    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    }