/*******************************************************************************
* Copyright (c) 2007 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.help.internal;
import java.io.StringReader;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionConverter;
import org.eclipse.core.expressions.ExpressionTagNames;
import org.eclipse.core.expressions.IEvaluationContext;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.help.HelpSystem;
import org.eclipse.help.IUAElement;
import org.eclipse.help.internal.dynamic.FilterResolver;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
/*
* Base class for UA model elements.
*/
public class UAElement implements IUAElement {
private static final String ELEMENT_FILTER = "filter"; //$NON-NLS-1$
private static final String ATTRIBUTE_FILTER = "filter"; //$NON-NLS-1$
private static final String ATTRIBUTE_NAME = "name"; //$NON-NLS-1$
private static final String ATTRIBUTE_VALUE = "value"; //$NON-NLS-1$
private static DocumentBuilder builder;
private static Document document;
public Element element;
public IUAElement src;
public UAElement parent;
public UAElement[] children; // cache
public UAElement(Element element) {
this.element = element;
}
public UAElement(String name) {
this.element = getDocument().createElement(name);
}
public UAElement(String name, IUAElement src) {
this(name);
this.src = src;
if (src instanceof UAElement) {
UAElement sourceElement = (UAElement) src;
String filter = sourceElement.getAttribute(ATTRIBUTE_FILTER);
if (filter != null && filter.length() > 0) {
this.setAttribute(ATTRIBUTE_FILTER, filter);
}
}
}
public void appendChild(UAElement uaElementToAppend) {
importElement(uaElementToAppend);
element.appendChild(uaElementToAppend.element);
uaElementToAppend.parent = this;
// cache is now invalid
children = null;
}
public void appendChildren(IUAElement[] children) {
for (int i=0;i<children.length;i++) {
appendChild(children[i] instanceof UAElement ? (UAElement)children[i] : UAElementFactory.newElement(children[i]));
}
}
public String getAttribute(String name) {
String value = element.getAttribute(name);
if (value.length() > 0) {
return value;
}
return null;
}
public IUAElement[] getChildren() {
if (children == null) {
if (element.hasChildNodes()) {
List list = new ArrayList();
Node node = element.getFirstChild();
while (node != null) {
if (node.getNodeType() == Node.ELEMENT_NODE) {
UAElement uaElement = UAElementFactory.newElement((Element)node);
uaElement.parent = this;
if (uaElement != null) {
list.add(uaElement);
}
}
node = node.getNextSibling();
}
children = (UAElement[])list.toArray(new UAElement[list.size()]);
}
else {
children = new UAElement[0];
}
}
return children;
}
public Object getChildren(Class clazz) {
IUAElement[] children = getChildren();
if (children.length > 0) {
List list = new ArrayList();
for (int i=0;i<children.length;++i) {
IUAElement child = children[i];
if (clazz.isAssignableFrom(child.getClass())) {
list.add(child);
}
}
return list.toArray((Object[])Array.newInstance(clazz, list.size()));
}
return Array.newInstance(clazz, 0);
}
public String getElementName() {
return element.getNodeName();
}
public static Document getDocument() {
if (document == null) {
if (builder == null) {
try {
builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
builder.setEntityResolver(new EntityResolver() {
public InputSource resolveEntity(String publicId, String systemId) throws SAXException {
return new InputSource(new StringReader("")); //$NON-NLS-1$
}
});
}
catch (ParserConfigurationException e) {
String msg = "Error creating document builder"; //$NON-NLS-1$
HelpPlugin.logError(msg, e);
}
}
document = builder.newDocument();
}
return document;
}
public UAElement getParentElement() {
return parent;
}
public void insertBefore(UAElement newChild, UAElement refChild) {
importElement(newChild);
element.insertBefore(newChild.element, refChild.element);
newChild.parent = this;
// cache is now invalid
children = null;
}
public boolean isEnabled(IEvaluationContext context) {
if (HelpSystem.isShared()) {
return true;
}
if (src != null) {
return src.isEnabled(context);
}
String filter = getAttribute(ATTRIBUTE_FILTER);
if (filter != null) {
return isEnabledByFilterAttribute(filter);
}
Node node = element.getFirstChild();
while (node != null) {
if (node.getNodeType() == Node.ELEMENT_NODE) {
String name = node.getNodeName();
if (ExpressionTagNames.ENABLEMENT.equals(name)) {
return isEnabledByEnablementElement((Element)node, context);
}
else if (ELEMENT_FILTER.equals(name)) {
// can be multiple filter elements; enabled if they all pass
if (!isEnabledByFilterElement((Element)node)) {
return false;
}
}
}
node = node.getNextSibling();
}
return true;
}
public void removeChild(UAElement elementToRemove) {
element.removeChild(elementToRemove.element);
elementToRemove.parent = null;
// cache is now invalid
children = null;
}
public void setAttribute(String name, String value) {
element.setAttribute(name, value);
}
private void importElement(UAElement uaElementToImport) {
Element elementToImport = uaElementToImport.element;
Document ownerDocument = element.getOwnerDocument();
if (!ownerDocument.equals(elementToImport.getOwnerDocument())) {
elementToImport = (Element)ownerDocument.importNode(elementToImport, true);
}
uaElementToImport.element = elementToImport;
}
private boolean isEnabledByEnablementElement(Element enablement, IEvaluationContext context) {
try {
Expression expression = ExpressionConverter.getDefault().perform(enablement);
return expression.evaluate(context) == EvaluationResult.TRUE;
}
catch (CoreException e) {
/*
* This can happen when attempting to resolve a UI variable (e.g. "workbench")
* in a non-UI environment (infocenter mode). Fail silently.
*/
return true;
}
}
private boolean isEnabledByFilterAttribute(String filter) {
return !FilterResolver.getInstance().isFiltered(filter);
}
private boolean isEnabledByFilterElement(Element filter) {
String name = filter.getAttribute(ATTRIBUTE_NAME);
String value = filter.getAttribute(ATTRIBUTE_VALUE);
if (name.length() > 0 && value.length() > 0) {
boolean not = false;
if (value.startsWith("!")) { //$NON-NLS-1$
not = true;
value = value.substring(1);
}
return !FilterResolver.getInstance().isFiltered(name, value, not);
}
// ignore invalid filters
return true;
}
}