1 /*
2 * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package de.smartics.properties.api.config.domain;
17
18 import java.util.ArrayList;
19 import java.util.List;
20
21 /**
22 * Helper to parse dependencies from a property value. A dependency is a place
23 * holder that is to be resolved to resolve the property's value.
24 */
25 final class DependenciesParser
26 {
27 // ********************************* Fields *********************************
28
29 // --- constants ------------------------------------------------------------
30
31 // --- members --------------------------------------------------------------
32
33 // ****************************** Initializer *******************************
34
35 // ****************************** Constructors ******************************
36
37 // ****************************** Inner Classes *****************************
38
39 // ********************************* Methods ********************************
40
41 // --- init -----------------------------------------------------------------
42
43 // --- get&set --------------------------------------------------------------
44
45 // --- business -------------------------------------------------------------
46
47 /**
48 * Returns the names of properties this property depends on. May be
49 * <code>null</code>, if this property does not refer to other properties.
50 *
51 * @param value the value to parse, may be <code>null</code>.
52 * @return the names of properties this property depends on.
53 */
54 List<String> getDependencies(final String value)
55 {
56 final List<String> dependencies = new ArrayList<String>();
57
58 if (value != null)
59 {
60 final int length = value.length();
61 for (int i = 0; i < length; i++)
62 {
63 final char c = value.charAt(i);
64 if (c == '$' && i < length - 1 && value.charAt(i + 1) == '{')
65 {
66 // CHECKSTYLE:OFF
67 i = readKey(dependencies, value, i + 1);
68 // CHECKSTYLE:ON
69 }
70 }
71 }
72
73 return dependencies;
74 }
75
76 private static int readKey(final List<String> dependencies,
77 final String value, final int index)
78 {
79 final int length = value.length() - 1;
80 final StringBuilder keyBuffer = new StringBuilder(64);
81 int i = index;
82 char n = value.charAt(++i);
83 while (n != '}' && i < length)
84 {
85 keyBuffer.append(n);
86 n = value.charAt(++i);
87 }
88
89 final String key = keyBuffer.toString();
90 dependencies.add(key);
91
92 return i;
93 }
94
95 // --- object basics --------------------------------------------------------
96
97 }