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/*
* Copyright (C) 2016-2018 the original author or authors.
*
* 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
*
* https://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 io.github.pustike.inject.utils;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
/**
* Reflection Utilities.
*/
public final class ReflectionUtils {
/**
* A comparator suitable for comparing two classes if they are loaded by the same classloader.
* Within a single classloader there can only be one class with a given name, so we just compare the names.
*/
private static final Comparator> classComparator = Comparator.comparing(Class::getName);
/**
* A comparator suitable for comparing two fields if they are owned by the same class.
* Within a single class it is sufficient to compare the non-generic field signature which consists of the
* field name and type.
*/
private static final Comparator fieldComparator = Comparator.comparing(Field::getName)
.thenComparing(Field::getType, classComparator);
/**
* A comparator suitable for comparing two methods if they are owned by the same class.
* Within a single class it is sufficient to compare the non-generic method signature which consists of name,
* return type and parameter types.
*/
private static final Comparator methodComparator = Comparator.comparing(Method::getName)
.thenComparing(Method::getReturnType, classComparator).thenComparing(method ->
Arrays.asList(method.getParameterTypes()), createLexicalOrderComparator(classComparator));
// An ordering which sorts iterables by comparing corresponding elements pairwise.
private static Comparator> createLexicalOrderComparator(Comparator elementComparator) {
return (o1, o2) -> {
Iterator left = o1.iterator(), right = o2.iterator();
while (left.hasNext()) {
if (!right.hasNext()) {
return 1; // because it is longer
}
int result = elementComparator.compare(left.next(), right.next());
if (result != 0) {
return result;
}
}
if (right.hasNext()) {
return -1; // because it is longer
}
return 0;
};
}
/**
* Fields in the returned array from {@link Class#getDeclaredFields()}, are not sorted and are not in any
* particular order. Additionally, Some JVMs actually randomize the order from run to run.
* @param clazz the declaring class
* @return the array of Field objects
*/
public static Field[] getDeclaredFields(Class clazz) {
Field[] declaredFields = clazz.getDeclaredFields();
Arrays.sort(declaredFields, fieldComparator);
return declaredFields;
}
/**
* Methods in the returned array from {@link Class#getDeclaredMethods()}, are not sorted and are not in any
* particular order. Additionally, Some JVMs actually randomize the order from run to run.
* @param clazz the declaring class
* @return the array of Method objects
*/
public static Method[] getDeclaredMethods(Class clazz) {
Method[] declaredMethods = clazz.getDeclaredMethods();
Arrays.sort(declaredMethods, methodComparator);
return declaredMethods;
}
private ReflectionUtils() {
}
}