/*
* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.ArrayList;
import java.util.List;
import jdk.dynalink.CallSiteDescriptor;
import jdk.dynalink.NamedOperation;
import jdk.dynalink.NamespaceOperation;
import jdk.dynalink.Operation;
import jdk.dynalink.StandardNamespace;
import jdk.dynalink.StandardOperation;
import jdk.dynalink.linker.GuardedInvocation;
import jdk.dynalink.linker.GuardingDynamicLinker;
import jdk.dynalink.linker.GuardingDynamicLinkerExporter;
import jdk.dynalink.linker.LinkRequest;
import jdk.dynalink.linker.LinkerServices;
import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;
import jdk.dynalink.linker.support.Guards;
import jdk.dynalink.linker.support.Lookup;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
/**
* This is a dynalink pluggable linker (see http://openjdk.java.net/jeps/276).
* This linker handles XML DOM Element objects specially. This linker links
* special properties starting with "_" and treats those as child element names
* to access. This kind of child element access makes it easy to write XML DOM
* accessing scripts. See for example ./dom_linker_gutenberg.js.
*/
public final class DOMLinkerExporter extends GuardingDynamicLinkerExporter {
static {
System.out.println("pluggable dynalink DOM linker loaded");
}
// return List of child Elements of the given Element matching the given name.
private static List<Element> getChildElements(final Element elem, final String name) {
final NodeList nodeList = elem.getChildNodes();
final List<Element> childElems = new ArrayList<>();
final int len = nodeList.getLength();
for (int i = 0; i < len; i++) {
final Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE &&
((Element)node).getTagName().equals(name)) {
childElems.add((Element)node);
}
}
return childElems;
}
// method that returns either unique child element matching given name
// or a list of child elements of that name (if there are more than one matches).
public static Object getElementsByName(final Object elem, final String name) {
final List<Element> elems = getChildElements((Element)elem, name);
return elems.size() == 1? elems.get(0) : elems;
}
// method to extract text context under a given DOM Element
public static Object getElementText(final Object elem) {
final NodeList nodeList = ((Element)elem).getChildNodes();
final int len = nodeList.getLength();
final StringBuilder text = new StringBuilder();
for (int i = 0; i < len; i++) {
final Node node = nodeList.item(i);
if (node.getNodeType() == Node.TEXT_NODE) {
text.append(node.getNodeValue());
}
}
return text.toString();
}
private static final MethodHandle ELEMENTS_BY_NAME;
private static final MethodHandle ELEMENT_TEXT;
private static final MethodHandle IS_ELEMENT;
static {
ELEMENTS_BY_NAME = Lookup.PUBLIC.findStatic(DOMLinkerExporter.class,
"getElementsByName",
MethodType.methodType(Object.class, Object.class, String.class));
ELEMENT_TEXT = Lookup.PUBLIC.findStatic(DOMLinkerExporter.class,
"getElementText",
MethodType.methodType(Object.class, Object.class));
IS_ELEMENT = Guards.isInstance(Element.class, MethodType.methodType(Boolean.TYPE, Object.class));
}
@Override
public List<GuardingDynamicLinker> get() {
final ArrayList<GuardingDynamicLinker> linkers = new ArrayList<>();
linkers.add(new TypeBasedGuardingDynamicLinker() {
@Override
public boolean canLinkType(final Class<?> type) {
return Element.class.isAssignableFrom(type);
}
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest request,
final LinkerServices linkerServices) throws Exception {
final Object self = request.getReceiver();
if (! (self instanceof Element)) {
return null;
}
final CallSiteDescriptor desc = request.getCallSiteDescriptor();
final Operation op = desc.getOperation();
final Object name = NamedOperation.getName(op);
final boolean getProp = NamespaceOperation.contains(
NamedOperation.getBaseOperation(op),
StandardOperation.GET, StandardNamespace.PROPERTY);
if (getProp && name instanceof String) {
final String nameStr = (String)name;
// Treat names starting with "_" as special names.
// Everything else is linked other dynalink bean linker!
// This avoids collision with Java methods of org.w3c.dom.Element class
// Assumption is that Java APIs won't start with "_" character!!
if (nameStr.equals("_")) {
// short-hand to get text content under a given DOM Element
return new GuardedInvocation(ELEMENT_TEXT, IS_ELEMENT);
} else if (nameStr.startsWith("_")) {
return new GuardedInvocation(
MethodHandles.insertArguments(ELEMENTS_BY_NAME, 1, nameStr.substring(1)),
IS_ELEMENT);
}
}
return null;
}
});
return linkers;
}
}