/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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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.
 * <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 {

 /**
 * 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 <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();
 tempctxt.setBindings(bindings, ScriptContext.ENGINE_SCOPE);
 tempctxt.setBindings(ctxt.getBindings(ScriptContext.GLOBAL_SCOPE),
 ScriptContext.GLOBAL_SCOPE);
 tempctxt.setWriter(ctxt.getWriter());
 tempctxt.setReader(ctxt.getReader());
 tempctxt.setErrorWriter(ctxt.getErrorWriter());
 ctxt = tempctxt;
 }

 return eval(ctxt);
 }


 /**
 * 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 <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();

}