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Reduced error messages for order_by

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rbock 2014-11-27 23:18:23 +01:00
parent 36d1a85339
commit bf2744d5f7
1 changed files with 20 additions and 9 deletions
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29
include/sqlpp11/order_by.h
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@ -178,34 +178,45 @@ namespace sqlpp
struct _methods_t
{
using _database_t = typename Policies::_database_t;
template<typename T>
using _new_statement_t = new_statement<Policies, no_order_by_t, T>;
template<typename... T>
using _check = detail::all_t<is_expression_t<T>::value...>;
template<typename Check, typename T>
using _new_statement_t = new_statement_t<Check::value, Policies, no_order_by_t, T>;
using _consistency_check = consistent_t;
template<typename... Expressions>
auto order_by(Expressions... expressions) const
-> _new_statement_t<order_by_t<void, Expressions...>>
-> _new_statement_t<_check<Expressions...>, order_by_t<void, Expressions...>>
{
static_assert(sizeof...(Expressions), "at least one expression (e.g. a column) required in order_by()");
return _order_by_impl<void>(expressions...);
static_assert(detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not an expression in order_by()");
return _order_by_impl<void>(_check<Expressions...>{}, expressions...);
}
template<typename... Expressions>
auto dynamic_order_by(Expressions... expressions) const
-> _new_statement_t<order_by_t<_database_t, Expressions...>>
-> _new_statement_t<_check<Expressions...>, order_by_t<_database_t, Expressions...>>
{
static_assert(not std::is_same<_database_t, void>::value, "dynamic_order_by must not be called in a static statement");
return _order_by_impl<_database_t>(expressions...);
static_assert(detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not an expression in order_by()");
return _order_by_impl<_database_t>(_check<Expressions...>{}, expressions...);
}
private:
template<typename Database, typename... Expressions>
auto _order_by_impl(Expressions... expressions) const
-> _new_statement_t<order_by_t<_database_t, Expressions...>>
auto _order_by_impl(const std::false_type&, Expressions... expressions) const
-> bad_statement;
template<typename Database, typename... Expressions>
auto _order_by_impl(const std::true_type&, Expressions... expressions) const
-> _new_statement_t<std::true_type, order_by_t<_database_t, Expressions...>>
{
static_assert(not detail::has_duplicates<Expressions...>::value, "at least one duplicate argument detected in order_by()");
static_assert(detail::all_t<is_sort_order_t<Expressions>::value...>::value, "at least one argument is not an expression in order_by()");
return { static_cast<const derived_statement_t<Policies>&>(*this), order_by_data_t<Database, Expressions...>{expressions...} };
};