), m);
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assert_implication(lhs, rhs);
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regex_terms_with_path_constraints.insert(str_in_re);
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m_trail_stack.push(insert_obj_trail<theory_str, expr>(regex_terms_with_path_constraints, str_in_re));
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} else {
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TRACE("str", tout << "zero-length solution not admitted by this automaton -- asserting conflict clause" << std::endl;);
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expr_ref_vector lhs_terms(m);
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if (current_assignment == l_true) {
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lhs_terms.push_back(str_in_re);
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} else {
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lhs_terms.push_back(m.mk_not(str_in_re));
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}
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lhs_terms.push_back(ctx.mk_eq_atom(mk_strlen(str), m_autil.mk_numeral(exact_length_value, true)));
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expr_ref lhs(mk_and(lhs_terms), m);
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expr_ref conflict(m.mk_not(lhs), m);
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assert_axiom(conflict);
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}
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regex_axiom_add = true;
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regex_inc_counter(regex_length_attempt_count, re);
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continue;
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} else {
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expr_ref pathConstraint(m);
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expr_ref characterConstraints(m);
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pathConstraint = generate_regex_path_constraints(str, assumption.get_automaton(), exact_length_value, characterConstraints);
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@ -9876,30 +9928,30 @@ namespace smt {
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TRACE("str", tout << "length attempt count for " << mk_pp(re, m) << " is " << v << std::endl;);
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}
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continue;
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} else {
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// no automata available, or else all bounds assumptions are invalid
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unsigned expected_complexity = estimate_regex_complexity(re);
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if (expected_complexity <= m_params.m_RegexAutomata_DifficultyThreshold || regex_get_counter(regex_fail_count, str_in_re) >= m_params.m_RegexAutomata_FailedAutomatonThreshold) {
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CTRACE("str", regex_get_counter(regex_fail_count, str_in_re) >= m_params.m_RegexAutomata_FailedAutomatonThreshold,
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tout << "failed automaton threshold reached for " << mk_pp(str_in_re, m) << " -- automatically constructing full automaton" << std::endl;);
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eautomaton * aut = m_mk_aut(re);
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aut->compress();
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regex_automata.push_back(aut);
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regex_automaton_under_assumptions new_aut(re, aut, true);
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if (!regex_automaton_assumptions.contains(re)) {
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regex_automaton_assumptions.insert(re, svector<regex_automaton_under_assumptions>());
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}
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regex_automaton_assumptions[re].push_back(new_aut);
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TRACE("str", tout << "add new automaton for " << mk_pp(re, m) << ": no assumptions" << std::endl;);
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regex_axiom_add = true;
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find_automaton_initial_bounds(str_in_re, aut);
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} else {
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regex_inc_counter(regex_fail_count, str_in_re);
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}
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continue;
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}
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} // !length is zero
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} else {
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// no automata available, or else all bounds assumptions are invalid
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unsigned expected_complexity = estimate_regex_complexity(re);
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if (expected_complexity <= m_params.m_RegexAutomata_DifficultyThreshold || regex_get_counter(regex_fail_count, str_in_re) >= m_params.m_RegexAutomata_FailedAutomatonThreshold) {
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CTRACE("str", regex_get_counter(regex_fail_count, str_in_re) >= m_params.m_RegexAutomata_FailedAutomatonThreshold,
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tout << "failed automaton threshold reached for " << mk_pp(str_in_re, m) << " -- automatically constructing full automaton" << std::endl;);
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eautomaton * aut = m_mk_aut(re);
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aut->compress();
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regex_automata.push_back(aut);
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regex_automaton_under_assumptions new_aut(re, aut, true);
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if (!regex_automaton_assumptions.contains(re)) {
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regex_automaton_assumptions.insert(re, svector<regex_automaton_under_assumptions>());
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}
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regex_automaton_assumptions[re].push_back(new_aut);
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TRACE("str", tout << "add new automaton for " << mk_pp(re, m) << ": no assumptions" << std::endl;);
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regex_axiom_add = true;
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find_automaton_initial_bounds(str_in_re, aut);
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} else {
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regex_inc_counter(regex_fail_count, str_in_re);
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}
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continue;
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}
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} // get_len_value()
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expr_ref str_len(mk_strlen(str), m);
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rational lower_bound_value;
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