standardtokenizer

/**
* 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.
*/

package org.apache.lucene.analysis.standard;

import java.io.IOException;
import java.io.Reader;

import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TermAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.Version;

/** A grammar-based tokenizer constructed with JFlex
*
* <p> This should be a good tokenizer for most European-language documents:
*
* <ul>
* <li>Splits words at punctuation characters, removing punctuation. However, a
* dot that's not followed by whitespace is considered part of a token.
* <li>Splits words at hyphens, unless there's a number in the token, in which case
* the whole token is interpreted as a product number and is not split.
* <li>Recognizes email addresses and internet hostnames as one token.
* </ul>
*
* <p>Many applications have specific tokenizer needs. If this tokenizer does
* not suit your application, please consider copying this source code
* directory to your project and maintaining your own grammar-based tokenizer.
*
* <a name="version"/>
* <p>You must specify the required {@link Version}
* compatibility when creating StandardAnalyzer:
* <ul>
* <li> As of 2.4, Tokens incorrectly identified as acronyms
* are corrected (see <a href="https://issues.apache.org/jira/browse/LUCENE-1068">LUCENE-1608</a>
* </ul>
*/

public class StandardTokenizer extends Tokenizer {
/** A private instance of the JFlex-constructed scanner */
private final StandardTokenizerImpl scanner;

public static final int ALPHANUM = 0;
public static final int APOSTROPHE = 1;
public static final int ACRONYM = 2;
public static final int COMPANY = 3;
public static final int EMAIL = 4;
public static final int HOST = 5;
public static final int NUM = 6;
public static final int CJ = 7;

/**
* @deprecated this solves a bug where HOSTs that end with '.' are identified
* as ACRONYMs. It is deprecated and will be removed in the next
* release.
*/
public static final int ACRONYM_DEP = 8;

/** String token types that correspond to token type int constants */
public static final String [] TOKEN_TYPES = new String [] {
"<ALPHANUM>",
"<APOSTROPHE>",
"<ACRONYM>",
"<COMPANY>",
"<EMAIL>",
"<HOST>",
"<NUM>",
"<CJ>",
"<ACRONYM_DEP>"
};

/** @deprecated Please use {@link #TOKEN_TYPES} instead */
public static final String [] tokenImage = TOKEN_TYPES;

/**
* Specifies whether deprecated acronyms should be replaced with HOST type.
* This is false by default to support backward compatibility.
*<p/>
* See http://issues.apache.org/jira/browse/LUCENE-1068
*
* @deprecated this should be removed in the next release (3.0).
*/
private boolean replaceInvalidAcronym;

private int maxTokenLength = StandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH;

/** Set the max allowed token length. Any token longer
* than this is skipped. */
public void setMaxTokenLength(int length) {
this.maxTokenLength = length;
}

/** @see #setMaxTokenLength */
public int getMaxTokenLength() {
return maxTokenLength;
}

/**
* Creates a new instance of the {@link StandardTokenizer}. Attaches the
* <code>input</code> to a newly created JFlex scanner.
*
* @deprecated Use {@link #StandardTokenizer(Version,
* Reader)} instead
*/
public StandardTokenizer(Reader input) {
this(Version.LUCENE_24, input);
}

/**
* Creates a new instance of the {@link org.apache.lucene.analysis.standard.StandardTokenizer}. Attaches
* the <code>input</code> to the newly created JFlex scanner.
*
* @param input The input reader
* @param replaceInvalidAcronym Set to true to replace mischaracterized acronyms with HOST.
*
* See http://issues.apache.org/jira/browse/LUCENE-1068
*
* @deprecated Use {@link #StandardTokenizer(Version, Reader)} instead
*/
public StandardTokenizer(Reader input, boolean replaceInvalidAcronym) {
super();
this.scanner = new StandardTokenizerImpl(input);
init(input, replaceInvalidAcronym);
}

/**
* Creates a new instance of the {@link org.apache.lucene.analysis.standard.StandardTokenizer}. Attaches
* the <code>input</code> to the newly created JFlex scanner.
*
* @param input The input reader
*
* See http://issues.apache.org/jira/browse/LUCENE-1068
*/
public StandardTokenizer(Version matchVersion, Reader input) {
super();
this.scanner = new StandardTokenizerImpl(input);
init(input, matchVersion);
}

/**
* Creates a new StandardTokenizer with a given {@link AttributeSource}.
*
* @deprecated Use {@link #StandardTokenizer(Version, AttributeSource, Reader)} instead
*/
public StandardTokenizer(AttributeSource source, Reader input, boolean replaceInvalidAcronym) {
super(source);
this.scanner = new StandardTokenizerImpl(input);
init(input, replaceInvalidAcronym);
}

/**
* Creates a new StandardTokenizer with a given {@link AttributeSource}.
*/
public StandardTokenizer(Version matchVersion, AttributeSource source, Reader input) {
super(source);
this.scanner = new StandardTokenizerImpl(input);
init(input, matchVersion);
}

/**
* Creates a new StandardTokenizer with a given {@link org.apache.lucene.util.AttributeSource.AttributeFactory}
*
* @deprecated Use {@link #StandardTokenizer(Version, org.apache.lucene.util.AttributeSource.AttributeFactory, Reader)} instead
*/
public StandardTokenizer(AttributeFactory factory, Reader input, boolean replaceInvalidAcronym) {
super(factory);
this.scanner = new StandardTokenizerImpl(input);
init(input, replaceInvalidAcronym);
}

/**
* Creates a new StandardTokenizer with a given {@link org.apache.lucene.util.AttributeSource.AttributeFactory}
*/
public StandardTokenizer(Version matchVersion, AttributeFactory factory, Reader input) {
super(factory);
this.scanner = new StandardTokenizerImpl(input);
init(input, matchVersion);
}

private void init(Reader input, boolean replaceInvalidAcronym) {
this.replaceInvalidAcronym = replaceInvalidAcronym;
this.input = input;
termAtt = (TermAttribute) addAttribute(TermAttribute.class);
offsetAtt = (OffsetAttribute) addAttribute(OffsetAttribute.class);
posIncrAtt = (PositionIncrementAttribute) addAttribute(PositionIncrementAttribute.class);
typeAtt = (TypeAttribute) addAttribute(TypeAttribute.class);
}

private void init(Reader input, Version matchVersion) {
if (matchVersion.onOrAfter(Version.LUCENE_24)) {
init(input, true);
} else {
init(input, false);
}
}

// this tokenizer generates three attributes:
// offset, positionIncrement and type
private TermAttribute termAtt;
private OffsetAttribute offsetAtt;
private PositionIncrementAttribute posIncrAtt;
private TypeAttribute typeAtt;

/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#next()
*/
public final boolean incrementToken() throws IOException {
clearAttributes();
int posIncr = 1;

while(true) {
int tokenType = scanner.getNextToken();

if (tokenType == StandardTokenizerImpl.YYEOF) {
return false;
}

if (scanner.yylength() <= maxTokenLength) {
posIncrAtt.setPositionIncrement(posIncr);
scanner.getText(termAtt);
final int start = scanner.yychar();
offsetAtt.setOffset(correctOffset(start), correctOffset(start+termAtt.termLength()));
// This 'if' should be removed in the next release. For now, it converts
// invalid acronyms to HOST. When removed, only the 'else' part should
// remain.
if (tokenType == StandardTokenizerImpl.ACRONYM_DEP) {
if (replaceInvalidAcronym) {
typeAtt.setType(StandardTokenizerImpl.TOKEN_TYPES[StandardTokenizerImpl.HOST]);
termAtt.setTermLength(termAtt.termLength() - 1); // remove extra '.'
} else {
typeAtt.setType(StandardTokenizerImpl.TOKEN_TYPES[StandardTokenizerImpl.ACRONYM]);
}
} else {
typeAtt.setType(StandardTokenizerImpl.TOKEN_TYPES[tokenType]);
}
return true;
} else
// When we skip a too-long term, we still increment the
// position increment
posIncr++;
}
}

public final void end() {
// set final offset
int finalOffset = correctOffset(scanner.yychar() + scanner.yylength());
offsetAtt.setOffset(finalOffset, finalOffset);
}

/** @deprecated Will be removed in Lucene 3.0. This method is final, as it should
* not be overridden. Delegates to the backwards compatibility layer. */
public final Token next(final Token reusableToken) throws IOException {
return super.next(reusableToken);
}

/** @deprecated Will be removed in Lucene 3.0. This method is final, as it should
* not be overridden. Delegates to the backwards compatibility layer. */
public final Token next() throws IOException {
return super.next();
}

/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#reset()
*/
public void reset() throws IOException {
super.reset();
scanner.yyreset(input);
}

public void reset(Reader reader) throws IOException {
super.reset(reader);
reset();
}

/**
* Prior to https://issues.apache.org/jira/browse/LUCENE-1068, StandardTokenizer mischaracterized as acronyms tokens like www.abc.com
* when they should have been labeled as hosts instead.
* @return true if StandardTokenizer now returns these tokens as Hosts, otherwise false
*
* @deprecated Remove in 3.X and make true the only valid value
*/
public boolean isReplaceInvalidAcronym() {
return replaceInvalidAcronym;
}

/**
*
* @param replaceInvalidAcronym Set to true to replace mischaracterized acronyms as HOST.
* @deprecated Remove in 3.X and make true the only valid value
*
* See https://issues.apache.org/jira/browse/LUCENE-1068
*/
public void setReplaceInvalidAcronym(boolean replaceInvalidAcronym) {
this.replaceInvalidAcronym = replaceInvalidAcronym;
}
}