    001// Copyright 2023, 2024 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007// http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.plastic;
    016
    017/**
    018 * <p>
    019 * Interface that can be implemented to provide access to field values based on their name.
    020 * Usually implemented with {@linkplain PlasticUtils#implementPropertyValueProvider(PlasticClass, java.util.Set)}.
    021 * </p>
    022 * <p>
    023 * The name of its abstract method is intended to avoid clashes with other existing methods
    024 * in the class.
    025 * </p>
    026 * @see PlasticUtils#implementPropertyValueProvider(PlasticClass, java.util.Set)
    027 * @since 5.8.4
    028 */
    029public interface PropertyValueProvider
    030{
    031    /**
    032     * Returns the value of a given field.
    033     * @param fieldName the field name.
    034     * @return the field value.
    035     */
    036    Object __propertyValueProvider__get(String fieldName);
    037
    038    /**
    039     * Sets the value of a given field.
    040     * @param fieldName the field name.
    041     * @param value the field value.
    042     * @since 5.8.7
    043     */
    044    void __propertyValueProvider__set(String fieldName, Object value);
    045
    046    /**
    047     * <p>
    048     * Returns the value of a given field in a given object if it belongs to a class
    049     * that implements {@linkplain PropertyValueProvider}. Otherwise, it throws an exception.
    050     * </p>
    051     * <p>
    052     * This is an utility method to avoid having to make casts very time you need to call
    053     * {@linkplain #__propertyValueProvider__get(String)}.
    054     * </p>
    055     * @param object an object.
    056     * @param fieldName the field name.
    057     * @return the field value.
    058     */
    059    static Object get(Object object, String fieldName)
    060    {
    061        if (object instanceof PropertyValueProvider)
    062        {
    063            return ((PropertyValueProvider) object).__propertyValueProvider__get(fieldName);
    064        }
    065        else
    066        {
    067            throw new RuntimeException("Class " + object.getClass().getName() + " doesn't implement " + PropertyValueProvider.class.getSimpleName());
    068        }
    069    }
    070
    071    /**
    072     * <p>
    073     * Sets the value of a given field in a given object if it belongs to a class
    074     * that implements {@linkplain PropertyValueProvider}. Otherwise, it throws an exception.
    075     * </p>
    076     * <p>
    077     * This is an utility method to avoid having to make casts very time you need to call
    078     * {@linkplain #__propertyValueProvider__set(String, Object)}.
    079     * </p>
    080     * @param object an object.
    081     * @param fieldName the field name.
    082     * @param value the field value.
    083     * @since 5.8.7
    084     */
    085    static void set(Object object, String fieldName, Object value)
    086    {
    087        if (object instanceof PropertyValueProvider)
    088        {
    089            ((PropertyValueProvider) object).__propertyValueProvider__set(fieldName, value);
    090        }
    091        else
    092        {
    093            throw new RuntimeException("Class " + object.getClass().getName() + " doesn't implement " + PropertyValueProvider.class.getSimpleName());
    094        }
    095    }
    096
    097}