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Regex membership (#7506)

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* Make finding a word in the regex iterative

* Fixed gc problem
This commit is contained in:
Clemens Eisenhofer 2025-01-12 02:41:37 +01:00 • committed by GitHub
parent 9a237d55ca
commit c572fc2e4f
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GPG key ID: B5690EEEBB952194
5 changed files with 103 additions and 169 deletions
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168
src/ast/rewriter/seq_rewriter.cpp
View file

@ -6152,91 +6152,115 @@ bool seq_rewriter::some_string_in_re(expr* r, zstring& s) {
// SASSERT(re().is_re(r, rs) && m_util.is_string(rs));
expr_mark visited;
unsigned_vector str;
expr_ref_vector pinned(m());
if (!some_string_in_re(pinned, visited, r, str))
if (!some_string_in_re(visited, r, str))
return false;
s = zstring(str.size(), str.data());
return true;
}
bool seq_rewriter::some_string_in_re(expr_ref_vector& pinned, expr_mark& visited, expr* r, unsigned_vector& str) {
if (visited.is_marked(r))
return false;
if (re().is_empty(r))
return false;
auto info = re().get_info(r);
if (info.nullable == l_true)
return true;
visited.mark(r);
pinned.push_back(r);
if (re().is_union(r))
return any_of(*to_app(r), [&](expr* arg) { return some_string_in_re(pinned, visited, arg, str); });
expr_ref r2 = mk_derivative(r);
struct re_eval_pos {
expr_ref e; // use reference to avoid gc
unsigned str_len;
buffer<std::pair<unsigned, unsigned>> exclude;
return append_char(pinned, visited, exclude, r2, str);
}
bool needs_derivation;
};
bool seq_rewriter::append_char(expr_ref_vector& pinned, expr_mark& visited, buffer<std::pair<unsigned, unsigned>>& exclude, expr* r, unsigned_vector& str) {
expr* c, * th, * el;
if (re().is_empty(r))
return false;
if (re().is_union(r))
return any_of(*to_app(r), [&](expr* arg) { return append_char(pinned, visited, exclude, arg, str); });
if (m().is_ite(r, c, th, el)) {
unsigned low = 0, high = zstring::unicode_max_char();
if (get_bounds(c, low, high)) {
SASSERT(low <= high);
str.push_back(low); // ASSERT: low .. high does not intersect with exclude
if (some_string_in_re(pinned, visited, th, str))
return true;
str.pop_back();
}
if (re().is_empty(el))
return false;
exclude.push_back({ low, high });
if (append_char(pinned, visited, exclude, el, str))
return true;
exclude.pop_back();
return false;
}
if (is_ground(r)) {
// ensure selected character is not in exclude
unsigned ch = 'a';
bool wrapped = false;
while (true) {
bool found = false;
for (auto [l, h] : exclude) {
if (l <= ch && ch <= h) {
found = true;
ch = h + 1;
}
}
if (!found)
break;
if (ch != zstring::unicode_max_char() + 1)
bool seq_rewriter::some_string_in_re(expr_mark& visited, expr* r, unsigned_vector& str) {
SASSERT(str.empty());
vector<re_eval_pos> todo;
todo.push_back({ expr_ref(r, m()), 0, {}, true });
while (!todo.empty()) {
re_eval_pos current = todo.back();
todo.pop_back();
r = current.e;
str.resize(current.str_len);
if (current.needs_derivation) {
SASSERT(current.exclude.empty());
// We are looking for the next character => generate derivation
if (visited.is_marked(r))
continue;
if (wrapped)
return false;
ch = 0;
wrapped = true;
}
str.push_back(ch);
if (some_string_in_re(pinned, visited, r, str))
return true;
str.pop_back();
return false;
}
if (re().is_empty(r))
continue;
auto info = re().get_info(r);
if (info.nullable == l_true)
return true;
visited.mark(r);
if (re().is_union(r)) {
for (expr* arg : *to_app(r)) {
todo.push_back({ expr_ref(arg, m()), str.size(), {}, true });
}
continue;
}
verbose_stream() << "todo append_char " << mk_pp(r, m()) << "\n";
// TODO: select characters from m_chars[ctx.rand(m_chars.size())]);
str.push_back('a');
r = mk_derivative(r);
}
// otw. we are still in the process of deciding case of the derivation to take
buffer<std::pair<unsigned, unsigned>> exclude = std::move(current.exclude);
expr* c, * th, * el;
if (re().is_empty(r))
continue;
if (re().is_union(r)) {
for (expr* arg : *to_app(r)) {
todo.push_back({ expr_ref(arg, m()), str.size(), exclude, false });
}
continue;
}
if (m().is_ite(r, c, th, el)) {
unsigned low = 0, high = zstring::unicode_max_char();
bool hasBounds = get_bounds(c, low, high);
if (!re().is_empty(el)) {
exclude.push_back({ low, high });
todo.push_back({ expr_ref(el, m()), str.size(), std::move(exclude), false });
}
if (hasBounds) {
// I want this case to be processed first => push it last
// reason: current string is only pruned
SASSERT(low <= high);
str.push_back(low); // ASSERT: low .. high does not intersect with exclude
todo.push_back({ expr_ref(th, m()), str.size(), {}, true });
}
continue;
}
if (is_ground(r)) {
// ensure selected character is not in exclude
unsigned ch = 'a';
bool wrapped = false;
bool failed = false;
while (true) {
bool found = false;
for (auto [l, h] : exclude) {
if (l <= ch && ch <= h) {
found = true;
ch = h + 1;
}
}
if (!found)
break;
if (ch != zstring::unicode_max_char() + 1)
continue;
if (wrapped) {
failed = true;
break;
}
ch = 0;
wrapped = true;
}
if (failed)
continue;
str.push_back(ch);
todo.push_back({ expr_ref(r, m()), str.size(), {}, true });
continue;
}
UNREACHABLE();
}
return false;
}
bool seq_rewriter::get_bounds(expr* e, unsigned& low, unsigned& high) {
low = 0;
high = zstring::unicode_max_char();

4
src/ast/rewriter/seq_rewriter.h
View file

@ -354,9 +354,7 @@ class seq_rewriter {
void intersect(unsigned lo, unsigned hi, svector<std::pair<unsigned, unsigned>>& ranges);
bool get_bounds(expr* e, unsigned& low, unsigned& high);
bool append_char(expr_ref_vector& pinned, expr_mark& visited, buffer<std::pair<unsigned, unsigned>>& exclude, expr* r, unsigned_vector& str);
bool some_string_in_re(expr_ref_vector& pinned, expr_mark& visited, expr* r, unsigned_vector& str);
bool some_string_in_re(expr_mark& visited, expr* r, unsigned_vector& str);
public:
seq_rewriter(ast_manager & m, params_ref const & p = params_ref()):