1 | // License: GPL. See LICENSE file for details.
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2 | package org.openstreetmap.josm.tools;
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3 |
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4 | import java.util.ArrayList;
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5 | import java.util.Collection;
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6 | import java.util.HashMap;
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7 | import java.util.LinkedHashSet;
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8 | import java.util.List;
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9 | import java.util.Map;
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10 | import java.util.Map.Entry;
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11 | import java.util.Set;
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12 |
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13 | /**
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14 | * MultiMap - maps keys to multiple values
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15 | *
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16 | * Corresponds to Google guava LinkedHashMultimap and Apache Collections MultiValueMap
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17 | * but it is an independent (simple) implementation.
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18 | *
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19 | */
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20 | public class MultiMap<A, B> {
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21 |
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22 | private final Map<A, Set<B>> map;
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23 |
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24 | public MultiMap() {
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25 | map = new HashMap<A, Set<B>>();
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26 | }
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27 |
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28 | public MultiMap(int capacity) {
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29 | map = new HashMap<A, Set<B>>(capacity);
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30 | }
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31 |
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32 | /**
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33 | * Map a key to a value.
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34 | *
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35 | * Can be called multiple times with the same key, but different value.
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36 | */
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37 | public void put(A key, B value) {
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38 | Set<B> vals = map.get(key);
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39 | if (vals == null) {
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40 | vals = new LinkedHashSet<B>();
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41 | map.put(key, vals);
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42 | }
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43 | vals.add(value);
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44 | }
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45 |
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46 | /**
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47 | * Put a key that maps to nothing. (Only if it is not already in the map)
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48 | *
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49 | * Afterwards containsKey(key) will return true and get(key) will return
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50 | * an empty Set instead of null.
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51 | */
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52 | public void putVoid(A key) {
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53 | if (map.containsKey(key))
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54 | return;
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55 | map.put(key, new LinkedHashSet<B>());
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56 | }
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57 |
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58 | /**
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59 | * Map the key to all the given values.
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60 | *
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61 | * Adds to the mappings that are already there.
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62 | */
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63 | public void putAll(A key, Collection<B> values) {
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64 | Set<B> vals = map.get(key);
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65 | if (vals == null) {
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66 | vals = new LinkedHashSet<B>(values);
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67 | map.put(key, vals);
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68 | }
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69 | vals.addAll(values);
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70 | }
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71 |
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72 | /**
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73 | * Get the keySet.
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74 | */
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75 | public Set<A> keySet() {
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76 | return map.keySet();
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77 | }
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78 |
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79 | /**
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80 | * Returns the Set associated with the given key. Result is null if
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81 | * nothing has been mapped to this key.
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82 | *
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83 | * Modifications of the returned list changes the underling map,
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84 | * but you should better not do that.
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85 | */
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86 | public Set<B> get(A key) {
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87 | return map.get(key);
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88 | }
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89 |
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90 | /**
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91 | * Like get, but returns an empty Set if nothing has been mapped to the key.
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92 | */
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93 | public Set<B> getValues(A key) {
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94 | if (!map.containsKey(key))
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95 | return new LinkedHashSet<B>();
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96 | return map.get(key);
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97 | }
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98 |
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99 | public boolean isEmpty() {
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100 | return map.isEmpty();
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101 | }
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102 |
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103 | public boolean containsKey(A key) {
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104 | return map.containsKey(key);
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105 | }
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106 |
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107 | /**
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108 | * Returns true if the multimap contains a value for a key.
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109 | *
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110 | * @param key The key
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111 | * @param value The value
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112 | * @return true if the key contains the value
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113 | */
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114 | public boolean contains(A key, B value) {
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115 | Set<B> values = get(key);
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116 | return (values == null) ? false : values.contains(value);
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117 | }
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118 |
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119 | public void clear() {
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120 | map.clear();
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121 | }
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122 |
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123 | public Set<Entry<A, Set<B>>> entrySet() {
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124 | return map.entrySet();
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125 | }
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126 |
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127 | /**
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128 | * Returns the number of keys.
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129 | */
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130 | public int size() {
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131 | return map.size();
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132 | }
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133 |
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134 | /**
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135 | * Returns a collection of all value sets.
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136 | */
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137 | public Collection<Set<B>> values() {
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138 | return map.values();
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139 | }
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140 |
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141 | /**
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142 | * Removes a cerain key=value mapping.
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143 | *
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144 | * @return true, if something was removed
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145 | */
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146 | public boolean remove(A key, B value) {
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147 | Set<B> values = get(key);
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148 | if (values != null) {
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149 | return values.remove(value);
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150 | }
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151 | return false;
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152 | }
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153 |
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154 | /**
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155 | * Removes all mappings for a certain key.
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156 | */
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157 | public Set<B> remove(A key) {
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158 | return map.remove(key);
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159 | }
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160 |
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161 | @Override
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162 | public String toString() {
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163 | List<String> entries = new ArrayList<String>(map.size());
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164 | for (A key : map.keySet()) {
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165 | entries.add(key + "->{" + Utils.join(",", map.get(key)) + "}");
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166 | }
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167 | return "(" + Utils.join(",", entries) + ")";
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168 | }
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169 | }
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