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sqlpp11/include/sqlpp11/is_null.h
Roland Bock d68744c432 Add is_equal_or_null(col, some_value_or_null)
This replaces the former implicit tvin logic with an explicit function.
2021-07-25 15:22:12 +02:00

90 lines
2.9 KiB
C++

/*
* Copyright (c) 2013-2015, 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 SQLPP11_IS_NULL_H
#define SQLPP11_IS_NULL_H
#include <sqlpp11/data_types/boolean.h>
#include <sqlpp11/type_traits.h>
#include <sqlpp11/char_sequence.h>
#include <sqlpp11/detail/type_set.h>
namespace sqlpp
{
struct is_null_alias_t
{
struct _alias_t
{
static constexpr const char _literal[] = "is_null_";
using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
template <typename T>
struct _member_t
{
T is_null;
};
};
};
template <typename Operand>
struct is_null_t : public expression_operators<is_null_t<Operand>, boolean>,
public alias_operators<is_null_t<Operand>>
{
using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable>;
using _nodes = detail::type_vector<Operand>;
using _auto_alias_t = is_null_alias_t;
is_null_t(Operand operand) : _operand(operand)
{
}
is_null_t(const is_null_t&) = default;
is_null_t(is_null_t&&) = default;
is_null_t& operator=(const is_null_t&) = default;
is_null_t& operator=(is_null_t&&) = default;
~is_null_t() = default;
Operand _operand;
};
template <typename Context, typename Operand>
struct serializer_t<Context, is_null_t<Operand>>
{
using _serialize_check = serialize_check_of<Context, Operand>;
using T = is_null_t<Operand>;
static Context& _(const T& t, Context& context)
{
context << "(";
serialize_operand(t._operand, context);
context << " IS NULL)";
return context;
}
};
} // namespace sqlpp
#endif