/*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Kowari Metadata Store.
*
* The Initial Developer of the Original Code is Plugged In Software Pty
* Ltd (http://www.pisoftware.com, mailto:info@pisoftware.com). Portions
* created by Plugged In Software Pty Ltd are Copyright (C) 2001,2002
* Plugged In Software Pty Ltd. All Rights Reserved.
*
* Contributor(s): N/A.
*
* [NOTE: The text of this Exhibit A may differ slightly from the text
* of the notices in the Source Code files of the Original Code. You
* should use the text of this Exhibit A rather than the text found in the
* Original Code Source Code for Your Modifications.]
*
*/
package org.mulgara.store.tuples;
// Third party packages
import org.apache.log4j.Logger;
// Locally written packages
import org.mulgara.query.TuplesException;
/**
* Remove trailing minterms (rows) in excess of a specified count.
*
* @created 2003-08-06
*
* @author <a href="http://staff.pisoftware.com/raboczi">Simon Raboczi</a>
*
* @version $Revision: 1.9 $
*
* @modified $Date: 2005/01/05 04:59:10 $
*
* @maintenanceAuthor $Author: newmana $
*
* @company <A href="mailto:info@PIsoftware.com">Plugged In Software</A>
*
* @copyright © 2003 <A href="http://www.PIsoftware.com/">Plugged In
* Software Pty Ltd</A>
*
* @licence <a href="{@docRoot}/../../LICENCE">Mozilla Public License v1.1</a>
*/
class LimitedTuples extends WrappedTuples {
/** Logger. */
@SuppressWarnings("unused")
private final static Logger logger = Logger.getLogger(LimitedTuples.class);
/**
* The maximum number of minterms (rows) to allow through.
*/
private long limit;
/**
* The current number of rows that have been allowed through.
*/
private long count;
/**
* Choose a window of tuples by their position in the current ordering.
*
* This method does not preserve the cursor position passed to it by the
* <var>tuples</var> parameter.
*
* @param tuples PARAMETER TO DO
* @param rowCount the number of minterms (rows) to permit before clipping
* trailing minterms
* @throws IllegalArgumentException if <var>tuples</var> is <code>null</code>
* on <var>rowCount</var> is negative
* @throws TuplesException EXCEPTION TO DO
*/
public LimitedTuples(Tuples tuples, long rowCount) throws TuplesException
{
super(tuples);
// Validate "rowCount" parameter
if (rowCount < 0) {
throw new IllegalArgumentException(
"Bad \"rowCount\" parameter: "+rowCount
);
}
this.tuples.beforeFirst(); // needed to obtain a known cursor position
this.count = 0;
this.limit = rowCount;
}
/**
* Gets the RowCount attribute of the WrappedTuples object
*
* @return The RowCount value
* @throws TuplesException Error accessing underlying tuples.
*/
public long getRowCount() throws TuplesException {
long rowCount = tuples.getRowCount();
return (rowCount < limit) ? rowCount : limit;
}
public long getRowUpperBound() throws TuplesException {
long rowCount = tuples.getRowUpperBound();
return (rowCount < limit) ? rowCount : limit;
}
public long getRowExpectedCount() throws TuplesException {
long rowCount = tuples.getRowExpectedCount();
return (rowCount < limit) ? rowCount : limit;
}
//
// Methods implementing Tuples
//
public void beforeFirst() throws TuplesException {
super.beforeFirst();
count = 0;
}
public void beforeFirst(long[] prefix, int suffixTruncation)
throws TuplesException
{
super.beforeFirst(prefix, suffixTruncation);
count = 0;
}
/**
* The number of times this method can be called is limited.
*
* @return RETURNED VALUE TO DO
* @throws TuplesException EXCEPTION TO DO
*/
public boolean next() throws TuplesException {
assert count <= limit;
if (count == limit) {
return false;
}
count++;
return tuples.next();
}
}