1 package org.apache.velocity.tools;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. 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,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.ArrayList;
23 import java.util.Collections;
24 import java.util.List;
25
26 /**
27 * A specialized constants class to provide some compile-time typo checking and
28 * runtime validation for scopes specified in annotations, toolbox configs, etc.
29 *
30 * @author Nathan Bubna
31 * @version $Id: Toolbox.java 511959 2007-02-26 19:24:39Z nbubna $
32 */
33 public final class Scope
34 {
35 public static final String REQUEST = "request";
36 public static final String SESSION = "session";
37 public static final String APPLICATION = "application";
38
39 private static final List<String> VALUES;
40 static
41 {
42 List<String> defaults = new ArrayList<String>(3);
43 defaults.add(REQUEST);
44 defaults.add(SESSION);
45 defaults.add(APPLICATION);
46 VALUES = Collections.synchronizedList(defaults);
47 }
48
49 // keep an instance available in case someone wants to
50 // drop this into a template for some reason
51 private static final Scope INSTANCE = new Scope();
52
53 public static final Scope getInstance()
54 {
55 return INSTANCE;
56 }
57
58 public static final void add(String newScope)
59 {
60 // keep everything lower case
61 newScope = newScope.toLowerCase();
62 // complain if it already exists
63 if (VALUES.contains(newScope))
64 {
65 throw new IllegalArgumentException("Scope '"+newScope+"' has already been registered.");
66 }
67 VALUES.add(newScope);
68 }
69
70 public static final boolean exists(String scope)
71 {
72 // keep everything lower case
73 scope = scope.toLowerCase();
74 return VALUES.contains(scope);
75 }
76
77 public static final List<String> values()
78 {
79 return Collections.unmodifiableList(VALUES);
80 }
81
82 private Scope()
83 {
84 // keep constructor private, this is a singleton
85 }
86
87 }