Attempt to follow suggestion from https://issues.apache.org/jira/brow…

…se/JXPATH-194

pom.xml

@@ -214,6 +214,11 @@
       <version>1.0</version>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>org.jdom</groupId>
+      <artifactId>jdom2</artifactId>
+      <version>2.0.6.1</version>
+    </dependency>
     <dependency>
       <groupId>commons-beanutils</groupId>
       <artifactId>commons-beanutils</artifactId>

src/main/java/org/apache/commons/jxpath/ri/JXPathContextReferenceImpl.java

@@ -97,6 +97,14 @@ public class JXPathContextReferenceImpl extends JXPathContext {
             nodeFactories.add(jdomFactory);
         }
 
+        // JDOM2 factory is only registered if JDOM2 is on the classpath
+        final Object jdom2Factory = allocateConditionally(
+                "org.apache.commons.jxpath.ri.model.jdom2.JDOMPointerFactory",
+                "org.jdom2.Document");
+        if (jdom2Factory != null) {
+            nodeFactories.add(jdom2Factory);
+        }
+
         // DynaBean factory is only registered if BeanUtils are on the classpath
         final Object dynaBeanFactory =
             allocateConditionally(

src/main/java/org/apache/commons/jxpath/ri/model/jdom2/JDOMAttributeIterator.java

@@ -0,0 +1,121 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.jxpath.ri.model.jdom2;
+
+import org.apache.commons.jxpath.ri.QName;
+import org.apache.commons.jxpath.ri.model.NodeIterator;
+import org.apache.commons.jxpath.ri.model.NodePointer;
+import org.jdom2.Attribute;
+import org.jdom2.Element;
+import org.jdom2.Namespace;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * An iterator of attributes of a DOM Node.
+ */
+public class JDOMAttributeIterator implements NodeIterator {
+    private NodePointer parent;
+    private List attributes;
+    private int position = 0;
+
+    /**
+     * Create a new JDOMAttributeIterator.
+     * @param parent pointer
+     * @param name test
+     */
+    public JDOMAttributeIterator(final NodePointer parent, final QName name) {
+        this.parent = parent;
+        if (parent.getNode() instanceof Element) {
+            final Element element = (Element) parent.getNode();
+            final String prefix = name.getPrefix();
+            Namespace ns = null;
+            if (prefix != null) {
+                if (prefix.equals("xml")) {
+                    ns = Namespace.XML_NAMESPACE;
+                }
+                else {
+                    final String uri = parent.getNamespaceResolver().getNamespaceURI(prefix);
+                    if (uri != null) {
+                        ns = Namespace.getNamespace(prefix, uri);
+                    }
+                    if (ns == null) {
+                        // TBD: no attributes
+                        attributes = Collections.EMPTY_LIST;
+                        return;
+                    }
+                }
+            }
+            else {
+                ns = Namespace.NO_NAMESPACE;
+            }
+
+            final String lname = name.getName();
+            if (!lname.equals("*")) {
+                attributes = new ArrayList();
+                final Attribute attr = element.getAttribute(lname, ns);
+                if (attr != null) {
+                    attributes.add(attr);
+                }
+            }
+            else {
+                attributes = new ArrayList();
+                final List allAttributes = element.getAttributes();
+                for (int i = 0; i < allAttributes.size(); i++) {
+                    final Attribute attr = (Attribute) allAttributes.get(i);
+                    if (ns == Namespace.NO_NAMESPACE
+                            || attr.getNamespace().equals(ns)) {
+                        attributes.add(attr);
+                    }
+                }
+            }
+        }
+    }
+
+    @Override
+    public NodePointer getNodePointer() {
+        if (position == 0) {
+            if (!setPosition(1)) {
+                return null;
+            }
+            position = 0;
+        }
+        int index = position - 1;
+        if (index < 0) {
+            index = 0;
+        }
+        return new JDOMAttributePointer(
+            parent,
+            (Attribute) attributes.get(index));
+    }
+
+    @Override
+    public int getPosition() {
+        return position;
+    }
+
+    @Override
+    public boolean setPosition(final int position) {
+        if (attributes == null) {
+            return false;
+        }
+        this.position = position;
+        return position >= 1 && position <= attributes.size();
+    }
+}

src/main/java/org/apache/commons/jxpath/ri/model/jdom2/JDOMAttributePointer.java

@@ -0,0 +1,136 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.jxpath.ri.model.jdom2;
+
+import org.apache.commons.jxpath.ri.QName;
+import org.apache.commons.jxpath.ri.model.NodePointer;
+import org.apache.commons.jxpath.util.TypeUtils;
+import org.jdom2.Attribute;
+
+/**
+ * A Pointer that points to a DOM node.
+ */
+public class JDOMAttributePointer extends NodePointer {
+    private final Attribute attr;
+
+    private static final long serialVersionUID = 8896050354479644028L;
+
+    /**
+     * Create a JDOMAttributePointer.
+     * @param parent NodePointer parent
+     * @param attr JDOM Attribute
+     */
+    public JDOMAttributePointer(final NodePointer parent, final Attribute attr) {
+        super(parent);
+        this.attr = attr;
+    }
+
+    @Override
+    public QName getName() {
+        return new QName(
+            JDOMNodePointer.getPrefix(attr),
+            JDOMNodePointer.getLocalName(attr));
+    }
+
+    @Override
+    public String getNamespaceURI() {
+        String uri = attr.getNamespaceURI();
+        if (uri != null && uri.equals("")) {
+            uri = null;
+        }
+        return uri;
+    }
+
+    @Override
+    public Object getValue() {
+        return attr.getValue();
+    }
+
+    @Override
+    public Object getBaseValue() {
+        return attr;
+    }
+
+    @Override
+    public boolean isCollection() {
+        return false;
+    }
+
+    @Override
+    public int getLength() {
+        return 1;
+    }
+
+    @Override
+    public Object getImmediateNode() {
+        return attr;
+    }
+
+    @Override
+    public boolean isActual() {
+        return true;
+    }
+
+    @Override
+    public boolean isLeaf() {
+        return true;
+    }
+
+    @Override
+    public void setValue(final Object value) {
+        attr.setValue((String) TypeUtils.convert(value, String.class));
+    }
+
+    @Override
+    public void remove() {
+        attr.getParent().removeAttribute(attr);
+    }
+
+    @Override
+    public String asPath() {
+        final StringBuffer buffer = new StringBuffer();
+        if (parent != null) {
+            buffer.append(parent.asPath());
+            if (buffer.length() == 0
+                || buffer.charAt(buffer.length() - 1) != '/') {
+                buffer.append('/');
+            }
+        }
+        buffer.append('@');
+        buffer.append(getName());
+        return buffer.toString();
+    }
+
+    @Override
+    public int hashCode() {
+        return System.identityHashCode(attr);
+    }
+
+    @Override
+    public boolean equals(final Object object) {
+        return object == this || object instanceof JDOMAttributePointer
+                && ((JDOMAttributePointer) object).attr == attr;
+    }
+
+    @Override
+    public int compareChildNodePointers(
+            final NodePointer pointer1,
+            final NodePointer pointer2) {
+        // Won't happen - attributes don't have children
+        return 0;
+    }
+}

src/main/java/org/apache/commons/jxpath/ri/model/jdom2/JDOMNamespaceIterator.java

@@ -0,0 +1,109 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.jxpath.ri.model.jdom2;
+
+import org.apache.commons.jxpath.ri.model.NodeIterator;
+import org.apache.commons.jxpath.ri.model.NodePointer;
+import org.jdom2.Document;
+import org.jdom2.Element;
+import org.jdom2.Namespace;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * An iterator of namespaces of a DOM Node.
+ */
+public class JDOMNamespaceIterator implements NodeIterator {
+    private final NodePointer parent;
+    private List namespaces;
+    private Set prefixes;
+    private int position = 0;
+
+    /**
+     * Create a new JDOMNamespaceIterator.
+     * @param parent the parent NodePointer.
+     */
+    public JDOMNamespaceIterator(final NodePointer parent) {
+        this.parent = parent;
+        Object node = parent.getNode();
+        if (node instanceof Document) {
+            node = ((Document) node).getRootElement();
+        }
+        if (node instanceof Element) {
+            namespaces = new ArrayList();
+            prefixes = new HashSet();
+            collectNamespaces((Element) node);
+        }
+    }
+
+    /**
+     * Collect the namespaces from a JDOM Element.
+     * @param element the source Element
+     */
+    private void collectNamespaces(final Element element) {
+        Namespace ns = element.getNamespace();
+        if (ns != null && !prefixes.contains(ns.getPrefix())) {
+            namespaces.add(ns);
+            prefixes.add(ns.getPrefix());
+        }
+        final List others = element.getAdditionalNamespaces();
+        for (int i = 0; i < others.size(); i++) {
+            ns = (Namespace) others.get(i);
+            if (ns != null && !prefixes.contains(ns.getPrefix())) {
+                namespaces.add(ns);
+                prefixes.add(ns.getPrefix());
+            }
+        }
+        final Object elementParent = element.getParent();
+        if (elementParent instanceof Element) {
+            collectNamespaces((Element) elementParent);
+        }
+    }
+
+    @Override
+    public NodePointer getNodePointer() {
+        if (position == 0) {
+            if (!setPosition(1)) {
+                return null;
+            }
+            position = 0;
+        }
+        int index = position - 1;
+        if (index < 0) {
+            index = 0;
+        }
+        final Namespace ns = (Namespace) namespaces.get(index);
+        return new JDOMNamespacePointer(parent, ns.getPrefix(), ns.getURI());
+    }
+
+    @Override
+    public int getPosition() {
+        return position;
+    }
+
+    @Override
+    public boolean setPosition(final int position) {
+        if (namespaces == null) {
+            return false;
+        }
+        this.position = position;
+        return position >= 1 && position <= namespaces.size();
+    }
+}