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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package javax.script;
import java.util.List;
/**
* <code>ScriptEngineFactory</code> is used to describe and instantiate
* <code>ScriptEngines</code>.
* <br><br>
* Each class implementing <code>ScriptEngine</code> has a corresponding factory
* that exposes metadata describing the engine class.
* <br><br>The <code>ScriptEngineManager</code>
* uses the service provider mechanism described in the <i>Jar File Specification</i> to obtain
* instances of all <code>ScriptEngineFactories</code> available in
* the current ClassLoader.
*
* @since 1.6
*/
public interface ScriptEngineFactory {
/**
* Returns the full name of the <code>ScriptEngine</code>. For
* instance an implementation based on the Mozilla Rhino Javascript engine
* might return <i>Rhino Mozilla Javascript Engine</i>.
* @return The name of the engine implementation.
*/
public String getEngineName();
/**
* Returns the version of the <code>ScriptEngine</code>.
* @return The <code>ScriptEngine</code> implementation version.
*/
public String getEngineVersion();
/**
* Returns an immutable list of filename extensions, which generally identify scripts
* written in the language supported by this <code>ScriptEngine</code>.
* The array is used by the <code>ScriptEngineManager</code> to implement its
* <code>getEngineByExtension</code> method.
* @return The list of extensions.
*/
public List<String> getExtensions();
/**
* Returns an immutable list of mimetypes, associated with scripts that
* can be executed by the engine. The list is used by the
* <code>ScriptEngineManager</code> class to implement its
* <code>getEngineByMimetype</code> method.
* @return The list of mime types.
*/
public List<String> getMimeTypes();
/**
* Returns an immutable list of short names for the <code>ScriptEngine</code>, which may be used to
* identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>.
* For instance, an implementation based on the Mozilla Rhino Javascript engine might
* return list containing {"javascript", "rhino"}.
* @return an immutable list of short names
*/
public List<String> getNames();
/**
* Returns the name of the scripting langauge supported by this
* <code>ScriptEngine</code>.
* @return The name of the supported language.
*/
public String getLanguageName();
/**
* Returns the version of the scripting language supported by this
* <code>ScriptEngine</code>.
* @return The version of the supported language.
*/
public String getLanguageVersion();
/**
* Returns the value of an attribute whose meaning may be implementation-specific.
* Keys for which the value is defined in all implementations are:
* <ul>
* <li>ScriptEngine.ENGINE</li>
* <li>ScriptEngine.ENGINE_VERSION</li>
* <li>ScriptEngine.NAME</li>
* <li>ScriptEngine.LANGUAGE</li>
* <li>ScriptEngine.LANGUAGE_VERSION</li>
* </ul>
* <p>
* The values for these keys are the Strings returned by <code>getEngineName</code>,
* <code>getEngineVersion</code>, <code>getName</code>, <code>getLanguageName</code> and
* <code>getLanguageVersion</code> respectively.<br><br>
* A reserved key, <code><b>THREADING</b></code>, whose value describes the behavior of the engine
* with respect to concurrent execution of scripts and maintenance of state is also defined.
* These values for the <code><b>THREADING</b></code> key are:<br><br>
* <ul>
* <li><code>null</code> - The engine implementation is not thread safe, and cannot
* be used to execute scripts concurrently on multiple threads.
* <li><code>"MULTITHREADED"</code> - The engine implementation is internally
* thread-safe and scripts may execute concurrently although effects of script execution
* on one thread may be visible to scripts on other threads.
* <li><code>"THREAD-ISOLATED"</code> - The implementation satisfies the requirements
* of "MULTITHREADED", and also, the engine maintains independent values
* for symbols in scripts executing on different threads.
* <li><code>"STATELESS"</code> - The implementation satisfies the requirements of
* <li><code>"THREAD-ISOLATED"</code>. In addition, script executions do not alter the
* mappings in the <code>Bindings</code> which is the engine scope of the
* <code>ScriptEngine</code>. In particular, the keys in the <code>Bindings</code>
* and their associated values are the same before and after the execution of the script.
* </ul>
* <br><br>
* Implementations may define implementation-specific keys.
*
* @param key The name of the parameter
* @return The value for the given parameter. Returns <code>null</code> if no
* value is assigned to the key.
*
*/
public Object getParameter(String key);
/**
* Returns a String which can be used to invoke a method of a Java object using the syntax
* of the supported scripting language. For instance, an implementaton for a Javascript
* engine might be;
* <p>
* <pre>{@code
* public String getMethodCallSyntax(String obj,
* String m, String... args) {
* String ret = obj;
* ret += "." + m + "(";
* for (int i = 0; i < args.length; i++) {
* ret += args[i];
* if (i < args.length - 1) {
* ret += ",";
* }
* }
* ret += ")";
* return ret;
* }
* } </pre>
* <p>
*
* @param obj The name representing the object whose method is to be invoked. The
* name is the one used to create bindings using the <code>put</code> method of
* <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code>
* <code>Bindings</code>,or the <code>setAttribute</code> method
* of <code>ScriptContext</code>. The identifier used in scripts may be a decorated form of the
* specified one.
*
* @param m The name of the method to invoke.
* @param args names of the arguments in the method call.
*
* @return The String used to invoke the method in the syntax of the scripting language.
*/
public String getMethodCallSyntax(String obj, String m, String... args);
/**
* Returns a String that can be used as a statement to display the specified String using
* the syntax of the supported scripting language. For instance, the implementaton for a Perl
* engine might be;
* <p>
* <pre><code>
* public String getOutputStatement(String toDisplay) {
* return "print(" + toDisplay + ")";
* }
* </code></pre>
*
* @param toDisplay The String to be displayed by the returned statement.
* @return The string used to display the String in the syntax of the scripting language.
*
*
*/
public String getOutputStatement(String toDisplay);
/**
* Returns a valid scripting language executable progam with given statements.
* For instance an implementation for a PHP engine might be:
* <p>
* <pre>{@code
* public String getProgram(String... statements) {
* String retval = "<?\n";
* int len = statements.length;
* for (int i = 0; i < len; i++) {
* retval += statements[i] + ";\n";
* }
* return retval += "?>";
* }
* }</pre>
*
* @param statements The statements to be executed. May be return values of
* calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods.
* @return The Program
*/
public String getProgram(String... statements);
/**
* Returns an instance of the <code>ScriptEngine</code> associated with this
* <code>ScriptEngineFactory</code>. A new ScriptEngine is generally
* returned, but implementations may pool, share or reuse engines.
*
* @return A new <code>ScriptEngine</code> instance.
*/
public ScriptEngine getScriptEngine();
}