core/api/src/main/java/org/apache/zest/api/association/GenericAssociationInfo.java

/*
 * Copyright 2008 Niclas Hedhman. All rights Reserved.
 *
 * Licensed  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 org.apache.zest.api.association;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import static org.apache.zest.api.util.Classes.typeOf;

/**
 * Generic Association info.
 */
public final class GenericAssociationInfo
{
    public static Type associationTypeOf( AccessibleObject accessor )
    {
        return toAssociationType( typeOf( accessor ) );
    }

    public static Type toAssociationType( Type methodReturnType )
    {
        if( methodReturnType instanceof ParameterizedType )
        {
            ParameterizedType parameterizedType = (ParameterizedType) methodReturnType;
            if( AbstractAssociation.class.isAssignableFrom( (Class<?>) parameterizedType.getRawType() ) )
            {
                return parameterizedType.getActualTypeArguments()[ 0 ];
            }
        }

        Type[] interfaces = ( (Class<?>) methodReturnType ).getGenericInterfaces();
        for( Type anInterface : interfaces )
        {
            Type associationType = toAssociationType( anInterface );
            if( associationType != null )
            {
                return associationType;
            }
        }
        return null;
    }
}