63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
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/*
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----
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This file is part of SECONDO.
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Copyright (C) 2004-2009, University in Hagen, Faculty of Mathematics
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and Computer Science, Database Systems for New Applications.
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SECONDO is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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SECONDO is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with SECONDO; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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----
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*/
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#pragma once
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#include "AlgebraTypes.h"
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#include "NestedList.h"
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#include "Operator.h"
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namespace CRelAlgebra
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{
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namespace Operators
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{
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/*
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Operator implementation of the 'attr' operator.
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This operator returns the column with a given name from a tuple-block.
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The Operator expects two parameters.
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The first parameter represents the tuple-block and must be of type 'tblock'.
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The second parameter represents the column's name and must be of type
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'symbol'.
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The returned value represents the matching column and is of type
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'attrarray'.
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*/
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class Attr : public Operator
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{
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public:
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Attr();
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private:
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static const OperatorInfo info;
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static ListExpr TypeMapping(ListExpr args);
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static int ValueMapping(ArgVector args, Word &result, int message,
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Word &local, Supplier s);
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};
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}
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}
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