# HG changeset patch
# User sundar
# Date 1448887607 -19800
# Node ID c34f322b89b996ad5749a6d724bd794eb89edd93
# Parent  b7fec92235d8b9cfcc6ed51db5b02b0f4a20b515
8144230: Add a sample for pluggable dynalink linker
Reviewed-by: hannesw, mhaupt

diff -r b7fec92235d8 -r c34f322b89b9 nashorn/samples/DOMLinkerExporter.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/samples/DOMLinkerExporter.java	Mon Nov 30 18:16:47 2015 +0530
@@ -0,0 +1,162 @@
+/*
+ * 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.CompositeOperation;
+import jdk.dynalink.NamedOperation;
+import jdk.dynalink.Operation;
+import jdk.dynalink.StandardOperation;
+import jdk.dynalink.linker.GuardingDynamicLinker;
+import jdk.dynalink.linker.GuardingDynamicLinkerExporter;
+import jdk.dynalink.linker.GuardedInvocation;
+import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;
+import jdk.dynalink.linker.LinkRequest;
+import jdk.dynalink.linker.LinkerServices;
+import jdk.dynalink.linker.support.Guards;
+import jdk.dynalink.linker.support.Lookup;
+import org.w3c.dom.Attr;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.w3c.dom.Element;
+
+/**
+ * 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(Element elem, String name) {
+        NodeList nodeList = elem.getChildNodes();
+        List<Element> childElems = new ArrayList<>();
+        int len = nodeList.getLength();
+        for (int i = 0; i < len; i++) {
+            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(Object elem, final String name) {
+        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(Object elem) {
+        NodeList nodeList = ((Element)elem).getChildNodes();
+        int len = nodeList.getLength();
+        StringBuilder text = new StringBuilder();
+        for (int i = 0; i < len; i++) {
+            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(LinkRequest request,
+                LinkerServices linkerServices) throws Exception {
+                final Object self = request.getReceiver();
+                if (! (self instanceof Element)) {
+                    return null;
+                }
+
+                CallSiteDescriptor desc = request.getCallSiteDescriptor();
+                Operation op = desc.getOperation();
+                Object name = NamedOperation.getName(op);
+                boolean getProp = CompositeOperation.contains(
+                        NamedOperation.getBaseOperation(op),
+                        StandardOperation.GET_PROPERTY);
+                if (getProp && name instanceof String) {
+                    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;
+    }
+}
diff -r b7fec92235d8 -r c34f322b89b9 nashorn/samples/META-INF/services/jdk.dynalink.linker.GuardingDynamicLinkerExporter
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/samples/META-INF/services/jdk.dynalink.linker.GuardingDynamicLinkerExporter	Mon Nov 30 18:16:47 2015 +0530
@@ -0,0 +1,1 @@
+DOMLinkerExporter
diff -r b7fec92235d8 -r c34f322b89b9 nashorn/samples/dom_linker.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/samples/dom_linker.js	Mon Nov 30 18:16:47 2015 +0530
@@ -0,0 +1,48 @@
+#! simple dom linker example
+
+/*
+ * 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.
+ */
+
+// This script assumes you've built jdk9 or using latest
+// jdk9 image and put the 'bin' directory in the PATH
+
+$EXEC.throwOnError=true
+
+// compile DOMLinkerExporter
+`javac -cp ../dist/nashorn.jar DOMLinkerExporter.java`
+
+// make a jar file out of pluggable linker
+`jar cvf dom_linker.jar DOMLinkerExporter*.class META-INF/`
+
+// run a sample script that uses pluggable linker
+// but make sure classpath points to the pluggable linker jar!
+
+`jjs -cp dom_linker.jar dom_linker_gutenberg.js`
diff -r b7fec92235d8 -r c34f322b89b9 nashorn/samples/dom_linker_gutenberg.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/samples/dom_linker_gutenberg.js	Mon Nov 30 18:16:47 2015 +0530
@@ -0,0 +1,114 @@
+#// Usage: jjs -scripting dom_linker_gutenberg.js
+
+/*
+ * 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.
+ */
+
+// Simple example that demonstrates reading XML Rss feed
+// to generate a HTML file from script and show it by browser.
+// Uses XML DOM parser along with DOM element pluggable dynalink linker
+// for ease of navigation of DOM (child) elements by name.
+
+// Java classes used
+var DocBuilderFac = Java.type("javax.xml.parsers.DocumentBuilderFactory");
+var Node = Java.type("org.w3c.dom.Node");
+var File = Java.type("java.io.File");
+var FileWriter = Java.type("java.io.FileWriter");
+var PrintWriter = Java.type("java.io.PrintWriter");
+
+// parse XML from uri and return Document
+function parseXML(uri) {
+    var docBuilder = DocBuilderFac.newInstance().newDocumentBuilder();
+    return docBuilder["parse(java.lang.String)"](uri);
+}
+
+// generate HTML using here-doc and string interpolation
+function getBooksHtml() {
+    var doc = parseXML("http://www.gutenberg.org/cache/epub/feeds/today.rss");
+    // wrap document root Element as script convenient object
+    var rss = doc.documentElement;
+
+    var str = <<HEAD
+
+<html>
+<title>${rss._channel._title._}</title>
+<body>
+<h1>${rss._channel._description._}</h1>
+<p>
+Published on ${rss._channel._pubDate._}
+</p>
+
+HEAD
+
+    var items = rss._channel._item;
+    for each (var i in items) {
+        str += <<LIST
+
+<dl>
+<dt><a href="${i._link._}">${i._title._}</a></dt>
+<dd>${i._description._}</dd>
+</dl>
+
+LIST
+    }
+    str += <<END
+
+</body>
+</html>
+
+END
+    return str;
+}
+
+// write the string to the given file
+function writeTo(file, str) {
+    var w = new PrintWriter(new FileWriter(file));
+    try {
+        w.print(str);
+    } finally {
+        w.close();
+    }
+}
+
+// generate books HTML
+var str = getBooksHtml();
+
+// write to file. __DIR__ is directory where
+// this script is stored.
+var file = new File(__DIR__ + "books.html");
+writeTo(file, str);
+
+// show it by desktop browser
+try {
+    var Desktop = Java.type("java.awt.Desktop");
+    Desktop.desktop.browse(file.toURI());
+} catch (e) {
+    print(e);
+}