/*
 * @(#)ScriptContext.java	1.4 05/11/17 14:24:13
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTAIL. Use is subject to license terms.
 */

package javax.script;
import java.util.List;
import java.io.Writer;
import java.io.Reader;

/**
 * The interface whose implementing classes are used to connect Script Engines
 * with objects, such as scoped Bindings, in hosting applications.  Each scope is a set
 * of named attributes whose values can be set and retrieved using the
 * <code>ScriptContext</code> methods. ScriptContexts also expose Readers and Writers
 * that can be used by the ScriptEngines for input and output.
 *
 * @author Mike Grogan
 * @version 1.0
 * @since 1.6
 */
public interface ScriptContext {
    
    
    /**
     * EngineScope attributes are visible during the lifetime of a single
     * <code>ScriptEngine</code> and a set of attributes is maintained for each
     * engine.
     */
    public static final int ENGINE_SCOPE = 100;
    
    /**
     * GlobalScope attributes are visible to all engines created by same ScriptEngineFactory.
     */
    public static final int GLOBAL_SCOPE = 200;
    
    
    /**
     * Associates a <code>Bindings</code> instance with a particular scope in this
     * <code>ScriptContext</code>.  Calls to the <code>getAttribute</code> and
     * <code>setAttribute</code> methods must map to the <code>get</code> and
     * <code>put</code> methods of the <code>Bindings</code> for the specified scope.
     *
     * @param  bindings The <code>Bindings</code> to associate with the given scope
     * @param scope The scope
     *
     * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
     * specified scope value in ScriptContexts of this type.
     * @throws NullPointerException if value of scope is <code>ENGINE_SCOPE</code> and
     * the specified <code>Bindings</code> is null.
     *
     */
    public void setBindings(Bindings bindings, int scope);
    
    /**
     * Gets the <code>Bindings</code>  associated with the given scope in this
     * <code>ScriptContext</code>.
     *
     * @return The associated <code>Bindings</code>.  Returns <code>null</code> if it has not
     * been set.
     *
     * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
     * specified scope value in <code>ScriptContext</code> of this type.
     */
    public Bindings getBindings(int scope);
    
    /**
     * Sets the value of an attribute in a given scope.
     *
     * @param name The name of the attribute to set
     * @param value The value of the attribute
     * @param scope The scope in which to set the attribute
     *
     * @throws IllegalArgumentException 
     *         if the name is empty or if the scope is invalid.
     * @throws NullPointerException if the name is null.
     */
    public void setAttribute(String name, Object value, int scope);
    
    /**
     * Gets the value of an attribute in a given scope.
     *
     * @param name The name of the attribute to retrieve.
     * @param scope The scope in which to retrieve the attribute.
     * @return The value of the attribute. Returns <code>null</code> is the name
     * does not exist in the given scope.
     *
     * @throws IllegalArgumentException
     *         if the name is empty or if the value of scope is invalid.
     * @throws NullPointerException if the name is null.
     */
    public Object getAttribute(String name, int scope);
    
    /**
     * Remove an attribute in a given scope.
     *
     * @param name The name of the attribute to remove
     * @param scope The scope in which to remove the attribute