    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.beanutils.expression;
    018
    019/**
    020 * Property Name Expression Resolver.
    021 * <p>
    022 * Methods such as PropertyUtilsBean's <code>setNestedProperty()</code> method
    023 * use a <code>Resolver</code> to process a <i>property name</i>
    024 * expression and resolve <i>nested</i>, <i>indexed</i> and <i>mapped</i>
    025 * property names. The following code provides an example usage
    026 * demonstrating all the methods:
    027 *
    028 * <pre>
    029 *      // Iterate through a nested property expression
    030 *      while (resolver.hasNested(name)) {
    031 *
    032 *          // isolate a single property from a nested expresion
    033 *          String next = resolver.next(name);
    034 *
    035 *          // Process...
    036 *          String property = resolver.getProperty(next);
    037 *          if (resolver.isIndexed(next)) {
    038 *
    039 *              int index = resolver.getIndex(next);
    040 *              bean = getIndexedProperty(bean, property, index);
    041 *
    042 *          } else if (resolver.isMapped(next)) {
    043 *
    044 *              String key = resolver.getKey(next);
    045 *              bean = getMappedProperty(bean, property, key);
    046 *
    047 *          } else {
    048 *
    049 *              bean = getSimpleProperty(bean, property);
    050 *
    051 *          }
    052 *
    053 *          // remove the processed property from the expression
    054 *          name = resolver.remove(name);
    055 *      }
    056 * </pre>
    057 *
    058 * In order to create an implementation, it is important to understand how
    059 * BeanUtils/PropertyUtils uses the <code>resolver</code>. The following are
    060 * the main methods that use it:
    061 * <ul>
    062 *   <li>{@link org.apache.commons.beanutils.PropertyUtilsBean}</li>
    063 *   <ul>
    064 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getIndexedProperty(Object, String)}</li>
    065 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getMappedProperty(Object, String)}</li>
    066 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getNestedProperty(Object, String)}</li>
    067 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li>
    068 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getSimpleProperty(Object, String)}</li>
    069 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li>
    070 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li>
    071 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li>
    072 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li>
    073 *   </ul>
    074 *   <li>{@link org.apache.commons.beanutils.BeanUtilsBean}</li>
    075 *   <ul>
    076 *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#copyProperty(Object, String, Object)}</li>
    077 *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#setProperty(Object, String, Object)}</li>
    078 *   </ul>
    079 *   <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean}</li>
    080 *   <ul>
    081 *       <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean#setProperty(Object,
    082 *        String, Object, String)}</li>
    083 *   </ul>
    084 * </ul>
    085 *
    086 * @version $Id$
    087 * @see org.apache.commons.beanutils.PropertyUtilsBean#setResolver(Resolver)
    088 * @since 1.8.0
    089 */
    090public interface Resolver {
    091
    092    /**
    093     * Extract the index value from the property expression or -1.
    094     *
    095     * @param expression The property expression
    096     * @return The index value or -1 if the property is not indexed
    097     * @throws IllegalArgumentException If the indexed property is illegally
    098     * formed or has an invalid (non-numeric) value
    099     */
    100    int getIndex(String expression);
    101
    102    /**
    103     * Extract the map key from the property expression or <code>null</code>.
    104     *
    105     * @param expression The property expression
    106     * @return The index value
    107     * @throws IllegalArgumentException If the mapped property is illegally formed
    108     */
    109    String getKey(String expression);
    110
    111    /**
    112     * Return the property name from the property expression.
    113     *
    114     * @param expression The property expression
    115     * @return The property name
    116     */
    117    String getProperty(String expression);
    118
    119    /**
    120     * Indicates whether or not the expression
    121     * contains nested property expressions or not.
    122     *
    123     * @param expression The property expression
    124     * @return The next property expression
    125     */
    126    boolean hasNested(String expression);
    127
    128    /**
    129     * Indicate whether the expression is for an indexed property or not.
    130     *
    131     * @param expression The property expression
    132     * @return <code>true</code> if the expresion is indexed,
    133     *  otherwise <code>false</code>
    134     */
    135    boolean isIndexed(String expression);
    136
    137    /**
    138     * Indicate whether the expression is for a mapped property or not.
    139     *
    140     * @param expression The property expression
    141     * @return <code>true</code> if the expresion is mapped,
    142     *  otherwise <code>false</code>
    143     */
    144    boolean isMapped(String expression);
    145
    146    /**
    147     * Extract the next property expression from the
    148     * current expression.
    149     *
    150     * @param expression The property expression
    151     * @return The next property expression
    152     */
    153    String next(String expression);
    154
    155    /**
    156     * Remove the last property expresson from the
    157     * current expression.
    158     *
    159     * @param expression The property expression
    160     * @return The new expression value, with first property
    161     * expression removed - null if there are no more expressions
    162     */
    163    String remove(String expression);
    164
    165}