list<list<name>> collect_choice_symbols(expr const & e) {
buffer<list<name>> r;
for_each(e, [&](expr const & e, unsigned) {
if (is_choice(e)) {
buffer<name> cs;
for (unsigned i = 0; i < get_num_choices(e); i++) {
expr const & c = get_app_fn(get_choice(e, i));
if (is_constant(c))
cs.push_back(const_name(c));
else if (is_local(c))
cs.push_back(mlocal_pp_name(c));
}
if (cs.size() > 1)
r.push_back(to_list(cs));
}
return true;
});
return to_list(r);
}
expr const & get_choice(expr const & e, unsigned i) {
lean_assert(is_choice(e));
return macro_arg(e, i);
}
static void check_choice(lua_State * L, int idx) {
if (!is_choice(to_expr(L, idx)))
throw exception(sstream() << "arg #" << idx << " is not a choice-expression");
}
unsigned get_num_choices(expr const & e) {
lean_assert(is_choice(e));
return macro_num_args(e);
}
static int is_choice(lua_State * L) {
return push_boolean(L, is_choice(to_expr(L, 1)));
}
