1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2019 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle;
21
22 import java.util.Enumeration;
23 import java.util.HashMap;
24 import java.util.Map;
25 import java.util.Properties;
26
27 /**
28 * Resolves external properties from an
29 * underlying {@code Properties} object.
30 *
31 */
32 public final class PropertiesExpander
33 implements PropertyResolver {
34
35 /** The underlying values. */
36 private final Map<String, String> values;
37
38 /**
39 * Creates a new PropertiesExpander.
40 * @param properties the underlying properties to use for
41 * property resolution.
42 * @throws IllegalArgumentException indicates null was passed
43 */
44 public PropertiesExpander(Properties properties) {
45 if (properties == null) {
46 throw new IllegalArgumentException("cannot pass null");
47 }
48 values = new HashMap<>(properties.size());
49 for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements();) {
50 final String name = (String) e.nextElement();
51 values.put(name, properties.getProperty(name));
52 }
53 }
54
55 @Override
56 public String resolve(String name) {
57 return values.get(name);
58 }
59
60 }