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Java > Open Source Codes > org > eclipse > jdt > core > dom > ChildListPropertyDescriptor


1 /*******************************************************************************
2  * Copyright (c) 2004 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 package org.eclipse.jdt.core.dom;
12
13 /**
14  * Descriptor for a child list property of an AST node.
15  * A child list property is one whose value is a list of
16  * {@link ASTNode}.
17  *
18  * @see org.eclipse.jdt.core.dom.ASTNode#getStructuralProperty(StructuralPropertyDescriptor)
19  * @since 3.0
20  */
21 public final class ChildListPropertyDescriptor extends StructuralPropertyDescriptor {
22     
23     /**
24      * Element type. For example, for a node type like
25      * CompilationUnit, the "imports" property is ImportDeclaration.class.
26      * <p>
27      * Field is private, but marked package-visible for fast
28      * access from ASTNode.
29      * </p>
30      */
31     final Class JavaDoc elementType;
32     
33     /**
34      * Indicates whether a cycle is possible.
35      * <p>
36      * Field is private, but marked package-visible for fast
37      * access from ASTNode.
38      * </p>
39      */
40     final boolean cycleRisk;
41     
42     /**
43      * Creates a new child list property descriptor with the given property id.
44      * Note that this constructor is declared package-private so that
45      * property descriptors can only be created by the AST
46      * implementation.
47      *
48      * @param nodeClass concrete AST node type that owns this property
49      * @param propertyId the property id
50      * @param elementType the element type of this property
51      * @param cycleRisk <code>true</code> if this property is at
52      * risk of cycles, and <code>false</code> if there is no worry about cycles
53      */
54     ChildListPropertyDescriptor(Class JavaDoc nodeClass, String JavaDoc propertyId, Class JavaDoc elementType, boolean cycleRisk) {
55         super(nodeClass, propertyId);
56         if (elementType == null) {
57             throw new IllegalArgumentException JavaDoc();
58         }
59         this.elementType = elementType;
60         this.cycleRisk = cycleRisk;
61     }
62     
63     /**
64      * Returns the element type of this list property.
65      * <p>
66      * For example, for a node type like CompilationUnit,
67      * the "imports" property returns <code>ImportDeclaration.class</code>.
68      * </p>
69      *
70      * @return the element type of the property
71      */
72     public final Class JavaDoc getElementType() {
73         return this.elementType;
74     }
75     
76     /**
77      * Returns whether this property is vulnerable to cycles.
78      * <p>
79      * A property is vulnerable to cycles if a node of the owning
80      * type (that is, the type that owns this property) could legally
81      * appear in the AST subtree below this property. For example,
82      * the body property of a
83      * {@link MethodDeclaration} node
84      * admits a body which might include statement that embeds
85      * another {@link MethodDeclaration} node.
86      * On the other hand, the name property of a
87      * MethodDeclaration node admits only names, and thereby excludes
88      * another MethodDeclaration node.
89      * </p>
90      *
91      * @return <code>true</code> if cycles are possible,
92      * and <code>false</code> if cycles are impossible
93      */
94     public final boolean cycleRisk() {
95         return this.cycleRisk;
96     }
97 }
98
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