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Java > Open Source Codes > javassist > compiler > ast > ASTList


1 /*
2  * Javassist, a Java-bytecode translator toolkit.
3  * Copyright (C) 1999-2005 Shigeru Chiba. All Rights Reserved.
4  *
5  * The contents of this file are subject to the Mozilla Public License Version
6  * 1.1 (the "License"); you may not use this file except in compliance with
7  * the License. Alternatively, the contents of this file may be used under
8  * the terms of the GNU Lesser General Public License Version 2.1 or later.
9  *
10  * Software distributed under the License is distributed on an "AS IS" basis,
11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12  * for the specific language governing rights and limitations under the
13  * License.
14  */
15
16 package javassist.compiler.ast;
17
18 import javassist.compiler.CompileError;
19
20 /**
21  * A linked list.
22  * The right subtree must be an ASTList object or null.
23  */
24 public class ASTList extends ASTree {
25     private ASTree left;
26     private ASTList right;
27
28     public ASTList(ASTree _head, ASTList _tail) {
29         left = _head;
30         right = _tail;
31     }
32
33     public ASTList(ASTree _head) {
34         left = _head;
35         right = null;
36     }
37
38     public static ASTList make(ASTree e1, ASTree e2, ASTree e3) {
39         return new ASTList(e1, new ASTList(e2, new ASTList(e3)));
40     }
41
42     public ASTree getLeft() { return left; }
43
44     public ASTree getRight() { return right; }
45
46     public void setLeft(ASTree _left) { left = _left; }
47
48     public void setRight(ASTree _right) {
49         right = (ASTList)_right;
50     }
51
52     /**
53      * Returns the car part of the list.
54      */
55     public ASTree head() { return left; }
56
57     public void setHead(ASTree _head) {
58         left = _head;
59     }
60
61     /**
62      * Returns the cdr part of the list.
63      */
64     public ASTList tail() { return right; }
65
66     public void setTail(ASTList _tail) {
67         right = _tail;
68     }
69
70     public void accept(Visitor v) throws CompileError { v.atASTList(this); }
71
72     public String JavaDoc toString() {
73         StringBuffer JavaDoc sbuf = new StringBuffer JavaDoc();
74         sbuf.append("(<");
75         sbuf.append(getTag());
76         sbuf.append('>');
77         ASTList list = this;
78         while (list != null) {
79             sbuf.append(' ');
80             ASTree a = list.left;
81             sbuf.append(a == null ? "<null>" : a.toString());
82             list = list.right;
83         }
84
85         sbuf.append(')');
86         return sbuf.toString();
87     }
88
89     /**
90      * Returns the number of the elements in this list.
91      */
92     public int length() {
93         return length(this);
94     }
95
96     public static int length(ASTList list) {
97         if (list == null)
98             return 0;
99
100         int n = 0;
101         while (list != null) {
102             list = list.right;
103             ++n;
104         }
105
106         return n;
107     }
108
109     /**
110      * Returns a sub list of the list. The sub list begins with the
111      * n-th element of the list.
112      *
113      * @param nth zero or more than zero.
114      */
115     public ASTList sublist(int nth) {
116         ASTList list = this;
117         while (nth-- > 0)
118             list = list.right;
119
120         return list;
121     }
122
123     /**
124      * Substitutes <code>newObj</code> for <code>oldObj</code> in the
125      * list.
126      */
127     public boolean subst(ASTree newObj, ASTree oldObj) {
128         for (ASTList list = this; list != null; list = list.right)
129             if (list.left == oldObj) {
130                 list.left = newObj;
131                 return true;
132             }
133
134         return false;
135     }
136
137     /**
138      * Appends an object to a list.
139      */
140     public static ASTList append(ASTList a, ASTree b) {
141         return concat(a, new ASTList(b));
142     }
143
144     /**
145      * Concatenates two lists.
146      */
147     public static ASTList concat(ASTList a, ASTList b) {
148         if (a == null)
149             return b;
150         else {
151             ASTList list = a;
152             while (list.right != null)
153                 list = list.right;
154
155             list.right = b;
156             return a;
157         }
158     }
159 }
160
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