ScriptEngineFactory


1   /*
2    * @(#)ScriptEngineFactory.java 1.3 05/11/17 14:24:14
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   
10  import java.util.List  ;
11  
12  /**
13   * <code>ScriptEngineFactory</code> is used to describe and instantiate
14   * <code>ScriptEngines</code>.
15   * <br><br>
16   * Each class implementing <code>ScriptEngine</code> has a corresponding factory
17   * that exposes metadata describing the engine class.
18   * <br><br>The <code>ScriptEngineManager</code>
19   * uses the service provider mechanism described in the <i>Jar File Specification</i> to obtain
20   * instances of all <code>ScriptEngineFactories</code> available in
21   * the current ClassLoader.
22   *
23   * @since 1.6
24   */
25  public interface ScriptEngineFactory {
26      /**
27       * Returns the full  name of the <code>ScriptEngine</code>.  For
28       * instance an implementation based on the Mozilla Rhino Javascript engine
29       * might return <i>Rhino Mozilla Javascript Engine</i>.
30       * @return The name of the engine implementation.
31       */
32      public String   getEngineName();
33      
34      /**
35       * Returns the version of the <code>ScriptEngine</code>.
36       * @return The <code>ScriptEngine</code> implementation version.
37       */
38      public String   getEngineVersion();
39      
40      
41      /**
42       * Returns an immutable list of filename extensions, which generally identify scripts
43       * written in the language supported by this <code>ScriptEngine</code>.
44       * The array is used by the <code>ScriptEngineManager</code> to implement its
45       * <code>getEngineByExtension</code> method.
46       * @return The list of extensions.
47       */
48      public List  <String  > getExtensions();
49      
50      
51      /**
52       * Returns an immutable list of mimetypes, associated with scripts that
53       * can be executed by the engine.  The list is used by the
54       * <code>ScriptEngineManager</code> class to implement its
55       * <code>getEngineByMimetype</code> method.
56       * @return The list of mime types.
57       */
58      public List  <String  > getMimeTypes();
59      
60      /**
61       * Returns an immutable list of  short names for the <code>ScriptEngine</code>, which may be used to
62       * identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>.
63       * For instance, an implementation based on the Mozilla Rhino Javascript engine might
64       * return list containing {&quot;javascript&quot;, &quot;rhino&quot;}.
65       */
66      public List  <String  > getNames();
67      
68      /**
69       * Returns the name of the scripting langauge supported by this
70       * <code>ScriptEngine</code>.
71       * @return The name of the supported language.
72       */
73      public String   getLanguageName();
74      
75      /**
76       * Returns the version of the scripting language supported by this
77       * <code>ScriptEngine</code>.
78       * @return The version of the supported language.
79       */
80      public String   getLanguageVersion();
81      
82      /**
83       * Returns the value of an attribute whose meaning may be implementation-specific.
84       * Keys for which the value is defined in all implementations are:
85       * <ul>
86       * <li>ScriptEngine.ENGINE</li>
87       * <li>ScriptEngine.ENGINE_VERSION</li>
88       * <li>ScriptEngine.NAME</li>
89       * <li>ScriptEngine.LANGUAGE</li>
90       * <li>ScriptEngine.LANGUAGE_VERSION</li>
91       * </ul>
92       * <p>
93       * The values for these keys are the Strings returned by <code>getEngineName</code>,
94       * <code>getEngineVersion</code>, <code>getName</code>, <code>getLanguageName</code> and
95       * <code>getLanguageVersion</code> respectively.<br><br>
96       * A reserved key, <code><b>THREADING</b></code>, whose value describes the behavior of the engine
97       * with respect to concurrent execution of scripts and maintenance of state is also defined.
98       * These values for the <code><b>THREADING</b></code> key are:<br><br>
99       * <ul>
100      * <p><code>null</code> - The engine implementation is not thread safe, and cannot
101      * be used to execute scripts concurrently on multiple threads.
102      * <p><code>&quot;MULTITHREADED&quot;</code> - The engine implementation is internally
103      * thread-safe and scripts may execute concurrently although effects of script execution
104      * on one thread may be visible to scripts on other threads.
105      * <p><code>&quot;THREAD-ISOLATED&quot;</code> - The implementation satisfies the requirements
106      * of &quot;MULTITHREADED&quot;, and also, the engine maintains independent values
107      * for symbols in scripts executing on different threads.
108      * <p><code>&quot;STATELESS&quot;</code> - The implementation satisfies the requirements of
109      * <code>&quot;THREAD-ISOLATED&quot;</code>.  In addition, script executions do not alter the
110      * mappings in the <code>Bindings</code> which is the engine scope of the
111      * <code>ScriptEngine</code>.  In particular, the keys in the <code>Bindings</code>
112      * and their associated values are the same before and after the execution of the script.
113      * </li>
114      * </ul>
115      * <br><br>
116      * Implementations may define implementation-specific keys.
117      *
118      * @param key The name of the parameter
119      * @return The value for the given parameter. Returns <code>null</code> if no
120      * value is assigned to the key.
121      *
122      */
123     public Object   getParameter(String   key);
124     
125     /**
126      * Returns a String which can be used to invoke a method of a  Java object using the syntax
127      * of the supported scripting language.  For instance, an implementaton for a Javascript
128      * engine might be;
129      * <p>
130      * <code><pre>
131      * public String getMethodCallSyntax(String obj,
132      *                                   String m, String... args) {
133      *      String ret = obj;
134      *      ret += "." + m + "(";
135      *      for (int i = 0; i < args.length; i++) {
136      *          ret += args[i];
137      *          if (i == args.length - 1) {
138      *              ret += ")";
139      *          } else {
140      *              ret += ",";
141      *          }
142      *      }
143      *      return ret;
144      * }
145      *</pre></code>
146      * <p>
147      *
148      * @param obj The name representing the object whose method is to be invoked. The
149      * name is the one used to create bindings using the <code>put</code> method of
150      * <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code>
151      * <code>Bindings</code>,or the <code>setAttribute</code> method
152      * of <code>ScriptContext</code>.  The identifier used in scripts may be a decorated form of the
153      * specified one.
154      *
155      * @param m The name of the method to invoke.
156      * @param args names of the arguments in the method call.
157      *
158      * @return The String used to invoke the method in the syntax of the scripting language.
159      */
160     public String   getMethodCallSyntax(String   obj, String   m, String  ... args);
161     
162     /**
163      * Returns a String that can be used as a statement to display the specified String  using
164      * the syntax of the supported scripting language.  For instance, the implementaton for a Perl
165      * engine might be;
166      * <p>
167      * <pre><code>
168      * public String getOutputStatement(String toDisplay) {
169      *      return "print(" + toDisplay + ")";
170      * }
171      * </code></pre>
172      *
173      * @param toDisplay The String to be displayed by the returned statement.
174      * @return The string used to display the String in the syntax of the scripting language.
175      *
176      *
177      */
178     public String   getOutputStatement(String   toDisplay);
179     
180     
181     /**
182      * Returns A valid scripting language executable progam with given statements.
183      * For instance an implementation for a PHP engine might be:
184      * <p>
185      * <pre><code>
186      * public String getProgram(String... statements) {
187      *      $retval = "&lt;?\n";
188      *      int len = statements.length;
189      *      for (int i = 0; i < len; i++) {
190      *          $retval += statements[i] + ";\n";
191      *      }
192      *      $retval += "?&gt;";
193      *
194      * }
195      * </code></pre>
196      *
197      *  @param statements The statements to be executed.  May be return values of
198      *  calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods.
199      *  @return The Program
200      */
201     
202     public String   getProgram(String  ... statements);
203     
204     /**
205      * Returns an instance of the <code>ScriptEngine</code> associated with this
206      * <code>ScriptEngineFactory</code>. A new ScriptEngine is generally
207      * returned, but implementations may pool, share or reuse engines.
208      *
209      * @return A new <code>ScriptEngine</code> instance.
210      */
211     public  ScriptEngine getScriptEngine();
212 }
213
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