RegexTokenizer.java

  1. /*
  2.  * Licensed to the Apache Software Foundation (ASF) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * The ASF licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *      http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.apache.commons.text.similarity;

  18. import java.util.ArrayList;
  19. import java.util.List;
  20. import java.util.regex.Matcher;
  21. import java.util.regex.Pattern;

  22. /**
  23.  * A simple word tokenizer that utilizes regex to find words. It applies a regex
  24.  * {@code}(\w)+{@code} over the input text to extract words from a given character
  25.  * sequence.
  26.  *
  27.  * @since 1.0
  28.  */
  29. class RegexTokenizer implements Tokenizer<CharSequence> {

  30.     /**
  31.      * {@inheritDoc}
  32.      *
  33.      * @throws IllegalArgumentException if the input text is blank
  34.      */
  35.     @Override
  36.     public CharSequence[] tokenize(final CharSequence text) {
  37.         if (text == null || text.toString().trim().equals("")) {
  38.             throw new IllegalArgumentException("Invalid text");
  39.         }
  40.         final Pattern pattern = Pattern.compile("(\\w)+");
  41.         final Matcher matcher = pattern.matcher(text.toString());
  42.         final List<String> tokens = new ArrayList<>();
  43.         while (matcher.find()) {
  44.             tokens.add(matcher.group(0));
  45.         }
  46.         return tokens.toArray(new String[0]);
  47.     }

  48. }