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 }