1 package org.apache.velocity.context;
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 /**
23 * Interface describing the application data context. This set of
24 * routines is used by the application to set and remove 'named' data
25 * object to pass them to the template engine to use when rendering
26 * a template.
27 *
28 * This is the same set of methods supported by the original Context
29 * class
30 *
31 * @see org.apache.velocity.context.AbstractContext
32 * @see org.apache.velocity.VelocityContext
33 *
34 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
35 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
36 * @version $Id: Context.java 463298 2006-10-12 16:10:32Z henning $
37 */
38 public interface Context
39 {
40 /**
41 * Adds a name/value pair to the context.
42 *
43 * @param key The name to key the provided value with.
44 * @param value The corresponding value.
45 * @return The old object or null if there was no old object.
46 */
47 Object put(String key, Object value);
48
49 /**
50 * Gets the value corresponding to the provided key from the context.
51 *
52 * @param key The name of the desired value.
53 * @return The value corresponding to the provided key.
54 */
55 Object get(String key);
56
57 /**
58 * Indicates whether the specified key is in the context.
59 *
60 * @param key The key to look for.
61 * @return Whether the key is in the context.
62 */
63 boolean containsKey(Object key);
64
65 /**
66 * Get all the keys for the values in the context.
67 * @return All the keys for the values in the context.
68 */
69 Object[] getKeys();
70
71 /**
72 * Removes the value associated with the specified key from the context.
73 *
74 * @param key The name of the value to remove.
75 * @return The value that the key was mapped to, or <code>null</code>
76 * if unmapped.
77 */
78 Object remove(Object key);
79 }