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1 /*******************************************************************************
2  * Copyright (c) 2004, 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 package org.eclipse.jdt.core.dom;
12
13 /**
14  * Abstract base class for all AST nodes that represent comments.
15  * There are exactly three kinds of comment:
16  * line comments ({@link LineComment}),
17  * block comments ({@link BlockComment}), and
18  * doc comments ({@link Javadoc}).
19  * <p>
20  * <pre>
21  * Comment:
22  * LineComment
23  * BlockComment
24  * Javadoc
25  * </pre>
26  * </p>
27  *
28  * @since 3.0
29  */
30 public abstract class Comment extends ASTNode {
31     
32     /**
33      * Alternate root node, or <code>null</code> if none.
34      * Initially <code>null</code>.
35      */
36     private ASTNode alternateRoot = null;
37
38     /**
39      * Creates a new AST node for a comment owned by the given AST.
40      * <p>
41      * N.B. This constructor is package-private.
42      * </p>
43      *
44      * @param ast the AST that is to own this node
45      */
46     Comment(AST ast) {
47         super(ast);
48     }
49     
50     /**
51      * Returns whether this comment is a block comment
52      * (<code>BlockComment</code>).
53      *
54      * @return <code>true</code> if this is a block comment, and
55      * <code>false</code> otherwise
56      */
57     public final boolean isBlockComment() {
58         return (this instanceof BlockComment);
59     }
60     
61     /**
62      * Returns whether this comment is a line comment
63      * (<code>LineComment</code>).
64      *
65      * @return <code>true</code> if this is a line comment, and
66      * <code>false</code> otherwise
67      */
68     public final boolean isLineComment() {
69         return (this instanceof LineComment);
70     }
71     
72     /**
73      * Returns whether this comment is a doc comment
74      * (<code>Javadoc</code>).
75      *
76      * @return <code>true</code> if this is a doc comment, and
77      * <code>false</code> otherwise
78      */
79     public final boolean isDocComment() {
80         return (this instanceof Javadoc);
81     }
82     
83     /**
84      * Returns the root AST node that this comment occurs
85      * within, or <code>null</code> if none (or not recorded).
86      * <p>
87      * Typically, the comment nodes created while parsing a compilation
88      * unit are not considered descendents of the normal AST
89      * root, namely an {@link CompilationUnit}. Instead, these
90      * comment nodes exist outside the normal AST and each is
91      * a root in its own right. This optional property provides
92      * a well-known way to navigate from the comment to the
93      * compilation unit in such cases. Note that the alternate root
94      * property is not one of the comment node's children. It is simply a
95      * reference to a node.
96      * </p>
97      *
98      * @return the alternate root node, or <code>null</code>
99      * if none
100      * @see #setAlternateRoot(ASTNode)
101      */
102     public final ASTNode getAlternateRoot() {
103         return this.alternateRoot;
104     }
105     
106     /**
107      * Returns the root AST node that this comment occurs
108      * within, or <code>null</code> if none (or not recorded).
109      * <p>
110      * </p>
111      *
112      * @param root the alternate root node, or <code>null</code>
113      * if none
114      * @see #getAlternateRoot()
115      */
116     public final void setAlternateRoot(ASTNode root) {
117         // alternate root is *not* considered a structural property
118 // but we protect them nevertheless
119 checkModifiable();
120         this.alternateRoot = root;
121     }
122
123     /* (omit javadoc for this method)
124      * Method declared on ASTNode.
125      */
126     int memSize() {
127         return BASE_NODE_SIZE + 1 * 4;
128     }
129 }
130
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