/*
 * Copyright 1996-2000 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package org.omg.CORBA;

/**
 * A modifiable list containing <code>NamedValue</code> objects.
 * <P>
 * The class <code>NVList</code> is used as follows:
 * <UL>
 * <LI>to describe arguments for a <code>Request</code> object
 * in the Dynamic Invocation Interface and
 * the Dynamic Skeleton Interface
 * <LI>to describe context values in a <code>Context</code> object
 * </UL>
 * <P>
 * Each <code>NamedValue</code> object consists of the following:
 * <UL>
 * <LI>a name, which is a <code>String</code> object
 * <LI>a value, as an <code>Any</code> object
 * <LI>an argument mode flag
 * </UL>
 * <P>
 * An <code>NVList</code> object
 * may be created using one of the following
 * <code>ORB</code> methods:
 * <OL>
 * <LI><code>org.omg.CORBA.ORB.create_list</code>
 * <PRE>
 *    org.omg.CORBA.NVList nv = orb.create_list(3);
 * </PRE>
 * The variable <code>nv</code> represents a newly-created
 * <code>NVList</code> object.  The argument is a memory-management
 * hint to the orb and does not imply the actual length of the list.
 * If, for example, you want to use an <code>NVList</code> object
 * in a request, and the method being invoked takes three parameters,
 * you might optimize by supplying 3 to the method
 * <code>create_list</code>.  Note that the new <code>NVList</code>
 * will not necessarily have a length of 3; it
 * could have a length of 2 or 4, for instance.
 * Note also that you can add any number of
 * <code>NamedValue</code> objects to this list regardless of
 * its original length.
 * <P>
 * <LI><code>org.omg.CORBA.ORB.create_operation_list</code>
 * <PRE>
 *    org.omg.CORBA.NVList nv = orb.create_operation_list(myOperationDef);
 * </PRE>
 * The variable <code>nv</code> represents a newly-created
 * <code>NVList</code> object that contains descriptions of the
 * arguments to the method described in the given
 * <code>OperationDef</code> object.
 * </OL>
 * <P>
 * The methods in the class <code>NVList</code> all deal with
 * the <code>NamedValue</code> objects in the list.
 * There are three methods for adding a <code>NamedValue</code> object,
 * a method for getting the count of <code>NamedValue</code> objects in
 * the list, a method for retrieving a <code>NamedValue</code> object
 * at a given index, and a method for removing a <code>NamedValue</code> object
 * at a given index.
 *
 * @see org.omg.CORBA.Request
 * @see org.omg.CORBA.ServerRequest
 * @see org.omg.CORBA.NamedValue
 * @see org.omg.CORBA.Context
 *
 * @since       JDK1.2
 */

public abstract class NVList {

    /**
     * Returns the number of <code>NamedValue</code> objects that have
     * been added to this <code>NVList</code> object.
     *
     * @return                  an <code>int</code> indicating the number of
     * <code>NamedValue</code> objects in this <code>NVList</code>.
     */

    public abstract int count();

    /**
     * Creates a new <code>NamedValue</code> object initialized with the given flag
     * and adds it to the end of this <code>NVList</code> object.
     * The flag can be any one of the argument passing modes:
     * <code>ARG_IN.value</code>, <code>ARG_OUT.value</code>, or
     * <code>ARG_INOUT.value</code>.
     *
     * @param flags             one of the argument mode flags
     * @return                  the newly-created <code>NamedValue</code> object
     */

    public abstract NamedValue add(int flags);

    /**
     * Creates a new <code>NamedValue</code> object initialized with the
     * given name and flag,
     * and adds it to the end of this <code>NVList</code> object.
     * The flag can be any one of the argument passing modes:
     * <code>ARG_IN.value</code>, <code>ARG_OUT.value</code>, or
     * <code>ARG_INOUT.value</code>.
     *
     * @param item_name the name for the new <code>NamedValue</code> object
     * @param flags             one of the argument mode flags
     * @return                  the newly-created <code>NamedValue</code> object
     */

    public abstract NamedValue add_item(String item_name, int flags);

    /**
     * Creates a new <code>NamedValue</code> object initialized with the
     * given name, value, and flag,
     * and adds it to the end of this <code>NVList</code> object.
     *
     * @param item_name the name for the new <code>NamedValue</code> object
     * @param val         an <code>Any</code> object containing the  value
     *                    for the new <code>NamedValue</code> object
     * @param flags       one of the following argument passing modes:
     *                    <code>ARG_IN.value</code>, <code>ARG_OUT.value</code>, or
     *                    <code>ARG_INOUT.value</code>
     * @return            the newly created <code>NamedValue</code> object
     */

    public abstract NamedValue add_value(String item_name, Any val, int flags);

    /**
     * Retrieves the <code>NamedValue</code> object at the given index.
     *
     * @param index             the index of the desired <code>NamedValue</code> object,
     *                    which must be between zero and the length of the list
     *                    minus one, inclusive.  The first item is at index zero.
     * @return                  the <code>NamedValue</code> object at the given index
     * @exception org.omg.CORBA.Bounds  if the index is greater than
     *                          or equal to number of <code>NamedValue</code> objects
     */

    public abstract NamedValue item(int index) throws org.omg.CORBA.Bounds;

    /**
     * Removes the <code>NamedValue</code> object at the given index.
     * Note that the indices of all <code>NamedValue</code> objects following
     * the one removed are shifted down by one.
     *
     * @param index             the index of the <code>NamedValue</code> object to be
     *                    removed, which must be between zero and the length
     *                    of the list minus one, inclusive.
     *                    The first item is at index zero.
     * @exception org.omg.CORBA.Bounds  if the index is greater than
     *                          or equal to number of <code>NamedValue</code> objects in
     *                the list
     */

    public abstract void remove(int index) throws org.omg.CORBA.Bounds;

}
