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83 lines
2.5 KiB
Java
83 lines
2.5 KiB
Java
// RotateIterator.java
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// (C) 2007 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 08.03.2007 on http://www.anomic.de
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//
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// This is a part of YaCy, a peer-to-peer based web search engine
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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//
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// LICENSE
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//
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// This program 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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//
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// This program 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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//
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// You should have received a copy of the GNU General Public License
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// along with this program; 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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package net.yacy.kelondro.util;
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import net.yacy.cora.order.CloneableIterator;
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public class RotateIterator<E> implements CloneableIterator<E> {
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private CloneableIterator<E> a, clone;
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Object modifier;
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private boolean nempty;
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int terminationCount;
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public RotateIterator(final CloneableIterator<E> a, final Object modifier, final int terminationCount) {
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// this works currently only for String-type key iterations
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this.a = a;
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this.modifier = modifier;
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this.terminationCount = terminationCount;
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this.clone = a.clone(modifier);
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this.nempty = this.clone.hasNext();
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}
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@Override
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public RotateIterator<E> clone(final Object modifier) {
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return new RotateIterator<E>(this.a, modifier, this.terminationCount - 1);
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}
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@Override
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public boolean hasNext() {
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return (this.terminationCount > 0) && (this.nempty);
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}
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@Override
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public E next() {
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// attention: this iterator has no termination - on purpose.
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// it must be taken care that a calling method has a termination predicate different
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// from the hasNext() method
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if (!(this.a.hasNext())) {
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this.a = this.clone.clone(this.modifier);
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assert this.a.hasNext();
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}
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this.terminationCount--;
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return this.a.next();
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}
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@Override
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public void remove() {
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this.a.remove();
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}
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@Override
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public void close() {
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this.a.close();
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this.clone.close();
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}
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}
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