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1   package org.apache.velocity.runtime.parser.node;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.    
20   */
21  
22  import java.util.ArrayList;
23  import java.util.List;
24  
25  import org.apache.velocity.context.InternalContextAdapter;
26  import org.apache.velocity.exception.MethodInvocationException;
27  import org.apache.velocity.runtime.parser.Parser;
28  
29  /**
30   * handles the range 'operator'  [ n .. m ]
31   *
32   * Please look at the Parser.jjt file which is
33   * what controls the generation of this class.
34   *
35   * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
36   */
37  public class ASTIntegerRange extends SimpleNode
38  {
39      /**
40       * @param id
41       */
42      public ASTIntegerRange(int id)
43      {
44          super(id);
45      }
46  
47      /**
48       * @param p
49       * @param id
50       */
51      public ASTIntegerRange(Parser p, int id)
52      {
53          super(p, id);
54      }
55  
56      /**
57       * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.node.ParserVisitor, java.lang.Object)
58       */
59      public Object jjtAccept(ParserVisitor visitor, Object data)
60      {
61          return visitor.visit(this, data);
62      }
63  
64      /**
65       *  does the real work.  Creates an Vector of Integers with the
66       *  right value range
67       *
68       *  @param context  app context used if Left or Right of .. is a ref
69       *  @return Object array of Integers
70       * @throws MethodInvocationException
71       */
72      public Object value( InternalContextAdapter context)
73          throws MethodInvocationException
74      {
75          /*
76           *  get the two range ends
77           */
78  
79          Object left = jjtGetChild(0).value( context );
80          Object right = jjtGetChild(1).value( context );
81  
82          /*
83           *  if either is null, lets log and bail
84           */
85  
86          if (left == null || right == null)
87          {
88              log.error((left == null ? "Left" : "Right")
89                             + " side of range operator [n..m] has null value."
90                             + " Operation not possible. "
91                             +  context.getCurrentTemplateName() + " [line " + getLine()
92                             + ", column " + getColumn() + "]");
93              return null;
94          }
95  
96          /*
97           *  if not a Number, not much we can do either
98           */
99  
100         if ( !( left instanceof Number )  || !( right instanceof Number ))
101         {
102             log.error((!(left instanceof Number) ? "Left" : "Right")
103                            + " side of range operator is not a valid type. "
104                            + "Currently only integers (1,2,3...) and the Number type are supported. "
105                            + context.getCurrentTemplateName() + " [line " + getLine()
106                            + ", column " + getColumn() + ']');
107 
108             return null;
109         }
110 
111 
112         /*
113          *  get the two integer values of the ends of the range
114          */
115 
116         int l = ((Number) left).intValue() ;
117         int r = ((Number) right).intValue();
118 
119         /*
120          *  find out how many there are
121          */
122 
123         int nbrElements = Math.abs( l - r );
124         nbrElements += 1;
125 
126         /*
127          *  Determine whether the increment is positive or negative.
128          */
129 
130         int delta = ( l >= r ) ? -1 : 1;
131 
132         /*
133          * Fill the range with the appropriate values.
134          */
135 
136         List elements = new ArrayList(nbrElements);
137         int value = l;
138 
139         for (int i = 0; i < nbrElements; i++)
140         {
141             // TODO: JDK 1.4+ -> valueOf()
142             elements.add(new Integer(value));
143             value += delta;
144         }
145 
146         return elements;
147     }
148 }