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1 /*******************************************************************************
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2 * Copyright (c) 2000, 2006 IBM Corporation 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 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module dwtx.jface.text.templates.TemplateVariableResolver;
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14
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15 import dwt.dwthelper.utils;
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16
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17 import dwtx.core.runtime.Assert;
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18
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19 /**
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20 * A <code>TemplateVariableResolver</code> resolves <code>TemplateVariables</code>
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21 * of a certain type inside a <code>TemplateContext</code>.
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22 * <p>
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23 * Clients may instantiate and extend this class.
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24 * </p>
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25 *
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26 * @see TemplateVariable
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27 * @since 3.0
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28 */
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29 public class TemplateVariableResolver {
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30
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31 /** Type of this resolver. */
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32 private String fType= null;
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33
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34 /** Description of the type resolved by this resolver. */
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35 private String fDescription= null;
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36
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37 /**
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38 * Creates an instance of <code>TemplateVariableResolver</code>.
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39 *
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40 * @param type the name of the type
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41 * @param description the description for the type
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42 */
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43 protected TemplateVariableResolver(String type, String description) {
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44 setType(type);
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45 setDescription(description);
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46 }
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47
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48 /**
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49 * Creates an empty instance.
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50 * <p>
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51 * This is a framework-only constructor that exists only so that resolvers
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52 * can be contributed via an extension point and that should not be called
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53 * in client code except for subclass constructors; use
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54 * {@link #TemplateVariableResolver(String, String)} instead.
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55 * </p>
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56 */
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57 public TemplateVariableResolver() {
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58 }
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59
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60 /**
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61 * Returns the type of this resolver.
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62 *
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63 * @return the type
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64 */
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65 public String getType() {
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66 return fType;
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67 }
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68
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69 /**
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70 * Returns the description for the resolver.
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71 *
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72 * @return the description for the resolver
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73 */
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74 public String getDescription() {
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75 return fDescription;
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76 }
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77
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78 /**
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79 * Returns an instance of the type resolved by the receiver available in <code>context</code>.
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80 * To resolve means to provide a binding to a concrete text object (a
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81 * <code>String</code>) in the given context.
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82 * <p>
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83 * The default implementation looks up the type in the context.</p>
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84 *
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85 * @param context the context in which to resolve the type
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86 * @return the name of the text object of this type, or <code>null</code> if it cannot be determined
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87 */
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88 protected String resolve(TemplateContext context) {
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89 return context.getVariable(getType());
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90 }
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91
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92 /**
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93 * Returns all possible bindings available in <code>context</code>. The default
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94 * implementation simply returns an array which contains the result of
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95 * {@link #resolve(TemplateContext)}, or an empty array if that call returns
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96 * <code>null</code>.
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97 *
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98 * @param context the context in which to resolve the type
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99 * @return an array of possible bindings of this type in <code>context</code>
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100 */
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101 protected String[] resolveAll(TemplateContext context) {
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102 String binding= resolve(context);
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103 if (binding is null)
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104 return new String[0];
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105 return new String[] { binding };
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106 }
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107
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108 /**
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109 * Resolves <code>variable</code> in <code>context</code>. To resolve
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110 * means to find a valid binding of the receiver's type in the given <code>TemplateContext</code>.
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111 * If the variable can be successfully resolved, its value is set using
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112 * {@link TemplateVariable#setValues(String[])}.
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113 *
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114 * @param context the context in which variable is resolved
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115 * @param variable the variable to resolve
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116 */
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117 public void resolve(TemplateVariable variable, TemplateContext context) {
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118 String[] bindings= resolveAll(context);
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119 if (bindings.length !is 0)
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120 variable.setValues(bindings);
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121 if (bindings.length > 1)
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122 variable.setUnambiguous(false);
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123 else
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124 variable.setUnambiguous(isUnambiguous(context));
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125 variable.setResolved(true);
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126 }
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127
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128 /**
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129 * Returns whether this resolver is able to resolve unambiguously. When
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130 * resolving a <code>TemplateVariable</code>, its <code>isUmambiguous</code>
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131 * state is set to the one of this resolver. By default, this method
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132 * returns <code>false</code>. Clients can overwrite this method to give
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133 * a hint about whether there should be e.g. prompting for input values for
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134 * ambiguous variables.
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135 *
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136 * @param context the context in which the resolved check should be
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137 * evaluated
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138 * @return <code>true</code> if the receiver is unambiguously resolvable
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139 * in <code>context</code>, <code>false</code> otherwise
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140 */
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141 protected bool isUnambiguous(TemplateContext context) {
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142 return false;
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143 }
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144
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145 /**
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146 * Sets the description.
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147 * <p>
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148 * This is a framework-only method that exists only so that resolvers
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149 * can be contributed via an extension point and that should not be called
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150 * in client code; use {@link #TemplateVariableResolver(String, String)} instead.
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151 * </p>
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152 *
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153 * @param description the description of this resolver
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154 */
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155 public final void setDescription(String description) {
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156 Assert.isNotNull(description);
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157 Assert.isTrue(fDescription is null); // may only be called once when initialized
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158 fDescription= description;
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159 }
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160
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161 /**
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162 * Sets the type name.
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163 * <p>
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164 * This is a framework-only method that exists only so that resolvers
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165 * can be contributed via an extension point and that should not be called
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166 * in client code; use {@link #TemplateVariableResolver(String, String)} instead.
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167 * </p>
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168 *
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169 * @param type the type name of this resolver
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170 */
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171 public final void setType(String type) {
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172 Assert.isNotNull(type);
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173 Assert.isTrue(fType is null); // may only be called once when initialized
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174 fType= type;
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175 }
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176 }
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