View Javadoc

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.scxml;
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       * Assigns a new value to an existing variable or creates a new one.
28       * The method searches the chain of parent Contexts for variable
29       * existence.
30       *
31       * @param name The variable name
32       * @param value The variable value
33       */
34      void set(String name, Object value);
35  
36      /***
37       * Assigns a new value to an existing variable or creates a new one.
38       * The method allows to shaddow a variable of the same name up the
39       * Context chain.
40       *
41       * @param name The variable name
42       * @param value The variable value
43       */
44      void setLocal(String name, Object value);
45  
46      /***
47       * Get the value of this variable; delegating to parent.
48       *
49       * @param name The name of the variable
50       * @return The value (or null)
51       */
52      Object get(String name);
53  
54      /***
55       * Check if this variable exists, delegating to parent.
56       *
57       * @param name The name of the variable
58       * @return Whether a variable with the name exists in this Context
59       */
60      boolean has(String name);
61  
62      /***
63       * Get the Map of all variables in this Context.
64       *
65       * @return Local variable entries Map
66       * To get variables in parent Context, call getParent().getVars().
67       * @see #getParent()
68       */
69      Map getVars();
70  
71      /***
72       * Clear this Context.
73       */
74      void reset();
75  
76      /***
77       * Get the parent Context, may be null.
78       *
79       * @return The parent Context in a chained Context environment
80       */
81      Context getParent();
82  
83  }