/*
 * 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.wikipedia;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.FlagsAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeFactory;
import org.apache.lucene.util.AttributeSource;

import java.io.IOException;
import java.util.*;


Extension of StandardTokenizer that is aware of Wikipedia syntax. It is based off of the Wikipedia tutorial available at http://en.wikipedia.org/wiki/Wikipedia:Tutorial, but it may not be complete.
@lucene.experimental
/** * Extension of StandardTokenizer that is aware of Wikipedia syntax. It is based off of the * Wikipedia tutorial available at http://en.wikipedia.org/wiki/Wikipedia:Tutorial, but it may not be complete. * @lucene.experimental */
public final class WikipediaTokenizer extends Tokenizer { public static final String INTERNAL_LINK = "il"; public static final String EXTERNAL_LINK = "el"; //The URL part of the link, i.e. the first token public static final String EXTERNAL_LINK_URL = "elu"; public static final String CITATION = "ci"; public static final String CATEGORY = "c"; public static final String BOLD = "b"; public static final String ITALICS = "i"; public static final String BOLD_ITALICS = "bi"; public static final String HEADING = "h"; public static final String SUB_HEADING = "sh"; public static final int ALPHANUM_ID = 0; public static final int APOSTROPHE_ID = 1; public static final int ACRONYM_ID = 2; public static final int COMPANY_ID = 3; public static final int EMAIL_ID = 4; public static final int HOST_ID = 5; public static final int NUM_ID = 6; public static final int CJ_ID = 7; public static final int INTERNAL_LINK_ID = 8; public static final int EXTERNAL_LINK_ID = 9; public static final int CITATION_ID = 10; public static final int CATEGORY_ID = 11; public static final int BOLD_ID = 12; public static final int ITALICS_ID = 13; public static final int BOLD_ITALICS_ID = 14; public static final int HEADING_ID = 15; public static final int SUB_HEADING_ID = 16; public static final int EXTERNAL_LINK_URL_ID = 17;
String token types that correspond to token type int constants
/** 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>", INTERNAL_LINK, EXTERNAL_LINK, CITATION, CATEGORY, BOLD, ITALICS, BOLD_ITALICS, HEADING, SUB_HEADING, EXTERNAL_LINK_URL };
Only output tokens
/** * Only output tokens */
public static final int TOKENS_ONLY = 0;
Only output untokenized tokens, which are tokens that would normally be split into several tokens
/** * Only output untokenized tokens, which are tokens that would normally be split into several tokens */
public static final int UNTOKENIZED_ONLY = 1;
Output the both the untokenized token and the splits
/** * Output the both the untokenized token and the splits */
public static final int BOTH = 2;
This flag is used to indicate that the produced "Token" would, if TOKENS_ONLY was used, produce multiple tokens.
/** * This flag is used to indicate that the produced "Token" would, if {@link #TOKENS_ONLY} was used, produce multiple tokens. */
public static final int UNTOKENIZED_TOKEN_FLAG = 1;
A private instance of the JFlex-constructed scanner
/** * A private instance of the JFlex-constructed scanner */
private final WikipediaTokenizerImpl scanner; private int tokenOutput = TOKENS_ONLY; private Set<String> untokenizedTypes = Collections.emptySet(); private Iterator<AttributeSource.State> tokens = null; private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class); private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class); private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class); private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class); private final FlagsAttribute flagsAtt = addAttribute(FlagsAttribute.class); private boolean first;
Creates a new instance of the WikipediaTokenizer. Attaches the input to a newly created JFlex scanner.
/** * Creates a new instance of the {@link WikipediaTokenizer}. Attaches the * <code>input</code> to a newly created JFlex scanner. */
public WikipediaTokenizer() { this(TOKENS_ONLY, Collections.<String>emptySet()); }
Creates a new instance of the WikipediaTokenizer. Attaches the input to the newly created JFlex scanner.
Params:
/** * Creates a new instance of the {@link org.apache.lucene.analysis.wikipedia.WikipediaTokenizer}. Attaches the * <code>input</code> to the newly created JFlex scanner. * * @param tokenOutput One of {@link #TOKENS_ONLY}, {@link #UNTOKENIZED_ONLY}, {@link #BOTH} */
public WikipediaTokenizer(int tokenOutput, Set<String> untokenizedTypes) { this.scanner = new WikipediaTokenizerImpl(this.input); init(tokenOutput, untokenizedTypes); }
Creates a new instance of the WikipediaTokenizer. Attaches the input to the newly created JFlex scanner. Uses the given AttributeFactory.
Params:
/** * Creates a new instance of the {@link org.apache.lucene.analysis.wikipedia.WikipediaTokenizer}. Attaches the * <code>input</code> to the newly created JFlex scanner. Uses the given {@link org.apache.lucene.util.AttributeFactory}. * * @param tokenOutput One of {@link #TOKENS_ONLY}, {@link #UNTOKENIZED_ONLY}, {@link #BOTH} */
public WikipediaTokenizer(AttributeFactory factory, int tokenOutput, Set<String> untokenizedTypes) { super(factory); this.scanner = new WikipediaTokenizerImpl(this.input); init(tokenOutput, untokenizedTypes); } private void init(int tokenOutput, Set<String> untokenizedTypes) { // TODO: cutover to enum if (tokenOutput != TOKENS_ONLY && tokenOutput != UNTOKENIZED_ONLY && tokenOutput != BOTH) { throw new IllegalArgumentException("tokenOutput must be TOKENS_ONLY, UNTOKENIZED_ONLY or BOTH"); } this.tokenOutput = tokenOutput; this.untokenizedTypes = untokenizedTypes; } /* * (non-Javadoc) * * @see org.apache.lucene.analysis.TokenStream#next() */ @Override public final boolean incrementToken() throws IOException { if (tokens != null && tokens.hasNext()){ AttributeSource.State state = tokens.next(); restoreState(state); return true; } clearAttributes(); int tokenType = scanner.getNextToken(); if (tokenType == WikipediaTokenizerImpl.YYEOF) { return false; } String type = WikipediaTokenizerImpl.TOKEN_TYPES[tokenType]; if (tokenOutput == TOKENS_ONLY || untokenizedTypes.contains(type) == false){ setupToken(); } else if (tokenOutput == UNTOKENIZED_ONLY && untokenizedTypes.contains(type) == true){ collapseTokens(tokenType); } else if (tokenOutput == BOTH){ //collapse into a single token, add it to tokens AND output the individual tokens //output the untokenized Token first collapseAndSaveTokens(tokenType, type); } int posinc = scanner.getPositionIncrement(); if (first && posinc == 0) { posinc = 1; // don't emit posinc=0 for the first token! } posIncrAtt.setPositionIncrement(posinc); typeAtt.setType(type); first = false; return true; } private void collapseAndSaveTokens(int tokenType, String type) throws IOException { //collapse StringBuilder buffer = new StringBuilder(32); int numAdded = scanner.setText(buffer); //TODO: how to know how much whitespace to add int theStart = scanner.yychar(); int lastPos = theStart + numAdded; int tmpTokType; int numSeen = 0; List<AttributeSource.State> tmp = new ArrayList<>(); setupSavedToken(0, type); tmp.add(captureState()); //while we can get a token and that token is the same type and we have not transitioned to a new wiki-item of the same type while ((tmpTokType = scanner.getNextToken()) != WikipediaTokenizerImpl.YYEOF && tmpTokType == tokenType && scanner.getNumWikiTokensSeen() > numSeen){ int currPos = scanner.yychar(); //append whitespace for (int i = 0; i < (currPos - lastPos); i++){ buffer.append(' '); } numAdded = scanner.setText(buffer); setupSavedToken(scanner.getPositionIncrement(), type); tmp.add(captureState()); numSeen++; lastPos = currPos + numAdded; } //trim the buffer // TODO: this is inefficient String s = buffer.toString().trim(); termAtt.setEmpty().append(s); offsetAtt.setOffset(correctOffset(theStart), correctOffset(theStart + s.length())); flagsAtt.setFlags(UNTOKENIZED_TOKEN_FLAG); //The way the loop is written, we will have proceeded to the next token. We need to pushback the scanner to lastPos if (tmpTokType != WikipediaTokenizerImpl.YYEOF){ scanner.yypushback(scanner.yylength()); } tokens = tmp.iterator(); } private void setupSavedToken(int positionInc, String type){ setupToken(); posIncrAtt.setPositionIncrement(positionInc); typeAtt.setType(type); } private void collapseTokens(int tokenType) throws IOException { //collapse StringBuilder buffer = new StringBuilder(32); int numAdded = scanner.setText(buffer); //TODO: how to know how much whitespace to add int theStart = scanner.yychar(); int lastPos = theStart + numAdded; int tmpTokType; int numSeen = 0; //while we can get a token and that token is the same type and we have not transitioned to a new wiki-item of the same type while ((tmpTokType = scanner.getNextToken()) != WikipediaTokenizerImpl.YYEOF && tmpTokType == tokenType && scanner.getNumWikiTokensSeen() > numSeen){ int currPos = scanner.yychar(); //append whitespace for (int i = 0; i < (currPos - lastPos); i++){ buffer.append(' '); } numAdded = scanner.setText(buffer); numSeen++; lastPos = currPos + numAdded; } //trim the buffer // TODO: this is inefficient String s = buffer.toString().trim(); termAtt.setEmpty().append(s); offsetAtt.setOffset(correctOffset(theStart), correctOffset(theStart + s.length())); flagsAtt.setFlags(UNTOKENIZED_TOKEN_FLAG); //The way the loop is written, we will have proceeded to the next token. We need to pushback the scanner to lastPos if (tmpTokType != WikipediaTokenizerImpl.YYEOF){ scanner.yypushback(scanner.yylength()); } else { tokens = null; } } private void setupToken() { scanner.getText(termAtt); final int start = scanner.yychar(); offsetAtt.setOffset(correctOffset(start), correctOffset(start + termAtt.length())); } @Override public void close() throws IOException { super.close(); scanner.yyreset(input); } /* * (non-Javadoc) * * @see org.apache.lucene.analysis.TokenStream#reset() */ @Override public void reset() throws IOException { super.reset(); scanner.yyreset(input); tokens = null; scanner.reset(); first = true; } @Override public void end() throws IOException { super.end(); // set final offset final int finalOffset = correctOffset(scanner.yychar() + scanner.yylength()); this.offsetAtt.setOffset(finalOffset, finalOffset); } }