void test_multi_arg()
{
test_one_arg<T>();
using Opt = std::optional<T>;
{
Opt opt;
auto &v = opt.emplace(101, 41);
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert( v == T(101, 41));
assert(*opt == T(101, 41));
}
{
Opt opt;
auto &v = opt.emplace({1, 2, 3, 4});
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert( v == T(4)); // T sets its value to the size of the init list
assert(*opt == T(4));
}
{
Opt opt;
auto &v = opt.emplace({1, 2, 3, 4, 5}, 6);
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert( v == T(5)); // T sets its value to the size of the init list
assert(*opt == T(5)); // T sets its value to the size of the init list
}
}
void test_one_arg() {
using Opt = std::optional<T>;
{
Opt opt;
auto & v = opt.emplace();
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert(*opt == T(0));
assert(&v == &*opt);
}
{
Opt opt;
auto & v = opt.emplace(1);
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert(*opt == T(1));
assert(&v == &*opt);
}
{
Opt opt(2);
auto & v = opt.emplace();
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert(*opt == T(0));
assert(&v == &*opt);
}
{
Opt opt(2);
auto & v = opt.emplace(1);
static_assert( std::is_same_v<T&, decltype(v)>, "" );
assert(static_cast<bool>(opt) == true);
assert(*opt == T(1));
assert(&v == &*opt);
}
}
