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Java > Open Source Codes > org > apache > velocity > runtime > parser > node > ASTIntegerRange


1 package org.apache.velocity.runtime.parser.node;
2
3 /*
4  * Copyright 2000-2001,2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19
20 /**
21  * handles the range 'operator' [ n .. m ]
22  *
23  * Please look at the Parser.jjt file which is
24  * what controls the generation of this class.
25  *
26  * @author <a HREF="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
27  * @version $Id: ASTIntegerRange.java,v 1.4.10.1 2004/03/03 23:22:58 geirm Exp $
28 */
29
30 import java.util.ArrayList JavaDoc;
31
32 import org.apache.velocity.context.InternalContextAdapter;
33 import org.apache.velocity.runtime.parser.Parser;
34
35 import org.apache.velocity.exception.MethodInvocationException;
36
37 public class ASTIntegerRange extends SimpleNode {
38   
39     public ASTIntegerRange(int id)
40     {
41         super(id);
42     }
43
44     public ASTIntegerRange(Parser p, int id)
45     {
46         super(p, id);
47     }
48
49     /** Accept the visitor. **/
50     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data)
51     {
52         return visitor.visit(this, data);
53     }
54
55     /**
56      * does the real work. Creates an Vector of Integers with the
57      * right value range
58      *
59      * @param context app context used if Left or Right of .. is a ref
60      * @return Object array of Integers
61      */
62     public Object JavaDoc value( InternalContextAdapter context)
63         throws MethodInvocationException
64     {
65         /*
66          * get the two range ends
67          */
68
69         Object JavaDoc left = jjtGetChild(0).value( context );
70         Object JavaDoc right = jjtGetChild(1).value( context );
71
72         /*
73          * if either is null, lets log and bail
74          */
75
76         if (left == null || right == null)
77         {
78             rsvc.error( ( left == null ? "Left" : "Right" ) + " side of range operator [n..m] has null value."
79                            + " Operation not possible. "
80                            + context.getCurrentTemplateName() + " [line " + getLine()
81                            + ", column " + getColumn() + "]");
82             return null;
83         }
84         
85         /*
86          * if not an Integer, not much we can do either
87          */
88
89         if ( !( left instanceof Integer JavaDoc ) || !( right instanceof Integer JavaDoc ))
90         {
91             rsvc.error( ( !( left instanceof Integer JavaDoc ) ? "Left" : "Right" )
92                            + " side of range operator is not a valid type. "
93                            + "Currently only integers (1,2,3...) and Integer type is supported. "
94                            + context.getCurrentTemplateName() + " [line " + getLine()
95                            + ", column " + getColumn() + "]");
96  
97             return null;
98         }
99
100
101         /*
102          * get the two integer values of the ends of the range
103          */
104
105         int l = ( (Integer JavaDoc) left ).intValue() ;
106         int r = ( (Integer JavaDoc) right ).intValue();
107
108         /*
109          * find out how many there are
110          */
111
112         int num = Math.abs( l - r );
113         num += 1;
114
115         /*
116          * see if your increment is Pos or Neg
117          */
118
119         int delta = ( l >= r ) ? -1 : 1;
120
121         /*
122          * make the vector and fill it
123          */
124
125         ArrayList JavaDoc foo = new ArrayList JavaDoc();
126         int val = l;
127
128         for(int i =0; i < num; i++)
129         {
130             foo.add( new Integer JavaDoc( val ));
131             val += delta;
132         }
133
134         return foo;
135     }
136 }
137
138
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