1 package org.codehaus.plexus.interpolation.util;
2
3 /*
4 * Copyright 2001-2006 Codehaus Foundation.
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 import java.util.Collection;
20
21 import org.codehaus.plexus.interpolation.ValueSource;
22
23 /**
24 * Utility methods shared by multiple {@link ValueSource} implementations.
25 *
26 * @author jdcasey
27 */
28 public final class ValueSourceUtils {
29
30 private ValueSourceUtils() {}
31
32 /**
33 * If the expression starts with one of the provided prefixes, trim that prefix
34 * and return the remaining expression. If it doesn't start with a provided
35 * prefix, and the allowUnprefixedExpressions flag is true, then return the
36 * expression unchanged; if the flag is false, return null. Finally, if the
37 * original expression is null, return null without attempting to process it.
38 *
39 * @param expression The expression to trim
40 * @param possiblePrefixes The list of possible expression prefixes to trim
41 * @param allowUnprefixedExpressions Whether to return the expression if it
42 * doesn't start with one of the prefixes. If true, simply return the
43 * original expression; if false, return null.
44 * @return The trimmed expression, or null. See the behavior of
45 * allowUnprefixedExpressions in this method for more detail.
46 */
47 public static String trimPrefix(
48 String expression, Collection<String> possiblePrefixes, boolean allowUnprefixedExpressions) {
49 if (expression == null) {
50 return null;
51 }
52
53 String realExpr = null;
54 for (String prefix : possiblePrefixes) {
55 if (expression.startsWith(prefix)) {
56 realExpr = expression.substring(prefix.length());
57 if (realExpr.startsWith(".")) {
58 realExpr = realExpr.substring(1);
59 }
60 break;
61 }
62 }
63
64 if (realExpr == null && allowUnprefixedExpressions) {
65 realExpr = expression;
66 }
67
68 return realExpr;
69 }
70
71 public static String trimPrefix(String expression, String[] possiblePrefixes, boolean allowUnprefixedExpressions) {
72 if (expression == null) {
73 return null;
74 }
75
76 String realExpr = null;
77 for (String prefix : possiblePrefixes) {
78 if (expression.startsWith(prefix)) {
79 realExpr = expression.substring(prefix.length());
80 if (realExpr.startsWith(".")) {
81 realExpr = realExpr.substring(1);
82 }
83 break;
84 }
85 }
86
87 if (realExpr == null && allowUnprefixedExpressions) {
88 realExpr = expression;
89 }
90
91 return realExpr;
92 }
93 }