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package org.apache.velocity.util.introspection;
/*
* 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.lang.reflect.Type;
/**
* A conversion handler adds admissible conversions between Java types whenever Velocity introspection has to map
* VTL methods and property accessors to Java methods.
* Both methods must be consistent: <code>getNeededConverter</code> must not return <code>null</code> whenever
* <code>isExplicitlyConvertible</code> returned true with the same arguments.
*
* @author <a href="mailto:claude.brisson@gmail.com">Claude Brisson</a>
* @version $Id: ConversionHandler.java $
* @since 2.1
*/
public interface TypeConversionHandler
{
/**
* Check to see if the conversion can be done using an explicit conversion
* @param formal expected formal type
* @param actual provided argument type
* @return null if no conversion is needed, or the appropriate Converter object
* @since 2.1
*/
boolean isExplicitlyConvertible(Type formal, Class actual, boolean possibleVarArg);
/**
* Returns the appropriate Converter object needed for an explicit conversion
* Returns null if no conversion is needed.
*
* @param formal expected formal type
* @param actual provided argument type
* @return null if no conversion is needed, or the appropriate Converter object
* @since 2.1
*/
Converter getNeededConverter(Type formal, Class actual);
/**
* Add the given converter to the handler. Implementation should be thread-safe.
*
* @param formal expected formal type
* @param actual provided argument type
* @param converter converter
* @since 2.1
*/
void addConverter(Type formal, Class actual, Converter converter);
}
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