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Lucene Wikipedia Contributions
/**
* 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.wikipedia.analysis;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.Tokenizer;
import java.io.IOException;
import java.io.Reader;
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.
*
*
* EXPERIMENTAL !!!!!!!!!
* NOTE: This Tokenizer is considered experimental and the grammar is subject to change in the trunk and in follow up releases.
*/
public 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 */
public static final String [] TOKEN_TYPES = new String [] {
"",
"",
"",
"",
"",
"",
"",
"",
INTERNAL_LINK,
EXTERNAL_LINK,
CITATION,
CATEGORY,
BOLD,
ITALICS,
BOLD_ITALICS,
HEADING,
SUB_HEADING,
EXTERNAL_LINK_URL
};
/** @deprecated Please use {@link #TOKEN_TYPES} instead */
public static final String [] tokenImage = TOKEN_TYPES;
public static final int TOKENS_ONLY = 0;
public static final int UNTOKENIZED_ONLY = 1;
public static final int BOTH = 2;
/**
* 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
*/
private final WikipediaTokenizerImpl scanner;
private int tokenOutput = TOKENS_ONLY;
private Set untokenizedTypes = Collections.EMPTY_SET;
private Iterator tokens = null;
void setInput(Reader reader) {
this.input = reader;
}
/**
* Creates a new instance of the {@link WikipediaTokenizer}. Attaches the
* input to a newly created JFlex scanner.
*
* @param input The Input Reader
*/
public WikipediaTokenizer(Reader input) {
this(input, TOKENS_ONLY, Collections.EMPTY_SET);
}
public WikipediaTokenizer(Reader input, int tokenOutput, Set untokenizedTypes) {
super(input);
this.tokenOutput = tokenOutput;
this.scanner = new WikipediaTokenizerImpl(input);
this.untokenizedTypes = untokenizedTypes;
}
/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#next()
*/
public Token next(final Token reusableToken) throws IOException {
assert reusableToken != null;
if (tokens != null && tokens.hasNext()){
return (Token)tokens.next();
}
int tokenType = scanner.getNextToken();
if (tokenType == WikipediaTokenizerImpl.YYEOF) {
return null;
}
String type = WikipediaTokenizerImpl.TOKEN_TYPES[tokenType];
if (tokenOutput == TOKENS_ONLY || untokenizedTypes.contains(type) == false){
setupToken(reusableToken);
} else if (tokenOutput == UNTOKENIZED_ONLY && untokenizedTypes.contains(type) == true){
collapseTokens(reusableToken, 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(reusableToken, tokenType, type);
}
reusableToken.setPositionIncrement(scanner.getPositionIncrement());
reusableToken.setType(type);
return reusableToken;
}
private void collapseAndSaveTokens(final Token reusableToken, int tokenType, String type) throws IOException {
//collapse
StringBuffer buffer = new StringBuffer(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 tmp = new ArrayList();
Token saved = new Token();
setupSavedToken(saved, 0, type);
tmp.add(saved);
//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);
saved = new Token();
setupSavedToken(saved, scanner.getPositionIncrement(), type);
tmp.add(saved);
numSeen++;
lastPos = currPos + numAdded;
}
//trim the buffer
String s = buffer.toString().trim();
reusableToken.setTermBuffer(s.toCharArray(), 0, s.length());
reusableToken.setStartOffset(theStart);
reusableToken.setEndOffset(theStart + s.length());
reusableToken.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(Token saved, int positionInc, String type){
setupToken(saved);
saved.setPositionIncrement(positionInc);
saved.setType(type);
}
private void collapseTokens(final Token reusableToken, int tokenType) throws IOException {
//collapse
StringBuffer buffer = new StringBuffer(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
String s = buffer.toString().trim();
reusableToken.setTermBuffer(s.toCharArray(), 0, s.length());
reusableToken.setStartOffset(theStart);
reusableToken.setEndOffset(theStart + s.length());
reusableToken.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(final Token reusableToken) {
scanner.getText(reusableToken);
final int start = scanner.yychar();
reusableToken.setStartOffset(start);
reusableToken.setEndOffset(start + reusableToken.termLength());
}
/*
* (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 {
input = reader;
reset();
}
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