[8378] | 1 | // License: GPL. For details, see LICENSE file.
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[5083] | 2 | package org.openstreetmap.josm.tools;
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| 3 |
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| 4 | /*
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| 5 | * The Alphanum Algorithm is an improved sorting algorithm for strings
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| 6 | * containing numbers. Instead of sorting numbers in ASCII order like a standard
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| 7 | * sort, this algorithm sorts numbers in numeric order.
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| 8 | *
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| 9 | * The Alphanum Algorithm is discussed at http://www.DaveKoelle.com
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| 10 | *
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| 11 | *
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| 12 | * This library is free software; you can redistribute it and/or modify it under
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| 13 | * the terms of the GNU Lesser General Public License as published by the Free
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| 14 | * Software Foundation; either version 2.1 of the License, or any later version.
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| 15 | *
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| 16 | * This library is distributed in the hope that it will be useful, but WITHOUT
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| 17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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| 18 | * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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| 19 | * details.
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| 20 | *
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| 21 | * You should have received a copy of the GNU Lesser General Public License
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| 22 | * along with this library; if not, write to the Free Software Foundation, Inc.,
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| 23 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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| 24 | *
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| 25 | */
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[8308] | 26 | import java.io.Serializable;
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[6126] | 27 | import java.text.Collator;
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[5083] | 28 | import java.util.Comparator;
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[6126] | 29 | import java.util.Locale;
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[5083] | 30 |
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| 31 | /**
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| 32 | * The Alphanum Algorithm is an improved sorting algorithm for strings
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| 33 | * containing numbers: Instead of sorting numbers in ASCII order like a standard
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| 34 | * sort, this algorithm sorts numbers in numeric order.
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| 35 | *
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| 36 | * The Alphanum Algorithm is discussed at http://www.DaveKoelle.com
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[6070] | 37 | *
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[5083] | 38 | * This is an updated version with enhancements made by Daniel Migowski, Andre
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[6126] | 39 | * Bogus, and David Koelle and others.
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[5083] | 40 | *
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| 41 | */
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[8419] | 42 | public final class AlphanumComparator implements Comparator<String>, Serializable {
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[5083] | 43 |
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[8308] | 44 | private static final long serialVersionUID = 1L;
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| 45 |
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[6804] | 46 | private static final AlphanumComparator INSTANCE = new AlphanumComparator();
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| 47 |
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[6985] | 48 | /**
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| 49 | * Replies the unique instance.
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| 50 | * @return the unique instance
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| 51 | */
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[6804] | 52 | public static AlphanumComparator getInstance() {
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| 53 | return INSTANCE;
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| 54 | }
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| 55 |
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[5083] | 56 | /**
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[6804] | 57 | * Constructs a new Alphanum Comparator.
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| 58 | */
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[6985] | 59 | private AlphanumComparator() {
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[6804] | 60 | }
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| 61 |
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| 62 | /**
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[8928] | 63 | * Returns an alphanum chunk.
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| 64 | * Length of string is passed in for improved efficiency (only need to calculate it once).
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| 65 | * @param s string
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| 66 | * @param slength string length
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| 67 | * @param marker position
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| 68 | * @return alphanum chunk found at given position
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[5083] | 69 | */
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[8870] | 70 | private static String getChunk(String s, int slength, int marker) {
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[5083] | 71 | StringBuilder chunk = new StringBuilder();
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| 72 | char c = s.charAt(marker);
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| 73 | chunk.append(c);
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| 74 | marker++;
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| 75 | if (Character.isDigit(c)) {
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| 76 | while (marker < slength) {
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| 77 | c = s.charAt(marker);
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| 78 | if (!Character.isDigit(c)) {
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| 79 | break;
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| 80 | }
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| 81 | chunk.append(c);
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| 82 | marker++;
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| 83 | }
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| 84 | } else {
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| 85 | while (marker < slength) {
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| 86 | c = s.charAt(marker);
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| 87 | if (Character.isDigit(c)) {
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| 88 | break;
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| 89 | }
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| 90 | chunk.append(c);
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| 91 | marker++;
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| 92 | }
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| 93 | }
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| 94 | return chunk.toString();
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| 95 | }
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| 96 |
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| 97 | @Override
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| 98 | public int compare(String s1, String s2) {
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[5087] | 99 | if (s1 == null && s2 == null) {
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| 100 | return 0;
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| 101 | } else if (s1 == null) {
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| 102 | return -1;
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| 103 | } else if (s2 == null) {
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| 104 | return 1;
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| 105 | }
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| 106 |
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[5083] | 107 | int thisMarker = 0;
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| 108 | int thatMarker = 0;
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| 109 | int s1Length = s1.length();
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| 110 | int s2Length = s2.length();
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| 111 |
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| 112 | while (thisMarker < s1Length && thatMarker < s2Length) {
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| 113 | String thisChunk = getChunk(s1, s1Length, thisMarker);
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| 114 | thisMarker += thisChunk.length();
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| 115 |
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| 116 | String thatChunk = getChunk(s2, s2Length, thatMarker);
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| 117 | thatMarker += thatChunk.length();
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| 118 |
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| 119 | // If both chunks contain numeric characters, sort them numerically
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| 120 | int result;
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| 121 | if (Character.isDigit(thisChunk.charAt(0)) && Character.isDigit(thatChunk.charAt(0))) {
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| 122 | // Simple chunk comparison by length.
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| 123 | int thisChunkLength = thisChunk.length();
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| 124 | result = thisChunkLength - thatChunk.length();
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| 125 | // If equal, the first different number counts
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| 126 | if (result == 0) {
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| 127 | for (int i = 0; i < thisChunkLength; i++) {
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| 128 | result = thisChunk.charAt(i) - thatChunk.charAt(i);
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| 129 | if (result != 0) {
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| 130 | return result;
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| 131 | }
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| 132 | }
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| 133 | }
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| 134 | } else {
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[6126] | 135 | // Instantiate the collator
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| 136 | Collator compareOperator = Collator.getInstance(Locale.getDefault());
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| 137 | // Compare regardless of accented letters
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| 138 | compareOperator.setStrength(Collator.SECONDARY);
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| 139 | result = compareOperator.compare(thisChunk, thatChunk);
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[5083] | 140 | }
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| 141 |
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| 142 | if (result != 0) {
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| 143 | return result;
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| 144 | }
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| 145 | }
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| 146 |
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| 147 | return s1Length - s2Length;
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| 148 | }
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| 149 | }
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