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    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.beanutils.expression;
    18
    19  /***
    20   * Property Name Expression Resolver.
    21   * <p>
    22   * Methods such as PropertyUtilsBean's <code>setNestedProperty()</code> method
    23   * use a <code>Resolver</code> to process a <i>property name</i>
    24   * expression and resolve <i>nested</i>, <i>indexed</i> and <i>mapped</i>
    25   * property names. The following code provides an example usage
    26   * demonstrating all the methods:
    27   *
    28   * <pre>
    29   *      // Iterate through a nested property expression
    30   *      while (resolver.hasNested(name)) {
    31   *
    32   *          // isolate a single property from a nested expresion
    33   *          String next = resolver.next(name);
    34   *
    35   *          // Process...
    36   *          String property = resolver.getProperty(next);
    37   *          if (resolver.isIndexed(next)) {
    38   *
    39   *              int index = resolver.getIndex(next);
    40   *              bean = getIndexedProperty(bean, property, index);
    41   *
    42   *          } else if (resolver.isMapped(next)) {
    43   *
    44   *              String key = resolver.getKey(next);
    45   *              bean = getMappedProperty(bean, property, key);
    46   *
    47   *          } else {
    48   *
    49   *              bean = getSimpleProperty(bean, property);
    50   *
    51   *          }
    52   *
    53   *          // remove the processed property from the expression
    54   *          name = resolver.remove(name);
    55   *      }
    56   * </pre>
    57   *
    58   * In order to create an implementation, it is important to understand how
    59   * BeanUtils/PropertyUtils uses the <code>resolver</code>. The following are
    60   * the main methods that use it:
    61   * <ul>
    62   *   <li>{@link org.apache.commons.beanutils.PropertyUtilsBean}</li>
    63   *   <ul>
    64   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getIndexedProperty(Object, String)}</li>
    65   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getMappedProperty(Object, String)}</li>
    66   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getNestedProperty(Object, String)}</li>
    67   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li>
    68   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getSimpleProperty(Object, String)}</li>
    69   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li>
    70   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li>
    71   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li>
    72   *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li>
    73   *   </ul>
    74   *   <li>{@link org.apache.commons.beanutils.BeanUtilsBean}</li>
    75   *   <ul>
    76   *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#copyProperty(Object, String, Object)}</li>
    77   *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#setProperty(Object, String, Object)}</li>
    78   *   </ul>
    79   *   <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean}</li>
    80   *   <ul>
    81   *       <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean#setProperty(Object,
    82   *        String, Object, String)}</li>
    83   *   </ul>
    84   * </ul>
    85   *
    86   * @version $Revision: 555845 $ $Date: 2007-07-13 03:52:05 +0100 (Fri, 13 Jul 2007) $
    87   * @see org.apache.commons.beanutils.PropertyUtilsBean#setResolver(Resolver)
    88   * @since 1.8.0
    89   */
    90  public interface Resolver {
    91
    92      /***
    93       * Extract the index value from the property expression or -1.
    94       *
    95       * @param expression The property expression
    96       * @return The index value or -1 if the property is not indexed
    97       * @throws IllegalArgumentException If the indexed property is illegally
    98       * formed or has an invalid (non-numeric) value
    99       */
    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 }