152 lines
3.8 KiB
C++
152 lines
3.8 KiB
C++
/*
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----
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This file is part of SECONDO.
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Copyright (C) 2004, University in Hagen, Department of Computer Science,
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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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#include "BlockingProgressEstimator.h"
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#include "Include.h"
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using namespace nr2a;
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using namespace std;
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Extract::~Extract()
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{
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}
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/*
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The first argument is expected to be an input stream and the second argument
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must be the name of an attribute of the first one. The resulting type is the
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one of the mentioned attribute.
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*/
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/*static*/ListExpr Extract::MapType(ListExpr args)
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{
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AutoWrite(args);
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ListExpr result = nl->TheEmptyList();
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if (!nl->HasLength(args, 2))
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{
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return listutils::typeError("Two arguments expected");
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}
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ListExpr inStreamType = nl->First(args);
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ListExpr attributeToExtract = nl->Second(args);
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if (!listutils::isTupleStream(inStreamType))
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{
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return listutils::typeError(
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"The first argument is expected to be an input stream");
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}
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string attributeUnnestName = "";
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if (listutils::isSymbol(attributeToExtract))
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{
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ListExpr type = nl->Empty();
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attributeUnnestName = nl->SymbolValue(attributeToExtract);
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if (listutils::findAttribute(nl->Second(nl->Second(inStreamType)),
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attributeUnnestName, type) == 0)
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{
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return listutils::typeError("The attribute mentioned in the "
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"second argument does not exist in input stream");
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}
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else
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{
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if (nl->IsEqual(nl->First(type), ARel::BasicType()))
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{
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result = type;
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}
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else
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{
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return listutils::typeError("The attribute mentioned in the "
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"second argument is not a nested relation");
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}
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}
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}
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else
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{
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return listutils::typeError("The second argument must be the name "
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"of an attribute of the first argument");
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}
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return result;
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}
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/*static*/ValueMapping Extract::functions[] = { ExtractValue, NULL };
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/*static*/int Extract::SelectFunction(ListExpr args)
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{
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return 0;
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}
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/*
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The operator consumes ther first tuple of the stream and ~extracts~ the value
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of the given attribute.
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*/
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/*static*/int Extract::ExtractValue(Word* args, Word& result, int message,
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Word& local, Supplier s)
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{
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int resultInt = 0;
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if (message == OPEN)
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{
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Word actual;
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ListExpr attributeTypes = nl->Second(
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nl->Second(qp->GetSupplierTypeExpr(qp->GetSon(s, 0))));
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string subRelName = nl->SymbolValue(
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qp->GetSupplierTypeExpr(qp->GetSon(s, 1)));
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ARel* arel = (ARel*) ((qp->ResultStorage(s)).addr);
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if (arel->GetTupleCount() > 0)
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{
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assert(false);
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}
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Tuple* tuple;
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ListExpr type;
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int attributeIndex = listutils::findAttribute(attributeTypes, subRelName,
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type);
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Stream<Tuple> stream(args[0]);
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stream.open();
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tuple = stream.request();
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if (tuple != NULL)
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{
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arel->CopyFrom(static_cast<ARel*>
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(tuple->GetAttribute(attributeIndex)));
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tuple->DeleteIfAllowed();
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}
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else
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{
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arel->SetDefined(false);
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}
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stream.close();
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result.setAddr(arel);
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}
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return resultInt;
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}
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/*
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List of functions for cost estimation.
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*/
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CreateCostEstimation Extract::costEstimators[] =
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{ BlockingProgressEstimator::Build };
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