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1 /*******************************************************************************
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2 * Copyright (c) 2008 Matthew Hall and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * Matthew Hall - initial API and implementation (bug 218269)
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10 * Boris Bokowski - bug 218269
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11 ******************************************************************************/
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12
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13 module org.eclipse.core.databinding.validation.MultiValidator;
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14
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15 import java.lang.all;
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16
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17 import java.util.ArrayList;
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18 import java.util.Arrays;
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19
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20 import org.eclipse.core.databinding.ValidationStatusProvider;
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21 import org.eclipse.core.databinding.observable.ChangeEvent;
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22 import org.eclipse.core.databinding.observable.IChangeListener;
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23 import org.eclipse.core.databinding.observable.IObservable;
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24 import org.eclipse.core.databinding.observable.ObservableTracker;
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25 import org.eclipse.core.databinding.observable.Observables;
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26 import org.eclipse.core.databinding.observable.Realm;
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27 import org.eclipse.core.databinding.observable.list.IListChangeListener;
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28 import org.eclipse.core.databinding.observable.list.IObservableList;
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29 import org.eclipse.core.databinding.observable.list.ListChangeEvent;
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30 import org.eclipse.core.databinding.observable.list.ListDiffVisitor;
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31 import org.eclipse.core.databinding.observable.list.WritableList;
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32 import org.eclipse.core.databinding.observable.map.IObservableMap;
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33 import org.eclipse.core.databinding.observable.set.IObservableSet;
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34 import org.eclipse.core.databinding.observable.value.IObservableValue;
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35 import org.eclipse.core.databinding.observable.value.WritableValue;
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36 import org.eclipse.core.internal.databinding.observable.ValidatedObservableList;
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37 import org.eclipse.core.internal.databinding.observable.ValidatedObservableMap;
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38 import org.eclipse.core.internal.databinding.observable.ValidatedObservableSet;
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39 import org.eclipse.core.internal.databinding.observable.ValidatedObservableValue;
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40 import org.eclipse.core.runtime.Assert;
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41 import org.eclipse.core.runtime.IStatus;
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42
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43 /**
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44 * A validator for cross-constraints between observables.
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45 *
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46 * <p>
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47 * Some practical examples of cross-constraints:
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48 * <ul>
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49 * <li>A start date cannot be later than an end date
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50 * <li>A list of percentages should add up to 100%
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51 * </ul>
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52 * <p>
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53 * Example: require two integer fields to contain either both even or both odd
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54 * numbers.
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55 *
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56 * <pre>
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57 * DataBindingContext dbc = new DataBindingContext();
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58 *
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59 * IObservableValue target0 = SWTObservables.observeText(text0, SWT.Modify);
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60 * IObservableValue target1 = SWTObservables.observeText(text1, SWT.Modify);
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61 *
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62 * // Binding in two stages (from target to middle, then from middle to model)
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63 * // simplifies the validation logic. Using the middle observables saves
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64 * // the trouble of converting the target values cast(Strings) to the model type
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65 * // (integers) manually during validation.
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66 * final IObservableValue middle0 = new WritableValue(null, Integer.TYPE);
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67 * final IObservableValue middle1 = new WritableValue(null, Integer.TYPE);
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68 * dbc.bind(target0, middle0, null, null);
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69 * dbc.bind(target1, middle1, null, null);
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70 *
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71 * // Create the multi-validator
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72 * MultiValidator validator = new class() MultiValidator {
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73 * protected IStatus validate() {
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74 * // Calculate the validation status
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75 * Integer value0 = cast(Integer) middle0.getValue();
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76 * Integer value1 = cast(Integer) middle1.getValue();
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77 * if (Math.abs(value0.intValue()) % 2 !is Math.abs(value1.intValue()) % 2)
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78 * return ValidationStatus
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79 * .error("Values must be both even or both odd");
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80 * return ValidationStatus.ok();
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81 * }
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82 * };
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83 * dbc.addValidationStatusProvider(validator);
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84 *
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85 * // Bind the middle observables to the model observables.
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86 * IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
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87 * IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
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88 * dbc.bind(middle0, model0, null, null);
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89 * dbc.bind(middle1, model1, null, null);
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90 * </pre>
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91 *
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92 * <p>
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93 * MultiValidator can also prevent invalid data from being copied to model. This
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94 * is done by wrapping each target observable in a validated observable, and
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95 * then binding the validated observable to the model.
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96 *
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97 * <pre>
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98 *
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99 * ...
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100 *
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101 * // Validated observables do not change value until the validator passes.
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102 * IObservableValue validated0 = validator.observeValidatedValue(middle0);
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103 * IObservableValue validated1 = validator.observeValidatedValue(middle1);
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104 * IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
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105 * IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
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106 * // Bind to the validated value, not the middle/target
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107 * dbc.bind(validated0, model0, null, null);
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108 * dbc.bind(validated1, model1, null, null);
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109 * </pre>
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110 *
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111 * Note: No guarantee is made as to the order of updates when multiple validated
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112 * observables change value at once (i.e. multiple updates pending when the
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113 * status becomes valid). Therefore the model may be in an invalid state after
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114 * the first but before the last pending update.
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115 *
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116 * @since 1.1
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117 */
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118 public abstract class MultiValidator : ValidationStatusProvider {
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119 private Realm realm;
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120 private IObservableValue validationStatus;
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121 private IObservableValue unmodifiableValidationStatus;
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122 private WritableList targets;
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123 private IObservableList unmodifiableTargets;
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124 private IObservableList models;
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125
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126 IListChangeListener targetsListener = new class() IListChangeListener {
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127 public void handleListChange(ListChangeEvent event) {
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128 event.diff.accept(new class() ListDiffVisitor {
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129 public void handleAdd(int index, Object element) {
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130 (cast(IObservable) element)
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131 .addChangeListener(dependencyListener);
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132 }
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133
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134 public void handleRemove(int index, Object element) {
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135 (cast(IObservable) element)
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136 .removeChangeListener(dependencyListener);
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137 }
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138 });
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139 }
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140 };
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141
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142 private IChangeListener dependencyListener = new class() IChangeListener {
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143 public void handleChange(ChangeEvent event) {
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144 revalidate();
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145 }
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146 };
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147
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148 /**
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149 * Constructs a MultiValidator on the default realm.
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150 */
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151 public this() {
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152 this(Realm.getDefault());
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153 }
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154
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155 /**
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156 * Constructs a MultiValidator on the given realm.
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157 *
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158 * @param realm
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159 * the realm on which validation takes place.
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160 */
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161 public this(Realm realm) {
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162 Assert.isNotNull(realm, "Realm cannot be null"); //$NON-NLS-1$
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163 this.realm = realm;
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164
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165 validationStatus = new WritableValue(realm, ValidationStatus.ok(),
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166 IStatus.classinfo);
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167
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168 targets = new WritableList(realm, new ArrayList(), IObservable.classinfo);
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169 targets.addListChangeListener(targetsListener);
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170 unmodifiableTargets = Observables.unmodifiableObservableList(targets);
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171
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172 models = Observables.emptyObservableList(realm);
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173 }
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174
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175 private void checkObservable(IObservable target) {
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176 Assert.isNotNull(target, "Target observable cannot be null"); //$NON-NLS-1$
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177 Assert
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178 .isTrue(realm.equals(target.getRealm()),
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179 "Target observable must be in the same realm as MultiValidator"); //$NON-NLS-1$
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180 }
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181
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182 /**
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183 * Returns an {@link IObservableValue} whose value is always the current
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184 * validation status of this MultiValidator. The returned observable is in
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185 * the same realm as this MultiValidator.
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186 *
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187 * @return an {@link IObservableValue} whose value is always the current
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188 * validation status of this MultiValidator.
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189 */
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190 public IObservableValue getValidationStatus() {
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191 if (unmodifiableValidationStatus is null) {
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192 revalidate();
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193 unmodifiableValidationStatus = Observables
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194 .unmodifiableObservableValue(validationStatus);
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195 }
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196 return unmodifiableValidationStatus;
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197 }
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198
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199 private void revalidate() {
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200 final IObservable[] dependencies = ObservableTracker.runAndMonitor(
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201 new class() Runnable {
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202 public void run() {
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203 try {
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204 IStatus status = validate();
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205 if (status is null)
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206 status = ValidationStatus.ok();
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207 validationStatus.setValue(status);
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208 } catch (RuntimeException e) {
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209 // Usually an NPE as dependencies are
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210 // init'ed
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211 validationStatus.setValue(ValidationStatus.error(e
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212 .getMessage(), e));
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213 }
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214 }
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215 }, null, null);
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216 ObservableTracker.runAndIgnore(new class() Runnable {
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217 public void run() {
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218 targets.clear();
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219 targets.addAll(Arrays.asList(dependencies));
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220 }
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221 });
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222 }
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223
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224 /**
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225 * Return the current validation status.
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226 * <p>
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227 * Note: To ensure that the validation status is kept current, all
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228 * dependencies used to calculate status should be accessed through
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229 * {@link IObservable} instances. Each dependency observable must be in the
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230 * same realm as the MultiValidator.
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231 *
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232 * @return the current validation status.
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233 */
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234 protected abstract IStatus validate();
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235
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236 /**
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237 * Returns a wrapper {@link IObservableValue} which stays in sync with the
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238 * given target observable only when the validation status is valid.
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239 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
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240 * {@link IStatus#WARNING WARNING} severity are considered valid.
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241 * <p>
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242 * The wrapper behaves as follows with respect to the validation status:
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243 * <ul>
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244 * <li>While valid, the wrapper stays in sync with its target observable.
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245 * <li>While invalid, the wrapper's value is the target observable's last
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246 * valid value. If the target changes value, a stale event is fired
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247 * signaling that a change is pending.
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248 * <li>When status changes from invalid to valid, the wrapper takes the
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249 * value of the target observable, and synchronization resumes.
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250 * </ul>
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251 *
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252 * @param target
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253 * the target observable being wrapped. Must be in the same realm
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254 * as the MultiValidator.
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255 * @return an IObservableValue which stays in sync with the given target
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256 * observable only with the validation status is valid.
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257 */
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258 public IObservableValue observeValidatedValue(IObservableValue target) {
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259 checkObservable(target);
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260 return new ValidatedObservableValue(target, getValidationStatus());
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261 }
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262
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263 /**
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264 * Returns a wrapper {@link IObservableList} which stays in sync with the
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265 * given target observable only when the validation status is valid.
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266 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
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267 * {@link IStatus#WARNING WARNING} severity are considered valid.
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268 * <p>
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269 * The wrapper behaves as follows with respect to the validation status:
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270 * <ul>
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271 * <li>While valid, the wrapper stays in sync with its target observable.
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272 * <li>While invalid, the wrapper's elements are the target observable's
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273 * last valid elements. If the target changes elements, a stale event is
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274 * fired signaling that a change is pending.
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275 * <li>When status changes from invalid to valid, the wrapper takes the
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276 * elements of the target observable, and synchronization resumes.
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277 * </ul>
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278 *
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279 * @param target
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280 * the target observable being wrapped. Must be in the same realm
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281 * as the MultiValidator.
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282 * @return an IObservableValue which stays in sync with the given target
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283 * observable only with the validation status is valid.
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284 */
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285 public IObservableList observeValidatedList(IObservableList target) {
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286 checkObservable(target);
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287 return new ValidatedObservableList(target, getValidationStatus());
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288 }
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289
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290 /**
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291 * Returns a wrapper {@link IObservableSet} which stays in sync with the
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292 * given target observable only when the validation status is valid.
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293 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
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294 * {@link IStatus#WARNING WARNING} severity are considered valid.
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295 * <p>
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296 * The wrapper behaves as follows with respect to the validation status:
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297 * <ul>
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298 * <li>While valid, the wrapper stays in sync with its target observable.
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299 * <li>While invalid, the wrapper's elements are the target observable's
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300 * last valid elements. If the target changes elements, a stale event is
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301 * fired signaling that a change is pending.
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302 * <li>When status changes from invalid to valid, the wrapper takes the
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303 * elements of the target observable, and synchronization resumes.
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304 * </ul>
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305 *
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306 * @param target
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307 * the target observable being wrapped. Must be in the same realm
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308 * as the MultiValidator.
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309 * @return an IObservableValue which stays in sync with the given target
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310 * observable only with the validation status is valid.
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311 */
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312 public IObservableSet observeValidatedSet(IObservableSet target) {
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313 checkObservable(target);
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314 return new ValidatedObservableSet(target, getValidationStatus());
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315 }
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316
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317 /**
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318 * Returns a wrapper {@link IObservableMap} which stays in sync with the
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319 * given target observable only when the validation status is valid.
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320 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
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321 * {@link IStatus#WARNING WARNING} severity are considered valid.
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322 * <p>
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323 * The wrapper behaves as follows with respect to the validation status:
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324 * <ul>
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325 * <li>While valid, the wrapper stays in sync with its target observable.
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326 * <li>While invalid, the wrapper's entries are the target observable's
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327 * last valid entries. If the target changes entries, a stale event is fired
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328 * signaling that a change is pending.
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329 * <li>When status changes from invalid to valid, the wrapper takes the
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330 * entries of the target observable, and synchronization resumes.
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331 * </ul>
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332 *
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333 * @param target
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334 * the target observable being wrapped. Must be in the same realm
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335 * as the MultiValidator.
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336 * @return an IObservableValue which stays in sync with the given target
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337 * observable only with the validation status is valid.
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338 */
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339 public IObservableMap observeValidatedMap(IObservableMap target) {
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340 checkObservable(target);
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341 return new ValidatedObservableMap(target, getValidationStatus());
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342 }
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343
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344 public IObservableList getTargets() {
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345 return unmodifiableTargets;
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346 }
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347
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348 public IObservableList getModels() {
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349 return models;
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350 }
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351
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352 public void dispose() {
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353 targets.clear(); // Remove listeners from dependencies
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354
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355 unmodifiableValidationStatus.dispose();
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356 validationStatus.dispose();
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357 unmodifiableTargets.dispose();
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358 targets.dispose();
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359 models.dispose();
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360
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361 realm = null;
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362 validationStatus = null;
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363 unmodifiableValidationStatus = null;
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364 targets = null;
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365 unmodifiableTargets = null;
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366 models = null;
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367
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368 super.dispose();
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369 }
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370
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371 }
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