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 org.apache.commons.lang3.Validate;
20
21 /**
22 * This stores a {@link SimilarityScore} implementation and a {@link CharSequence} "left" string.
23 * The {@link #apply(CharSequence right)} method accepts the "right" string and invokes the
24 * comparison function for the pair of strings.
25 *
26 * <p>
27 * The following is an example which finds the most similar string:
28 * </p>
29 * <pre>
30 * SimilarityScore<Integer> similarityScore = new LevenshteinDistance();
31 * String target = "Apache";
32 * SimilarityScoreFrom<Integer> similarityScoreFrom =
33 * new SimilarityScoreFrom<Integer>(similarityScore, target);
34 * String mostSimilar = null;
35 * Integer shortestDistance = null;
36 *
37 * for (String test : new String[] { "Appaloosa", "a patchy", "apple" }) {
38 * Integer distance = similarityScoreFrom.apply(test);
39 * if (shortestDistance == null || distance < shortestDistance) {
40 * shortestDistance = distance;
41 * mostSimilar = test;
42 * }
43 * }
44 *
45 * System.out.println("The string most similar to \"" + target + "\" "
46 * + "is \"" + mostSimilar + "\" because "
47 * + "its distance is only " + shortestDistance + ".");
48 * </pre>
49 *
50 * @param <R> This is the type of similarity score used by the SimilarityScore function.
51 * @since 1.0
52 */
53 public class SimilarityScoreFrom<R> {
54
55 /**
56 * Similarity score.
57 */
58 private final SimilarityScore<R> similarityScore;
59
60 /**
61 * Left parameter used in distance function.
62 */
63 private final CharSequence left;
64
65 /**
66 * This accepts the similarity score implementation and the "left" string.
67 *
68 * @param similarityScore This may not be null.
69 * @param left This may be null here,
70 * but the SimilarityScore#compare(CharSequence left, CharSequence right)
71 * implementation may not accept nulls.
72 */
73 public SimilarityScoreFrom(final SimilarityScore<R> similarityScore, final CharSequence left) {
74 Validate.isTrue(similarityScore != null, "The edit distance may not be null.");
75
76 this.similarityScore = similarityScore;
77 this.left = left;
78 }
79
80 /**
81 * This compares "left" field against the "right" parameter
82 * using the "similarity score" implementation.
83 *
84 * @param right the second CharSequence
85 * @return The similarity score between two CharSequences
86 */
87 public R apply(final CharSequence right) {
88 return similarityScore.apply(left, right);
89 }
90
91 /**
92 * Gets the left parameter.
93 *
94 * @return The left parameter
95 */
96 public CharSequence getLeft() {
97 return left;
98 }
99
100 /**
101 * Gets the edit distance.
102 *
103 * @return The edit distance
104 */
105 public SimilarityScore<R> getSimilarityScore() {
106 return similarityScore;
107 }
108
109 }