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Simplify regex splits

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This commit is contained in:
CEisenhofer 2026-03-20 13:33:53 +01:00
parent 5d912bdfa5
commit 737c5d44ed
3 changed files with 32 additions and 77 deletions
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84
src/smt/seq/seq_nielsen.cpp
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@ -1922,66 +1922,40 @@ namespace seq {
euf::snode_vector minterms;
sg.compute_minterms(mem.m_regex, minterms);
VERIFY(!minterms.empty());
euf::snode* uniform = nullptr;
bool is_uniform = true;
for (euf::snode* mt : minterms) {
if (!mt || mt->is_fail())
continue;
euf::snode* deriv = sg.brzozowski_deriv(mem.m_regex, mt);
if (!deriv) {
is_uniform = false;
break;
}
if (!uniform)
uniform = deriv;
else if (uniform->id() != deriv->id()) {
is_uniform = false;
break;
}
}
if (is_uniform && uniform) {
if (uniform->is_fail()) {
m_is_general_conflict = true;
m_reason = backtrack_reason::regex;
return simplify_result::conflict;
}
mem.m_str = sg.drop_left(mem.m_str, 1);
mem.m_regex = uniform;
mem.m_history = sg.mk_concat(mem.m_history, tok);
continue;
}
// Uniform derivative failed — try char_range subset approach.
// try char_range subset approach.
// If the symbolic char has a char_range constraint and that
// range is a subset of exactly one minterm's character class,
// we can deterministically take that minterm's derivative.
if (m_char_ranges.contains(tok->id()) && m_graph.m_parikh) {
char_set const& cs = m_char_ranges[tok->id()];
if (!cs.is_empty()) {
euf::snode* matching_deriv = nullptr;
bool found = false;
for (euf::snode* mt : minterms) {
if (!mt || mt->is_fail()) continue;
if (!mt->get_expr()) continue;
char_set mt_cs = m_graph.m_seq_regex->minterm_to_char_set(mt->get_expr());
if (cs.is_subset(mt_cs)) {
euf::snode* deriv = sg.brzozowski_deriv(mem.m_regex, mt);
if (!deriv) { found = false; break; }
if (deriv->is_fail()) {
m_is_general_conflict = true;
m_reason = backtrack_reason::regex;
return simplify_result::conflict;
}
matching_deriv = deriv;
found = true;
break;
SASSERT(m_graph.m_parikh);
char_set const& cs = m_char_ranges.contains(tok->id())
? m_char_ranges[tok->id()]
: char_set::full(zstring::max_char());
if (!cs.is_empty()) {
euf::snode* matching_deriv = nullptr;
bool found = false;
for (euf::snode* mt : minterms) {
SASSERT(mt && mt->get_expr());
SASSERT(!mt->is_fail());
char_set mt_cs = m_graph.m_seq_regex->minterm_to_char_set(mt->get_expr());
if (cs.is_subset(mt_cs)) {
euf::snode* deriv = sg.brzozowski_deriv(mem.m_regex, mt);
if (!deriv) { found = false; break; }
if (deriv->is_fail()) {
m_is_general_conflict = true;
m_reason = backtrack_reason::regex;
return simplify_result::conflict;
}
matching_deriv = deriv;
found = true;
break;
}
if (found && matching_deriv) {
mem.m_str = sg.drop_left(mem.m_str, 1);
mem.m_regex = matching_deriv;
mem.m_history = sg.mk_concat(mem.m_history, tok);
continue;
}
}
if (found && matching_deriv) {
mem.m_str = sg.drop_left(mem.m_str, 1);
mem.m_regex = matching_deriv;
mem.m_history = sg.mk_concat(mem.m_history, tok);
continue;
}
}
break;