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secondo/Algebras/CRel/Operators/StreamValueMapping.h
2026-01-23 17:03:45 +08:00

92 lines
2.0 KiB
C++

/*
----
This file is part of SECONDO.
Copyright (C) 2004-2009, University in Hagen, Faculty of Mathematics
and Computer Science, Database Systems for New Applications.
SECONDO is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
SECONDO is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with SECONDO; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
----
*/
#pragma once
#include "AlgebraTypes.h"
#include <exception>
#include "LogMsg.h"
namespace CRelAlgebra
{
namespace Operators
{
template<class T>
T *DefaultCreate(ArgVector args, Supplier s)
{
return new T(args, s);
}
template<class T, T *(*create)(ArgVector, Supplier) = DefaultCreate<T>>
int StreamValueMapping(ArgVector args, Word &result, int message,
Word &local, Supplier s)
{
try
{
switch (message)
{
case OPEN:
{
if (local.addr != nullptr)
{
delete (T*)local.addr;
}
local.addr = create(args, s);
break;
}
case REQUEST:
{
if ((result.addr = ((T*)local.addr)->Request()) == nullptr)
{
return CANCEL;
}
return YIELD;
}
case CLOSE:
{
if (local.addr != nullptr)
{
delete (T*)local.addr;
local.addr = nullptr;
}
break;
}
}
return 0;
}
catch (const std::exception &e)
{
ErrorReporter::ReportError(e.what());
}
return FAILURE;
};
}
}