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: }
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