public column_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>

{

struct _traits

{

using _value_type = value_type_of<ColumnSpec>;

using _tags = detail::make_joined_set_t<detail::type_set<tag::is_column, tag::is_expression, tag::is_selectable>,

typename ColumnSpec::_traits::_tags>;

};

using _nodes = detail::type_vector<>;

using _required_tables = detail::type_set<Table>;

using _can_be_null = column_spec_can_be_null_t<ColumnSpec>;

using _spec_t = ColumnSpec;

using _table = Table;

using _alias_t = typename _spec_t::_alias_t;

template <typename T>

using _is_valid_assignment_operand = is_valid_assignment_operand<value_type_of<ColumnSpec>, T>;

// disambiguation for C++20 / clang

// (see https://bugs.llvm.org/show_bug.cgi?id=46508)

using expression_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>::operator==;

using expression_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>::operator!=;

column_t() = default;

column_t(const column_t&) = default;

column_t(column_t&&) = default;

column_t& operator=(const column_t&) = default;

column_t& operator=(column_t&&) = default;

~column_t() = default;

template <typename T = _table>

auto table() const -> _table

{

static_assert(is_table_t<T>::value, "cannot call get_table for columns of a sub-selects or cte");

return _table{};

}

template <typename alias_provider>

expression_alias_t<column_t, alias_provider> as(const alias_provider& /*unused*/) const

{

return {*this};

}

template <typename T>

auto operator=(T t) const -> assignment_t<column_t, wrap_operand_t<T>>

{

using rhs = wrap_operand_t<T>;

static_assert(_is_valid_assignment_operand<rhs>::value, "invalid rhs assignment operand");

return {*this, {rhs{t}}};

}

auto operator=(null_t /*unused*/) const -> assignment_t<column_t, null_t>

{

static_assert(can_be_null_t<column_t>::value, "column cannot be null");

return {*this, null_t{}};

}

auto operator=(default_value_t /*unused*/) const -> assignment_t<column_t, default_value_t>

{

return {*this, default_value_t{}};

}