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- Committing forgotten classes for LUCENE-759 

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@517477 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Otis Gospodnetic 2007-03-13 00:30:13 +00:00
parent 11fb1314e6
commit 1a48e218d6
2 changed files with 258 additions and 0 deletions
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159
contrib/analyzers/src/java/org/apache/lucene/analysis/ngram/EdgeNGramTokenFilter.java Normal file
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package org.apache.lucene.analysis.ngram;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import java.io.IOException;
import java.util.LinkedList;
/**
* Tokenizes the given token into n-grams of given size(s).
* @author Otis Gospodnetic
*/
public class EdgeNGramTokenFilter extends TokenFilter {
public static final Side DEFAULT_SIDE = Side.FRONT;
public static final int DEFAULT_MAX_GRAM_SIZE = 1;
public static final int DEFAULT_MIN_GRAM_SIZE = 1;
// Replace this with an enum when the Java 1.5 upgrade is made, the impl will be simplified
/** Specifies which side of the input the n-gram should be generated from */
public static class Side {
private String label;
/** Get the n-gram from the front of the input */
public static Side FRONT = new Side("front");
/** Get the n-gram from the end of the input */
public static Side BACK = new Side("back");
// Private ctor
private Side(String label) { this.label = label; }
public String getLabel() { return label; }
// Get the appropriate Side from a string
public static Side getSide(String sideName) {
if (FRONT.getLabel().equals(sideName)) {
return FRONT;
}
else if (BACK.getLabel().equals(sideName)) {
return BACK;
}
return null;
}
}
private int minGram;
private int maxGram;
private Side side;
private LinkedList ngrams;
protected EdgeNGramTokenFilter(TokenStream input) {
super(input);
this.ngrams = new LinkedList();
}
/**
* Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range
*
* @param input TokenStream holding the input to be tokenized
* @param side the {@link Side} from which to chop off an n-gram
* @param minGram the smallest n-gram to generate
* @param maxGram the largest n-gram to generate
*/
public EdgeNGramTokenFilter(TokenStream input, Side side, int minGram, int maxGram) {
super(input);
if (side == null) {
throw new IllegalArgumentException("sideLabel must be either front or back");
}
if (minGram < 1) {
throw new IllegalArgumentException("minGram must be greater than zero");
}
if (minGram > maxGram) {
throw new IllegalArgumentException("minGram must not be greater than maxGram");
}
this.minGram = minGram;
this.maxGram = maxGram;
this.side = side;
this.ngrams = new LinkedList();
}
/**
* Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range
*
* @param input TokenStream holding the input to be tokenized
* @param sideLabel the name of the {@link Side} from which to chop off an n-gram
* @param minGram the smallest n-gram to generate
* @param maxGram the largest n-gram to generate
*/
public EdgeNGramTokenFilter(TokenStream input, String sideLabel, int minGram, int maxGram) {
this(input, Side.getSide(sideLabel), minGram, maxGram);
}
/** Returns the next token in the stream, or null at EOS. */
public final Token next() throws IOException {
if (ngrams.size() > 0) {
return (Token) ngrams.removeFirst();
}
Token token = input.next();
if (token == null) {
return null;
}
ngram(token);
if (ngrams.size() > 0)
return (Token) ngrams.removeFirst();
else
return null;
}
private void ngram(Token token) {
String inStr = token.termText();
int inLen = inStr.length();
int gramSize = minGram;
while (gramSize <= maxGram) {
// if the remaining input is too short, we can't generate any n-grams
if (gramSize > inLen) {
return;
}
// if we have hit the end of our n-gram size range, quit
if (gramSize > maxGram) {
return;
}
Token tok;
if (side == Side.FRONT) {
tok = new Token(inStr.substring(0, gramSize), 0, gramSize);
}
else {
tok = new Token(inStr.substring(inLen-gramSize), inLen-gramSize, inLen);
}
ngrams.add(tok);
gramSize++;
}
}
}

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contrib/analyzers/src/java/org/apache/lucene/analysis/ngram/NGramTokenFilter.java Normal file
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package org.apache.lucene.analysis.ngram;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import java.io.IOException;
import java.util.LinkedList;
/**
* Tokenizes the input into n-grams of the given size(s).
* @author Otis Gospodnetic
*/
public class NGramTokenFilter extends TokenFilter {
public static final int DEFAULT_MIN_NGRAM_SIZE = 1;
public static final int DEFAULT_MAX_NGRAM_SIZE = 2;
private int minGram, maxGram;
private LinkedList ngrams;
/**
* Creates NGramTokenFilter with given min and max n-grams.
* @param input TokenStream holding the input to be tokenized
* @param minGram the smallest n-gram to generate
* @param maxGram the largest n-gram to generate
*/
public NGramTokenFilter(TokenStream input, int minGram, int maxGram) {
super(input);
if (minGram < 1) {
throw new IllegalArgumentException("minGram must be greater than zero");
}
if (minGram > maxGram) {
throw new IllegalArgumentException("minGram must not be greater than maxGram");
}
this.minGram = minGram;
this.maxGram = maxGram;
this.ngrams = new LinkedList();
}
/**
* Creates NGramTokenFilter with default min and max n-grams.
* @param input TokenStream holding the input to be tokenized
*/
public NGramTokenFilter(TokenStream input) {
this(input, DEFAULT_MIN_NGRAM_SIZE, DEFAULT_MAX_NGRAM_SIZE);
}
/** Returns the next token in the stream, or null at EOS. */
public final Token next() throws IOException {
if (ngrams.size() > 0) {
return (Token) ngrams.removeFirst();
}
Token token = input.next();
if (token == null) {
return null;
}
ngram(token);
if (ngrams.size() > 0)
return (Token) ngrams.removeFirst();
else
return null;
}
private void ngram(Token token) {
String inStr = token.termText();
int inLen = inStr.length();
int gramSize = minGram;
while (gramSize <= maxGram) {
int pos = 0; // reset to beginning of string
while (pos+gramSize <= inLen) { // while there is input
String gram = inStr.substring(pos, pos+gramSize);
Token tok = new Token(gram, pos, pos+gramSize);
// tok.setPositionIncrement(pos);
ngrams.add(tok);
pos++;
}
gramSize++; // increase n-gram size
}
}
}