/*

  * Copyright (c) 2011 David Saff

  * Copyright (c) 2011 Christian Gruber

  *

  * 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.truth0.util;

 import com.google.common.annotations.GwtIncompatible;

 import java.lang.reflect.Field;

 import java.lang.reflect.ParameterizedType;

 import java.lang.reflect.Type;

 /**

  * Reflection utility methods.

  *

  * @author Christian Gruber (cgruber@israfil.net)

  */

 @GwtIncompatible("java.lang.reflect.*")

 public class ReflectionUtil {

   /** Returns the captured type. */

   public static Class<?> typeParameter(Class<?> clazz, int paramIndex) {

     Type superclass = clazz.getGenericSuperclass();

     if (!(superclass instanceof ParameterizedType)) {

       throw new IllegalArgumentException ("" + superclass + " isn't parameterized");

     }

     Type[] typeParams = ((ParameterizedType) superclass).getActualTypeArguments();

     return (Class<?>)typeParams[paramIndex];

   }

   public static Field getField(Class<?> clazz, String fieldName) throws NoSuchFieldException {

     Class<?> currentClass = clazz;

     while (currentClass != null) {

       try {

         return clazz.getDeclaredField(fieldName);

       } catch (NoSuchFieldException e) {

         currentClass = currentClass.getSuperclass();

       }

     }

     throw new NoSuchFieldException("No such field " + fieldName + " declared on " +

         clazz.getSimpleName() + " or its parent classes.");

   }

 }