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110 lines
4.0 KiB
110 lines
4.0 KiB
// indexWord.java
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// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 26.03.2008 on http://yacy.net
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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: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
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// $LastChangedRevision: 1986 $
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// $LastChangedBy: orbiter $
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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 de.anomic.index;
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import java.util.HashSet;
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import java.util.Hashtable;
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import java.util.Iterator;
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import java.util.Locale;
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import java.util.Set;
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import java.util.TreeSet;
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import de.anomic.kelondro.order.Base64Order;
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import de.anomic.kelondro.order.Bitfield;
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import de.anomic.kelondro.order.Digest;
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import de.anomic.yacy.yacySeedDB;
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public class indexWord {
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// object carries statistics for words and sentences
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public int count; // number of occurrences
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public int posInText; // unique handle, is initialized with word position (excluding double occurring words)
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public int posInPhrase; // position of word in phrase
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public int numOfPhrase; // number of phrase. 'normal' phrases begin with number 100
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HashSet<Integer> phrases; // a set of handles to all phrases where this word appears
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public Bitfield flags; // the flag bits for each word
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public indexWord(final int handle, final int pip, final int nop) {
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this.count = 1;
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this.posInText = handle;
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this.posInPhrase = pip;
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this.numOfPhrase = nop;
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this.phrases = new HashSet<Integer>();
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this.flags = null;
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}
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public void inc() {
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count++;
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}
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public int occurrences() {
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return count;
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}
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public void check(final int i) {
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phrases.add(Integer.valueOf(i));
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}
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public Iterator<Integer> phrases() {
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// returns an iterator to handles of all phrases where the word appears
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return phrases.iterator();
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}
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// static methods
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// create a word hash
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private static final Hashtable<String, String> hashCache = new Hashtable<String, String>();
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public static final String word2hash(final String word) {
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String h = hashCache.get(word);
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if (h != null) return h;
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h = Base64Order.enhancedCoder.encode(Digest.encodeMD5Raw(word.toLowerCase(Locale.ENGLISH))).substring(0, yacySeedDB.commonHashLength);
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hashCache.put(word, h); // prevent expensive MD5 computation and encoding
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if (hashCache.size() > 100000) hashCache.clear(); // prevent memory laeak
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return h;
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}
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public static final Set<String> words2hashSet(final String[] words) {
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final TreeSet<String> hashes = new TreeSet<String>(Base64Order.enhancedComparator);
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for (int i = 0; i < words.length; i++) hashes.add(word2hash(words[i]));
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return hashes;
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}
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public static final String words2hashString(final String[] words) {
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final StringBuilder sb = new StringBuilder();
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for (int i = 0; i < words.length; i++) sb.append(word2hash(words[i]));
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return new String(sb);
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}
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public static final TreeSet<String> words2hashes(final Set<String> words) {
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final Iterator<String> i = words.iterator();
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final TreeSet<String> hashes = new TreeSet<String>(Base64Order.enhancedComparator);
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while (i.hasNext()) hashes.add(word2hash(i.next()));
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return hashes;
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}
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}
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