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16 package org.apache.commons.jexl.parser;
17
18 import org.apache.commons.jexl.JexlContext;
19
20 /***
21 * reference - any variable expression
22 *
23 * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
24 * @version $Id: ASTReference.java,v 1.4 2004/09/01 00:35:38 dion Exp $
25 */
26 public class ASTReference extends SimpleNode
27 {
28 SimpleNode root;
29
30 public ASTReference(int id)
31 {
32 super(id);
33 }
34
35 public ASTReference(Parser p, int id)
36 {
37 super(p, id);
38 }
39
40
41 /*** Accept the visitor. **/
42 public Object jjtAccept(ParserVisitor visitor, Object data)
43 {
44 return visitor.visit(this, data);
45 }
46
47 public Object value(JexlContext jc)
48 throws Exception
49 {
50 return execute(null,jc);
51 }
52
53 public void jjtClose()
54 {
55 root = (SimpleNode) jjtGetChild(0);
56 }
57
58 public Object execute(Object obj, JexlContext jc)
59 throws Exception
60 {
61 Object o = root.value(jc);
62
63
64
65
66 for(int i=1; i<jjtGetNumChildren(); i++)
67 {
68 o = ( (SimpleNode) jjtGetChild(i)).execute(o,jc);
69
70
71
72 if(o == null) {
73 String varName = getIdentifierToDepth(i);
74 o = jc.getVars().get(varName);
75 }
76 }
77
78 return o;
79 }
80
81 /***
82 * This method returns a variable from this identifier and
83 * it's children. For an expression like 'a.b.c', a is child
84 * zero, b is child 1 and c is child 2.
85 *
86 * @param i the depth of the child nodes to go to
87 * @return the a dotted variable from this identifier and it's
88 * child nodes.
89 */
90 private String getIdentifierToDepth(int i) {
91 StringBuffer varName = new StringBuffer();
92 for (int j = 0; j <=i; j++) {
93 SimpleNode node = (SimpleNode) jjtGetChild(j);
94 if (node instanceof ASTIdentifier) {
95 varName.append(((ASTIdentifier)node).getIdentifierString());
96 if (j != i) varName.append('.');
97 }
98 }
99 return varName.toString();
100 }
101
102 public String getRootString()
103 throws Exception
104 {
105 if ( root instanceof ASTIdentifier)
106 return ((ASTIdentifier) root).getIdentifierString();
107
108 if (root instanceof ASTArrayAccess)
109 return ((ASTArrayAccess) root).getIdentifierString();
110
111 throw new Exception("programmer error : ASTReference : root not known"
112 + root );
113 }
114 }