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sqlpp11/include/sqlpp11/vendor/offset.h

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3.8 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_OFFSET_H
#define SQLPP_OFFSET_H
#include <sqlpp11/type_traits.h>
#include <sqlpp11/vendor/policy_update.h>
namespace sqlpp
{
namespace vendor
{
// OFFSET
template<typename Offset>
struct offset_t
{
using _is_offset = std::true_type;
static_assert(is_integral_t<Offset>::value, "offset requires an integral value or integral parameter");
offset_t(Offset value):
_value(value)
{}
offset_t(const offset_t&) = default;
offset_t(offset_t&&) = default;
offset_t& operator=(const offset_t&) = default;
offset_t& operator=(offset_t&&) = default;
~offset_t() = default;
Offset _value;
};
template<typename Database>
struct dynamic_offset_t
{
using _is_offset = std::true_type;
using _is_dynamic = std::true_type;
dynamic_offset_t():
_value(noop())
{
}
template<typename Offset>
dynamic_offset_t(Offset value):
_initialized(true),
_value(typename wrap_operand<Offset>::type(value))
{
}
dynamic_offset_t(const dynamic_offset_t&) = default;
dynamic_offset_t(dynamic_offset_t&&) = default;
dynamic_offset_t& operator=(const dynamic_offset_t&) = default;
dynamic_offset_t& operator=(dynamic_offset_t&&) = default;
~dynamic_offset_t() = default;
template<typename Offset>
void set_offset(Offset value)
{
using arg_t = typename wrap_operand<Offset>::type;
_value = arg_t(value);
_initialized = true;
}
bool _initialized = false;
interpretable_t<Database> _value;
};
struct no_offset_t
{
using _is_noop = std::true_type;
};
// Interpreters
template<typename Context, typename Offset>
struct interpreter_t<Context, offset_t<Offset>>
{
using T = offset_t<Offset>;
static Context& _(const T& t, Context& context)
{
context << " OFFSET ";
interpret(t._value, context);
return context;
}
};
template<typename Context, typename Database>
struct interpreter_t<Context, dynamic_offset_t<Database>>
{
using T = dynamic_offset_t<Database>;
static Context& _(const T& t, Context& context)
{
if (t._initialized)
{
context << " OFFSET ";
interpret(t._value, context);
}
return context;
}
};
template<typename Context>
struct interpreter_t<Context, no_offset_t>
{
using T = no_offset_t;
static Context& _(const T& t, Context& context)
{
return context;
}
};
}
}
#endif