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package javax.script;

import java.io.Reader;
import java.util.Map;
import java.util.Set;


ScriptEngine is the fundamental interface whose methods must be
fully functional in every implementation of this specification.



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.



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.



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
/**
 * <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.

/**
     * 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.

/**
     * 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 ScriptEngine implementation.

/**
     * 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 ScriptEngine implementation.

/**
     * 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
ScriptEngineManager to locate a ScriptEngine
with a given name in the getEngineByName method.

/**
     * 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.

/**
     * 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.

/**
     * 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.

Params:
  • script – The script to be executed by the script engine.
  • context – A ScriptContext exposing sets of attributes in
different scopes.  The meanings of the scopes ScriptContext.GLOBAL_SCOPE,
and ScriptContext.ENGINE_SCOPE are defined in the specification.


    
The ENGINE_SCOPE Bindings of the ScriptContext contains the
bindings of scripting variables to application objects to be used during this
script execution.
Throws:
  • ScriptException – if an error occurs in script. ScriptEngines should create and throw
ScriptException wrappers for checked Exceptions thrown by underlying scripting
implementations.
  • NullPointerException – if either argument is null.
Returns:The value returned from the execution of the script.
/**
     * 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 eval(String, ScriptContext) where the source of the script
is read from a Reader.

Params:
  • reader – The source of the script to be executed by the script engine.
  • context – The ScriptContext passed to the script engine.
Throws:
Returns:The value returned from the execution of the script.
/**
     * 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 ScriptContext for the ScriptEngine
is used.

Params:
  • script – The script language source to be executed.
Throws:
Returns:The value returned from the execution of the script.
/**
     * 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 eval(String) except that the source of the script is
provided as a Reader

Params:
  • reader – The source of the script.
Throws:
Returns:The value returned by the script.
/**
     * 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 Bindings argument as the ENGINE_SCOPE
Bindings of the ScriptEngine during the script execution.  The
Reader, Writer and non-ENGINE_SCOPE Bindings of the
default ScriptContext are used. The ENGINE_SCOPE
Bindings of the ScriptEngine is not changed, and its
mappings are unaltered by the script execution.

Params:
  • script – The source for the script.
  • n – The Bindings of attributes to be used for script execution.
Throws:
Returns:The value returned by the script.
/**
     * 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 eval(String, Bindings) except that the source of the script
is provided as a Reader.

Params:
  • reader – The source of the script.
  • n – The Bindings of attributes.
Throws:
Returns:The value returned by the script.
/**
     * 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
getBindings(ScriptContext.ENGINE_SCOPE).put.

Params:
  • key – The name of named value to add
  • value – The value of named value to add.
Throws:
/**
     * 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 setValue or some other value in the state
of the ScriptEngine, depending on the implementation.  Must have the same effect
as getBindings(ScriptContext.ENGINE_SCOPE).get

Params:
  • key – The key whose value is to be returned
Throws:
Returns:the value for the given key
/**
     * 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:




    

  • ScriptContext.GLOBAL_SCOPE - The set of named values representing global
scope. If this ScriptEngine is created by a ScriptEngineManager,
then the manager sets global scope bindings. This may be null if no global
scope is associated with this ScriptEngine
    • 

  • ScriptContext.ENGINE_SCOPE - The set of named values representing the state of
this ScriptEngine.  The values are generally visible in scripts using
the associated keys as variable names.
    • 

  • Any other value of scope defined in the default ScriptContext of the ScriptEngine.

    • 





The Bindings instances that are returned must be identical to those returned by the
getBindings method of ScriptContext called with corresponding arguments on
the default ScriptContext of the ScriptEngine.

Params:
  • scope – Either ScriptContext.ENGINE_SCOPE or ScriptContext.GLOBAL_SCOPE
which specifies the Bindings to return.  Implementations of ScriptContext
may define additional scopes.  If the default ScriptContext of the ScriptEngine
defines additional scopes, any of them can be passed to get the corresponding Bindings.
Throws:
Returns:The Bindings with the specified scope.
/**
     * 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:




    

  • ScriptContext.ENGINE_SCOPE - The specified Bindings replaces the
engine scope of the ScriptEngine.

    • 

  • ScriptContext.GLOBAL_SCOPE - The specified Bindings must be visible
as the GLOBAL_SCOPE.

    • 

  • Any other value of scope defined in the default ScriptContext of the ScriptEngine.

    • 





The method must have the same effect as calling the setBindings method of
ScriptContext with the corresponding value of scope on the default
ScriptContext of the ScriptEngine.

Params:
  • bindings – The Bindings for the specified scope.
  • scope – The specified scope.  Either ScriptContext.ENGINE_SCOPE,
ScriptContext.GLOBAL_SCOPE, or any other valid value of scope.
Throws:
/**
     * 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 Bindings.

Returns:A Bindings that can be used to replace the state of this ScriptEngine.
/**
     * 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 ScriptContext of the ScriptEngine whose Bindings, Reader
and Writers are used for script executions when no ScriptContext is specified.

Returns:The default ScriptContext of the ScriptEngine.
/**
     * 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 ScriptContext of the ScriptEngine whose Bindings, Reader
and Writers are used for script executions when no ScriptContext is specified.

Params:
  • context – A ScriptContext that will replace the default ScriptContext in
the ScriptEngine.
Throws:
/**
     * 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 ScriptEngineFactory for the class to which this ScriptEngine belongs.

Returns:The ScriptEngineFactory
/**
     * Returns a <code>ScriptEngineFactory</code> for the class to which this <code>ScriptEngine</code> belongs.
     *
     * @return The <code>ScriptEngineFactory</code>
     */
    public ScriptEngineFactory getFactory();
}