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sqlpp11/include/sqlpp11/alias.h

66 lines
2.7 KiB
C++

#pragma once
/*
* 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.
*/
#include <sqlpp11/type_traits.h>
namespace sqlpp
{
template <typename Expression, typename AliasProvider>
struct expression_alias_t
{
using _traits = make_traits<value_type_of<Expression>, tag::is_selectable, tag::is_alias>;
using _nodes = detail::type_vector<Expression>;
static_assert(is_expression_t<Expression>::value, "invalid argument for an expression alias");
static_assert(not is_alias_t<Expression>::value, "cannot create an alias of an alias");
using _alias_t = typename AliasProvider::_alias_t;
expression_alias_t(Expression expression) : _expression(expression)
{
}
expression_alias_t(const expression_alias_t&) = default;
expression_alias_t(expression_alias_t&&) = default;
expression_alias_t& operator=(const expression_alias_t&) = default;
expression_alias_t& operator=(expression_alias_t&&) = default;
~expression_alias_t() = default;
Expression _expression;
};
template <typename Context, typename Expression, typename AliasProvider>
Context& serialize(const expression_alias_t<Expression, AliasProvider>& t, Context& context)
{
serialize_operand(t._expression, context);
context << " AS ";
context << name_of<expression_alias_t<Expression, AliasProvider>>::template char_ptr<Context>();
return context;
}
} // namespace sqlpp