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73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
/*
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* Copyright (c) 2013-2015, Roland Bock
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SQLPP_VALUE_OR_NULL_H
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#define SQLPP_VALUE_OR_NULL_H
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#include <sqlpp11/wrap_operand.h>
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#include <sqlpp11/type_traits.h>
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namespace sqlpp
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{
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template <typename ValueType>
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struct value_or_null_t
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{
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using _cpp_value_type = typename ValueType::_cpp_value_type;
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using _traits = make_traits<ValueType, tag::is_expression>;
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using _nodes = detail::type_vector<>;
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value_or_null_t(_cpp_value_type value) : _value(value), _is_null(false)
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{
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}
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value_or_null_t(const null_t&) : _value(), _is_null(true)
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{
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}
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typename ValueType::_cpp_value_type _value;
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bool _is_null;
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};
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template <typename T>
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auto value_or_null(T t) -> value_or_null_t<value_type_of<wrap_operand_t<T>>>
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{
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static_assert(is_wrapped_value_t<wrap_operand_t<T>>::value,
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"value_or_null() is to be called with non-sql-type like int, or string or null");
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return {t};
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}
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template <typename ValueType>
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auto value_or_null(null_t t) -> value_or_null_t<ValueType>
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{
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static_assert(is_value_type_t<ValueType>::value,
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"value_or_null() is to be called with non-sql-type like int, or string");
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return {t};
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}
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}
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#endif
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