101 lines
2.4 KiB
C++
101 lines
2.4 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 "Feed.h"
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#include "../TypeConstructors/CRelTC.h"
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#include "ListUtils.h"
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#include "LogMsg.h"
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#include "OperatorUtils.h"
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#include "Project.h"
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#include "QueryProcessor.h"
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#include "StandardTypes.h"
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#include "StreamValueMapping.h"
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#include <string>
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#include "Symbols.h"
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#include "../TypeConstructors/TBlockTC.h"
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using namespace CRelAlgebra;
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using namespace CRelAlgebra::Operators;
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using std::string;
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extern NestedList *nl;
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extern QueryProcessor *qp;
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//Feed--------------------------------------------------------------------------
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Feed::Feed() :
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Operator(info, StreamValueMapping<State>, TypeMapping)
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{
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}
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const OperatorInfo Feed::info = OperatorInfo(
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"feed", "crel -> stream(tblock)",
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"_ feed",
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"Creates a stream of tuple blocks from a column-oriented relation.",
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"query people feed consume");
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ListExpr Feed::TypeMapping(ListExpr args)
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{
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//Expect one parameter
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if (!nl->HasLength(args, 1))
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{
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return GetTypeError("Expected one argument.");
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}
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ListExpr crelType = nl->First(args);
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//Check parameter for 'crel' type
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if (!CRelTI::Check(crelType))
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{
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return GetTypeError(0, "relation", "Not a crel.");
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}
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//Return type is stream of 'tblock'
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return TBlockTI(CRelTI(crelType, false)).GetTypeExpr(true);
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}
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//Feed::State-------------------------------------------------------------------
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Feed::State::State(ArgVector args, Supplier s) :
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m_relation(*(CRel*)args[0].addr),
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m_blockIndex(0)
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{
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qp->DeleteResultStorage(s);
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}
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TBlock *Feed::State::Request()
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{
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if (m_blockIndex < m_relation.GetBlockCount())
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{
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TBlock *block = &m_relation.GetBlock(m_blockIndex++);
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block->IncRef();
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return block;
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}
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return nullptr;
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}
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