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 * (the "License"); you may not use this file except in compliance with
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.beanutils.expression;

Property Name Expression Resolver.

Methods such as PropertyUtilsBean's setNestedProperty() method
use a Resolver to process a property name
expression and resolve nested, indexed and mapped
property names. The following code provides an example usage
demonstrating all the methods:
     // Iterate through a nested property expression
     while (resolver.hasNested(name)) {
         // isolate a single property from a nested expresion
         String next = resolver.next(name);
         // Process...
         String property = resolver.getProperty(next);
         if (resolver.isIndexed(next)) {
             int index = resolver.getIndex(next);
             bean = getIndexedProperty(bean, property, index);
         } else if (resolver.isMapped(next)) {
             String key = resolver.getKey(next);
             bean = getMappedProperty(bean, property, key);
         } else {
             bean = getSimpleProperty(bean, property);
         }
         // remove the processed property from the expression
         name = resolver.remove(name);
     }

In order to create an implementation, it is important to understand how
BeanUtils/PropertyUtils uses the resolver. The following are
the main methods that use it:

  
PropertyUtilsBean
  

      
PropertyUtilsBean.getIndexedProperty(Object, String)
      
PropertyUtilsBean.getMappedProperty(Object, String)
      
PropertyUtilsBean.getNestedProperty(Object, String)
      
PropertyUtilsBean.getPropertyDescriptor(Object, String)
      
PropertyUtilsBean.getSimpleProperty(Object, String)
      
PropertyUtilsBean.setIndexedProperty(Object, String, Object)
      
PropertyUtilsBean.setMappedProperty(Object, String, Object)
      
PropertyUtilsBean.setNestedProperty(Object, String, Object)
      
PropertyUtilsBean.setSimpleProperty(Object, String, Object)
  
  
BeanUtilsBean
  

      
BeanUtilsBean.copyProperty(Object, String, Object)
      
BeanUtilsBean.setProperty(Object, String, Object)
  
  
LocaleBeanUtilsBean
  

      
LocaleBeanUtilsBean.setProperty(Object, String, Object, String)
  

See Also:
PropertyUtilsBean.setResolver(Resolver)
Version:
$Id$
Since:
1.8.0/**
 * Property Name Expression Resolver.
 * <p>
 * Methods such as PropertyUtilsBean's <code>setNestedProperty()</code> method
 * use a <code>Resolver</code> to process a <i>property name</i>
 * expression and resolve <i>nested</i>, <i>indexed</i> and <i>mapped</i>
 * property names. The following code provides an example usage
 * demonstrating all the methods:
 *
 * <pre>
 *      // Iterate through a nested property expression
 *      while (resolver.hasNested(name)) {
 *
 *          // isolate a single property from a nested expresion
 *          String next = resolver.next(name);
 *
 *          // Process...
 *          String property = resolver.getProperty(next);
 *          if (resolver.isIndexed(next)) {
 *
 *              int index = resolver.getIndex(next);
 *              bean = getIndexedProperty(bean, property, index);
 *
 *          } else if (resolver.isMapped(next)) {
 *
 *              String key = resolver.getKey(next);
 *              bean = getMappedProperty(bean, property, key);
 *
 *          } else {
 *
 *              bean = getSimpleProperty(bean, property);
 *
 *          }
 *
 *          // remove the processed property from the expression
 *          name = resolver.remove(name);
 *      }
 * </pre>
 *
 * In order to create an implementation, it is important to understand how
 * BeanUtils/PropertyUtils uses the <code>resolver</code>. The following are
 * the main methods that use it:
 * <ul>
 *   <li>{@link org.apache.commons.beanutils.PropertyUtilsBean}</li>
 *   <ul>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getIndexedProperty(Object, String)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getMappedProperty(Object, String)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getNestedProperty(Object, String)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getSimpleProperty(Object, String)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li>
 *       <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li>
 *   </ul>
 *   <li>{@link org.apache.commons.beanutils.BeanUtilsBean}</li>
 *   <ul>
 *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#copyProperty(Object, String, Object)}</li>
 *       <li>{@link org.apache.commons.beanutils.BeanUtilsBean#setProperty(Object, String, Object)}</li>
 *   </ul>
 *   <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean}</li>
 *   <ul>
 *       <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean#setProperty(Object,
 *        String, Object, String)}</li>
 *   </ul>
 * </ul>
 *
 * @version $Id$
 * @see org.apache.commons.beanutils.PropertyUtilsBean#setResolver(Resolver)
 * @since 1.8.0
 */
public interface Resolver {

    
Extract the index value from the property expression or -1.
Params:
expression – The property expression
Throws:
IllegalArgumentException – If the indexed property is illegally
formed or has an invalid (non-numeric) value
Returns:
The index value or -1 if the property is not indexed/**
     * Extract the index value from the property expression or -1.
     *
     * @param expression The property expression
     * @return The index value or -1 if the property is not indexed
     * @throws IllegalArgumentException If the indexed property is illegally
     * formed or has an invalid (non-numeric) value
     */
    int getIndex(String expression);

    
Extract the map key from the property expression or null.
Params:
expression – The property expression
Throws:
IllegalArgumentException – If the mapped property is illegally formed
Returns:
The index value/**
     * Extract the map key from the property expression or <code>null</code>.
     *
     * @param expression The property expression
     * @return The index value
     * @throws IllegalArgumentException If the mapped property is illegally formed
     */
    String getKey(String expression);

    
Return the property name from the property expression.
Params:
expression – The property expression
Returns:
The property name/**
     * Return the property name from the property expression.
     *
     * @param expression The property expression
     * @return The property name
     */
    String getProperty(String expression);

    
Indicates whether or not the expression
contains nested property expressions or not.
Params:
expression – The property expression
Returns:
The next property expression/**
     * Indicates whether or not the expression
     * contains nested property expressions or not.
     *
     * @param expression The property expression
     * @return The next property expression
     */
    boolean hasNested(String expression);

    
Indicate whether the expression is for an indexed property or not.
Params:
expression – The property expression
Returns:
true if the expresion is indexed,
 otherwise false/**
     * Indicate whether the expression is for an indexed property or not.
     *
     * @param expression The property expression
     * @return <code>true</code> if the expresion is indexed,
     *  otherwise <code>false</code>
     */
    boolean isIndexed(String expression);

    
Indicate whether the expression is for a mapped property or not.
Params:
expression – The property expression
Returns:
true if the expresion is mapped,
 otherwise false/**
     * Indicate whether the expression is for a mapped property or not.
     *
     * @param expression The property expression
     * @return <code>true</code> if the expresion is mapped,
     *  otherwise <code>false</code>
     */
    boolean isMapped(String expression);

    
Extract the next property expression from the
current expression.
Params:
expression – The property expression
Returns:
The next property expression/**
     * Extract the next property expression from the
     * current expression.
     *
     * @param expression The property expression
     * @return The next property expression
     */
    String next(String expression);

    
Remove the last property expresson from the
current expression.
Params:
expression – The property expression
Returns:
The new expression value, with first property
expression removed - null if there are no more expressions/**
     * Remove the last property expresson from the
     * current expression.
     *
     * @param expression The property expression
     * @return The new expression value, with first property
     * expression removed - null if there are no more expressions
     */
    String remove(String expression);

}