ScriptContext


1   /*
2    * @(#)ScriptContext.java   1.4 05/11/17 14:24:13
3    *
4    * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTAIL. Use is subject to license terms.
6    */
7   
8   package javax.script;
9   import java.util.List  ;
10  import java.io.Writer  ;
11  import java.io.Reader  ;
12  
13  /**
14   * The interface whose implementing classes are used to connect Script Engines
15   * with objects, such as scoped Bindings, in hosting applications.  Each scope is a set
16   * of named attributes whose values can be set and retrieved using the
17   * <code>ScriptContext</code> methods. ScriptContexts also expose Readers and Writers
18   * that can be used by the ScriptEngines for input and output.
19   *
20   * @author Mike Grogan
21   * @version 1.0
22   * @since 1.6
23   */
24  public interface ScriptContext {
25      
26      
27      /**
28       * EngineScope attributes are visible during the lifetime of a single
29       * <code>ScriptEngine</code> and a set of attributes is maintained for each
30       * engine.
31       */
32      public static final int ENGINE_SCOPE = 100;
33      
34      /**
35       * GlobalScope attributes are visible to all engines created by same ScriptEngineFactory.
36       */
37      public static final int GLOBAL_SCOPE = 200;
38      
39      
40      /**
41       * Associates a <code>Bindings</code> instance with a particular scope in this
42       * <code>ScriptContext</code>.  Calls to the <code>getAttribute</code> and
43       * <code>setAttribute</code> methods must map to the <code>get</code> and
44       * <code>put</code> methods of the <code>Bindings</code> for the specified scope.
45       *
46       * @param  bindings The <code>Bindings</code> to associate with the given scope
47       * @param scope The scope
48       *
49       * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
50       * specified scope value in ScriptContexts of this type.
51       * @throws NullPointerException if value of scope is <code>ENGINE_SCOPE</code> and
52       * the specified <code>Bindings</code> is null.
53       *
54       */
55      public void setBindings(Bindings bindings, int scope);
56      
57      /**
58       * Gets the <code>Bindings</code>  associated with the given scope in this
59       * <code>ScriptContext</code>.
60       *
61       * @return The associated <code>Bindings</code>.  Returns <code>null</code> if it has not
62       * been set.
63       *
64       * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
65       * specified scope value in <code>ScriptContext</code> of this type.
66       */
67      public Bindings getBindings(int scope);
68      
69      /**
70       * Sets the value of an attribute in a given scope.
71       *
72       * @param name The name of the attribute to set
73       * @param value The value of the attribute
74       * @param scope The scope in which to set the attribute
75       *
76       * @throws IllegalArgumentException 
77       *         if the name is empty or if the scope is invalid.
78       * @throws NullPointerException if the name is null.
79       */
80      public void setAttribute(String   name, Object   value, int scope);
81      
82      /**
83       * Gets the value of an attribute in a given scope.
84       *
85       * @param name The name of the attribute to retrieve.
86       * @param scope The scope in which to retrieve the attribute.
87       * @return The value of the attribute. Returns <code>null</code> is the name
88       * does not exist in the given scope.
89       *
90       * @throws IllegalArgumentException
91       *         if the name is empty or if the value of scope is invalid.
92       * @throws NullPointerException if the name is null.
93       */
94      public Object   getAttribute(String   name, int scope);
95      
96      /**
97       * Remove an attribute in a given scope.
98       *
99       * @param name The name of the attribute to remove
100      * @param scope The scope in which to remove the attribute
101      *
102      * @return The removed value.
103      * @throws IllegalArgumentException
104      *         if the name is empty or if the scope is invalid.
105      * @throws NullPointerException if the name is null.
106      */
107     public Object   removeAttribute(String   name, int scope);
108     
109     /**
110      * Retrieves the value of the attribute with the given name in
111      * the scope occurring earliest in the search order.  The order
112      * is determined by the numeric value of the scope parameter (lowest
113      * scope values first.)
114      *
115      * @param name The name of the the attribute to retrieve.
116      * @return The value of the attribute in the lowest scope for
117      * which an attribute with the given name is defined.  Returns
118      * null if no attribute with the name exists in any scope.
119      * @throws NullPointerException if the name is null.
120      * @throws IllegalArgumentException if the name is empty.
121      */
122     public Object   getAttribute(String   name);
123     
124     
125     /**
126      * Get the lowest scope in which an attribute is defined.
127      * @param name Name of the attribute
128      * .
129      * @return The lowest scope.  Returns -1 if no attribute with the given
130      * name is defined in any scope.
131      * @throws NullPointerException if name is null.
132      * @throws IllegalArgumentException if name is empty.
133      */
134     public int getAttributesScope(String   name);
135     
136     /**
137      * Returns the <code>Writer</code> for scripts to use when displaying output.
138      *
139      * @return The <code>Writer</code>.
140      */
141     public Writer   getWriter();
142     
143     
144     /**
145      * Returns the <code>Writer</code> used to display error output.
146      *
147      * @return The <code>Writer</code>
148      */
149     public Writer   getErrorWriter();
150     
151     /**
152      * Sets the <code>Writer</code> for scripts to use when displaying output.
153      *
154      * @param writer The new <code>Writer</code>.
155      */
156     public void setWriter(Writer   writer);
157     
158     
159     /**
160      * Sets the <code>Writer</code> used to display error output.
161      *
162      * @param writer The <code>Writer</code>.
163      */
164     public void setErrorWriter(Writer   writer);
165     
166     /**
167      * Returns a <code>Reader</code> to be used by the script to read
168      * input.
169      *
170      * @return The <code>Reader</code>.
171      */
172     public Reader   getReader();
173     
174     
175     /**
176      * Sets the <code>Reader</code> for scripts to read input
177      * .
178      * @param reader The new <code>Reader</code>.
179      */
180     public void setReader(Reader   reader);
181     
182     /**
183      * Returns immutable <code>List</code> of all the valid values for
184      * scope in the ScriptContext.
185      *
186      * @return list of scope values
187      */
188     public List  <Integer  > getScopes();
189 }
190
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