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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4 | import java.util.AbstractSet;
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5 | import java.util.Collection;
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6 | import java.util.ConcurrentModificationException;
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7 | import java.util.Iterator;
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8 | import java.util.Map;
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9 | import java.util.NoSuchElementException;
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10 | import java.util.Set;
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11 |
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12 | import org.openstreetmap.josm.tools.Utils;
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13 |
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14 | /**
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15 | * A Set-like class that allows looking up equivalent preexising instance.
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16 | * It is useful whereever one would use self-mapping construct like
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17 | * <code>Map<T,T>.put(t,t)</code>, that is, for caches, uniqueness filters or similar.
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18 | *
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19 | * The semantics of equivalency can be external to the object, using the
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20 | * {@link Hash} interface. The set also supports querying for entries using
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21 | * different key type, in case you can provide a Hash implementation
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22 | * that can resolve the equality.
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23 | *
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24 | * <h2>Examples</h2>
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25 | * <ul><li>A String cache:
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26 | * <pre>
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27 | * Storage<String> cache = new Storage(); // use default Hash
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28 | * for (String input : data) {
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29 | * String onlyOne = cache.putIfUnique(input);
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30 | * ....
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31 | * }
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32 | * </pre></li>
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33 | * <li>Identity-based set:
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34 | * <pre>
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35 | * Storage<Object> identity = new Storage(new Hash<Object,Object> {
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36 | * public int getHashCode(Object o) {
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37 | * return System.identityHashCode(o);
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38 | * }
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39 | * public boolean equals(Object o1, Object o2) {
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40 | * return o1 == o2;
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41 | * }
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42 | * });
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43 | * </pre></li>
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44 | * <li>An object with int ID and id-based lookup:
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45 | * <pre>
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46 | * class Thing { int id; }
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47 | * Storage<Thing> things = new Storage(new Hash<Thing,Thing>() {
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48 | * public int getHashCode(Thing t) {
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49 | * return t.id;
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50 | * }
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51 | * public boolean equals(Thing t1, Thing t2) {
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52 | * return t1 == t2;
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53 | * }
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54 | * });
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55 | * Map<Integer,Thing> fk = things.foreignKey(new Hash<Integer,Thing>() {
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56 | * public int getHashCode(Integer i) {
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57 | * return i.getIntValue();
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58 | * }
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59 | * public boolean equals(Integer k, Thing t) {
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60 | * return t.id == k.getIntvalue();
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61 | * }
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62 | * }
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63 | *
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64 | * things.put(new Thing(3));
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65 | * assert things.get(new Thing(3)) == fk.get(3);
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66 | * </pre></li>
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67 | * </ul>
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68 | *
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69 | * @author nenik
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70 | * @param <T> type of stored objects
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71 | */
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72 | public class Storage<T> extends AbstractSet<T> {
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73 |
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74 | public static class PrimitiveIdHash implements Hash<PrimitiveId, PrimitiveId> {
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75 |
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76 | @Override
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77 | public int getHashCode(PrimitiveId k) {
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78 | return (int) k.getUniqueId() ^ k.getType().hashCode();
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79 | }
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80 |
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81 | @Override
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82 | public boolean equals(PrimitiveId key, PrimitiveId value) {
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83 | if (key == null || value == null) return false;
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84 | return key.getUniqueId() == value.getUniqueId() && key.getType() == value.getType();
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85 | }
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86 | }
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87 |
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88 | private final Hash<? super T, ? super T> hash;
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89 | private T[] data;
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90 | private int mask;
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91 | private int size;
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92 | private volatile int modCount;
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93 | private static final double LOAD_FACTOR = 0.6d;
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94 | private static final int DEFAULT_CAPACITY = 16;
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95 | private final boolean safeIterator;
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96 | private boolean arrayCopyNecessary;
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97 |
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98 | /**
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99 | * Constructs a new {@code Storage} with default capacity (16).
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100 | */
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101 | public Storage() {
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102 | this(Storage.<T>defaultHash(), DEFAULT_CAPACITY, false);
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103 | }
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104 |
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105 | /**
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106 | * Constructs a new {@code Storage} with given capacity.
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107 | * @param capacity capacity
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108 | */
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109 | public Storage(int capacity) {
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110 | this(Storage.<T>defaultHash(), capacity, false);
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111 | }
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112 |
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113 | public Storage(Hash<? super T, ? super T> ha) {
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114 | this(ha, DEFAULT_CAPACITY, false);
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115 | }
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116 |
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117 | public Storage(boolean safeIterator) {
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118 | this(Storage.<T>defaultHash(), DEFAULT_CAPACITY, safeIterator);
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119 | }
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120 |
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121 | public Storage(int capacity, boolean safeIterator) {
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122 | this(Storage.<T>defaultHash(), capacity, safeIterator);
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123 | }
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124 |
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125 | public Storage(Hash<? super T, ? super T> ha, boolean safeIterator) {
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126 | this(ha, DEFAULT_CAPACITY, safeIterator);
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127 | }
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128 |
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129 | public Storage(Hash<? super T, ? super T> ha, int capacity) {
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130 | this(ha, capacity, false);
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131 | }
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132 |
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133 | /**
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134 | * constructor
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135 | * @param ha hash
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136 | * @param capacity capacity
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137 | * @param safeIterator If set to false, you must not modify the Storage
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138 | * while iterating over it. If set to true, you can safely
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139 | * modify, but the read-only iteration will happen on a copy
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140 | * of the unmodified Storage.
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141 | * This is similar to CopyOnWriteArrayList.
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142 | */
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143 | public Storage(Hash<? super T, ? super T> ha, int capacity, boolean safeIterator) {
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144 | this.hash = ha;
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145 | int cap = 1 << (int) (Math.ceil(Math.log(capacity/LOAD_FACTOR) / Math.log(2)));
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146 | @SuppressWarnings("unchecked")
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147 | T[] newData = (T[]) new Object[cap];
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148 | data = newData;
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149 | mask = data.length - 1;
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150 | this.safeIterator = safeIterator;
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151 | }
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152 |
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153 | private void copyArray() {
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154 | if (arrayCopyNecessary) {
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155 | data = Utils.copyArray(data);
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156 | arrayCopyNecessary = false;
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157 | }
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158 | }
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159 |
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160 | // --------------- Collection implementation ------------------------
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161 | @Override
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162 | public synchronized int size() {
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163 | return size;
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164 | }
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165 |
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166 | @Override
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167 | public synchronized Iterator<T> iterator() {
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168 | if (safeIterator) {
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169 | arrayCopyNecessary = true;
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170 | return new SafeReadonlyIter(data);
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171 | } else
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172 | return new Iter();
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173 |
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174 | }
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175 |
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176 | @Override
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177 | public synchronized boolean contains(Object o) {
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178 | @SuppressWarnings("unchecked")
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179 | T t = (T) o;
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180 | int bucket = getBucket(hash, t);
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181 | return bucket >= 0;
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182 | }
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183 |
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184 | @Override
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185 | public synchronized boolean add(T t) {
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186 | T orig = putUnique(t);
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187 | return orig == t;
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188 | }
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189 |
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190 | @Override
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191 | public synchronized boolean remove(Object o) {
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192 | @SuppressWarnings("unchecked")
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193 | T t = (T) o;
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194 | T tOrig = removeElem(t);
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195 | return tOrig != null;
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196 | }
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197 |
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198 | @Override
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199 | public synchronized void clear() {
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200 | copyArray();
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201 | modCount++;
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202 | size = 0;
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203 | for (int i = 0; i < data.length; i++) {
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204 | data[i] = null;
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205 | }
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206 | }
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207 |
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208 | @Override
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209 | public synchronized int hashCode() {
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210 | int h = 0;
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211 | for (T t : this) {
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212 | h += hash.getHashCode(t);
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213 | }
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214 | return h;
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215 | }
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216 |
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217 | // ----------------- Extended API ----------------------------
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218 |
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219 | public synchronized T put(T t) {
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220 | copyArray();
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221 | modCount++;
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222 | ensureSpace();
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223 |
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224 | int bucket = getBucket(hash, t);
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225 | if (bucket < 0) {
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226 | size++;
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227 | bucket = ~bucket;
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228 | assert data[bucket] == null;
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229 | }
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230 |
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231 | T old = data[bucket];
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232 | data[bucket] = t;
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233 |
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234 | return old;
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235 | }
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236 |
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237 | public synchronized T get(T t) {
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238 | int bucket = getBucket(hash, t);
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239 | return bucket < 0 ? null : data[bucket];
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240 | }
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241 |
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242 | public synchronized T putUnique(T t) {
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243 | copyArray();
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244 | modCount++;
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245 | ensureSpace();
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246 |
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247 | int bucket = getBucket(hash, t);
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248 | if (bucket < 0) { // unique
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249 | size++;
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250 | assert data[~bucket] == null;
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251 | data[~bucket] = t;
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252 | return t;
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253 | }
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254 |
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255 | return data[bucket];
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256 | }
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257 |
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258 | public synchronized T removeElem(T t) {
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259 | copyArray();
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260 | modCount++;
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261 | int bucket = getBucket(hash, t);
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262 | return bucket < 0 ? null : doRemove(bucket);
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263 | }
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264 |
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265 | public <K> Map<K, T> foreignKey(Hash<K, ? super T> h) {
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266 | return new FMap<>(h);
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267 | }
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268 |
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269 | // ---------------- Implementation
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270 |
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271 | /**
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272 | * Additional mixing of hash
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273 | * @param h hash
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274 | * @return new hash
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275 | */
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276 | private static int rehash(int h) {
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277 | return (1_103_515_245*h) >> 2;
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278 | }
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279 |
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280 | /**
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281 | * Finds a bucket for given key.
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282 | * @param <K> type for hashCode and first equals parameter
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283 | * @param ha hash function
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284 | *
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285 | * @param key The key to compare
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286 | * @return the bucket equivalent to the key or -(bucket) as an empty slot
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287 | * where such an entry can be stored.
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288 | */
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289 | private <K> int getBucket(Hash<K, ? super T> ha, K key) {
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290 | T entry;
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291 | int hcode = rehash(ha.getHashCode(key));
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292 | int bucket = hcode & mask;
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293 | while ((entry = data[bucket]) != null) {
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294 | if (ha.equals(key, entry))
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295 | return bucket;
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296 | bucket = (bucket+1) & mask;
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297 | }
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298 | return ~bucket;
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299 | }
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300 |
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301 | private T doRemove(int slot) {
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302 | T t = data[slot];
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303 | assert t != null;
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304 |
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305 | fillTheHole(slot); // fill the hole (or null it)
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306 | size--;
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307 | return t;
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308 | }
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309 |
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310 | private void fillTheHole(int hole) {
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311 | int bucket = (hole+1) & mask;
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312 | T entry;
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313 |
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314 | while ((entry = data[bucket]) != null) {
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315 | int right = rehash(hash.getHashCode(entry)) & mask;
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316 | // if the entry should be in <hole+1,bucket-1> (circular-wise)
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317 | // we can't move it. The move can be proved safe otherwise,
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318 | // because the entry safely belongs to <previous_null+1,hole>
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319 | if ((bucket < right && (right <= hole || hole <= bucket)) ||
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320 | (right <= hole && hole <= bucket)) {
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321 |
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322 | data[hole] = data[bucket];
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323 | hole = bucket;
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324 | }
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325 | bucket = (bucket+1) & mask;
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326 | }
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327 |
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328 | // no entry belongs here, just null out the slot
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329 | data[hole] = null;
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330 | }
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331 |
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332 | private void ensureSpace() {
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333 | if (size > data.length*LOAD_FACTOR) { // rehash
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334 | @SuppressWarnings("unchecked")
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335 | T[] big = (T[]) new Object[data.length * 2];
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336 | int nMask = big.length - 1;
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337 |
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338 | for (T o : data) {
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339 | if (o == null) {
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340 | continue;
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341 | }
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342 | int bucket = rehash(hash.getHashCode(o)) & nMask;
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343 | while (big[bucket] != null) {
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344 | bucket = (bucket+1) & nMask;
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345 | }
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346 | big[bucket] = o;
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347 | }
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348 |
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349 | data = big;
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350 | mask = nMask;
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351 | }
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352 | }
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353 |
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354 | // -------------- factories --------------------
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355 | /**
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356 | * A factory for default hash implementation.
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357 | * @param <O> type for hash
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358 | * @return a hash implementation that just delegates to object's own hashCode and equals.
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359 | */
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360 | public static <O> Hash<O, O> defaultHash() {
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361 | return new Hash<O, O>() {
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362 | @Override
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363 | public int getHashCode(O t) {
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364 | return t.hashCode();
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365 | }
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366 |
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367 | @Override
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368 | public boolean equals(O t1, O t2) {
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369 | return t1.equals(t2);
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370 | }
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371 | };
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372 | }
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373 |
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374 | private final class FMap<K> implements Map<K, T> {
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375 | private final Hash<K, ? super T> fHash;
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376 |
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377 | private FMap(Hash<K, ? super T> h) {
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378 | fHash = h;
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379 | }
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380 |
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381 | @Override
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382 | public int size() {
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383 | return Storage.this.size();
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384 | }
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385 |
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386 | @Override
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387 | public boolean isEmpty() {
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388 | return Storage.this.isEmpty();
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389 | }
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390 |
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391 | @Override
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392 | public boolean containsKey(Object o) {
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393 | @SuppressWarnings("unchecked")
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394 | K key = (K) o;
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395 | int bucket = getBucket(fHash, key);
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396 | return bucket >= 0;
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397 | }
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398 |
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399 | @Override
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400 | public boolean containsValue(Object value) {
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401 | return Storage.this.contains(value);
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402 | }
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403 |
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404 | @Override
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405 | public T get(Object o) {
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406 | @SuppressWarnings("unchecked")
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407 | K key = (K) o;
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408 | int bucket = getBucket(fHash, key);
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409 | return bucket < 0 ? null : data[bucket];
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410 | }
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411 |
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412 | @Override
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413 | public T put(K key, T value) {
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414 | if (!fHash.equals(key, value)) throw new IllegalArgumentException("inconsistent key");
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415 | return Storage.this.put(value);
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416 | }
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417 |
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418 | @Override
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419 | public T remove(Object o) {
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420 | synchronized (Storage.this) {
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421 | modCount++;
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422 | @SuppressWarnings("unchecked")
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423 | K key = (K) o;
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424 | int bucket = getBucket(fHash, key);
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425 |
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426 | return bucket < 0 ? null : doRemove(bucket);
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427 | }
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428 | }
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429 |
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430 | @Override
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431 | public void putAll(Map<? extends K, ? extends T> m) {
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432 | if (m instanceof Storage.FMap) {
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433 | Storage.this.addAll(m.values());
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434 | } else {
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435 | for (Map.Entry<? extends K, ? extends T> e : m.entrySet()) {
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436 | put(e.getKey(), e.getValue());
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437 | }
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438 | }
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439 | }
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440 |
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441 | @Override
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442 | public void clear() {
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443 | Storage.this.clear();
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444 | }
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445 |
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446 | @Override
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447 | public Set<K> keySet() {
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448 | throw new UnsupportedOperationException();
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449 | }
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450 |
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451 | @Override
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452 | public Collection<T> values() {
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453 | return Storage.this;
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454 | }
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455 |
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456 | @Override
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457 | public Set<Entry<K, T>> entrySet() {
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458 | throw new UnsupportedOperationException();
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459 | }
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460 | }
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461 |
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462 | private final class SafeReadonlyIter implements Iterator<T> {
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463 | private final T[] data;
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464 | private int slot;
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465 |
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466 | SafeReadonlyIter(T[] data) {
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467 | this.data = data;
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468 | }
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469 |
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470 | @Override
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471 | public boolean hasNext() {
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472 | align();
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473 | return slot < data.length;
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474 | }
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475 |
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476 | @Override
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477 | public T next() {
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478 | if (!hasNext()) throw new NoSuchElementException();
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479 | return data[slot++];
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480 | }
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481 |
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482 | @Override
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483 | public void remove() {
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484 | throw new UnsupportedOperationException();
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485 | }
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486 |
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487 | private void align() {
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488 | while (slot < data.length && data[slot] == null) {
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489 | slot++;
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490 | }
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491 | }
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492 | }
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493 |
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494 | private final class Iter implements Iterator<T> {
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495 | private final int mods;
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496 | private int slot;
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497 | private int removeSlot = -1;
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498 |
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499 | Iter() {
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500 | mods = modCount;
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501 | }
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502 |
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503 | @Override
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504 | public boolean hasNext() {
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505 | align();
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506 | return slot < data.length;
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507 | }
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508 |
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509 | @Override
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510 | public T next() {
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511 | if (!hasNext()) throw new NoSuchElementException();
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512 | removeSlot = slot;
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513 | return data[slot++];
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514 | }
|
---|
515 |
|
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516 | @Override
|
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517 | public void remove() {
|
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518 | if (removeSlot == -1) throw new IllegalStateException();
|
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519 |
|
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520 | doRemove(removeSlot);
|
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521 | slot = removeSlot; // some entry might have been relocated here
|
---|
522 | removeSlot = -1;
|
---|
523 | }
|
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524 |
|
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525 | private void align() {
|
---|
526 | if (mods != modCount)
|
---|
527 | throw new ConcurrentModificationException();
|
---|
528 | while (slot < data.length && data[slot] == null) {
|
---|
529 | slot++;
|
---|
530 | }
|
---|
531 | }
|
---|
532 | }
|
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533 |
|
---|
534 | }
|
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