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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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	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.
	* @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 error occurs in script.
	* @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.
	* @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.
	* @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.
	* @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();
	}

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