lucene 4: remove Pattern tokenizer and filter
This commit is contained in:
Igor Motov
Shay Banon
parent
097cb2dac7
commit
6fad75df82
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/*
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* Licensed to ElasticSearch and Shay Banon under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. ElasticSearch licenses this
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* file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.apache.lucene.analysis.pattern;
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import org.apache.lucene.analysis.TokenFilter;
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import org.apache.lucene.analysis.TokenStream;
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import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
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import java.io.IOException;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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/**
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* A TokenFilter which applies a Pattern to each token in the stream,
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* replacing match occurances with the specified replacement string.
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* <p/>
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* <p>
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* <b>Note:</b> Depending on the input and the pattern used and the input
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* TokenStream, this TokenFilter may produce Tokens whose text is the empty
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* string.
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* </p>
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*
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* @see Pattern
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*/
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public final class PatternReplaceFilter extends TokenFilter {
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private final Pattern p;
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private final String replacement;
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private final boolean all;
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private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
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private final Matcher m;
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/**
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* Constructs an instance to replace either the first, or all occurances
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*
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* @param in the TokenStream to process
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* @param p the patterm to apply to each Token
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* @param replacement the "replacement string" to substitute, if null a
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* blank string will be used. Note that this is not the literal
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* string that will be used, '$' and '\' have special meaning.
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* @param all if true, all matches will be replaced otherwise just the first match.
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* @see Matcher#quoteReplacement
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*/
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public PatternReplaceFilter(TokenStream in,
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Pattern p,
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String replacement,
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boolean all) {
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super(in);
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this.p = p;
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this.replacement = (null == replacement) ? "" : replacement;
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this.all = all;
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this.m = p.matcher(termAtt);
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}
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@Override
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public boolean incrementToken() throws IOException {
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if (!input.incrementToken()) return false;
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m.reset();
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if (m.find()) {
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// replaceAll/replaceFirst will reset() this previous find.
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String transformed = all ? m.replaceAll(replacement) : m.replaceFirst(replacement);
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termAtt.setEmpty().append(transformed);
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}
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return true;
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}
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}
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@ -1,153 +0,0 @@
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/*
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* Licensed to ElasticSearch and Shay Banon under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. ElasticSearch licenses this
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* file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.apache.lucene.analysis.pattern;
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import org.apache.lucene.analysis.Tokenizer;
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import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
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import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
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import java.io.IOException;
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import java.io.Reader;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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/**
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* This tokenizer uses regex pattern matching to construct distinct tokens
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* for the input stream. It takes two arguments: "pattern" and "group".
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* <p/>
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* <ul>
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* <li>"pattern" is the regular expression.</li>
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* <li>"group" says which group to extract into tokens.</li>
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* </ul>
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* <p>
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* group=-1 (the default) is equivalent to "split". In this case, the tokens will
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* be equivalent to the output from (without empty tokens):
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* {@link String#split(java.lang.String)}
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* </p>
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* <p>
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* Using group >= 0 selects the matching group as the token. For example, if you have:<br/>
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* <pre>
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* pattern = \'([^\']+)\'
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* group = 0
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* input = aaa 'bbb' 'ccc'
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* </pre>
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* the output will be two tokens: 'bbb' and 'ccc' (including the ' marks). With the same input
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* but using group=1, the output would be: bbb and ccc (no ' marks)
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* </p>
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* <p>NOTE: This Tokenizer does not output tokens that are of zero length.</p>
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*
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* @see Pattern
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*/
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public final class PatternTokenizer extends Tokenizer {
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private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
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private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
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private final StringBuilder str = new StringBuilder();
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private int index;
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private final Pattern pattern;
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private final int group;
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private final Matcher matcher;
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/**
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* creates a new PatternTokenizer returning tokens from group (-1 for split functionality)
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*/
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public PatternTokenizer(Reader input, Pattern pattern, int group) throws IOException {
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super(input);
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this.pattern = pattern;
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this.group = group;
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fillBuffer(str, input);
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matcher = pattern.matcher(str);
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index = 0;
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}
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@Override
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public boolean incrementToken() throws IOException {
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if (index >= str.length()) return false;
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clearAttributes();
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if (group >= 0) {
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// match a specific group
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while (matcher.find()) {
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index = matcher.start(group);
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final int endIndex = matcher.end(group);
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if (index == endIndex) continue;
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termAtt.setEmpty().append(str, index, endIndex);
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offsetAtt.setOffset(correctOffset(index), correctOffset(endIndex));
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return true;
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}
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index = Integer.MAX_VALUE; // mark exhausted
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return false;
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} else {
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// String.split() functionality
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while (matcher.find()) {
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if (matcher.start() - index > 0) {
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// found a non-zero-length token
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termAtt.setEmpty().append(str, index, matcher.start());
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offsetAtt.setOffset(correctOffset(index), correctOffset(matcher.start()));
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index = matcher.end();
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return true;
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}
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index = matcher.end();
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}
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if (str.length() - index == 0) {
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index = Integer.MAX_VALUE; // mark exhausted
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return false;
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}
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termAtt.setEmpty().append(str, index, str.length());
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offsetAtt.setOffset(correctOffset(index), correctOffset(str.length()));
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index = Integer.MAX_VALUE; // mark exhausted
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return true;
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}
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}
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@Override
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public void end() throws IOException {
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final int ofs = correctOffset(str.length());
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offsetAtt.setOffset(ofs, ofs);
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}
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@Override
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public void reset(Reader input) throws IOException {
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super.reset(input);
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fillBuffer(str, input);
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matcher.reset(str);
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index = 0;
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}
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// TODO: we should see if we can make this tokenizer work without reading
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// the entire document into RAM, perhaps with Matcher.hitEnd/requireEnd ?
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final char[] buffer = new char[8192];
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private void fillBuffer(StringBuilder sb, Reader input) throws IOException {
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int len;
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sb.setLength(0);
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while ((len = input.read(buffer)) > 0) {
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sb.append(buffer, 0, len);
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}
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}
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}
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