1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.scxml2;
18
19 import java.util.Map;
20
21 /**
22 * A Context or "scope" for storing variables; usually tied to
23 * a SCXML root or State object.
24 */
25 public interface Context {
26
27 /**
28 * Current namespaces are saved under this key in the context.
29 */
30 String NAMESPACES_KEY = "_ALL_NAMESPACES";
31
32 /**
33 * Assigns a new value to an existing variable or creates a new one.
34 * The method searches the chain of parent Contexts for variable
35 * existence.
36 *
37 * @param name The variable name
38 * @param value The variable value
39 */
40 void set(String name, Object value);
41
42 /**
43 * Assigns a new value to an existing variable or creates a new one.
44 * The method allows to shaddow a variable of the same name up the
45 * Context chain.
46 *
47 * @param name The variable name
48 * @param value The variable value
49 */
50 void setLocal(String name, Object value);
51
52 /**
53 * Get the value of this variable; delegating to parent.
54 *
55 * @param name The name of the variable
56 * @return The value (or null)
57 */
58 Object get(String name);
59
60 /**
61 * Check if this variable exists, delegating to parent.
62 *
63 * @param name The name of the variable
64 * @return Whether a variable with the name exists in this Context
65 */
66 boolean has(String name);
67
68 /**
69 * Check if this variable exists, only checking this Context
70 *
71 * @param name The name of the variable
72 * @return Whether a variable with the name exists in this Context
73 */
74 boolean hasLocal(String name);
75
76 /**
77 * Get the Map of all variables in this Context.
78 *
79 * @return Local variable entries Map
80 * To get variables in parent Context, call getParent().getVars().
81 * @see #getParent()
82 */
83 Map<String, Object> getVars();
84
85 /**
86 * Clear this Context.
87 */
88 void reset();
89
90 /**
91 * Get the parent Context, may be null.
92 *
93 * @return The parent Context in a chained Context environment
94 */
95 Context getParent();
96
97 /**
98 * Get the SCXMLSystemContext for this Context, should not be null unless this is the root Context
99 *
100 * @return The SCXMLSystemContext in a chained Context environment
101 */
102 SCXMLSystemContext getSystemContext();
103
104 }