1 package org.codehaus.plexus.interpolation;
2
3 import java.util.List;
4
5 /*
6 * Copyright 2001-2008 Codehaus Foundation.
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License");
9 * you may not use this file except in compliance with the License.
10 * 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, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 /**
22 * Supplies one strategy for resolving a value for an interpolation expression.
23 * ValueSources may be stacked.
24 */
25 public interface ValueSource {
26
27 /**
28 * @param expression The string expression.
29 * @return the value related to the expression, or null if not found.
30 */
31 public Object getValue(String expression);
32
33 /**
34 * Return the feedback about resolution failures for a particular expression.
35 *
36 * @return a combination of String and Throwable instances, where strings
37 * related to throwables are listed first.
38 */
39 List getFeedback();
40
41 /**
42 * Clear the feedback accumulated by a prior interpolation run.
43 */
44 void clearFeedback();
45 }