113 lines
2.5 KiB
C++
113 lines
2.5 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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#include "Repeat.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 "QueryProcessor.h"
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#include "StandardTypes.h"
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#include "StreamValueMapping.h"
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#include "TypeUtils.h"
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using namespace CRelAlgebra::Operators;
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using listutils::isStream;
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extern QueryProcessor *qp;
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Repeat::Repeat() :
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Operator(info, StreamValueMapping<State>, TypeMapping)
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{
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SetUsesArgsInTypeMapping();
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}
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const OperatorInfo Repeat::info = OperatorInfo(
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"repeat", "stream(T) x int -> stream(T)",
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"repeat( _, _ )",
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"Creates a stream by repeating a stream the specified number of times.",
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"query repeat('Test' feed, 2) count");
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ListExpr Repeat::TypeMapping(ListExpr args)
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{
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if (!nl->HasLength(args, 2))
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{
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return GetTypeError("Expected two arguments.");
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}
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const ListExpr firstArg = nl->First(nl->First(args));
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if (!isStream(firstArg))
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{
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return GetTypeError(0, "Isn't a stream.");
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}
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const ListExpr count = nl->Second(args);
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if (!CcInt::checkType(nl->First(count)) ||
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nl->IntValue(nl->Second(count)) < 0)
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{
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return GetTypeError(1, "Isn't a int >= 0.");
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}
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return firstArg;
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}
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Repeat::State::State(Word *args, Supplier s) :
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m_count(((CcInt*)args[1].addr)->GetValue()),
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m_index(0),
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m_stream(args[0].addr)
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{
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qp->DeleteResultStorage(s);
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m_stream.open();
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}
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Repeat::State::~State()
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{
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m_stream.close();
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}
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void *Repeat::State::Request()
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{
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void *value = m_stream.request();
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if (value == nullptr)
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{
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if (++m_index < m_count)
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{
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m_stream.close();
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m_stream.open();
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if ((value = m_stream.request()) != nullptr)
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{
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return value;
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}
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}
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return nullptr;
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}
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return value;
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}
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