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/*
* 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.
*/
package javax.el;
import java.util.Iterator;
/**
* @author Jacob Hookom [jacob/hookom.net]
*
*/
public abstract class ELResolver {
public static final String TYPE = "type";
public static final String RESOLVABLE_AT_DESIGN_TIME = "resolvableAtDesignTime";
/**
* Obtain the value of the given property on the given object using the
* given context.
*
* @param context The EL context for this evaluation
* @param base The base object on which the property is to be found
* @param property The property whose value is to be returned
* @return the value of the provided property
* @throws NullPointerException
* If the supplied context is <code>null</code>
* @throws PropertyNotFoundException
* If the base/property combination provided to the resolver is
* one that the resolver can handle but no match was found or a
* match was found but was not readable
* @throws ELException
* Wraps any exception throw whilst resolving the property
*/
public abstract Object getValue(ELContext context, Object base,
Object property);
/**
* Invokes a method on the the given object. This default implementation
* always returns <code>null</code>.
*
* @param context The EL context for this evaluation
* @param base The base object on which the method is to be found
* @param method The method to invoke
* @param paramTypes The types of the parameters of the method to invoke
* @param params The parameters with which to invoke the method
*
* @return Always <code>null</code>
*
* @since EL 2.2
*/
public Object invoke(ELContext context, Object base, Object method,
Class<?>[] paramTypes, Object[] params) {
return null;
}
/**
* Obtain the type of the given property on the given object using the given
* context.
*
* @param context The EL context for this evaluation
* @param base The base object on which the property is to be found
* @param property The property whose type is to be returned
* @return the type of the provided property
* @throws NullPointerException
* If the supplied context is <code>null</code>
* @throws PropertyNotFoundException
* If the base/property combination provided to the resolver is
* one that the resolver can handle but no match was found or a
* match was found but was not readable
* @throws ELException
* Wraps any exception throw whilst resolving the property
*/
public abstract Class<?> getType(ELContext context, Object base,
Object property);
/**
* Set the value of the given property on the given object using the given
* context.
*
* @param context The EL context for this evaluation
* @param base The base object on which the property is to be found
* @param property The property whose value is to be set
* @param value The value to set the property to
* @throws NullPointerException
* If the supplied context is <code>null</code>
* @throws PropertyNotFoundException
* If the base/property combination provided to the resolver is
* one that the resolver can handle but no match was found
* @throws PropertyNotWritableException
* If the base/property combination provided to the resolver is
* one that the resolver can handle but the property was not
* writable
* @throws ELException
* Wraps any exception throw whilst resolving the property
*/
public abstract void setValue(ELContext context, Object base,
Object property, Object value);
/**
* Determine if the given property on the given object is read-only using
* the given context.
*
* @param context The EL context for this evaluation
* @param base The base object on which the property is to be found
* @param property The property to be checked for read only status
* @return <code>true</code> if the identified property is read only,
* otherwise <code>false</code>
* @throws NullPointerException
* If the supplied context is <code>null</code>
* @throws PropertyNotFoundException
* If the base/property combination provided to the resolver is
* one that the resolver can handle but no match was found
* @throws ELException
* Wraps any exception throw whilst resolving the property
*/
public abstract boolean isReadOnly(ELContext context, Object base,
Object property);
/**
* Obtain the feature descriptors for the resolvable properties of the given
* object.
*
* @param context The context in which the examination takes place
* @param base The object to examine
*
* @return An iterator, possibly empty, of feature descriptors of the given
* object
*/
public abstract Iterator<java.beans.FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base);
/**
* Obtain the most common type that is acceptable for the given base object.
*
* @param context The context in which the examination takes place
* @param base The object to examine
*
* @return {code null} if the most common type cannot be determine,
* otherwise the most common type
*/
public abstract Class<?> getCommonPropertyType(ELContext context,
Object base);
/**
* Converts the given object to the given type. This default implementation
* always returns <code>null</code>.
*
* @param context The EL context for this evaluation
* @param obj The object to convert
* @param type The type to which the object should be converted
*
* @return Always <code>null</code>
*
* @since EL 3.0
*/
public Object convertToType(ELContext context, Object obj, Class<?> type) {
context.setPropertyResolved(false);
return null;
}
}
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