std::pair<level, justification> substitution::instantiate_metavars(level const & l, bool use_jst) {
if (!has_meta(l))
return mk_pair(l, justification());
justification j;
auto save_jst = [&](justification const & j2) { j = mk_composite1(j, j2); };
level r = replace(l, [&](level const & l) {
if (!has_meta(l)) {
return some_level(l);
} else if (is_meta(l)) {
auto p1 = get_assignment(l);
if (p1) {
auto p2 = instantiate_metavars(p1->first, use_jst);
if (use_jst) {
justification new_jst = mk_composite1(p1->second, p2.second);
assign(meta_id(l), p2.first, new_jst);
save_jst(new_jst);
} else {
assign(meta_id(l), p2.first);
}
return some_level(p2.first);
}
}
return none_level();
});
return mk_pair(r, j);
}
level collect(level const & l) {
return replace(l, [&](level const & l) {
if (is_meta(l)) {
name const & id = meta_id(l);
if (auto r = m_univ_meta_to_param.find(id)) {
return some_level(*r);
} else {
name n = m_prefix.append_after(m_next_idx);
m_next_idx++;
level new_r = mk_param_univ(n);
m_univ_meta_to_param.insert(id, new_r);
m_univ_meta_to_param_inv.insert(n, l);
m_level_params.push_back(n);
return some_level(new_r);
}
} else if (is_param(l)) {
name const & id = param_id(l);
if (!m_found_univ_params.contains(id)) {
m_found_univ_params.insert(id);
m_level_params.push_back(id);
}
}
return none_level();
});
}
level instantiate(level const & l, level_param_names const & ps, levels const & ls) {
lean_assert(length(ps) == length(ls));
return replace(l, [=](level const & l) {
if (!has_param(l)) {
return some_level(l);
} else if (is_param(l)) {
name const & id = param_id(l);
list<name> const *it1 = &ps;
list<level> const * it2 = &ls;
while (!is_nil(*it1)) {
if (head(*it1) == id)
return some_level(head(*it2));
it1 = &tail(*it1);
it2 = &tail(*it2);
}
return some_level(l);
} else {
return none_level();
}
});
}
optional<level> substitution::get_level(name const & m) const {
auto it = m_level_subst.find(m);
return it ? some_level(*it) : none_level();
}
