com.google.inject.internal.DeclaredMembers Maven / Gradle / Ivy
/*
* Copyright (C) 2019 Google Inc.
*
* 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 com.google.inject.internal;
import com.google.common.collect.ComparisonChain;
import com.google.common.collect.Ordering;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
/**
* Utility class for retrieving declared fields or methods in a particular order, because the JVM
* doesn't guarantee ordering for listing declared methods. We don't externally guarantee an
* ordering, but having a consistent ordering allows deterministic behavior and simpler tests.
*/
public final class DeclaredMembers {
private DeclaredMembers() {}
public static Field[] getDeclaredFields(Class type) {
Field[] fields = type.getDeclaredFields();
Arrays.sort(fields, FIELD_ORDERING);
return fields;
}
public static Method[] getDeclaredMethods(Class type) {
Method[] methods = type.getDeclaredMethods();
Arrays.sort(methods, METHOD_ORDERING);
return methods;
}
/**
* An ordering 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 Ordering> CLASS_ORDERING =
new Ordering>() {
@Override
public int compare(Class o1, Class o2) {
return o1.getName().compareTo(o2.getName());
}
};
/**
* An ordering suitable for comparing two fields if they are owned by the same class.
*
* Within a single class it is sufficent to compare the non-generic field signature which
* consists of the field name and type.
*/
private static final Ordering FIELD_ORDERING =
new Ordering() {
@Override
public int compare(Field left, Field right) {
return ComparisonChain.start()
.compare(left.getName(), right.getName())
.compare(left.getType(), right.getType(), CLASS_ORDERING)
.result();
}
};
/**
* An ordering 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 the name, return type and parameter types.
*/
private static final Ordering METHOD_ORDERING =
new Ordering() {
@Override
public int compare(Method left, Method right) {
return ComparisonChain.start()
.compare(left.getName(), right.getName())
.compare(left.getReturnType(), right.getReturnType(), CLASS_ORDERING)
.compare(
Arrays.asList(left.getParameterTypes()),
Arrays.asList(right.getParameterTypes()),
CLASS_ORDERING.lexicographical())
.result();
}
};
}