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regex length linearity check WIP

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This commit is contained in:
Murphy Berzish 2018-01-16 13:16:31 -05:00
parent 191cc30e2a
commit 6c4c9a10e4
2 changed files with 36 additions and 0 deletions
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34
src/smt/theory_str.cpp
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@ -6604,6 +6604,40 @@ namespace smt {
return 1;
}
}
// Check whether a regex translates well to a linear set of length constraints.
bool theory_str::check_regex_length_linearity(expr * re) {
return check_regex_length_linearity_helper(re, false);
}
bool theory_str::check_regex_length_linearity_helper(expr * re, bool already_star) {
expr * sub1;
expr * sub2;
if (u.re.is_to_re(re)) {
return true;
} else if (u.re.is_concat(re, sub1, sub2)) {
return check_regex_length_linearity_helper(sub1, already_star) && check_regex_length_linearity_helper(sub2, already_star);
} else if (u.re.is_union(re, sub1, sub2)) {
return check_regex_length_linearity_helper(sub1, already_star) && check_regex_length_linearity_helper(sub2, already_star);
} else if (u.re.is_star(re, sub1) || u.re.is_plus(re, sub1)) {
if (already_star) {
return false;
} else {
return check_regex_length_linearity_helper(sub1, true);
}
} else if (u.re.is_range(re)) {
return true;
} else if (u.re.is_full(re)) {
return true;
} else if (u.re.is_complement(re)) {
// TODO can we do better?
return false;
} else {
TRACE("str", tout << "WARNING: unknown regex term " << mk_pp(re, get_manager()) << std::endl;);
UNREACHABLE(); return false;
}
}
/*
* Infer all length constraints implied by the given regular expression `re`
* in order to constrain `lenVar` (which must be of sort Int).

2
src/smt/theory_str.h
View file

@ -544,6 +544,8 @@ protected:
// regex automata and length-aware regex
unsigned estimate_regex_complexity(expr * re);
unsigned estimate_regex_complexity_under_complement(expr * re);
bool check_regex_length_linearity(expr * re);
bool check_regex_length_linearity_helper(expr * re, bool already_star);
expr_ref infer_all_regex_lengths(expr * lenVar, expr * re, expr_ref_vector & freeVariables);
bool refine_automaton_lower_bound(eautomaton * aut, rational current_lower_bound, rational & refined_lower_bound);
bool refine_automaton_upper_bound(eautomaton * aut, rational current_upper_bound, rational & refined_upper_bound);