225 lines
7.1 KiB
Java
225 lines
7.1 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.decoder;
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/**
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* The base class for element handlers.
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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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* @see DocumentHandler
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*/
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public abstract class ElementHandler {
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private DocumentHandler owner;
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private ElementHandler parent;
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private String id;
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/**
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* Returns the document handler that creates this element handler.
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*
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* @return the owner document handler
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*/
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public final DocumentHandler getOwner() {
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return this.owner;
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}
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/**
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* Sets the document handler that creates this element handler.
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* The owner document handler should be set after instantiation.
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* Such approach is used to simplify the extensibility.
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*
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* @param owner the owner document handler
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* @see DocumentHandler#startElement
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*/
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final void setOwner(DocumentHandler owner) {
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if (owner == null) {
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throw new IllegalArgumentException("Every element should have owner");
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}
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this.owner = owner;
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}
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/**
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* Returns the element handler that contains this one.
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*
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* @return the parent element handler
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*/
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public final ElementHandler getParent() {
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return this.parent;
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}
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/**
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* Sets the element handler that contains this one.
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* The parent element handler should be set after instantiation.
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* Such approach is used to simplify the extensibility.
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*
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* @param parent the parent element handler
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* @see DocumentHandler#startElement
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*/
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final void setParent(ElementHandler parent) {
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this.parent = parent;
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}
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/**
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* Returns the value of the variable with specified identifier.
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*
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* @param id the identifier
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* @return the value of the variable
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*/
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protected final Object getVariable(String id) {
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if (id.equals(this.id)) {
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ValueObject value = getValueObject();
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if (value.isVoid()) {
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throw new IllegalStateException("The element does not return value");
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}
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return value.getValue();
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}
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return (this.parent != null)
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? this.parent.getVariable(id)
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: this.owner.getVariable(id);
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}
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/**
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* Returns the value of the parent element.
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*
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* @return the value of the parent element
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*/
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protected Object getContextBean() {
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if (this.parent != null) {
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ValueObject value = this.parent.getValueObject();
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if (!value.isVoid()) {
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return value.getValue();
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}
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throw new IllegalStateException("The outer element does not return value");
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} else {
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Object value = this.owner.getOwner();
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if (value != null) {
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return value;
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}
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throw new IllegalStateException("The topmost element does not have context");
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}
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}
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/**
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* Parses attributes of the element.
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* By default, the following attribute is supported:
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* <dl>
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* <dt>id
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* <dd>the identifier of the variable that is intended to store the result
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* </dl>
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*
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* @param name the attribute name
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* @param value the attribute value
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*/
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public void addAttribute(String name, String value) {
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if (name.equals("id")) { // NON-NLS: the attribute name
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this.id = value;
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} else {
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throw new IllegalArgumentException("Unsupported attribute: " + name);
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}
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}
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/**
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* This method is called before parsing of the element's body.
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* All attributes are parsed at this point.
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* By default, do nothing.
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*/
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public void startElement() {
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}
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/**
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* This method is called after parsing of the element's body.
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* By default, it calculates the value of this element.
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* The following tasks are executing for any non-void value:
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* <ol>
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* <li>If the {@code id} attribute is set
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* the value of the variable with the specified identifier
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* is set to the value of this element.</li>
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* <li>This element is used as an argument of parent element if it is possible.</li>
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* </ol>
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*
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* @see #isArgument
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*/
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public void endElement() {
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// do nothing if no value returned
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ValueObject value = getValueObject();
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if (!value.isVoid()) {
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if (this.id != null) {
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this.owner.setVariable(this.id, value.getValue());
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}
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if (isArgument()) {
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if (this.parent != null) {
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this.parent.addArgument(value.getValue());
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} else {
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this.owner.addObject(value.getValue());
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}
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}
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}
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}
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/**
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* Adds the character that contained in this element.
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* By default, only whitespaces are acceptable.
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*
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* @param ch the character
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*/
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public void addCharacter(char ch) {
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if ((ch != ' ') && (ch != '\n') && (ch != '\t') && (ch != '\r')) {
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throw new IllegalStateException("Illegal character with code " + (int) ch);
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}
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}
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/**
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* Adds the argument that is used to calculate the value of this element.
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* By default, no arguments are acceptable.
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*
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* @param argument the value of the element that contained in this one
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*/
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protected void addArgument(Object argument) {
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throw new IllegalStateException("Could not add argument to simple element");
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}
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/**
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* Tests whether the value of this element can be used
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* as an argument of the element that contained in this one.
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*
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* @return {@code true} if the value of this element can be used
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* as an argument of the element that contained in this one,
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* {@code false} otherwise
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*/
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protected boolean isArgument() {
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return this.id == null;
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}
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/**
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* Returns the value of this element.
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*
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* @return the value of this element
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*/
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protected abstract ValueObject getValueObject();
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}
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