lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/CapitalizationFilterFactory.java

/*
 * 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.miscellaneous;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.TokenFilterFactory;
import org.apache.lucene.analysis.TokenStream;

/**
 * Factory for {@link CapitalizationFilter}.
 *
 * <p>The factory takes parameters:
 *
 * <ul>
 *   <li>"onlyFirstWord" - should each word be capitalized or all of the words?
 *   <li>"keep" - a keep word list. Each word that should be kept separated by whitespace.
 *   <li>"keepIgnoreCase - true or false. If true, the keep list will be considered
 *       case-insensitive.
 *   <li>"forceFirstLetter" - Force the first letter to be capitalized even if it is in the keep
 *       list
 *   <li>"okPrefix" - do not change word capitalization if a word begins with something in this
 *       list. for example if "McK" is on the okPrefix list, the word "McKinley" should not be
 *       changed to "Mckinley"
 *   <li>"minWordLength" - how long the word needs to be to get capitalization applied. If the
 *       minWordLength is 3, "and" &gt; "And" but "or" stays "or"
 *   <li>"maxWordCount" - if the token contains more then maxWordCount words, the capitalization is
 *       assumed to be correct.
 * </ul>
 *
 * <pre class="prettyprint">
 * &lt;fieldType name="text_cptlztn" class="solr.TextField" positionIncrementGap="100"&gt;
 *   &lt;analyzer&gt;
 *     &lt;tokenizer class="solr.WhitespaceTokenizerFactory"/&gt;
 *     &lt;filter class="solr.CapitalizationFilterFactory" onlyFirstWord="true"
 *           keep="java solr lucene" keepIgnoreCase="false"
 *           okPrefix="McK McD McA"/&gt;
 *   &lt;/analyzer&gt;
 * &lt;/fieldType&gt;</pre>
 *
 * @since solr 1.3
 * @lucene.spi {@value #NAME}
 */
public class CapitalizationFilterFactory extends TokenFilterFactory {

  /** SPI name */
  public static final String NAME = "capitalization";

  public static final String KEEP = "keep";
  public static final String KEEP_IGNORE_CASE = "keepIgnoreCase";
  public static final String OK_PREFIX = "okPrefix";
  public static final String MIN_WORD_LENGTH = "minWordLength";
  public static final String MAX_WORD_COUNT = "maxWordCount";
  public static final String MAX_TOKEN_LENGTH = "maxTokenLength";
  public static final String ONLY_FIRST_WORD = "onlyFirstWord";
  public static final String FORCE_FIRST_LETTER = "forceFirstLetter";

  CharArraySet keep;

  Collection<char[]> okPrefix = Collections.emptyList(); // for Example: McK

  final int minWordLength; // don't modify capitalization for words shorter then this
  final int maxWordCount;
  final int maxTokenLength;
  final boolean onlyFirstWord;

  // make sure the first letter is capital even if it is in the keep list
  final boolean forceFirstLetter;

  /** Creates a new CapitalizationFilterFactory */
  public CapitalizationFilterFactory(Map<String, String> args) {
    super(args);
    boolean ignoreCase = getBoolean(args, KEEP_IGNORE_CASE, false);
    Set<String> k = getSet(args, KEEP);
    if (k != null) {
      keep = new CharArraySet(10, ignoreCase);
      keep.addAll(k);
    }

    k = getSet(args, OK_PREFIX);
    if (k != null) {
      okPrefix = new ArrayList<>();
      for (String item : k) {
        okPrefix.add(item.toCharArray());
      }
    }

    minWordLength = getInt(args, MIN_WORD_LENGTH, 0);
    maxWordCount = getInt(args, MAX_WORD_COUNT, CapitalizationFilter.DEFAULT_MAX_WORD_COUNT);
    maxTokenLength = getInt(args, MAX_TOKEN_LENGTH, CapitalizationFilter.DEFAULT_MAX_TOKEN_LENGTH);
    onlyFirstWord = getBoolean(args, ONLY_FIRST_WORD, true);
    forceFirstLetter = getBoolean(args, FORCE_FIRST_LETTER, true);
    if (!args.isEmpty()) {
      throw new IllegalArgumentException("Unknown parameters: " + args);
    }
  }

  /** Default ctor for compatibility with SPI */
  public CapitalizationFilterFactory() {
    throw defaultCtorException();
  }

  @Override
  public CapitalizationFilter create(TokenStream input) {
    return new CapitalizationFilter(
        input,
        onlyFirstWord,
        keep,
        forceFirstLetter,
        okPrefix,
        minWordLength,
        maxWordCount,
        maxTokenLength);
  }
}