/*

 * Copyright (c) 2008, 2013, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.beans.decoder;

/**

 * This is base class that simplifies access to entities (fields or properties).

 * The {@code name} attribute specifies the name of the accessible entity.

 * The element defines getter if it contains no argument

 * or setter if it contains one argument.

 *

 * @since 1.7

 *

 * @author Sergey A. Malenkov

 */

abstract class AccessorElementHandler extends ElementHandler {

    private String name;

    private ValueObject value;

    /**

     * Parses attributes of the element.

     * The following attributes are supported:

     * <dl>

     * <dt>name

     * <dd>the name of the accessible entity

     * <dt>id

     * <dd>the identifier of the variable that is intended to store the result

     * </dl>

     *

     * @param name   the attribute name

     * @param value  the attribute value

     */

    @Override

    public void addAttribute(String name, String value) {

        if (name.equals("name")) { // NON-NLS: the attribute name

            this.name = value;

        } else {

            super.addAttribute(name, value);

        }

    }

    /**

     * Adds the argument that is used to set the value of this element.

     *

     * @param argument  the value of the element that contained in this one

     */

    @Override

    protected final void addArgument(Object argument) {

        if (this.value != null) {

            throw new IllegalStateException("Could not add argument to evaluated element");

        }

        setValue(this.name, argument);

        this.value = ValueObjectImpl.VOID;

    }

    /**

     * Returns the value of this element.

     *

     * @return the value of this element

     */

    @Override

    protected final ValueObject getValueObject() {

        if (this.value == null) {

            this.value = ValueObjectImpl.create(getValue(this.name));

        }

        return this.value;

    }

    /**

     * Returns the value of the entity with specified {@code name}.

     *

     * @param name  the name of the accessible entity

     * @return the value of the specified entity

     */

    protected abstract Object getValue(String name);

    /**

     * Sets the new value for the entity with specified {@code name}.

     *

     * @param name   the name of the accessible entity

     * @param value  the new value for the specified entity

     */

    protected abstract void setValue(String name, Object value);

}