149 lines
5.3 KiB
Java
149 lines
5.3 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.text.similarity;
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import java.util.Locale;
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/**
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* A matching algorithm that is similar to the searching algorithms implemented in editors such
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* as Sublime Text, TextMate, Atom and others.
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*
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* <p>
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* One point is given for every matched character. Subsequent matches yield two bonus points.
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* A higher score indicates a higher similarity.
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* </p>
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*
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* <p>
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* This code has been adapted from Apache Commons Lang 3.3.
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* </p>
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*
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* @since 1.0
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*
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* Note: This class was forked from
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* <a href="https://git.io/JyYJg">
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* apache/commons-text (8cfdafc) FuzzyScore.java
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* </a>
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*/
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public class FuzzyScore {
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/**
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* Locale used to change the case of text.
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*/
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private final Locale locale;
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/**
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* This returns a {@link Locale}-specific {@link FuzzyScore}.
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*
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* @param locale The string matching logic is case insensitive.
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A {@link Locale} is necessary to normalize both Strings to lower case.
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* @throws IllegalArgumentException
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* This is thrown if the {@link Locale} parameter is {@code null}.
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*/
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public FuzzyScore(final Locale locale) {
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if (locale == null) {
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throw new IllegalArgumentException("Locale must not be null");
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}
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this.locale = locale;
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}
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/**
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* Find the Fuzzy Score which indicates the similarity score between two
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* Strings.
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*
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* <pre>
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* score.fuzzyScore(null, null) = IllegalArgumentException
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* score.fuzzyScore("not null", null) = IllegalArgumentException
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* score.fuzzyScore(null, "not null") = IllegalArgumentException
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* score.fuzzyScore("", "") = 0
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* score.fuzzyScore("Workshop", "b") = 0
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* score.fuzzyScore("Room", "o") = 1
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* score.fuzzyScore("Workshop", "w") = 1
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* score.fuzzyScore("Workshop", "ws") = 2
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* score.fuzzyScore("Workshop", "wo") = 4
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* score.fuzzyScore("Apache Software Foundation", "asf") = 3
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* </pre>
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*
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* @param term a full term that should be matched against, must not be null
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* @param query the query that will be matched against a term, must not be
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* null
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* @return result score
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* @throws IllegalArgumentException if the term or query is {@code null}
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*/
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public Integer fuzzyScore(final CharSequence term, final CharSequence query) {
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if (term == null || query == null) {
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throw new IllegalArgumentException("CharSequences must not be null");
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}
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// fuzzy logic is case insensitive. We normalize the Strings to lower
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// case right from the start. Turning characters to lower case
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// via Character.toLowerCase(char) is unfortunately insufficient
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// as it does not accept a locale.
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final String termLowerCase = term.toString().toLowerCase(locale);
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final String queryLowerCase = query.toString().toLowerCase(locale);
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// the resulting score
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int score = 0;
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// the position in the term which will be scanned next for potential
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// query character matches
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int termIndex = 0;
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// index of the previously matched character in the term
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int previousMatchingCharacterIndex = Integer.MIN_VALUE;
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for (int queryIndex = 0; queryIndex < queryLowerCase.length(); queryIndex++) {
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final char queryChar = queryLowerCase.charAt(queryIndex);
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boolean termCharacterMatchFound = false;
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for (; termIndex < termLowerCase.length()
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&& !termCharacterMatchFound; termIndex++) {
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final char termChar = termLowerCase.charAt(termIndex);
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if (queryChar == termChar) {
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// simple character matches result in one point
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score++;
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// subsequent character matches further improve
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// the score.
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if (previousMatchingCharacterIndex + 1 == termIndex) {
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score += 2;
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}
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previousMatchingCharacterIndex = termIndex;
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// we can leave the nested loop. Every character in the
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// query can match at most one character in the term.
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termCharacterMatchFound = true;
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}
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}
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}
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return score;
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}
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/**
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* Gets the locale.
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*
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* @return The locale
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*/
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public Locale getLocale() {
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return locale;
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}
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}
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