1 /*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * - Neither the name of Oracle nor the names of its
16 * contributors may be used to endorse or promote products derived
17 * from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 import java.lang.invoke.MethodHandle;
33 import java.lang.invoke.MethodHandles;
34 import java.lang.invoke.MethodType;
35 import java.util.ArrayList;
36 import java.util.List;
37 import jdk.dynalink.CallSiteDescriptor;
38 import jdk.dynalink.NamedOperation;
39 import jdk.dynalink.NamespaceOperation;
40 import jdk.dynalink.Operation;
41 import jdk.dynalink.StandardNamespace;
42 import jdk.dynalink.StandardOperation;
43 import jdk.dynalink.linker.GuardedInvocation;
44 import jdk.dynalink.linker.GuardingDynamicLinker;
45 import jdk.dynalink.linker.GuardingDynamicLinkerExporter;
46 import jdk.dynalink.linker.LinkRequest;
47 import jdk.dynalink.linker.LinkerServices;
48 import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;
49 import jdk.dynalink.linker.support.Guards;
50 import jdk.dynalink.linker.support.Lookup;
51 import org.w3c.dom.Element;
52 import org.w3c.dom.Node;
53 import org.w3c.dom.NodeList;
54
55 /**
56 * This is a dynalink pluggable linker (see http://openjdk.java.net/jeps/276).
57 * This linker handles XML DOM Element objects specially. This linker links
58 * special properties starting with "_" and treats those as child element names
59 * to access. This kind of child element access makes it easy to write XML DOM
60 * accessing scripts. See for example ./dom_linker_gutenberg.js.
61 */
62 public final class DOMLinkerExporter extends GuardingDynamicLinkerExporter {
63 static {
64 System.out.println("pluggable dynalink DOM linker loaded");
65 }
66
67 // return List of child Elements of the given Element matching the given name.
68 private static List<Element> getChildElements(final Element elem, final String name) {
69 final NodeList nodeList = elem.getChildNodes();
70 final List<Element> childElems = new ArrayList<>();
71 final int len = nodeList.getLength();
72 for (int i = 0; i < len; i++) {
73 final Node node = nodeList.item(i);
74 if (node.getNodeType() == Node.ELEMENT_NODE &&
75 ((Element)node).getTagName().equals(name)) {
76 childElems.add((Element)node);
77 }
78 }
79 return childElems;
80 }
81
82 // method that returns either unique child element matching given name
83 // or a list of child elements of that name (if there are more than one matches).
84 public static Object getElementsByName(final Object elem, final String name) {
85 final List<Element> elems = getChildElements((Element)elem, name);
86 return elems.size() == 1? elems.get(0) : elems;
87 }
88
89 // method to extract text context under a given DOM Element
90 public static Object getElementText(final Object elem) {
91 final NodeList nodeList = ((Element)elem).getChildNodes();
92 final int len = nodeList.getLength();
93 final StringBuilder text = new StringBuilder();
94 for (int i = 0; i < len; i++) {
95 final Node node = nodeList.item(i);
96 if (node.getNodeType() == Node.TEXT_NODE) {
97 text.append(node.getNodeValue());
98 }
99 }
100 return text.toString();
101 }
102
103 private static final MethodHandle ELEMENTS_BY_NAME;
104 private static final MethodHandle ELEMENT_TEXT;
105 private static final MethodHandle IS_ELEMENT;
106 static {
107 ELEMENTS_BY_NAME = Lookup.PUBLIC.findStatic(DOMLinkerExporter.class,
108 "getElementsByName",
109 MethodType.methodType(Object.class, Object.class, String.class));
110 ELEMENT_TEXT = Lookup.PUBLIC.findStatic(DOMLinkerExporter.class,
111 "getElementText",
112 MethodType.methodType(Object.class, Object.class));
113 IS_ELEMENT = Guards.isInstance(Element.class, MethodType.methodType(Boolean.TYPE, Object.class));
114 }
115
116 @Override
117 public List<GuardingDynamicLinker> get() {
118 final ArrayList<GuardingDynamicLinker> linkers = new ArrayList<>();
119 linkers.add(new TypeBasedGuardingDynamicLinker() {
120 @Override
121 public boolean canLinkType(final Class<?> type) {
122 return Element.class.isAssignableFrom(type);
123 }
124
125 @Override
126 public GuardedInvocation getGuardedInvocation(final LinkRequest request,
127 final LinkerServices linkerServices) throws Exception {
128 final Object self = request.getReceiver();
129 if (! (self instanceof Element)) {
130 return null;
131 }
132
133 final CallSiteDescriptor desc = request.getCallSiteDescriptor();
134 final Operation op = desc.getOperation();
135 final Object name = NamedOperation.getName(op);
136 final boolean getProp = NamespaceOperation.contains(
137 NamedOperation.getBaseOperation(op),
138 StandardOperation.GET, StandardNamespace.PROPERTY);
139 if (getProp && name instanceof String) {
140 final String nameStr = (String)name;
141
142 // Treat names starting with "_" as special names.
143 // Everything else is linked other dynalink bean linker!
144 // This avoids collision with Java methods of org.w3c.dom.Element class
145 // Assumption is that Java APIs won't start with "_" character!!
146 if (nameStr.equals("_")) {
147 // short-hand to get text content under a given DOM Element
148 return new GuardedInvocation(ELEMENT_TEXT, IS_ELEMENT);
149 } else if (nameStr.startsWith("_")) {
150 return new GuardedInvocation(
151 MethodHandles.insertArguments(ELEMENTS_BY_NAME, 1, nameStr.substring(1)),
152 IS_ELEMENT);
153 }
154
155 }
156
157 return null;
158 }
159 });
160 return linkers;
161 }
162 }