    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.beanutils2.expression;
    018
    019/**
    020 * Property Name Expression Resolver.
    021 * <p>
    022 * Methods such as PropertyUtilsBean's {@code setNestedProperty()} method use a {@code Resolver} to process a <em>property name</em> expression and resolve
    023 * <em>nested</em>, <em>indexed</em> and <em>mapped</em> property names. The following code provides an example usage demonstrating all the methods:
    024 *
    025 * <pre>
    026 * // Iterate through a nested property expression
    027 * while (resolver.hasNested(name)) {
    028 *
    029 *     // isolate a single property from a nested expression
    030 *     String next = resolver.next(name);
    031 *
    032 *     // Process...
    033 *     String property = resolver.getProperty(next);
    034 *     if (resolver.isIndexed(next)) {
    035 *
    036 *         int index = resolver.getIndex(next);
    037 *         bean = getIndexedProperty(bean, property, index);
    038 *
    039 *     } else if (resolver.isMapped(next)) {
    040 *
    041 *         String key = resolver.getKey(next);
    042 *         bean = getMappedProperty(bean, property, key);
    043 *
    044 *     } else {
    045 *
    046 *         bean = getSimpleProperty(bean, property);
    047 *
    048 *     }
    049 *
    050 *     // remove the processed property from the expression
    051 *     name = resolver.remove(name);
    052 * }
    053 * </pre>
    054 *
    055 * In order to create an implementation, it is important to understand how BeanUtils/PropertyUtils uses the {@code resolver}. The following are the main methods
    056 * that use it:
    057 * <ul>
    058 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean}
    059 * <ul>
    060 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getIndexedProperty(Object, String)}</li>
    061 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getMappedProperty(Object, String)}</li>
    062 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getNestedProperty(Object, String)}</li>
    063 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li>
    064 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getSimpleProperty(Object, String)}</li>
    065 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li>
    066 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li>
    067 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li>
    068 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li>
    069 * </ul>
    070 * </li>
    071 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean}
    072 * <ul>
    073 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean#copyProperty(Object, String, Object)}</li>
    074 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean#setProperty(Object, String, Object)}</li>
    075 * </ul>
    076 * </li>
    077 * <li>{@link org.apache.commons.beanutils2.locale.LocaleBeanUtilsBean}
    078 * <ul>
    079 * <li>{@link org.apache.commons.beanutils2.locale.LocaleBeanUtilsBean#setProperty(Object, String, Object, String)}</li>
    080 * </ul>
    081 * </li>
    082 * </ul>
    083 *
    084 * @see org.apache.commons.beanutils2.PropertyUtilsBean#setResolver(Resolver)
    085 * @since 1.8.0
    086 */
    087public interface Resolver {
    088
    089    /**
    090     * Extract the index value from the property expression or -1.
    091     *
    092     * @param expression The property expression
    093     * @return The index value or -1 if the property is not indexed
    094     * @throws IllegalArgumentException If the indexed property is illegally formed or has an invalid (non-numeric) value
    095     */
    096    int getIndex(String expression);
    097
    098    /**
    099     * Extract the map key from the property expression or {@code null}.
    100     *
    101     * @param expression The property expression
    102     * @return The index value
    103     * @throws IllegalArgumentException If the mapped property is illegally formed
    104     */
    105    String getKey(String expression);
    106
    107    /**
    108     * Gets the property name from the property expression.
    109     *
    110     * @param expression The property expression
    111     * @return The property name
    112     */
    113    String getProperty(String expression);
    114
    115    /**
    116     * Indicates whether or not the expression contains nested property expressions or not.
    117     *
    118     * @param expression The property expression
    119     * @return The next property expression
    120     */
    121    boolean hasNested(String expression);
    122
    123    /**
    124     * Indicate whether the expression is for an indexed property or not.
    125     *
    126     * @param expression The property expression
    127     * @return {@code true} if the expression is indexed, otherwise {@code false}
    128     */
    129    boolean isIndexed(String expression);
    130
    131    /**
    132     * Indicate whether the expression is for a mapped property or not.
    133     *
    134     * @param expression The property expression
    135     * @return {@code true} if the expression is mapped, otherwise {@code false}
    136     */
    137    boolean isMapped(String expression);
    138
    139    /**
    140     * Extract the next property expression from the current expression.
    141     *
    142     * @param expression The property expression
    143     * @return The next property expression
    144     */
    145    String next(String expression);
    146
    147    /**
    148     * Remove the last property expression from the current expression.
    149     *
    150     * @param expression The property expression
    151     * @return The new expression value, with first property expression removed - null if there are no more expressions
    152     */
    153    String remove(String expression);
    154
    155}