ThisExpression


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  
12  package org.eclipse.jdt.core.dom;
13  
14  import java.util.ArrayList  ;
15  import java.util.List  ;
16  
17  /**
18   * Simple or qualified "this" AST node type.
19   *
20   * <pre>
21   * ThisExpression:
22   *     [ ClassName <b>.</b> ] <b>this</b>
23   * </pre>
24   * <p>
25   * See <code>FieldAccess</code> for guidelines on handling other expressions
26   * that resemble qualified names.
27   * </p>
28   * 
29   * @see FieldAccess
30   * @since 2.0
31   */
32  public class ThisExpression extends Expression {
33              
34      /**
35       * The "qualifier" structural property of this node type.
36       * @since 3.0
37       */
38      public static final ChildPropertyDescriptor QUALIFIER_PROPERTY = 
39          new ChildPropertyDescriptor(ThisExpression.class, "qualifier", Name.class, OPTIONAL, NO_CYCLE_RISK); //$NON-NLS-1$
40  
41      /**
42       * A list of property descriptors (element type: 
43       * {@link StructuralPropertyDescriptor}),
44       * or null if uninitialized.
45       */
46      private static final List   PROPERTY_DESCRIPTORS;
47      
48      static {
49          List   propertyList = new ArrayList  (2);
50          createPropertyList(ThisExpression.class, propertyList);
51          addProperty(QUALIFIER_PROPERTY, propertyList);
52          PROPERTY_DESCRIPTORS = reapPropertyList(propertyList);
53      }
54  
55      /**
56       * Returns a list of structural property descriptors for this node type.
57       * Clients must not modify the result.
58       * 
59       * @param apiLevel the API level; one of the
60       * <code>AST.JLS*</code> constants
61       * @return a list of property descriptors (element type: 
62       * {@link StructuralPropertyDescriptor})
63       * @since 3.0
64       */
65      public static List   propertyDescriptors(int apiLevel) {
66          return PROPERTY_DESCRIPTORS;
67      }
68              
69      /**
70       * The optional qualifier; <code>null</code> for none; defaults to none.
71       */
72      private Name optionalQualifier = null;
73  
74      /**
75       * Creates a new AST node for a "this" expression owned by the 
76       * given AST. By default, there is no qualifier.
77       * 
78       * @param ast the AST that is to own this node
79       */
80      ThisExpression(AST ast) {
81          super(ast);
82      }
83  
84      /* (omit javadoc for this method)
85       * Method declared on ASTNode.
86       */
87      final List   internalStructuralPropertiesForType(int apiLevel) {
88          return propertyDescriptors(apiLevel);
89      }
90      
91      /* (omit javadoc for this method)
92       * Method declared on ASTNode.
93       */
94      final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) {
95          if (property == QUALIFIER_PROPERTY) {
96              if (get) {
97                  return getQualifier();
98              } else {
99                  setQualifier((Name) child);
100                 return null;
101             }
102         }
103         // allow default implementation to flag the error
104         return super.internalGetSetChildProperty(property, get, child);
105     }
106     
107     /* (omit javadoc for this method)
108      * Method declared on ASTNode.
109      */
110     final int getNodeType0() {
111         return THIS_EXPRESSION;
112     }
113 
114     /* (omit javadoc for this method)
115      * Method declared on ASTNode.
116      */
117     ASTNode clone0(AST target) {
118         ThisExpression result = new ThisExpression(target);
119         result.setSourceRange(this.getStartPosition(), this.getLength());
120         result.setQualifier((Name) ASTNode.copySubtree(target, getQualifier()));
121         return result;
122     }
123 
124     /* (omit javadoc for this method)
125      * Method declared on ASTNode.
126      */
127     final boolean subtreeMatch0(ASTMatcher matcher, Object   other) {
128         // dispatch to correct overloaded match method
129         return matcher.match(this, other);
130     }
131 
132     /* (omit javadoc for this method)
133      * Method declared on ASTNode.
134      */
135     void accept0(ASTVisitor visitor) {
136         boolean visitChildren = visitor.visit(this);
137         if (visitChildren) {
138             acceptChild(visitor, getQualifier());
139         }
140         visitor.endVisit(this);
141     }
142     
143     /**
144      * Returns the qualifier of this "this" expression, or 
145      * <code>null</code> if there is none.
146      * 
147      * @return the qualifier name node, or <code>null</code> if there is none
148      */ 
149     public Name getQualifier() {
150         return this.optionalQualifier;
151     }
152     
153     /**
154      * Sets or clears the qualifier of this "this" expression.
155      * 
156      * @param name the qualifier name node, or <code>null</code> if 
157      *    there is none
158      * @exception IllegalArgumentException if:
159      * <ul>
160      * <li>the node belongs to a different AST</li>
161      * <li>the node already has a parent</li>
162      * </ul>
163      */ 
164     public void setQualifier(Name name) {
165         ASTNode oldChild = this.optionalQualifier;
166         preReplaceChild(oldChild, name, QUALIFIER_PROPERTY);
167         this.optionalQualifier = name;
168         postReplaceChild(oldChild, name, QUALIFIER_PROPERTY);
169     }
170 
171     /* (omit javadoc for this method)
172      * Method declared on ASTNode.
173      */
174     int memSize() {
175         // treat Operator as free
176         return BASE_NODE_SIZE + 1 * 4;
177     }
178     
179     /* (omit javadoc for this method)
180      * Method declared on ASTNode.
181      */
182     int treeSize() {
183         return 
184             memSize()
185             + (this.optionalQualifier == null ? 0 : getQualifier().treeSize());
186     }
187 }
188
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