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sqlpp11/include/sqlpp11/value_or_null.h
2014-08-01 18:21:23 +02:00

87 lines
2.9 KiB
C++

/*
* Copyright (c) 2013-2014, 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_VALUE_OR_NULL_H
#define SQLPP_VALUE_OR_NULL_H
#include <sqlpp11/parameter.h>
#include <sqlpp11/parameter_list.h>
#include <sqlpp11/column_types.h>
#include <sqlpp11/in.h>
#include <sqlpp11/value_type.h>
#include <sqlpp11/exists.h>
#include <sqlpp11/any.h>
#include <sqlpp11/some.h>
#include <sqlpp11/count.h>
#include <sqlpp11/min.h>
#include <sqlpp11/max.h>
#include <sqlpp11/avg.h>
#include <sqlpp11/sum.h>
#include <sqlpp11/verbatim_table.h> // Csaba Csoma suggests: unsafe_sql instead of verbatim
#include <sqlpp11/value_or_null.h>
namespace sqlpp
{
template<typename ValueType>
struct value_or_null_t
{
using _cpp_value_type = typename ValueType::_cpp_value_type;
using _traits = make_traits<ValueType, tag::is_expression>;
using _recursive_traits = make_recursive_traits<>;
value_or_null_t(_cpp_value_type value):
_value(value),
_is_null(false)
{}
value_or_null_t(const null_t&):
_value(),
_is_null(true)
{}
typename ValueType::_cpp_value_type _value;
bool _is_null;
};
template<typename T>
auto value_or_null(T t) -> value_or_null_t<value_type_of<wrap_operand_t<T>>>
{
static_assert(is_wrapped_value_t<wrap_operand_t<T>>::value, "value_or_null() is to be called with non-sql-type like int, or string or null");
return { t };
}
template<typename ValueType>
auto value_or_null(null_t t) -> value_or_null_t<ValueType>
{
static_assert(is_value_type_t<ValueType>::value, "value_or_null() is to be called with non-sql-type like int, or string");
return { t };
}
}
#endif