1 | /*
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2 | * Copyright 2000-2004 The Apache Software Foundation
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | */
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17 |
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18 | package org.apache.tools.ant.types;
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19 |
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20 |
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21 | import java.util.Stack;
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22 | import org.apache.tools.ant.BuildException;
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23 | import org.apache.tools.ant.Project;
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24 | import org.apache.tools.ant.ProjectComponent;
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25 |
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26 | /**
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27 | * Base class for those classes that can appear inside the build file
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28 | * as stand alone data types.
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29 | *
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30 | * <p>This class handles the common description attribute and provides
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31 | * a default implementation for reference handling and checking for
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32 | * circular references that is appropriate for types that can not be
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33 | * nested inside elements of the same type (i.e. <patternset>
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34 | * but not <path>).</p>
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35 | *
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36 | */
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37 | public abstract class DataType extends ProjectComponent {
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38 | /**
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39 | * The description the user has set.
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40 | *
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41 | * @deprecated The user should not be directly referencing
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42 | * variable. Please use {@link #setDescription} or
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43 | * {@link #getDescription} instead.
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44 | */
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45 | protected String description;
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46 |
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47 | /**
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48 | * Value to the refid attribute.
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49 | *
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50 | * @deprecated The user should not be directly referencing
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51 | * variable. Please use {@link #getRefid} instead.
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52 | */
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53 | protected Reference ref;
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54 |
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55 | /**
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56 | * Are we sure we don't hold circular references?
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57 | *
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58 | * <p>Subclasses are responsible for setting this value to false
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59 | * if we'd need to investigate this condition (usually because a
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60 | * child element has been added that is a subclass of
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61 | * DataType).</p>
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62 | *
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63 | * @deprecated The user should not be directly referencing
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64 | * variable. Please use {@link #setChecked} or
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65 | * {@link #isChecked} instead.
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66 | */
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67 | protected boolean checked = true;
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68 |
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69 | /**
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70 | * Sets a description of the current data type. It will be useful
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71 | * in commenting what we are doing.
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72 | */
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73 | public void setDescription(final String desc) {
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74 | description = desc;
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75 | }
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76 |
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77 | /**
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78 | * Return the description for the current data type.
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79 | */
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80 | public String getDescription() {
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81 | return description;
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82 | }
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83 |
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84 | /**
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85 | * Has the refid attribute of this element been set?
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86 | */
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87 | public boolean isReference() {
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88 | return ref != null;
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89 | }
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90 |
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91 | /**
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92 | * Set the value of the refid attribute.
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93 | *
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94 | * <p>Subclasses may need to check whether any other attributes
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95 | * have been set as well or child elements have been created and
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96 | * thus override this method. if they do the must call
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97 | * <code>super.setRefid</code>.</p>
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98 | */
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99 | public void setRefid(final Reference ref) {
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100 | this.ref = ref;
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101 | checked = false;
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102 | }
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103 |
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104 | /**
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105 | * Check to see whether any DataType we hold references to is
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106 | * included in the Stack (which holds all DataType instances that
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107 | * directly or indirectly reference this instance, including this
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108 | * instance itself).
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109 | *
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110 | * <p>If one is included, throw a BuildException created by {@link
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111 | * #circularReference circularReference}.</p>
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112 | *
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113 | * <p>This implementation is appropriate only for a DataType that
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114 | * cannot hold other DataTypes as children.</p>
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115 | *
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116 | * <p>The general contract of this method is that it shouldn't do
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117 | * anything if {@link #checked <code>checked</code>} is true and
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118 | * set it to true on exit.</p>
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119 | */
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120 | protected void dieOnCircularReference(final Stack stack,
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121 | final Project project)
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122 | throws BuildException {
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123 |
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124 | if (checked || !isReference()) {
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125 | return;
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126 | }
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127 | Object o = ref.getReferencedObject(project);
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128 |
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129 | if (o instanceof DataType) {
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130 | if (stack.contains(o)) {
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131 | throw circularReference();
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132 | } else {
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133 | stack.push(o);
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134 | ((DataType) o).dieOnCircularReference(stack, project);
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135 | stack.pop();
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136 | }
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137 | }
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138 | checked = true;
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139 | }
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140 |
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141 | /**
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142 | * Performs the check for circular references and returns the
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143 | * referenced object.
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144 | */
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145 | protected Object getCheckedRef(final Class requiredClass,
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146 | final String dataTypeName) {
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147 | if (!checked) {
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148 | Stack stk = new Stack();
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149 | stk.push(this);
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150 | dieOnCircularReference(stk, getProject());
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151 | }
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152 |
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153 | Object o = ref.getReferencedObject(getProject());
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154 | if (!(requiredClass.isAssignableFrom(o.getClass()))) {
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155 | String msg = ref.getRefId() + " doesn\'t denote a " + dataTypeName;
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156 | throw new BuildException(msg);
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157 | } else {
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158 | return o;
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159 | }
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160 | }
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161 |
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162 | /**
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163 | * Creates an exception that indicates that refid has to be the
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164 | * only attribute if it is set.
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165 | */
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166 | protected BuildException tooManyAttributes() {
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167 | return new BuildException("You must not specify more than one "
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168 | + "attribute when using refid");
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169 | }
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170 |
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171 | /**
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172 | * Creates an exception that indicates that this XML element must
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173 | * not have child elements if the refid attribute is set.
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174 | */
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175 | protected BuildException noChildrenAllowed() {
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176 | return new BuildException("You must not specify nested elements "
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177 | + "when using refid");
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178 | }
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179 |
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180 | /**
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181 | * Creates an exception that indicates the user has generated a
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182 | * loop of data types referencing each other.
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183 | */
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184 | protected BuildException circularReference() {
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185 | return new BuildException("This data type contains a circular "
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186 | + "reference.");
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187 | }
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188 |
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189 | protected boolean isChecked() {
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190 | return checked;
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191 | }
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192 |
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193 | protected void setChecked(final boolean checked) {
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194 | this.checked = checked;
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195 | }
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196 |
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197 | /**
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198 | * get the reference set on this object
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199 | * @return the reference or null
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200 | */
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201 | protected Reference getRefid() {
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202 | return ref;
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203 | }
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204 |
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205 | /**
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206 | * check that it is ok to set attributes, i.e that no reference is defined
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207 | * @since Ant 1.6
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208 | * @throws BuildException if not allowed
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209 | */
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210 | protected void checkAttributesAllowed() {
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211 | if (isReference()) {
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212 | throw tooManyAttributes();
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213 | }
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214 | }
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215 |
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216 | /**
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217 | * check that it is ok to add children, i.e that no reference is defined
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218 | * @since Ant 1.6
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219 | * @throws BuildException if not allowed
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220 | */
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221 | protected void checkChildrenAllowed() {
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222 | if (isReference()) {
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223 | throw noChildrenAllowed();
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224 | }
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225 | }
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226 | }
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