[9649] | 1 | // License: GPL. For details, see LICENSE file.
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| 2 | package org.openstreetmap.josm.data.osm;
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| 3 |
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[10604] | 4 | import java.io.Serializable;
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[9649] | 5 | import java.util.AbstractMap;
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| 6 | import java.util.AbstractSet;
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[10604] | 7 | import java.util.ArrayList;
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[9649] | 8 | import java.util.Arrays;
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[10736] | 9 | import java.util.Collection;
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[9649] | 10 | import java.util.ConcurrentModificationException;
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| 11 | import java.util.Iterator;
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[10604] | 12 | import java.util.List;
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| 13 | import java.util.Map;
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[9649] | 14 | import java.util.NoSuchElementException;
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[11553] | 15 | import java.util.Objects;
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[9649] | 16 | import java.util.Set;
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| 17 |
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| 18 | /**
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| 19 | * This class provides a read/write map that uses the same format as {@link AbstractPrimitive#keys}.
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| 20 | * It offers good performance for few keys.
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| 21 | * It uses copy on write, so there cannot be a {@link ConcurrentModificationException} while iterating through it.
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| 22 | *
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| 23 | * @author Michael Zangl
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| 24 | */
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[10604] | 25 | public class TagMap extends AbstractMap<String, String> implements Serializable {
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| 26 | static final long serialVersionUID = 1;
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[9649] | 27 | /**
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| 28 | * We use this array every time we want to represent an empty map.
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| 29 | * This saves us the burden of checking for null every time but saves some object allocations.
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| 30 | */
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| 31 | private static final String[] EMPTY_TAGS = new String[0];
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| 32 |
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| 33 | /**
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| 34 | * An iterator that iterates over the tags in this map. The iterator always represents the state of the map when it was created.
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| 35 | * Further changes to the map won't change the tags that we iterate over but they also won't raise any exceptions.
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| 36 | * @author Michael Zangl
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| 37 | */
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| 38 | private static class TagEntryInterator implements Iterator<Entry<String, String>> {
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| 39 | /**
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| 40 | * The current state of the tags we iterate over.
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| 41 | */
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| 42 | private final String[] tags;
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| 43 | /**
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| 44 | * Current tag index. Always a multiple of 2.
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| 45 | */
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[9978] | 46 | private int currentIndex;
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[9649] | 47 |
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| 48 | /**
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| 49 | * Create a new {@link TagEntryInterator}
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| 50 | * @param tags The tags array. It is never changed but should also not be changed by you.
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| 51 | */
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[11747] | 52 | TagEntryInterator(String... tags) {
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[9649] | 53 | super();
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| 54 | this.tags = tags;
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| 55 | }
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| 56 |
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| 57 | @Override
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| 58 | public boolean hasNext() {
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| 59 | return currentIndex < tags.length;
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| 60 | }
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| 61 |
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| 62 | @Override
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| 63 | public Entry<String, String> next() {
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| 64 | if (!hasNext()) {
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| 65 | throw new NoSuchElementException();
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| 66 | }
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| 67 |
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| 68 | Tag tag = new Tag(tags[currentIndex], tags[currentIndex + 1]);
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| 69 | currentIndex += 2;
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| 70 | return tag;
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| 71 | }
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| 72 |
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| 73 | @Override
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| 74 | public void remove() {
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| 75 | throw new UnsupportedOperationException();
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| 76 | }
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| 77 |
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| 78 | }
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| 79 |
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| 80 | /**
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| 81 | * This is the entry set of this map. It represents the state when it was created.
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| 82 | * @author Michael Zangl
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| 83 | */
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| 84 | private static class TagEntrySet extends AbstractSet<Entry<String, String>> {
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| 85 | private final String[] tags;
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| 86 |
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| 87 | /**
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| 88 | * Create a new {@link TagEntrySet}
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| 89 | * @param tags The tags array. It is never changed but should also not be changed by you.
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| 90 | */
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[11747] | 91 | TagEntrySet(String... tags) {
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[9649] | 92 | super();
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| 93 | this.tags = tags;
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| 94 | }
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| 95 |
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| 96 | @Override
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| 97 | public Iterator<Entry<String, String>> iterator() {
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| 98 | return new TagEntryInterator(tags);
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| 99 | }
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| 100 |
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| 101 | @Override
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| 102 | public int size() {
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| 103 | return tags.length / 2;
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| 104 | }
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| 105 |
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| 106 | }
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| 107 |
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| 108 | /**
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| 109 | * The tags field. This field is guarded using RCU.
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| 110 | */
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| 111 | private volatile String[] tags;
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| 112 |
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| 113 | /**
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| 114 | * Creates a new, empty tag map.
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| 115 | */
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| 116 | public TagMap() {
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[10604] | 117 | this((String[]) null);
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[9649] | 118 | }
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| 119 |
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| 120 | /**
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[10604] | 121 | * Create a new tag map and load it from the other map.
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| 122 | * @param tags The map to load from.
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| 123 | * @since 10604
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| 124 | */
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| 125 | public TagMap(Map<String, String> tags) {
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| 126 | putAll(tags);
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| 127 | }
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| 128 |
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| 129 | /**
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| 130 | * Copy constructor.
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| 131 | * @param tagMap The map to copy from.
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| 132 | * @since 10604
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| 133 | */
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| 134 | public TagMap(TagMap tagMap) {
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| 135 | this(tagMap.tags);
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| 136 | }
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| 137 |
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| 138 | /**
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[9649] | 139 | * Creates a new read only tag map using a key/value/key/value/... array.
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| 140 | * <p>
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| 141 | * The array that is passed as parameter may not be modified after passing it to this map.
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| 142 | * @param tags The tags array. It is not modified by this map.
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| 143 | */
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[11747] | 144 | public TagMap(String... tags) {
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[9649] | 145 | if (tags == null || tags.length == 0) {
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| 146 | this.tags = EMPTY_TAGS;
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| 147 | } else {
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| 148 | if (tags.length % 2 != 0) {
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| 149 | throw new IllegalArgumentException("tags array length needs to be multiple of two.");
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| 150 | }
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| 151 | this.tags = tags;
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| 152 | }
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| 153 | }
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| 154 |
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[10736] | 155 | /**
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| 156 | * Creates a new map using the given list of tags. For dupplicate keys the last value found is used.
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| 157 | * @param tags The tags
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| 158 | * @since 10736
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| 159 | */
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| 160 | public TagMap(Collection<Tag> tags) {
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| 161 | for (Tag tag : tags) {
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| 162 | put(tag.getKey(), tag.getValue());
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| 163 | }
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| 164 | }
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| 165 |
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[9649] | 166 | @Override
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| 167 | public Set<Entry<String, String>> entrySet() {
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| 168 | return new TagEntrySet(tags);
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| 169 | }
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| 170 |
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| 171 | @Override
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| 172 | public boolean containsKey(Object key) {
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| 173 | return indexOfKey(tags, key) >= 0;
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| 174 | }
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| 175 |
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| 176 | @Override
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| 177 | public String get(Object key) {
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| 178 | String[] tags = this.tags;
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| 179 | int index = indexOfKey(tags, key);
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| 180 | return index < 0 ? null : tags[index + 1];
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| 181 | }
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| 182 |
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| 183 | @Override
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| 184 | public boolean containsValue(Object value) {
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| 185 | String[] tags = this.tags;
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| 186 | for (int i = 1; i < tags.length; i += 2) {
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| 187 | if (value.equals(tags[i])) {
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| 188 | return true;
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| 189 | }
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| 190 | }
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| 191 | return false;
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| 192 | }
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| 193 |
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| 194 | @Override
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| 195 | public synchronized String put(String key, String value) {
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[11553] | 196 | Objects.requireNonNull(key);
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| 197 | Objects.requireNonNull(value);
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[9649] | 198 | int index = indexOfKey(tags, key);
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| 199 | int newTagArrayLength = tags.length;
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| 200 | if (index < 0) {
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| 201 | index = newTagArrayLength;
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| 202 | newTagArrayLength += 2;
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| 203 | }
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| 204 |
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| 205 | String[] newTags = Arrays.copyOf(tags, newTagArrayLength);
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| 206 | String old = newTags[index + 1];
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| 207 | newTags[index] = key;
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| 208 | newTags[index + 1] = value;
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| 209 | tags = newTags;
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| 210 | return old;
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| 211 | }
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| 212 |
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| 213 | @Override
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| 214 | public synchronized String remove(Object key) {
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| 215 | int index = indexOfKey(tags, key);
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| 216 | if (index < 0) {
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| 217 | return null;
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| 218 | }
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| 219 | String old = tags[index + 1];
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| 220 | int newLength = tags.length - 2;
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| 221 | if (newLength == 0) {
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| 222 | tags = EMPTY_TAGS;
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| 223 | } else {
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| 224 | String[] newTags = new String[newLength];
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| 225 | System.arraycopy(tags, 0, newTags, 0, index);
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| 226 | System.arraycopy(tags, index + 2, newTags, index, newLength - index);
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| 227 | tags = newTags;
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| 228 | }
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| 229 |
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| 230 | return old;
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| 231 | }
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| 232 |
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| 233 | @Override
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| 234 | public synchronized void clear() {
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| 235 | tags = EMPTY_TAGS;
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| 236 | }
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| 237 |
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| 238 | @Override
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| 239 | public int size() {
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| 240 | return tags.length / 2;
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| 241 | }
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| 242 |
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| 243 | /**
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[10604] | 244 | * Gets a list of all tags contained in this map.
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| 245 | * @return The list of tags in the order they were added.
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| 246 | * @since 10604
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| 247 | */
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| 248 | public List<Tag> getTags() {
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| 249 | List<Tag> tagList = new ArrayList<>();
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| 250 | for (int i = 0; i < tags.length; i += 2) {
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| 251 | tagList.add(new Tag(tags[i], tags[i+1]));
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| 252 | }
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| 253 | return tagList;
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| 254 | }
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| 255 |
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| 256 | /**
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[9649] | 257 | * Finds a key in an array that is structured like the {@link #tags} array and returns the position.
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| 258 | * <p>
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| 259 | * We allow the parameter to be passed to allow for better synchronization.
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| 260 | *
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| 261 | * @param tags The tags array to search through.
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| 262 | * @param key The key to search.
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| 263 | * @return The index of the key (a multiple of two) or -1 if it was not found.
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| 264 | */
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| 265 | private static int indexOfKey(String[] tags, Object key) {
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| 266 | for (int i = 0; i < tags.length; i += 2) {
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| 267 | if (tags[i].equals(key)) {
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| 268 | return i;
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| 269 | }
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| 270 | }
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| 271 | return -1;
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| 272 | }
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| 273 |
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| 274 | @Override
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| 275 | public String toString() {
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| 276 | StringBuilder stringBuilder = new StringBuilder();
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| 277 | stringBuilder.append("TagMap[");
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| 278 | boolean first = true;
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[10755] | 279 | for (Map.Entry<String, String> e : entrySet()) {
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[9649] | 280 | if (!first) {
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[9969] | 281 | stringBuilder.append(',');
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[9649] | 282 | }
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| 283 | stringBuilder.append(e.getKey());
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[9969] | 284 | stringBuilder.append('=');
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[9649] | 285 | stringBuilder.append(e.getValue());
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| 286 | first = false;
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| 287 | }
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[9969] | 288 | stringBuilder.append(']');
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[9649] | 289 | return stringBuilder.toString();
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| 290 | }
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| 291 |
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| 292 | /**
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| 293 | * Gets the backing tags array. Do not modify this array.
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| 294 | * @return The tags array.
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| 295 | */
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| 296 | String[] getTagsArray() {
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| 297 | return tags;
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| 298 | }
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| 299 | }
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