01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * http://www.apache.org/licenses/LICENSE-2.0
10: *
11: * Unless required by applicable law or agreed to in writing, software
12: * distributed under the License is distributed on an "AS IS" BASIS,
13: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14: * See the License for the specific language governing permissions and
15: * limitations under the License.
16: */
17: package org.apache.commons.betwixt.expression;
18:
19: /** <p><code>StringExpression</code> returns the current context object as a string.</p>
20: *
21: * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
22: * @version $Revision: 438373 $
23: */
24: public class StringExpression implements Expression {
25:
26: /** We only need only <code>StringExpression</code> */
27: private static final StringExpression singleton = new StringExpression();
28:
29: /**
30: * Gets the singleton
31: * @return the singleton <code>StringExpression</code> instance
32: */
33: public static StringExpression getInstance() {
34: return singleton;
35: }
36:
37: /** Base constructor. Should this be private? */
38: public StringExpression() {
39: }
40:
41: /** Return the context bean as a string
42: *
43: * @param context evaluate expression against this context
44: * @return the <code>toString()</code> representation of the context bean
45: */
46: public Object evaluate(Context context) {
47: Object value = context.getBean();
48: if (value != null) {
49: return value.toString();
50: }
51: return null;
52: }
53:
54: /**
55: * Do nothing
56: * @see org.apache.commons.betwixt.expression.Expression
57: */
58: public void update(Context context, String newValue) {
59: // do nothing
60: }
61:
62: /**
63: * Returns something useful for logging.
64: * @return the (short) class name
65: */
66: public String toString() {
67: return "StringExpression";
68: }
69:
70: }
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