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 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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 {&quot;javascript&quot;, &quot;rhino&quot;}.
 * @return an immutable list of short names
 */
 public List<String> getNames();

 /**
 * Returns the name of the scripting language 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.LANGUAGE</li>
 * <li>ScriptEngine.LANGUAGE_VERSION</li>
 * <li>ScriptEngine.NAME</li>
 * </ul>
 * <p>
 * The values for these keys are the Strings returned by <code>getEngineName</code>,
 * <code>getEngineVersion</code>, <code>getLanguageName</code>,
 * <code>getLanguageVersion</code> for the first four keys respectively. For NAME, one of the Strings
 * returned by <code>getNames</code> is returned.<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>&quot;MULTITHREADED&quot;</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>&quot;THREAD-ISOLATED&quot;</code> - The implementation satisfies the requirements
 * of &quot;MULTITHREADED&quot;, and also, the engine maintains independent values
 * for symbols in scripts executing on different threads.
 * <li><code>&quot;STATELESS&quot;</code> - The implementation satisfies the requirements of
 * <li><code>&quot;THREAD-ISOLATED&quot;</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 implementation for a Javascript
 * engine might be;
 *
 * <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 implementation for a Perl
 * engine might be;
 *
 * <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 program with given statements.
 * For instance an implementation for a PHP engine might be:
 *
 * <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();
}