116 lines
2.5 KiB
C++
116 lines
2.5 KiB
C++
/*
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----
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This file is part of SECONDO.
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Copyright (C) 2004-2007, University in Hagen, Faculty of Mathematics and
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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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May 2007. M. Spiekermann.
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The class ~RTuple~ (Referenced Tuple) manages the calls needed to do a correct
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handling of reference counting. This is helpful for complex operator
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implementations, which need to manage many pointers of class ~Tuple~ and which
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need to keep their values during two REQUEST messages, e.g. refer to the
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implementation of ~mergejoin~ for its usage.
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*/
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#ifndef SEC_RTUPLE_H
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#define SEC_RTUPLE_H
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#include "Algebras/Relation-C++/RelationAlgebra.h"
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class RTuple {
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public:
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RTuple() : tuple(0) {}
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inline RTuple(Tuple* p) : tuple(p)
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{
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holdTuple();
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}
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inline RTuple(const RTuple& r) : tuple(r.tuple)
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{
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holdTuple();
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}
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inline ~RTuple()
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{
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releaseTuple();
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}
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inline RTuple& operator=(const RTuple& r)
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{
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releaseTuple();
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tuple = r.tuple;
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holdTuple();
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return *this;
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}
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inline RTuple& operator=(Tuple* t)
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{
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releaseTuple();
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tuple = t;
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holdTuple();
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return *this;
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}
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/*
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Note: Function ~setTuple~ decrements the reference counter for the previously
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assigned tuple but does *not* increment it for the new one!
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*/
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inline void setTuple(Tuple* tuple){
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releaseTuple();
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this->tuple=tuple;
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}
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inline void init() { tuple = 0; }
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inline friend bool operator==(const RTuple& r, const void* p)
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{
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return r.tuple == p;
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}
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inline friend bool operator!=(const RTuple& r, const void* p)
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{
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return r.tuple != p;
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}
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Tuple* tuple;
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private:
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inline void releaseTuple()
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{
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if (tuple) {
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tuple->DeleteIfAllowed();
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}
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}
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inline void holdTuple()
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{
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if (tuple) {
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tuple->IncReference();
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}
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}
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};
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#endif
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