package org.apache.lucene.analysis.miscellaneous;
/**
* 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 java.io.IOException;
import java.util.Collection;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.util.CharArraySet;
/**
* A filter to apply normal capitalization rules to Tokens. It will make the first letter
* capital and the rest lower case.
* <p/>
* This filter is particularly useful to build nice looking facet parameters. This filter
* is not appropriate if you intend to use a prefix query.
*/
public final class CapitalizationFilter extends TokenFilter {
public static final int DEFAULT_MAX_WORD_COUNT = Integer.MAX_VALUE;
public static final int DEFAULT_MAX_TOKEN_LENGTH = Integer.MAX_VALUE;
private final boolean onlyFirstWord;
private final CharArraySet keep;
private final boolean forceFirstLetter;
private final Collection<char[]> okPrefix;
private final int minWordLength;
private final int maxWordCount;
private final int maxTokenLength;
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
/**
* Creates a CapitalizationFilter with the default parameters.
* <p>
* Calls {@link #CapitalizationFilter(TokenStream, boolean, CharArraySet, boolean, Collection, int, int, int)
* CapitalizationFilter(in, true, null, true, null, 0, DEFAULT_MAX_WORD_COUNT, DEFAULT_MAX_TOKEN_LENGTH)}
*/
public CapitalizationFilter(TokenStream in) {
this(in, true, null, true, null, 0, DEFAULT_MAX_WORD_COUNT, DEFAULT_MAX_TOKEN_LENGTH);
}
/**
* Creates a CapitalizationFilter with the specified parameters.
* @param in input tokenstream
* @param onlyFirstWord should each word be capitalized or all of the words?
* @param keep a keep word list. Each word that should be kept separated by whitespace.
* @param forceFirstLetter Force the first letter to be capitalized even if it is in the keep list.
* @param okPrefix do not change word capitalization if a word begins with something in this list.
* @param minWordLength how long the word needs to be to get capitalization applied. If the
* minWordLength is 3, "and" > "And" but "or" stays "or".
* @param maxWordCount if the token contains more then maxWordCount words, the capitalization is
* assumed to be correct.
* @param maxTokenLength ???
*/
public CapitalizationFilter(TokenStream in, boolean onlyFirstWord, CharArraySet keep,
boolean forceFirstLetter, Collection<char[]> okPrefix, int minWordLength,
int maxWordCount, int maxTokenLength) {
super(in);
this.onlyFirstWord = onlyFirstWord;
this.keep = keep;
this.forceFirstLetter = forceFirstLetter;
this.okPrefix = okPrefix;
this.minWordLength = minWordLength;
this.maxWordCount = maxWordCount;
this.maxTokenLength = maxTokenLength;
}
@Override
public boolean incrementToken() throws IOException {
if (!input.incrementToken()) return false;
char[] termBuffer = termAtt.buffer();
int termBufferLength = termAtt.length();
char[] backup = null;
if (maxWordCount < DEFAULT_MAX_WORD_COUNT) {
//make a backup in case we exceed the word count
backup = new char[termBufferLength];
System.arraycopy(termBuffer, 0, backup, 0, termBufferLength);
}
if (termBufferLength < maxTokenLength) {
int wordCount = 0;
int lastWordStart = 0;
for (int i = 0; i < termBufferLength; i++) {
char c = termBuffer[i];
if (c <= ' ' || c == '.') {
int len = i - lastWordStart;
if (len > 0) {
processWord(termBuffer, lastWordStart, len, wordCount++);
lastWordStart = i + 1;
i++;
}
}
}
// process the last word
if (lastWordStart < termBufferLength) {
processWord(termBuffer, lastWordStart, termBufferLength - lastWordStart, wordCount++);
}
if (wordCount > maxWordCount) {
termAtt.copyBuffer(backup, 0, termBufferLength);
}
}
return true;
}
private void processWord(char[] buffer, int offset, int length, int wordCount) {
if (length < 1) {
return;
}
if (onlyFirstWord && wordCount > 0) {
for (int i = 0; i < length; i++) {
buffer[offset + i] = Character.toLowerCase(buffer[offset + i]);
}
return;
}
if (keep != null && keep.contains(buffer, offset, length)) {
if (wordCount == 0 && forceFirstLetter) {
buffer[offset] = Character.toUpperCase(buffer[offset]);
}
return;
}
if (length < minWordLength) {
return;
}
if (okPrefix != null) {
for (char[] prefix : okPrefix) {
if (length >= prefix.length) { //don't bother checking if the buffer length is less than the prefix
boolean match = true;
for (int i = 0; i < prefix.length; i++) {
if (prefix[i] != buffer[offset + i]) {
match = false;
break;
}
}
if (match == true) {
return;
}
}
}
}
// We know it has at least one character
/*char[] chars = w.toCharArray();
StringBuilder word = new StringBuilder( w.length() );
word.append( Character.toUpperCase( chars[0] ) );*/
buffer[offset] = Character.toUpperCase(buffer[offset]);
for (int i = 1; i < length; i++) {
buffer[offset + i] = Character.toLowerCase(buffer[offset + i]);
}
//return word.toString();
}
}