1 /*
2 * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.script;
27
28 import java.util.List;
29
30 /**
31 * <code>ScriptEngineFactory</code> is used to describe and instantiate
32 * <code>ScriptEngines</code>.
33 * <br><br>
34 * Each class implementing <code>ScriptEngine</code> has a corresponding factory
35 * that exposes metadata describing the engine class.
36 * <br><br>The <code>ScriptEngineManager</code>
37 * uses the service provider mechanism described in the <i>Jar File Specification</i> to obtain
38 * instances of all <code>ScriptEngineFactories</code> available in
39 * the current ClassLoader.
40 *
41 * @since 1.6
42 */
43 public interface ScriptEngineFactory {
44 /**
45 * Returns the full name of the <code>ScriptEngine</code>. For
46 * instance an implementation based on the Mozilla Rhino Javascript engine
47 * might return <i>Rhino Mozilla Javascript Engine</i>.
48 * @return The name of the engine implementation.
49 */
50 public String getEngineName();
51
52 /**
53 * Returns the version of the <code>ScriptEngine</code>.
54 * @return The <code>ScriptEngine</code> implementation version.
55 */
56 public String getEngineVersion();
57
58
59 /**
60 * Returns an immutable list of filename extensions, which generally identify scripts
61 * written in the language supported by this <code>ScriptEngine</code>.
62 * The array is used by the <code>ScriptEngineManager</code> to implement its
63 * <code>getEngineByExtension</code> method.
64 * @return The list of extensions.
65 */
66 public List<String> getExtensions();
67
68
69 /**
70 * Returns an immutable list of mimetypes, associated with scripts that
71 * can be executed by the engine. The list is used by the
72 * <code>ScriptEngineManager</code> class to implement its
73 * <code>getEngineByMimetype</code> method.
74 * @return The list of mime types.
75 */
76 public List<String> getMimeTypes();
77
78 /**
79 * Returns an immutable list of short names for the <code>ScriptEngine</code>, which may be used to
80 * identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>.
81 * For instance, an implementation based on the Mozilla Rhino Javascript engine might
82 * return list containing {"javascript", "rhino"}.
83 */
84 public List<String> getNames();
85
86 /**
87 * Returns the name of the scripting langauge supported by this
88 * <code>ScriptEngine</code>.
89 * @return The name of the supported language.
90 */
91 public String getLanguageName();
92
93 /**
94 * Returns the version of the scripting language supported by this
95 * <code>ScriptEngine</code>.
96 * @return The version of the supported language.
97 */
98 public String getLanguageVersion();
99
100 /**
101 * Returns the value of an attribute whose meaning may be implementation-specific.
102 * Keys for which the value is defined in all implementations are:
103 * <ul>
104 * <li>ScriptEngine.ENGINE</li>
105 * <li>ScriptEngine.ENGINE_VERSION</li>
106 * <li>ScriptEngine.NAME</li>
107 * <li>ScriptEngine.LANGUAGE</li>
108 * <li>ScriptEngine.LANGUAGE_VERSION</li>
109 * </ul>
110 * <p>
111 * The values for these keys are the Strings returned by <code>getEngineName</code>,
112 * <code>getEngineVersion</code>, <code>getName</code>, <code>getLanguageName</code> and
113 * <code>getLanguageVersion</code> respectively.<br><br>
114 * A reserved key, <code><b>THREADING</b></code>, whose value describes the behavior of the engine
115 * with respect to concurrent execution of scripts and maintenance of state is also defined.
116 * These values for the <code><b>THREADING</b></code> key are:<br><br>
117 * <ul>
118 * <li><code>null</code> - The engine implementation is not thread safe, and cannot
119 * be used to execute scripts concurrently on multiple threads.
120 * <li><code>"MULTITHREADED"</code> - The engine implementation is internally
121 * thread-safe and scripts may execute concurrently although effects of script execution
122 * on one thread may be visible to scripts on other threads.
123 * <li><code>"THREAD-ISOLATED"</code> - The implementation satisfies the requirements
124 * of "MULTITHREADED", and also, the engine maintains independent values
125 * for symbols in scripts executing on different threads.
126 * <li><code>"STATELESS"</code> - The implementation satisfies the requirements of
127 * <li><code>"THREAD-ISOLATED"</code>. In addition, script executions do not alter the
128 * mappings in the <code>Bindings</code> which is the engine scope of the
129 * <code>ScriptEngine</code>. In particular, the keys in the <code>Bindings</code>
130 * and their associated values are the same before and after the execution of the script.
131 * </ul>
132 * <br><br>
133 * Implementations may define implementation-specific keys.
134 *
135 * @param key The name of the parameter
136 * @return The value for the given parameter. Returns <code>null</code> if no
137 * value is assigned to the key.
138 *
139 */
140 public Object getParameter(String key);
141
142 /**
143 * Returns a String which can be used to invoke a method of a Java object using the syntax
144 * of the supported scripting language. For instance, an implementaton for a Javascript
145 * engine might be;
146 * <p>
147 * <pre>
148 * <code>
149 * public String getMethodCallSyntax(String obj,
150 * String m, String... args) {
151 * String ret = obj;
152 * ret += "." + m + "(";
153 * for (int i = 0; i < args.length; i++) {
154 * ret += args[i];
155 * if (i < args.length - 1) {
156 * ret += ",";
157 * }
158 * }
159 * ret += ")";
160 * return ret;
161 * }
162 *</code>
163 *</pre>
164 * <p>
165 *
166 * @param obj The name representing the object whose method is to be invoked. The
167 * name is the one used to create bindings using the <code>put</code> method of
168 * <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code>
169 * <code>Bindings</code>,or the <code>setAttribute</code> method
170 * of <code>ScriptContext</code>. The identifier used in scripts may be a decorated form of the
171 * specified one.
172 *
173 * @param m The name of the method to invoke.
174 * @param args names of the arguments in the method call.
175 *
176 * @return The String used to invoke the method in the syntax of the scripting language.
177 */
178 public String getMethodCallSyntax(String obj, String m, String... args);
179
180 /**
181 * Returns a String that can be used as a statement to display the specified String using
182 * the syntax of the supported scripting language. For instance, the implementaton for a Perl
183 * engine might be;
184 * <p>
185 * <pre><code>
186 * public String getOutputStatement(String toDisplay) {
187 * return "print(" + toDisplay + ")";
188 * }
189 * </code></pre>
190 *
191 * @param toDisplay The String to be displayed by the returned statement.
192 * @return The string used to display the String in the syntax of the scripting language.
193 *
194 *
195 */
196 public String getOutputStatement(String toDisplay);
197
198
199 /**
200 * Returns A valid scripting language executable progam with given statements.
201 * For instance an implementation for a PHP engine might be:
202 * <p>
203 * <pre><code>
204 * public String getProgram(String... statements) {
205 * $retval = "<?\n";
206 * int len = statements.length;
207 * for (int i = 0; i < len; i++) {
208 * $retval += statements[i] + ";\n";
209 * }
210 * $retval += "?>";
211 *
212 * }
213 * </code></pre>
214 *
215 * @param statements The statements to be executed. May be return values of
216 * calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods.
217 * @return The Program
218 */
219
220 public String getProgram(String... statements);
221
222 /**
223 * Returns an instance of the <code>ScriptEngine</code> associated with this
224 * <code>ScriptEngineFactory</code>. A new ScriptEngine is generally
225 * returned, but implementations may pool, share or reuse engines.
226 *
227 * @return A new <code>ScriptEngine</code> instance.
228 */
229 public ScriptEngine getScriptEngine();
230 }