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/*
 * 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.ngram;


import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.util.TokenizerFactory;
import org.apache.lucene.util.AttributeFactory;

import java.io.Reader;
import java.util.Map;

/**
 * Factory for {@link NGramTokenizer}.
 *  * <fieldType name="text_ngrm" class="solr.TextField" positionIncrementGap="100">
 *   <analyzer>
 *     <tokenizer class="solr.NGramTokenizerFactory" minGramSize="1" maxGramSize="2"/>
 *   </analyzer>
 * </fieldType>
 *
 * @since 3.1
 * @lucene.spi {@value #NAME}
 */
public class NGramTokenizerFactory extends TokenizerFactory {

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

  private final int maxGramSize;
  private final int minGramSize;

  /** Creates a new NGramTokenizerFactory */
  public NGramTokenizerFactory(Map args) {
    super(args);
    minGramSize = getInt(args, "minGramSize", NGramTokenizer.DEFAULT_MIN_NGRAM_SIZE);
    maxGramSize = getInt(args, "maxGramSize", NGramTokenizer.DEFAULT_MAX_NGRAM_SIZE);
    if (!args.isEmpty()) {
      throw new IllegalArgumentException("Unknown parameters: " + args);
    }
  }
  
  /** Creates the {@link TokenStream} of n-grams from the given {@link Reader} and {@link AttributeFactory}. */
  @Override
  public Tokenizer create(AttributeFactory factory) {
    return new NGramTokenizer(factory, minGramSize, maxGramSize);
  }
}