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sqlpp11/multi_column.h
2013-08-13 22:43:10 +02:00

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2.9 KiB
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/*
* Copyright (c) 2013, Roland Bock
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef SQLPP_MULTI_COLUMN_H
#define SQLPP_MULTI_COLUMN_H
#include <sqlpp11/detail/make_expression_tuple.h>
#include <sqlpp11/no_value.h>
namespace sqlpp
{
template<typename AliasProvider, typename T>
struct multi_column_t
{
static_assert(detail::wrong<T>::value, "invalid argument for multicolumn_t");
};
template<typename AliasProvider, typename... NamedExpr>
struct multi_column_t<AliasProvider, std::tuple<NamedExpr...>>
{
using _named_expr_set = typename detail::make_set_if<is_named_expression_t, NamedExpr...>::type;
static_assert(_named_expr_set::size::value == sizeof...(NamedExpr), "multi_column parameters need to be named expressions");
using _name_t = typename AliasProvider::_name_t;
template<typename T>
using _member_t = typename AliasProvider::template _member_t<T>;
struct _value_type: public no_value_t
{
using _is_named_expression = tag_yes;
};
using _is_multi_column = tag_yes;
template<typename Db>
void serialize(std::ostream& os, Db& db) const
{
detail::serialize_tuple(os, db, _columns, ',');
}
std::tuple<NamedExpr...> _columns;
};
namespace detail
{
template<typename AliasProvider, typename... Expr>
using make_multi_column_t =
multi_column_t<typename std::decay<AliasProvider>::type, decltype(make_expression_tuple(std::declval<Expr>()...))>;
}
template<typename AliasProvider, typename... NamedExpr>
detail::make_multi_column_t<AliasProvider, NamedExpr...> multi_column(AliasProvider&& aliasProvider, NamedExpr&&... namedExpr)
{
return { {std::forward<NamedExpr>(namedExpr)...}};
}
}
#endif