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
18 package org.apache.commons.text.similarity;
19
20 import java.util.Objects;
21
22 /**
23 * An ordered input of elements used to compute a similarity score.
24 * <p>
25 * You can implement a SimilarityInput on a domain object instead of CharSequence where implementing CharSequence does not make sense.
26 * </p>
27 *
28 * @param <E> the type of elements in this input.
29 * @since 1.13.0
30 */
31 public interface SimilarityInput<E> {
32
33 /**
34 * Creates a new input for a {@link CharSequence}.
35 *
36 * @param cs input character sequence.
37 * @return a new input.
38 */
39 static SimilarityInput<Character> input(final CharSequence cs) {
40 return new SimilarityCharacterInput(cs);
41 }
42
43 /**
44 * Creates a new input for a {@link CharSequence} or {@link SimilarityInput}.
45 *
46 * @param <T> The type of similarity score unit.
47 * @param input character sequence or similarity input.
48 * @return a new input.
49 * @throws IllegalArgumentException when the input type is neither {@link CharSequence} or {@link SimilarityInput}.
50 */
51 @SuppressWarnings("unchecked")
52 static <T> SimilarityInput<T> input(final Object input) {
53 if (input instanceof SimilarityInput) {
54 return (SimilarityInput<T>) input;
55 }
56 if (input instanceof CharSequence) {
57 return (SimilarityInput<T>) input((CharSequence) input);
58 }
59 throw new IllegalArgumentException(Objects.requireNonNull(input, "input").getClass().getName());
60 }
61
62 /**
63 * Gets the element in the input at the given 0-based index.
64 *
65 * @param index a 0-based index.
66 * @return the element in the input at the given 0-based index.
67 */
68 E at(int index);
69
70 /**
71 * Gets the length of the input.
72 *
73 * @return the length of the input.
74 */
75 int length();
76
77 }