MethodParameter.java

/*
 * Copyright 2011 Blazebit
 */
package com.blazebit.reflection;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

/**
 * 
 * @author Christian Beikov
 */
public class MethodParameter {

	private Constructor<?> constructor;
	private Method method;
	private int index;

	MethodParameter(Method method, int index) {
		if (method == null) {
			throw new NullPointerException("Method must not be null");
		}

		this.method = method;
		this.index = index;
	}

	MethodParameter(Constructor<?> constructor, int index) {
		if (constructor == null) {
			throw new NullPointerException("Method must not be null");
		}

		this.constructor = constructor;
		this.index = index;
	}

	public Constructor<?> getConstructor() {
		return constructor;
	}

	public int getIndex() {
		return index;
	}

	public Class<?> getType() {
		return method != null ? method.getParameterTypes()[index] : constructor
				.getParameterTypes()[index];
	}

	public Class<?> getResolvedType(Class<?> concreteClass) {
		Type t = method != null ? method.getGenericParameterTypes()[index]
				: constructor.getGenericParameterTypes()[index];

		if (t instanceof TypeVariable<?>) {
			return ReflectionUtils.resolveTypeVariable(concreteClass,
					(TypeVariable<?>) t);
		}

		return getType();
	}

	public Class<?>[] getResolvedTypeParameters(Class<?> concreteClass) {
		Type t = method != null ? method.getGenericParameterTypes()[index]
				: constructor.getGenericParameterTypes()[index];
		return ReflectionUtils.resolveTypeArguments(concreteClass, t);
	}

	public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
		if (annotationClass == null) {
			throw new NullPointerException("annotationClass must not be null");
		}

		for (Annotation a : getAnnotations()) {
			if (annotationClass.isInstance(a)) {
				return annotationClass.cast(a);
			}
		}

		return null;
	}

	public Annotation[] getAnnotations() {
		return method != null ? method.getParameterAnnotations()[index]
				: constructor.getParameterAnnotations()[index];
	}

	public Method getMethod() {
		return method;
	}
}