1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17 package org.apache.commons.jexl.parser;
18
19 import org.apache.commons.jexl.JexlContext;
20 import org.apache.commons.jexl.util.Coercion;
21 import org.apache.commons.jexl.util.Introspector;
22 import org.apache.commons.jexl.util.introspection.Info;
23 import org.apache.commons.jexl.util.introspection.VelPropertyGet;
24
25 import java.util.List;
26 import java.util.Map;
27 import java.lang.reflect.Array;
28
29 /***
30 * Like an ASTIdentifier, but with array access allowed.
31 *
32 * $foo[2]
33 *
34 * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
35 * @version $Id: ASTArrayAccess.java 398180 2006-04-29 15:40:35Z dion $
36 */
37 public class ASTArrayAccess extends SimpleNode {
38 /*** dummy velocity info. */
39 private static final Info DUMMY = new Info("", 1, 1);
40
41 /***
42 * Create the node given an id.
43 *
44 * @param id node id.
45 */
46 public ASTArrayAccess(int id) {
47 super(id);
48 }
49
50 /***
51 * Create a node with the given parser and id.
52 *
53 * @param p a parser.
54 * @param id node id.
55 */
56 public ASTArrayAccess(Parser p, int id) {
57 super(p, id);
58 }
59
60 /*** {@inheritDoc} */
61 public Object jjtAccept(ParserVisitor visitor, Object data) {
62 return visitor.visit(this, data);
63 }
64
65 /***
66 * evaluate array access upon a base object.
67 *
68 * foo.bar[2]
69 *
70 * makes me rethink the array operator :)
71 * @param jc the {@link JexlContext} to evaluate against.
72 * @param obj not used.
73 * @return the value of the array expression.
74 * @throws Exception on any error
75 */
76 public Object execute(Object obj, JexlContext jc) throws Exception {
77 ASTIdentifier base = (ASTIdentifier) jjtGetChild(0);
78
79 Object result = base.execute(obj, jc);
80
81
82
83
84 for (int i = 1; i < jjtGetNumChildren(); i++) {
85 Object loc = ((SimpleNode) jjtGetChild(i)).value(jc);
86
87 if (loc == null) {
88 return null;
89 }
90
91 result = evaluateExpr(result, loc);
92 }
93
94 return result;
95 }
96
97 /*** {@inheritDoc} */
98 public Object value(JexlContext jc) throws Exception {
99
100
101
102
103 ASTIdentifier base = (ASTIdentifier) jjtGetChild(0);
104
105 Object o = base.value(jc);
106
107
108
109
110 for (int i = 1; i < jjtGetNumChildren(); i++) {
111 Object loc = ((SimpleNode) jjtGetChild(i)).value(jc);
112
113 if (loc == null) {
114 return null;
115 }
116
117 o = evaluateExpr(o, loc);
118 }
119
120 return o;
121 }
122
123 /***
124 * Evaluate the Array expression 'loc' on the given object, o.
125 * e.g. in 'a[2]', <code>2</code> is 'loc' and <code>a</code> is 'o'.
126 *
127 * If o or loc are null, null is returned.
128 * If o is a Map, o.get(loc) is returned.
129 * If o is a List, o.get(loc) is returned. loc must resolve to an int value.
130 * If o is an Array, o[loc] is returned. loc must resolve to an int value.
131 * Otherwise loc is treated as a bean property of o.
132 *
133 * @param o an object to be accessed using the array operator or '.' operator.
134 * @param loc the index of the object to be returned.
135 * @return the resulting value.
136 * @throws Exception on any error.
137 */
138 public static Object evaluateExpr(Object o, Object loc) throws Exception {
139
140
141
142
143 if (o == null) {
144 return null;
145 }
146
147 if (loc == null) {
148 return null;
149 }
150
151 if (o instanceof Map) {
152 if (!((Map) o).containsKey(loc)) {
153 return null;
154 }
155
156 return ((Map) o).get(loc);
157 } else if (o instanceof List) {
158 int idx = Coercion.coerceInteger(loc).intValue();
159
160 try {
161 return ((List) o).get(idx);
162 } catch (IndexOutOfBoundsException iobe) {
163 return null;
164 }
165 } else if (o.getClass().isArray()) {
166 int idx = Coercion.coerceInteger(loc).intValue();
167
168 try {
169 return Array.get(o, idx);
170 } catch (ArrayIndexOutOfBoundsException aiobe) {
171 return null;
172 }
173 } else {
174
175
176
177
178 String s = loc.toString();
179
180 VelPropertyGet vg = Introspector.getUberspect().getPropertyGet(o, s, DUMMY);
181
182 if (vg != null) {
183 return vg.invoke(o);
184 }
185 }
186
187 throw new Exception("Unsupported object type for array [] accessor");
188 }
189
190 /***
191 * Gets the variable name piece of the expression.
192 * @return a String of the identifer.
193 * @see ASTIdentifier#getIdentifierString().
194 */
195 public String getIdentifierString() {
196 return ((ASTIdentifier) jjtGetChild(0)).getIdentifierString();
197 }
198 }