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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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23
src/ast/euf/euf_sgraph.cpp
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@ -524,7 +524,7 @@ namespace euf {
return n;
}
snode* sgraph::brzozowski_deriv(snode* re, snode* elem, snode* allowed_range) {
snode* sgraph::brzozowski_deriv(snode* re, snode* elem) {
expr* re_expr = re->get_expr();
expr* elem_expr = elem->get_expr();
SASSERT(re_expr);
@ -549,26 +549,7 @@ namespace euf {
// This avoids generating massive 'ite' structures for symbolic variables.
sort* seq_sort = nullptr, *ele_sort = nullptr;
if (m_seq.is_re(re_expr, seq_sort) && m_seq.is_seq(seq_sort, ele_sort)) {
if (allowed_range && allowed_range->get_expr()) {
expr* range_expr = allowed_range->get_expr();
expr* lo = nullptr, *hi = nullptr;
if (m_seq.re.is_full_char(range_expr)) {
// For full char, we can't substitute a representative without losing info.
// Fallback to testing the symbolic character.
}
else if (m_seq.re.is_range(range_expr, lo, hi) && lo) {
expr* lo_ch = nullptr;
zstring zs;
if (m_seq.str.is_unit(lo, lo_ch))
elem_expr = lo_ch;
else if (m_seq.str.is_string(lo, zs) && zs.length() > 0)
elem_expr = m_seq.str.mk_char(zs[0]);
else
elem_expr = lo; // Use representative to take the derivative
}
}
// Fallback: If elem itself is a regex predicate, extract representative
else if (ele_sort != elem_expr->get_sort()) {
if (ele_sort != elem_expr->get_sort()) {
// std::cout << "Different sorts: " << ele_sort->get_name() << " vs " << elem_expr->get_sort()->get_name() << std::endl;
expr* lo = nullptr, *hi = nullptr;
if (m_seq.re.is_full_char(elem_expr))

2
src/ast/euf/euf_sgraph.h
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@ -142,7 +142,7 @@ namespace euf {
// Brzozowski derivative of regex re with respect to element elem.
// allowed_range can explicitly provide a concrete character or range to use
// for deriving symbolic variables.
snode* brzozowski_deriv(snode* re, snode* elem, snode* allowed_range = nullptr);
snode* brzozowski_deriv(snode* re, snode* elem);
// Decode a character expression that may be represented as a const-char,
// a unit string containing a const-char, or a one-character string literal.