src/main/java/org/apache/commons/ognl/ObjectIndexedPropertyDescriptor.java

package org.apache.commons.ognl;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;

/**
 * <p>
 * PropertyDescriptor subclass that describes an indexed set of read/write methods to get a property. Unlike
 * IndexedPropertyDescriptor this allows the "key" to be an arbitrary object rather than just an int. Consequently it
 * does not have a "readMethod" or "writeMethod" because it only expects a pattern like:
 * </p>
 * 
 * <pre>
 *    public void set<i>Property</i>(<i>KeyType</i>, <i>ValueType</i>);
 *    public <i>ValueType</i> get<i>Property</i>(<i>KeyType</i>);
 * </pre>
 * <p>
 * and does not require the methods that access it as an array. OGNL can get away with this without losing functionality
 * because if the object does expose the properties they are most probably in a Map and that case is handled by the
 * normal OGNL property accessors.
 * </p>
 * <p>
 * For example, if an object were to have methods that accessed and "attributes" property it would be natural to index
 * them by String rather than by integer and expose the attributes as a map with a different property name:
 * 
 * <pre>
 * public void setAttribute( String name, Object value );
 * 
 * public Object getAttribute( String name );
 * 
 * public Map getAttributes();
 * </pre>
 * <p>
 * Note that the index get/set is called get/set <code>Attribute</code> whereas the collection getter is called
 * <code>Attributes</code>. This case is handled unambiguously by the OGNL property accessors because the set/get
 * <code>Attribute</code> methods are detected by this object and the "attributes" case is handled by the
 * <code>MapPropertyAccessor</code>. Therefore OGNL expressions calling this code would be handled in the following way:
 * </p>
 * <table>
 * <tr>
 * <th>OGNL Expression</th>
 * <th>Handling</th>
 * </tr>
 * <tr>
 * <td><code>attribute["name"]</code></td>
 * <td>Handled by an index getter, like <code>getAttribute(String)</code>.</td>
 * </tr>
 * <tr>
 * <td><code>attribute["name"] = value</code></td>
 * <td>Handled by an index setter, like <code>setAttribute(String, Object)</code>.</td>
 * </tr>
 * <tr>
 * <td><code>attributes["name"]</code></td>
 * <td>Handled by <code>MapPropertyAccessor</code> via a <code>Map.get()</code>. This will <b>not</b> go through the
 * index get accessor.</td>
 * </tr>
 * <tr>
 * <td><code>attributes["name"] = value</code></td>
 * <td>Handled by <code>MapPropertyAccessor</code> via a <code>Map.put()</code>. This will <b>not</b> go through the
 * index set accessor.</td>
 * </tr>
 * </table>
 */
public class ObjectIndexedPropertyDescriptor
    extends PropertyDescriptor
{
    private final Method indexedReadMethod;

    private final Method indexedWriteMethod;

    private final Class<?> propertyType;

    public ObjectIndexedPropertyDescriptor( String propertyName, Class<?> propertyType, Method indexedReadMethod,
                                            Method indexedWriteMethod )
        throws IntrospectionException
    {
        super( propertyName, null, null );
        this.propertyType = propertyType;
        this.indexedReadMethod = indexedReadMethod;
        this.indexedWriteMethod = indexedWriteMethod;
    }

    public Method getIndexedReadMethod()
    {
        return indexedReadMethod;
    }

    public Method getIndexedWriteMethod()
    {
        return indexedWriteMethod;
    }

    @Override
    public Class<?> getPropertyType()
    {
        return propertyType;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
        {
            return true;
        }

        if (!(o instanceof ObjectIndexedPropertyDescriptor))
        {
            return false;
        }

        if (!super.equals(o))
        {
            return false;
        }

        ObjectIndexedPropertyDescriptor that = (ObjectIndexedPropertyDescriptor) o;

        if (indexedReadMethod != null ? !indexedReadMethod.equals(that.indexedReadMethod) : that.indexedReadMethod != null)
        {
            return false;
        }

        if (indexedWriteMethod != null ? !indexedWriteMethod.equals(that.indexedWriteMethod) : that.indexedWriteMethod != null)
        {
            return false;
        }

        if (propertyType != null ? !propertyType.equals(that.propertyType) : that.propertyType != null)
        {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode() {
        int result = super.hashCode();
        result = 31 * result + (indexedReadMethod != null ? indexedReadMethod.hashCode() : 0);
        result = 31 * result + (indexedWriteMethod != null ? indexedWriteMethod.hashCode() : 0);
        result = 31 * result + (propertyType != null ? propertyType.hashCode() : 0);
        return result;
    }
}