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 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package javax.script;

import java.io.Reader;

import java.util.Map;

import java.util.Set;

/**

 * <code>ScriptEngine</code> is the fundamental interface whose methods must be

 * fully functional in every implementation of this specification.

 * <br><br>

 * These methods provide basic scripting functionality.  Applications written to this

 * simple interface are expected to work with minimal modifications in every implementation.

 * It includes methods that execute scripts, and ones that set and get values.

 * <br><br>

 * The values are key/value pairs of two types.  The first type of pairs consists of

 * those whose keys are reserved and defined in this specification or  by individual

 * implementations.  The values in the pairs with reserved keys have specified meanings.

 * <br><br>

 * The other type of pairs consists of those that create Java language Bindings, the values are

 * usually represented in scripts by the corresponding keys or by decorated forms of them.

 *

 * @author Mike Grogan

 * @since 1.6

 */

public interface ScriptEngine  {

    /**

     * Reserved key for a named value that passes

     * an array of positional arguments to a script.

     */

    public static final String ARGV="javax.script.argv";

    /**

     * Reserved key for a named value that is

     * the name of the file being executed.

     */

    public static final String FILENAME = "javax.script.filename";

    /**

     * Reserved key for a named value that is

     * the name of the <code>ScriptEngine</code> implementation.

     */

    public static final String ENGINE = "javax.script.engine";

    /**

     * Reserved key for a named value that identifies

     * the version of the <code>ScriptEngine</code> implementation.

     */

    public static final String ENGINE_VERSION = "javax.script.engine_version";

    /**

     * Reserved key for a named value that identifies

     * the short name of the scripting language.  The name is used by the

     * <code>ScriptEngineManager</code> to locate a <code>ScriptEngine</code>

     * with a given name in the <code>getEngineByName</code> method.

     */

    public static final String NAME = "javax.script.name";

    /**

     * Reserved key for a named value that is

     * the full name of Scripting Language supported by the implementation.

     */

    public static final String LANGUAGE = "javax.script.language";

    /**

     * Reserved key for the named value that identifies

     * the version of the scripting language supported by the implementation.

     */

    public static final String LANGUAGE_VERSION ="javax.script.language_version";

    /**

     * Causes the immediate execution of the script whose source is the String

     * passed as the first argument.  The script may be reparsed or recompiled before

     * execution.  State left in the engine from previous executions, including

     * variable values and compiled procedures may be visible during this execution.

     *

     * @param script The script to be executed by the script engine.

     *

     * @param context A <code>ScriptContext</code> exposing sets of attributes in

     * different scopes.  The meanings of the scopes <code>ScriptContext.GLOBAL_SCOPE</code>,

     * and <code>ScriptContext.ENGINE_SCOPE</code> are defined in the specification.

     * <br><br>

     * The <code>ENGINE_SCOPE</code> <code>Bindings</code> of the <code>ScriptContext</code> contains the

     * bindings of scripting variables to application objects to be used during this

     * script execution.

     *

     *

     * @return The value returned from the execution of the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if either argument is null.

     */

    public Object eval(String script, ScriptContext context) throws ScriptException;

    /**

     * Same as <code>eval(String, ScriptContext)</code> where the source of the script

     * is read from a <code>Reader</code>.

     *

     * @param reader The source of the script to be executed by the script engine.

     *

     * @param context The <code>ScriptContext</code> passed to the script engine.

     *

     * @return The value returned from the execution of the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if either argument is null.

     */

    public Object eval(Reader reader , ScriptContext context) throws ScriptException;

    /**

     * Executes the specified script.  The default <code>ScriptContext</code> for the <code>ScriptEngine</code>

     * is used.

     *

     * @param script The script language source to be executed.

     *

     * @return The value returned from the execution of the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if the argument is null.

     */

    public Object eval(String script) throws ScriptException;

    /**

     * Same as <code>eval(String)</code> except that the source of the script is

     * provided as a <code>Reader</code>

     *

     * @param reader The source of the script.

     *

     * @return The value returned by the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if the argument is null.

     */

    public Object eval(Reader reader) throws ScriptException;

    /**

     * Executes the script using the <code>Bindings</code> argument as the <code>ENGINE_SCOPE</code>

     * <code>Bindings</code> of the <code>ScriptEngine</code> during the script execution.  The

     * <code>Reader</code>, <code>Writer</code> and non-<code>ENGINE_SCOPE</code> <code>Bindings</code> of the

     * default <code>ScriptContext</code> are used. The <code>ENGINE_SCOPE</code>

     * <code>Bindings</code> of the <code>ScriptEngine</code> is not changed, and its

     * mappings are unaltered by the script execution.

     *

     * @param script The source for the script.

     *

     * @param n The <code>Bindings</code> of attributes to be used for script execution.

     *

     * @return The value returned by the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if either argument is null.

     */

    public Object eval(String script, Bindings n) throws ScriptException;

    /**

     * Same as <code>eval(String, Bindings)</code> except that the source of the script

     * is provided as a <code>Reader</code>.

     *

     * @param reader The source of the script.

     * @param n The <code>Bindings</code> of attributes.

     *

     * @return The value returned by the script.

     *

     * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw

     * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting

     * implementations.

     * @throws NullPointerException if either argument is null.

     */

    public Object eval(Reader reader , Bindings n) throws ScriptException;

    /**

     * Sets a key/value pair in the state of the ScriptEngine that may either create

     * a Java Language Binding to be used in the execution of scripts or be used in some

     * other way, depending on whether the key is reserved.  Must have the same effect as

     * <code>getBindings(ScriptContext.ENGINE_SCOPE).put</code>.

     *

     * @param key The name of named value to add

     * @param value The value of named value to add.

     *

     * @throws NullPointerException if key is null.

     * @throws IllegalArgumentException if key is empty.

     */

    public void put(String key, Object value);

    /**

     * Retrieves a value set in the state of this engine.  The value might be one

     * which was set using <code>setValue</code> or some other value in the state

     * of the <code>ScriptEngine</code>, depending on the implementation.  Must have the same effect

     * as <code>getBindings(ScriptContext.ENGINE_SCOPE).get</code>

     *

     * @param key The key whose value is to be returned

     * @return the value for the given key

     *

     * @throws NullPointerException if key is null.

     * @throws IllegalArgumentException if key is empty.

     */

    public Object get(String key);

    /**

     * Returns a scope of named values.  The possible scopes are:

     * <br><br>

     * <ul>

     * <li><code>ScriptContext.GLOBAL_SCOPE</code> - The set of named values representing global

     * scope. If this <code>ScriptEngine</code> is created by a <code>ScriptEngineManager</code>,

     * then the manager sets global scope bindings. This may be <code>null</code> if no global

     * scope is associated with this <code>ScriptEngine</code></li>

     * <li><code>ScriptContext.ENGINE_SCOPE</code> - The set of named values representing the state of

     * this <code>ScriptEngine</code>.  The values are generally visible in scripts using

     * the associated keys as variable names.</li>

     * <li>Any other value of scope defined in the default <code>ScriptContext</code> of the <code>ScriptEngine</code>.

     * </li>

     * </ul>

     * <br><br>

     * The <code>Bindings</code> instances that are returned must be identical to those returned by the

     * <code>getBindings</code> method of <code>ScriptContext</code> called with corresponding arguments on

     * the default <code>ScriptContext</code> of the <code>ScriptEngine</code>.

     *

     * @param scope Either <code>ScriptContext.ENGINE_SCOPE</code> or <code>ScriptContext.GLOBAL_SCOPE</code>

     * which specifies the <code>Bindings</code> to return.  Implementations of <code>ScriptContext</code>

     * may define additional scopes.  If the default <code>ScriptContext</code> of the <code>ScriptEngine</code>

     * defines additional scopes, any of them can be passed to get the corresponding <code>Bindings</code>.

     *

     * @return The <code>Bindings</code> with the specified scope.

     *

     * @throws IllegalArgumentException if specified scope is invalid

     *

     */

    public Bindings getBindings(int scope);

    /**

     * Sets a scope of named values to be used by scripts.  The possible scopes are:

     *<br><br>

     * <ul>

     * <li><code>ScriptContext.ENGINE_SCOPE</code> - The specified <code>Bindings</code> replaces the

     * engine scope of the <code>ScriptEngine</code>.

     * </li>

     * <li><code>ScriptContext.GLOBAL_SCOPE</code> - The specified <code>Bindings</code> must be visible

     * as the <code>GLOBAL_SCOPE</code>.

     * </li>

     * <li>Any other value of scope defined in the default <code>ScriptContext</code> of the <code>ScriptEngine</code>.

     *</li>

     * </ul>

     * <br><br>

     * The method must have the same effect as calling the <code>setBindings</code> method of

     * <code>ScriptContext</code> with the corresponding value of <code>scope</code> on the default

     * <code>ScriptContext</code> of the <code>ScriptEngine</code>.

     *

     * @param bindings The <code>Bindings</code> for the specified scope.

     * @param scope The specified scope.  Either <code>ScriptContext.ENGINE_SCOPE</code>,

     * <code>ScriptContext.GLOBAL_SCOPE</code>, or any other valid value of scope.

     *

     * @throws IllegalArgumentException if the scope is invalid

     * @throws NullPointerException if the bindings is null and the scope is

     * <code>ScriptContext.ENGINE_SCOPE</code>

     */

    public void setBindings(Bindings bindings, int scope);

    /**

     * Returns an uninitialized <code>Bindings</code>.

     *

     * @return A <code>Bindings</code> that can be used to replace the state of this <code>ScriptEngine</code>.

     **/

    public Bindings createBindings();

    /**

     * Returns the default <code>ScriptContext</code> of the <code>ScriptEngine</code> whose Bindings, Reader

     * and Writers are used for script executions when no <code>ScriptContext</code> is specified.

     *

     * @return The default <code>ScriptContext</code> of the <code>ScriptEngine</code>.

     */

    public ScriptContext getContext();

    /**

     * Sets the default <code>ScriptContext</code> of the <code>ScriptEngine</code> whose Bindings, Reader

     * and Writers are used for script executions when no <code>ScriptContext</code> is specified.

     *

     * @param context A <code>ScriptContext</code> that will replace the default <code>ScriptContext</code> in

     * the <code>ScriptEngine</code>.

     * @throws NullPointerException if context is null.

     */

    public void setContext(ScriptContext context);

    /**

     * Returns a <code>ScriptEngineFactory</code> for the class to which this <code>ScriptEngine</code> belongs.

     *

     * @return The <code>ScriptEngineFactory</code>

     */

    public ScriptEngineFactory getFactory();

}