| /* |
| * 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.pattern; |
| |
| import java.io.IOException; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| import org.apache.lucene.analysis.TokenFilter; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.analysis.tokenattributes.CharTermAttribute; |
| import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute; |
| import org.apache.lucene.util.CharsRefBuilder; |
| |
| /** |
| * CaptureGroup uses Java regexes to emit multiple tokens - one for each capture group in one or |
| * more patterns. |
| * |
| * <p>For example, a pattern like: |
| * |
| * <p><code>"(https?://([a-zA-Z\-_0-9.]+))"</code> |
| * |
| * <p>when matched against the string "http://www.foo.com/index" would return the tokens |
| * "https://www.foo.com" and "www.foo.com". |
| * |
| * <p>If none of the patterns match, or if preserveOriginal is true, the original token will be |
| * preserved. |
| * |
| * <p>Each pattern is matched as often as it can be, so the pattern <code> "(...)"</code>, when |
| * matched against <code>"abcdefghi"</code> would produce <code>["abc","def","ghi"]</code> |
| * |
| * <p>A camelCaseFilter could be written as: |
| * |
| * <p><code> |
| * "([A-Z]{2,})", |
| * "(?<![A-Z])([A-Z][a-z]+)", |
| * "(?:^|\\b|(?<=[0-9_])|(?<=[A-Z]{2}))([a-z]+)", |
| * "([0-9]+)" |
| * </code> |
| * |
| * <p>plus if {@link #preserveOriginal} is true, it would also return <code>"camelCaseFilter"</code> |
| */ |
| public final class PatternCaptureGroupTokenFilter extends TokenFilter { |
| |
| private final CharTermAttribute charTermAttr = addAttribute(CharTermAttribute.class); |
| private final PositionIncrementAttribute posAttr = addAttribute(PositionIncrementAttribute.class); |
| private State state; |
| private final Matcher[] matchers; |
| private final CharsRefBuilder spare = new CharsRefBuilder(); |
| private final int[] groupCounts; |
| private final boolean preserveOriginal; |
| private int[] currentGroup; |
| private int currentMatcher; |
| |
| /** |
| * @param input the input {@link TokenStream} |
| * @param preserveOriginal set to true to return the original token even if one of the patterns |
| * matches |
| * @param patterns an array of {@link Pattern} objects to match against each token |
| */ |
| public PatternCaptureGroupTokenFilter( |
| TokenStream input, boolean preserveOriginal, Pattern... patterns) { |
| super(input); |
| this.preserveOriginal = preserveOriginal; |
| this.matchers = new Matcher[patterns.length]; |
| this.groupCounts = new int[patterns.length]; |
| this.currentGroup = new int[patterns.length]; |
| for (int i = 0; i < patterns.length; i++) { |
| this.matchers[i] = patterns[i].matcher(""); |
| this.groupCounts[i] = this.matchers[i].groupCount(); |
| this.currentGroup[i] = -1; |
| } |
| } |
| |
| private boolean nextCapture() { |
| int min_offset = Integer.MAX_VALUE; |
| currentMatcher = -1; |
| Matcher matcher; |
| |
| for (int i = 0; i < matchers.length; i++) { |
| matcher = matchers[i]; |
| if (currentGroup[i] == -1) { |
| currentGroup[i] = matcher.find() ? 1 : 0; |
| } |
| if (currentGroup[i] != 0) { |
| while (currentGroup[i] < groupCounts[i] + 1) { |
| final int start = matcher.start(currentGroup[i]); |
| final int end = matcher.end(currentGroup[i]); |
| if (start == end || preserveOriginal && start == 0 && spare.length() == end) { |
| currentGroup[i]++; |
| continue; |
| } |
| if (start < min_offset) { |
| min_offset = start; |
| currentMatcher = i; |
| } |
| break; |
| } |
| if (currentGroup[i] == groupCounts[i] + 1) { |
| currentGroup[i] = -1; |
| i--; |
| } |
| } |
| } |
| return currentMatcher != -1; |
| } |
| |
| @Override |
| public boolean incrementToken() throws IOException { |
| |
| if (currentMatcher != -1 && nextCapture()) { |
| assert state != null; |
| clearAttributes(); |
| restoreState(state); |
| final int start = matchers[currentMatcher].start(currentGroup[currentMatcher]); |
| final int end = matchers[currentMatcher].end(currentGroup[currentMatcher]); |
| |
| posAttr.setPositionIncrement(0); |
| charTermAttr.copyBuffer(spare.chars(), start, end - start); |
| currentGroup[currentMatcher]++; |
| return true; |
| } |
| |
| if (!input.incrementToken()) { |
| return false; |
| } |
| |
| char[] buffer = charTermAttr.buffer(); |
| int length = charTermAttr.length(); |
| spare.copyChars(buffer, 0, length); |
| state = captureState(); |
| |
| for (int i = 0; i < matchers.length; i++) { |
| matchers[i].reset(spare.get()); |
| currentGroup[i] = -1; |
| } |
| |
| if (preserveOriginal) { |
| currentMatcher = 0; |
| } else if (nextCapture()) { |
| final int start = matchers[currentMatcher].start(currentGroup[currentMatcher]); |
| final int end = matchers[currentMatcher].end(currentGroup[currentMatcher]); |
| |
| // if we start at 0 we can simply set the length and save the copy |
| if (start == 0) { |
| charTermAttr.setLength(end); |
| } else { |
| charTermAttr.copyBuffer(spare.chars(), start, end - start); |
| } |
| currentGroup[currentMatcher]++; |
| } |
| return true; |
| } |
| |
| @Override |
| public void reset() throws IOException { |
| super.reset(); |
| state = null; |
| currentMatcher = -1; |
| } |
| } |