forked from D-Net/dnet-hadoop
131 lines
3.8 KiB
Java
131 lines
3.8 KiB
Java
/*
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* This file is part of CoAnSys project.
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* Copyright (c) 2012-2015 ICM-UW
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*
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* CoAnSys is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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* CoAnSys is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with CoAnSys. If not, see <http://www.gnu.org/licenses/>.
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*/
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package eu.dnetlib.dhp.common.string;
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import java.io.Serializable;
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import java.util.List;
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import org.apache.commons.lang3.StringUtils;
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import com.google.common.collect.ImmutableList;
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/**
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* An implementation of {@link StringNormalizer} that normalizes strings for non-strict comparisons
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* in which one does not care about characters other than letters and digits or about differently written diacritics.
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*
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* @author Łukasz Dumiszewski
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*
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*/
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public final class LenientComparisonStringNormalizer implements StringNormalizer, Serializable {
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private static final long serialVersionUID = 1L;
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private List<Character> whitelistCharacters;
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//------------------------ CONSTRUCTORS --------------------------
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public LenientComparisonStringNormalizer() {
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this(ImmutableList.of());
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}
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/**
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* @param whitelistCharacters - non alphanumeric characters that will not be removed
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* during normalization
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*/
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public LenientComparisonStringNormalizer(List<Character> whitelistCharacters) {
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this.whitelistCharacters = whitelistCharacters;
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}
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//------------------------ LOGIC --------------------------
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/**
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* Normalizes the given value. <br/>
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* The normalized strings are better suited for non-strict comparisons, in which one does NOT care about characters that are
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* neither letters nor digits; about accidental spaces or different diacritics etc. <br/><br/>
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* This method:
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* <ul>
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* <li>Replaces all characters that are not letters or digits with spaces (except those on whitelist characters list)</li>
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* <li>Replaces white spaces with spaces </li>
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* <li>Trims</li>
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* <li>Compacts multi-space gaps to one-space gaps</li>
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* <li>Removes diacritics</li>
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* <li>Changes characters to lower case</li>
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* </ul>
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* Returns "" if the passed value is null or blank
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*
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* @param value the string to normalize
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* @see DiacriticsRemover#removeDiacritics(String, boolean)
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*
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*
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*/
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public String normalize(String value) {
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if (StringUtils.isBlank(value)) {
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return "";
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}
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String result = value;
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result = DiacriticsRemover.removeDiacritics(result);
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result = removeNonLetterDigitCharacters(result);
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result = result.toLowerCase();
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result = result.trim().replaceAll(" +", " ");
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return result;
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}
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//------------------------ PRIVATE --------------------------
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private String removeNonLetterDigitCharacters(final String value) {
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StringBuilder sb = new StringBuilder();
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for (int i = 0; i < value.length(); ++i) {
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char c = value.charAt(i);
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if (Character.isLetterOrDigit(c) || whitelistCharacters.contains(c)) {
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sb.append(c);
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} else {
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sb.append(' ');
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}
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}
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return sb.toString();
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}
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}
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