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git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@5599 6c8d7289-2bf4-0310-a012-ef5d649a1542
85 lines
3.3 KiB
Java
85 lines
3.3 KiB
Java
// kelondroBinSearch.java
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// -----------------------
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// part of The Kelondro Database
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2005
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// created 22.11.2005
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//
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// $LastChangedDate: 2005-09-22 22:01:26 +0200 (Thu, 22 Sep 2005) $
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// $LastChangedRevision: 774 $
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// $LastChangedBy: orbiter $
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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 de.anomic.kelondro.index;
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import de.anomic.kelondro.order.ByteOrder;
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import de.anomic.kelondro.order.NaturalOrder;
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public class BinSearch {
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private final byte[] chunks;
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private final int chunksize;
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private final int count;
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private static final ByteOrder objectOrder = new NaturalOrder(true);
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public BinSearch(final byte[] chunks, final int chunksize) {
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this.chunks = chunks;
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this.chunksize = chunksize;
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this.count = chunks.length / chunksize;
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}
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public boolean contains(final byte[] t) {
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return contains(t, 0, this.count);
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}
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private synchronized boolean contains(final byte[] t, final int beginPos, final int endPos) {
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// the endPos is exclusive, beginPos is inclusive
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// this method is synchronized to make the use of the buffer possible
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assert t.length == this.chunksize;
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if (beginPos >= endPos) return false;
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final int pivot = (beginPos + endPos) / 2;
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if ((pivot < 0) || (pivot >= this.count)) return false;
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final int c = objectOrder.compare(this.chunks, pivot * this.chunksize, this.chunksize, t, 0, t.length);
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if (c == 0) return true;
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if (c < 0) /* buffer < t */ return contains(t, pivot + 1, endPos);
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if (c > 0) /* buffer > t */ return contains(t, beginPos, pivot);
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return false;
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}
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public int size() {
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return count;
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}
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public byte[] get(final int element) {
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final byte[] a = new byte[chunksize];
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System.arraycopy(this.chunks, element * this.chunksize, a, 0, chunksize);
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return a;
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}
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public static void main(final String[] args) {
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final String s = "4CEvsI8FRczRBo_ApRCkwfEbFLn1pIFXg39QGMgj5RHM6HpIMJq67QX3M5iQYr_LyI_5aGDaa_bYbRgJ9XnQjpmq6QkOoGWAoEaihRqhV3kItLFHjRtqauUR";
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final BinSearch bs = new BinSearch(s.getBytes(), 6);
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for (int i = 0; i + 6 <= s.length(); i = i + 6) {
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System.out.println(s.substring(i, i + 6) + ":" + ((bs.contains(s.substring(i, i + 6).getBytes())) ? "drin" : "draussen"));
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}
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for (int i = 0; i + 7 <= s.length(); i = i + 6) {
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System.out.println(s.substring(i + 1, i + 7) + ":" + ((bs.contains(s.substring(i + 1, i + 7).getBytes())) ? "drin" : "draussen"));
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}
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}
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}
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