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