1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.beanutils2.expression;
18
19 /**
20 * Property Name Expression Resolver.
21 * <p>
22 * Methods such as PropertyUtilsBean's {@code setNestedProperty()} method use a {@code Resolver} to process a <em>property name</em> expression and resolve
23 * <em>nested</em>, <em>indexed</em> and <em>mapped</em> property names. The following code provides an example usage demonstrating all the methods:
24 *
25 * <pre>
26 * // Iterate through a nested property expression
27 * while (resolver.hasNested(name)) {
28 *
29 * // isolate a single property from a nested expression
30 * String next = resolver.next(name);
31 *
32 * // Process...
33 * String property = resolver.getProperty(next);
34 * if (resolver.isIndexed(next)) {
35 *
36 * int index = resolver.getIndex(next);
37 * bean = getIndexedProperty(bean, property, index);
38 *
39 * } else if (resolver.isMapped(next)) {
40 *
41 * String key = resolver.getKey(next);
42 * bean = getMappedProperty(bean, property, key);
43 *
44 * } else {
45 *
46 * bean = getSimpleProperty(bean, property);
47 *
48 * }
49 *
50 * // remove the processed property from the expression
51 * name = resolver.remove(name);
52 * }
53 * </pre>
54 *
55 * In order to create an implementation, it is important to understand how BeanUtils/PropertyUtils uses the {@code resolver}. The following are the main methods
56 * that use it:
57 * <ul>
58 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean}
59 * <ul>
60 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getIndexedProperty(Object, String)}</li>
61 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getMappedProperty(Object, String)}</li>
62 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getNestedProperty(Object, String)}</li>
63 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li>
64 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#getSimpleProperty(Object, String)}</li>
65 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li>
66 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li>
67 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li>
68 * <li>{@link org.apache.commons.beanutils2.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li>
69 * </ul>
70 * </li>
71 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean}
72 * <ul>
73 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean#copyProperty(Object, String, Object)}</li>
74 * <li>{@link org.apache.commons.beanutils2.BeanUtilsBean#setProperty(Object, String, Object)}</li>
75 * </ul>
76 * </li>
77 * <li>{@link org.apache.commons.beanutils2.locale.LocaleBeanUtilsBean}
78 * <ul>
79 * <li>{@link org.apache.commons.beanutils2.locale.LocaleBeanUtilsBean#setProperty(Object, String, Object, String)}</li>
80 * </ul>
81 * </li>
82 * </ul>
83 *
84 * @see org.apache.commons.beanutils2.PropertyUtilsBean#setResolver(Resolver)
85 * @since 1.8.0
86 */
87 public interface Resolver {
88
89 /**
90 * Extract the index value from the property expression or -1.
91 *
92 * @param expression The property expression
93 * @return The index value or -1 if the property is not indexed
94 * @throws IllegalArgumentException If the indexed property is illegally formed or has an invalid (non-numeric) value
95 */
96 int getIndex(String expression);
97
98 /**
99 * 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 }