/*
* NOTICE: THE FILE HAS BEEN MODIFIED TO SUIT THE NEEDS OF THE PROJECT.
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.robobinding.util;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Member;
import java.lang.reflect.Modifier;
/**
* Migrated some of methods from
* {@link org.apache.commons.lang3.reflect.MemberUtils}.
*
* @since 1.0
* @version $Revision: 1.0 $
* @author Cheng Wei
*/
class MemberUtils {
private MemberUtils() {
}
private static final int ACCESS_TEST = Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;
/** Array of primitive number types ordered by "promotability". */
private static final Class<?>[] ORDERED_PRIMITIVE_TYPES = { Byte.TYPE, Short.TYPE, Character.TYPE, Integer.TYPE, Long.TYPE, Float.TYPE, Double.TYPE };
/**
*
* When a public class has a default access superclass with public members,
* these members are accessible. Calling them from compiled code works fine.
* Unfortunately, on some JVMs, using reflection to invoke these members
* seems to (wrongly) prevent access even when the modifier is public.
* Calling setAccessible(true) solves the problem but will only work from
* sufficiently privileged code. Better workarounds would be gratefully
* accepted.
*
* @param o
* the AccessibleObject to set as accessible
*/
static void setAccessibleWorkaround(final AccessibleObject o) {
if (o == null || o.isAccessible()) {
return;
}
final Member m = (Member) o;
if (Modifier.isPublic(m.getModifiers()) && isPackageAccess(m.getDeclaringClass().getModifiers())) {
try {
o.setAccessible(true);
} catch (final SecurityException e) { // NOPMD
// ignore in favor of
// subsequent
// IllegalAccessException
}
}
}
/**
* Returns whether a given set of modifiers implies package access.
*
* @param modifiers
* to test
* @return true unless package/protected/private modifier detected
*/
static boolean isPackageAccess(final int modifiers) {
return (modifiers & ACCESS_TEST) == 0;
}
/**
* Returns whether a Member is accessible.
*
* @param m
* Member to check
* @return true if <code>m</code> is accessible
*/
static boolean isAccessible(final Member m) {
return m != null && Modifier.isPublic(m.getModifiers()) && !m.isSynthetic();
}
/**
* Compares the relative fitness of two sets of parameter types in terms of
* matching a third set of runtime parameter types, such that a list ordered
* by the results of the comparison would return the best match first
* (least).
*
* @param left
* the "left" parameter set
* @param right
* the "right" parameter set
* @param actual
* the runtime parameter types to match against <code>left</code>
* /<code>right</code>
* @return int consistent with <code>compare</code> semantics
*/
static int compareParameterTypes(final Class<?>[] left, final Class<?>[] right, final Class<?>[] actual) {
final float leftCost = getTotalTransformationCost(actual, left);
final float rightCost = getTotalTransformationCost(actual, right);
return leftCost < rightCost ? -1 : rightCost < leftCost ? 1 : 0;
}
/**
* Returns the sum of the object transformation cost for each class in the
* source argument list.
*
* @param srcArgs
* The source arguments
* @param destArgs
* The destination arguments
* @return The total transformation cost
*/
private static float getTotalTransformationCost(final Class<?>[] srcArgs, final Class<?>[] destArgs) {
float totalCost = 0.0f;
for (int i = 0; i < srcArgs.length; i++) {
Class<?> srcClass, destClass;
srcClass = srcArgs[i];
destClass = destArgs[i];
totalCost += getObjectTransformationCost(srcClass, destClass);
}
return totalCost;
}
/**
* Gets the number of steps required needed to turn the source class into
* the destination class. This represents the number of steps in the object
* hierarchy graph.
*
* @param srcClass
* The source class
* @param destClass
* The destination class
* @return The cost of transforming an object
*/
private static float getObjectTransformationCost(Class<?> srcClass, final Class<?> destClass) {
if (destClass.isPrimitive()) {
return getPrimitivePromotionCost(srcClass, destClass);
}
float cost = 0.0f;
while (srcClass != null && !destClass.equals(srcClass)) {
if (destClass.isInterface() && ClassUtils.isAssignable(srcClass, destClass)) {
// slight penalty for interface match.
// we still want an exact match to override an interface match,
// but
// an interface match should override anything where we have to
// get a superclass.
cost += 0.25f;
break;
}
cost++;
srcClass = srcClass.getSuperclass();
}
/*
* If the destination class is null, we've travelled all the way up to
* an Object match. We'll penalize this by adding 1.5 to the cost.
*/
if (srcClass == null) {
cost += 1.5f;
}
return cost;
}
/**
* Gets the number of steps required to promote a primitive number to
* another type.
*
* @param srcClass
* the (primitive) source class
* @param destClass
* the (primitive) destination class
* @return The cost of promoting the primitive
*/
private static float getPrimitivePromotionCost(final Class<?> srcClass, final Class<?> destClass) {
float cost = 0.0f;
Class<?> cls = srcClass;
if (!cls.isPrimitive()) {
// slight unwrapping penalty
cost += 0.1f;
cls = ClassUtils.wrapperToPrimitive(cls);
}
for (int i = 0; cls != destClass && i < ORDERED_PRIMITIVE_TYPES.length; i++) {
if (cls == ORDERED_PRIMITIVE_TYPES[i]) {
cost += 0.1f;
if (i < ORDERED_PRIMITIVE_TYPES.length - 1) {
cls = ORDERED_PRIMITIVE_TYPES[i + 1];
}
}
}
return cost;
}
}