/*
* Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package com.sun.beans.finder;
import java.lang.reflect.Executable;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
/**
* This abstract class provides functionality
* to find a public method or constructor
* with specified parameter types.
* It supports a variable number of parameters.
*
* @since 1.7
*
* @author Sergey A. Malenkov
*/
abstract class AbstractFinder<T extends Executable> {
private final Class<?>[] args;
/**
* Creates finder for array of classes of arguments.
* If a particular element of array equals {@code null},
* than the appropriate pair of classes
* does not take into consideration.
*
* @param args array of classes of arguments
*/
protected AbstractFinder(Class<?>[] args) {
this.args = args;
}
/**
* Checks validness of the method.
* At least the valid method should be public.
*
* @param method the object that represents method
* @return {@code true} if the method is valid,
* {@code false} otherwise
*/
protected boolean isValid(T method) {
return Modifier.isPublic(method.getModifiers());
}
/**
* Performs a search in the {@code methods} array.
* The one method is selected from the array of the valid methods.
* The list of parameters of the selected method shows
* the best correlation with the list of arguments
* specified at class initialization.
* If more than one method is both accessible and applicable
* to a method invocation, it is necessary to choose one
* to provide the descriptor for the run-time method dispatch.
* The most specific method should be chosen.
*
* @param methods the array of methods to search within
* @return the object that represents found method
* @throws NoSuchMethodException if no method was found or several
* methods meet the search criteria
* @see #isAssignable
*/
final T find(T[] methods) throws NoSuchMethodException {
Map<T, Class<?>[]> map = new HashMap<T, Class<?>[]>();
T oldMethod = null;
Class<?>[] oldParams = null;
boolean ambiguous = false;
for (T newMethod : methods) {
if (isValid(newMethod)) {
Class<?>[] newParams = newMethod.getParameterTypes();
if (newParams.length == this.args.length) {
PrimitiveWrapperMap.replacePrimitivesWithWrappers(newParams);
if (isAssignable(newParams, this.args)) {
if (oldMethod == null) {
oldMethod = newMethod;
oldParams = newParams;
} else {
boolean useNew = isAssignable(oldParams, newParams);
boolean useOld = isAssignable(newParams, oldParams);
if (useOld && useNew) {
// only if parameters are equal
useNew = !newMethod.isSynthetic();
useOld = !oldMethod.isSynthetic();
}
if (useOld == useNew) {
ambiguous = true;
} else if (useNew) {
oldMethod = newMethod;
oldParams = newParams;
ambiguous = false;
}
}
}
}
if (newMethod.isVarArgs()) {
int length = newParams.length - 1;
if (length <= this.args.length) {
Class<?>[] array = new Class<?>[this.args.length];
System.arraycopy(newParams, 0, array, 0, length);
if (length < this.args.length) {
Class<?> type = newParams[length].getComponentType();
if (type.isPrimitive()) {
type = PrimitiveWrapperMap.getType(type.getName());
}
for (int i = length; i < this.args.length; i++) {
array[i] = type;
}
}
map.put(newMethod, array);
}
}
}
}
for (T newMethod : methods) {
Class<?>[] newParams = map.get(newMethod);
if (newParams != null) {
if (isAssignable(newParams, this.args)) {
if (oldMethod == null) {
oldMethod = newMethod;
oldParams = newParams;
} else {
boolean useNew = isAssignable(oldParams, newParams);
boolean useOld = isAssignable(newParams, oldParams);
if (useOld && useNew) {
// only if parameters are equal
useNew = !newMethod.isSynthetic();
useOld = !oldMethod.isSynthetic();
}
if (useOld == useNew) {
if (oldParams == map.get(oldMethod)) {
ambiguous = true;
}
} else if (useNew) {
oldMethod = newMethod;
oldParams = newParams;
ambiguous = false;
}
}
}
}
}
if (ambiguous) {
throw new NoSuchMethodException("Ambiguous methods are found");
}
if (oldMethod == null) {
throw new NoSuchMethodException("Method is not found");
}
return oldMethod;
}
/**
* Determines if every class in {@code min} array is either the same as,
* or is a superclass of, the corresponding class in {@code max} array.
* The length of every array must equal the number of arguments.
* This comparison is performed in the {@link #find} method
* before the first call of the isAssignable method.
* If an argument equals {@code null}
* the appropriate pair of classes does not take into consideration.
*
* @param min the array of classes to be checked
* @param max the array of classes that is used to check
* @return {@code true} if all classes in {@code min} array
* are assignable from corresponding classes in {@code max} array,
* {@code false} otherwise
*
* @see Class#isAssignableFrom
*/
private boolean isAssignable(Class<?>[] min, Class<?>[] max) {
for (int i = 0; i < this.args.length; i++) {
if (null != this.args[i]) {
if (!min[i].isAssignableFrom(max[i])) {
return false;
}
}
}
return true;
}
}