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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.
 *
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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();
}