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

69 lines
2.4 KiB
C++

/*
* 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_GROUP_BY_H
#define SQLPP_GROUP_BY_H
#include <tuple>
#include <sqlpp11/select_fwd.h>
#include <sqlpp11/expression.h>
#include <sqlpp11/detail/serialize_tuple.h>
#include <sqlpp11/detail/set.h>
#include <sqlpp11/type_traits.h>
namespace sqlpp
{
template<typename... Expr>
struct group_by_t
{
// ensure one argument at least
static_assert(sizeof...(Expr), "at least one expression (e.g. a column) required in group_by()");
// check for duplicate expressions
static_assert(not detail::has_duplicates<Expr...>::value, "at least one duplicate argument detected in group_by()");
// check for invalid expressions
using _valid_expressions = typename detail::make_set_if<is_expression_t, Expr...>::type;
static_assert(_valid_expressions::size::value == sizeof...(Expr), "at least one argument is not an expression in group_by()");
using _is_group_by = tag_yes;
template<typename Db>
void serialize(std::ostream& os, Db& db) const
{
os << " GROUP BY ";
detail::serialize_tuple(os, db, _expressions, ',');
}
std::tuple<Expr...> _expressions;
};
}
#endif