/*

 * Copyright (c) 2005, 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

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 */

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

 * @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

     *

     * @return The removed value.

     * @throws IllegalArgumentException

     *         if the name is empty or if the scope is invalid.

     * @throws NullPointerException if the name is null.

     */

    public Object removeAttribute(String name, int scope);

    /**

     * Retrieves the value of the attribute with the given name in

     * the scope occurring earliest in the search order.  The order

     * is determined by the numeric value of the scope parameter (lowest

     * scope values first.)

     *

     * @param name The name of the the attribute to retrieve.

     * @return The value of the attribute in the lowest scope for

     * which an attribute with the given name is defined.  Returns

     * null if no attribute with the name exists in any scope.

     * @throws NullPointerException if the name is null.

     * @throws IllegalArgumentException if the name is empty.

     */

    public Object getAttribute(String name);

    /**

     * Get the lowest scope in which an attribute is defined.

     * @param name Name of the attribute

     * .

     * @return The lowest scope.  Returns -1 if no attribute with the given

     * name is defined in any scope.

     * @throws NullPointerException if name is null.

     * @throws IllegalArgumentException if name is empty.

     */

    public int getAttributesScope(String name);

    /**

     * Returns the <code>Writer</code> for scripts to use when displaying output.

     *

     * @return The <code>Writer</code>.

     */

    public Writer getWriter();

    /**

     * Returns the <code>Writer</code> used to display error output.

     *

     * @return The <code>Writer</code>

     */

    public Writer getErrorWriter();

    /**

     * Sets the <code>Writer</code> for scripts to use when displaying output.

     *

     * @param writer The new <code>Writer</code>.

     */

    public void setWriter(Writer writer);

    /**

     * Sets the <code>Writer</code> used to display error output.

     *

     * @param writer The <code>Writer</code>.

     */

    public void setErrorWriter(Writer writer);

    /**

     * Returns a <code>Reader</code> to be used by the script to read

     * input.

     *

     * @return The <code>Reader</code>.

     */

    public Reader getReader();

    /**

     * Sets the <code>Reader</code> for scripts to read input

     * .

     * @param reader The new <code>Reader</code>.

     */

    public void setReader(Reader reader);

    /**

     * Returns immutable <code>List</code> of all the valid values for

     * scope in the ScriptContext.

     *

     * @return list of scope values

     */

    public List<Integer> getScopes();

}