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adding regex simplification rewriter (#4440)

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Margus Veanes 2020-05-22 09:55:29 -07:00 • committed by GitHub
parent 18bb90f93d
commit 5d6be3f17f
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3 changed files with 94 additions and 0 deletions
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84
src/ast/rewriter/seq_rewriter.cpp
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@ -409,7 +409,91 @@ void seq_rewriter::get_param_descrs(param_descrs & r) {
seq_rewriter_params::collect_param_descrs(r);
}
br_status seq_rewriter::mk_bool_app(func_decl* f, unsigned n, expr* const* args, expr_ref& result) {
switch (f->get_decl_kind()) {
case OP_AND:
return mk_bool_app_helper(true, n, args, result);
case OP_OR:
return mk_bool_app_helper(false, n, args, result);
default:
return BR_FAILED;
}
}
br_status seq_rewriter::mk_bool_app_helper(bool is_and, unsigned n, expr* const* args, expr_ref& result) {
bool found = false;
expr* arg = nullptr;
for (unsigned i = 0; i < n && !found; ++i) {
found = m_util.str.is_in_re(args[i]) || (m().is_not(args[i], arg) && m_util.str.is_in_re(arg));
}
if (!found) return BR_FAILED;
obj_map<expr, expr*> in_re, not_in_re;
bool found_pair = false;
for (unsigned i = 0; i < n; ++i) {
expr* args_i = args[i];
expr* x = nullptr;
expr* y = nullptr;
expr* z = nullptr;
if (m_util.str.is_in_re(args_i, x, y)) {
if (in_re.find(x, z)) {
in_re[x] = is_and ? m_util.re.mk_inter(z, y) : m_util.re.mk_union(z, y);
found_pair = true;
}
else {
in_re.insert(x, y);
}
found_pair |= not_in_re.contains(x);
}
else if (m().is_not(args_i, arg) && m_util.str.is_in_re(arg, x, y)) {
if (not_in_re.find(x, z)) {
not_in_re[x] = is_and ? m_util.re.mk_union(z, y) : m_util.re.mk_inter(z, y);
found_pair = true;
}
else {
not_in_re.insert(x, y);
}
found_pair |= in_re.contains(x);
}
}
if (!found_pair) {
return BR_FAILED;
}
ptr_buffer<expr> new_args;
for (auto const & kv : in_re) {
expr* x = kv.m_key;
expr* y = kv.m_value;
expr* z = nullptr;
if (not_in_re.find(x, z)) {
expr* z_c = m_util.re.mk_complement(z);
expr* w = is_and ? m_util.re.mk_inter(y, z_c) : m_util.re.mk_union(y, z_c);
new_args.push_back(m_util.re.mk_in_re(x, w));
}
else {
new_args.push_back(m_util.re.mk_in_re(x, y));
}
}
for (auto const& kv : not_in_re) {
expr* x = kv.m_key;
expr* y = kv.m_value;
if (!in_re.contains(x)) {
new_args.push_back(m_util.re.mk_in_re(x, m_util.re.mk_complement(y)));
}
}
for (unsigned i = 0; i < n; ++i) {
expr* arg = args[i], * x;
if (!m_util.str.is_in_re(arg) && !(m().is_not(arg, x) && m_util.str.is_in_re(x))) {
new_args.push_back(arg);
}
}
result = is_and ? m().mk_and(new_args.size(), new_args.c_ptr()) : m().mk_or(new_args.size(), new_args.c_ptr());
return BR_REWRITE_FULL;
}
br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
SASSERT(f->get_family_id() == get_fid());