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package javax.script;

import java.util.Map;

Extended by classes that store results of compilations.  State
might be stored in the form of Java classes, Java class files or scripting
language opcodes.  The script may be executed repeatedly
without reparsing.



Each CompiledScript is associated with a ScriptEngine -- A call to an  eval
method of the CompiledScript causes the execution of the script by the
ScriptEngine.  Changes in the state of the ScriptEngine caused by execution
of the CompiledScript  may visible during subsequent executions of scripts by the engine.
Author:
Mike Grogan
Since:
1.6/**
 * Extended by classes that store results of compilations.  State
 * might be stored in the form of Java classes, Java class files or scripting
 * language opcodes.  The script may be executed repeatedly
 * without reparsing.
 * <br><br>
 * Each <code>CompiledScript</code> is associated with a <code>ScriptEngine</code> -- A call to an  <code>eval</code>
 * method of the <code>CompiledScript</code> causes the execution of the script by the
 * <code>ScriptEngine</code>.  Changes in the state of the <code>ScriptEngine</code> caused by execution
 * of the <code>CompiledScript</code>  may visible during subsequent executions of scripts by the engine.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public abstract class CompiledScript {
    
Constructor for subclasses to call.
/**
     * Constructor for subclasses to call.
     */
    public CompiledScript() {}

    
Executes the program stored in this CompiledScript object.
Params:
context – A ScriptContext that is used in the same way as
the ScriptContext passed to the eval methods of
ScriptEngine.
Throws:
ScriptException – if an error occurs.
NullPointerException – if context is null.
Returns:
The value returned by the script execution, if any.  Should return null
if no value is returned by the script execution./**
     * Executes the program stored in this <code>CompiledScript</code> object.
     *
     * @param context A <code>ScriptContext</code> that is used in the same way as
     * the <code>ScriptContext</code> passed to the <code>eval</code> methods of
     * <code>ScriptEngine</code>.
     *
     * @return The value returned by the script execution, if any.  Should return <code>null</code>
     * if no value is returned by the script execution.
     *
     * @throws ScriptException if an error occurs.
     * @throws NullPointerException if context is null.
     */

    public abstract Object eval(ScriptContext context) throws ScriptException;

    
Executes the program stored in the CompiledScript object using
the supplied Bindings of attributes as the ENGINE_SCOPE of the
associated ScriptEngine during script execution.  If bindings is null,
then the effect of calling this method is same as that of eval(getEngine().getContext()).
.
The GLOBAL_SCOPE Bindings, Reader and Writer
associated with the default ScriptContext of the associated ScriptEngine are used.
Params:
bindings – The bindings of attributes used for the ENGINE_SCOPE.
Throws:
ScriptException – if an error occurs.
Returns:
The return value from the script execution/**
     * Executes the program stored in the <code>CompiledScript</code> object using
     * the supplied <code>Bindings</code> of attributes as the <code>ENGINE_SCOPE</code> of the
     * associated <code>ScriptEngine</code> during script execution.  If bindings is null,
     * then the effect of calling this method is same as that of eval(getEngine().getContext()).
     * <p>.
     * The <code>GLOBAL_SCOPE</code> <code>Bindings</code>, <code>Reader</code> and <code>Writer</code>
     * associated with the default <code>ScriptContext</code> of the associated <code>ScriptEngine</code> are used.
     *
     * @param bindings The bindings of attributes used for the <code>ENGINE_SCOPE</code>.
     *
     * @return The return value from the script execution
     *
     * @throws ScriptException if an error occurs.
     */
    public Object eval(Bindings bindings) throws ScriptException {

        ScriptContext ctxt = getEngine().getContext();

        if (bindings != null) {
            SimpleScriptContext tempctxt = new SimpleScriptContext(ctxt.getReader(), ctxt.getWriter(), ctxt.getErrorWriter());
            tempctxt.setBindings(bindings, ScriptContext.ENGINE_SCOPE);
            tempctxt.setBindings(ctxt.getBindings(ScriptContext.GLOBAL_SCOPE),
                    ScriptContext.GLOBAL_SCOPE);
            ctxt = tempctxt;
        }

        return eval(ctxt);
    }


    
Executes the program stored in the CompiledScript object.  The
default ScriptContext of the associated ScriptEngine is used.
The effect of calling this method is same as that of eval(getEngine().getContext()).
Throws:
ScriptException – if an error occurs.
Returns:
The return value from the script execution/**
     * Executes the program stored in the <code>CompiledScript</code> object.  The
     * default <code>ScriptContext</code> of the associated <code>ScriptEngine</code> is used.
     * The effect of calling this method is same as that of eval(getEngine().getContext()).
     *
     * @return The return value from the script execution
     *
     * @throws ScriptException if an error occurs.
     */
    public Object eval() throws ScriptException {
        return eval(getEngine().getContext());
    }

    
Returns the ScriptEngine whose compile method created this CompiledScript.
The CompiledScript will execute in this engine.
Returns:
The ScriptEngine that created this CompiledScript/**
     * Returns the <code>ScriptEngine</code> whose <code>compile</code> method created this <code>CompiledScript</code>.
     * The <code>CompiledScript</code> will execute in this engine.
     *
     * @return The <code>ScriptEngine</code> that created this <code>CompiledScript</code>
     */
    public abstract ScriptEngine getEngine();

}