Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||||||
MultiKey |
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| 4.857142857142857;4.857 |
1 | // Copyright 2004, 2005 The Apache Software Foundation |
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2 | // |
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3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
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4 | // you may not use this file except in compliance with the License. |
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5 | // You may obtain a copy of the License at |
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6 | // |
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7 | // http://www.apache.org/licenses/LICENSE-2.0 |
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8 | // |
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9 | // Unless required by applicable law or agreed to in writing, software |
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10 | // distributed under the License is distributed on an "AS IS" BASIS, |
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11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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12 | // See the License for the specific language governing permissions and |
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13 | // limitations under the License. |
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14 | ||
15 | package org.apache.tapestry.util; |
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16 | ||
17 | import org.apache.tapestry.Tapestry; |
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18 | ||
19 | import java.io.Externalizable; |
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20 | import java.io.IOException; |
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21 | import java.io.ObjectInput; |
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22 | import java.io.ObjectOutput; |
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23 | ||
24 | /** |
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25 | * A complex key that may be used as an alternative to nested {@link java.util.Map}s. |
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26 | * |
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27 | * @author Howard Lewis Ship |
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28 | */ |
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29 | ||
30 | public class MultiKey implements Externalizable |
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31 | { |
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32 | ||
33 | /** |
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34 | * @since 2.0.4 |
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35 | */ |
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36 | ||
37 | private static final long serialVersionUID = 4465448607415788806L; |
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38 | ||
39 | private static final int HASH_CODE_UNSET = -1; |
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40 | ||
41 | 0 | private transient int hashCode = HASH_CODE_UNSET; |
42 | ||
43 | private Object[] _keys; |
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44 | ||
45 | /** |
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46 | * Public no-arguments constructor needed to be compatible with |
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47 | * {@link Externalizable}; this leaves the new MultiKey in a non-usable |
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48 | * state and shouldn't be used by user code. |
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49 | */ |
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50 | ||
51 | public MultiKey() |
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52 | 0 | { |
53 | 0 | } |
54 | ||
55 | /** |
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56 | * Builds a <code>MultiKey</code> from an array of keys. If the array is |
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57 | * not copied, then it must not be modified. |
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58 | * |
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59 | * @param keys |
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60 | * The components of the key. |
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61 | * @param makeCopy |
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62 | * If true, a copy of the keys is created. If false, the keys are |
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63 | * simple retained by the <code>MultiKey</code>. |
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64 | * @throws IllegalArgumentException |
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65 | * if keys is null, of if the first element of keys is null. |
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66 | */ |
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67 | ||
68 | public MultiKey(Object[] keys, boolean makeCopy) |
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69 | { |
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70 | 0 | super(); |
71 | ||
72 | 0 | if (keys == null || keys.length == 0) |
73 | 0 | throw new IllegalArgumentException(Tapestry.getMessage("MultiKey.null-keys")); |
74 | ||
75 | 0 | if (keys[0] == null) |
76 | 0 | throw new IllegalArgumentException(Tapestry.getMessage("MultiKey.first-element-may-not-be-null")); |
77 | ||
78 | 0 | if (makeCopy) |
79 | { |
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80 | 0 | _keys = new Object[keys.length]; |
81 | 0 | System.arraycopy(keys, 0, this._keys, 0, keys.length); |
82 | } |
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83 | else |
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84 | 0 | _keys = keys; |
85 | 0 | } |
86 | ||
87 | /** |
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88 | * Returns true if. : |
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89 | * <ul> |
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90 | * <li>The other object is a <code>MultiKey</code> |
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91 | * <li>They have the same number of key elements |
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92 | * <li>Every element is an exact match or is equal |
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93 | * </ul> |
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94 | */ |
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95 | ||
96 | public boolean equals(Object other) |
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97 | { |
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98 | int i; |
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99 | ||
100 | 0 | if (other == null) |
101 | 0 | return false; |
102 | ||
103 | 0 | if (_keys == null) |
104 | 0 | throw new IllegalStateException(Tapestry.getMessage("MultiKey.no-keys")); |
105 | ||
106 | // Would a hashCode check be worthwhile here? |
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107 | ||
108 | try |
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109 | { |
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110 | 0 | MultiKey otherMulti = (MultiKey) other; |
111 | ||
112 | 0 | if (_keys.length != otherMulti._keys.length) return false; |
113 | ||
114 | 0 | for(i = 0; i < _keys.length; i++) |
115 | { |
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116 | // On an exact match, continue. This means that null matches |
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117 | // null. |
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118 | ||
119 | 0 | if (_keys[i] == otherMulti._keys[i]) |
120 | 0 | continue; |
121 | ||
122 | // If either is null, but not both, then |
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123 | // not a match. |
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124 | ||
125 | 0 | if (_keys[i] == null || otherMulti._keys[i] == null) |
126 | 0 | return false; |
127 | ||
128 | 0 | if (!_keys[i].equals(otherMulti._keys[i])) |
129 | 0 | return false; |
130 | } |
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131 | ||
132 | // Every key equal. A match. |
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133 | ||
134 | 0 | return true; |
135 | } |
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136 | 0 | catch (ClassCastException e) |
137 | { |
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138 | } |
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139 | ||
140 | 0 | return false; |
141 | } |
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142 | ||
143 | /** |
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144 | * Returns the hash code of the receiver, which is computed from all the |
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145 | * non-null key elements. This value is computed once and then cached, so |
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146 | * elements should not change their hash codes once created (note that this |
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147 | * is the same constraint that would be used if the individual key elements |
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148 | * were themselves {@link java.util.Map} keys. |
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149 | */ |
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150 | ||
151 | public int hashCode() |
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152 | { |
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153 | 0 | if (hashCode == HASH_CODE_UNSET) |
154 | { |
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155 | 0 | hashCode = _keys[0].hashCode(); |
156 | ||
157 | 0 | for(int i = 1; i < _keys.length; i++) |
158 | { |
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159 | 0 | if (_keys[i] != null) hashCode ^= _keys[i].hashCode(); |
160 | } |
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161 | } |
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162 | ||
163 | 0 | return hashCode; |
164 | } |
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165 | ||
166 | /** |
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167 | * Identifies all the keys stored by this <code>MultiKey</code>. |
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168 | */ |
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169 | ||
170 | public String toString() |
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171 | { |
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172 | StringBuffer buffer; |
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173 | int i; |
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174 | ||
175 | 0 | buffer = new StringBuffer("MultiKey["); |
176 | ||
177 | 0 | for(i = 0; i < _keys.length; i++) |
178 | { |
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179 | 0 | if (i > 0) buffer.append(", "); |
180 | ||
181 | 0 | if (_keys[i] == null) |
182 | 0 | buffer.append("<null>"); |
183 | 0 | else buffer.append(_keys[i]); |
184 | } |
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185 | ||
186 | 0 | buffer.append(']'); |
187 | ||
188 | 0 | return buffer.toString(); |
189 | } |
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190 | ||
191 | /** |
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192 | * Writes a count of the keys, then writes each individual key. |
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193 | */ |
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194 | ||
195 | public void writeExternal(ObjectOutput out) |
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196 | throws IOException |
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197 | { |
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198 | 0 | out.writeInt(_keys.length); |
199 | ||
200 | 0 | for(int i = 0; i < _keys.length; i++) |
201 | 0 | out.writeObject(_keys[i]); |
202 | 0 | } |
203 | ||
204 | /** |
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205 | * Reads the state previously written by |
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206 | * {@link #writeExternal(ObjectOutput)}. |
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207 | */ |
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208 | ||
209 | public void readExternal(ObjectInput in) |
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210 | throws IOException, ClassNotFoundException |
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211 | { |
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212 | int count; |
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213 | ||
214 | 0 | count = in.readInt(); |
215 | 0 | _keys = new Object[count]; |
216 | ||
217 | 0 | for(int i = 0; i < count; i++) |
218 | 0 | _keys[i] = in.readObject(); |
219 | 0 | } |
220 | } |