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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  
19  import java.util.HashMap;
20  import java.util.Map;
21  import java.util.stream.Stream;
22  
23  /**
24   * Java implementation of Python's collections Counter module.
25   *
26   * <p>It counts how many times each element provided occurred in an array and
27   * returns a map with the element as key and the count as value.</p>
28   *
29   * @see <a href="https://docs.python.org/dev/library/collections.html#collections.Counter">
30   * https://docs.python.org/dev/library/collections.html#collections.Counter</a>
31   *
32   * @since 1.0
33   */
34  final class Counter {
35  
36      /**
37       * Counts how many times each element provided occurred in an array and
38       * returns a map with the element as key and the count as value.
39       *
40       * @param tokens array of tokens.
41       * @return a map, where the elements are key, and the count the value.
42       */
43      public static Map<CharSequence, Integer> of(final CharSequence[] tokens) {
44          final Map<CharSequence, Integer> map = new HashMap<>();
45          Stream.of(tokens).forEach(token -> map.compute(token, (k, v) -> v != null ? v + 1 : 1));
46          return map;
47      }
48  
49      /**
50       * Hidden constructor.
51       */
52      private Counter() {
53      }
54  
55  }