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 */
017 package 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 $Revision: 555845 $ $Date: 2007-07-13 03:52:05 +0100 (Fri, 13 Jul 2007) $
087 * @see org.apache.commons.beanutils.PropertyUtilsBean#setResolver(Resolver)
088 * @since 1.8.0
089 */
090 public 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 }