Show XPath location of an error

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@306542 13f79535-47bb-0310-9956-ffa450edef68

plugin/src/main/org/apache/maven/XPathLocationTracker.java

@@ -0,0 +1,206 @@
+package org.apache.maven;
+
+/* ====================================================================
+ *   Copyright 2001-2005 The Apache Software Foundation.
+ *
+ *   Licensed 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.
+ * ====================================================================
+ */
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.ContentHandler;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.XMLFilterImpl;
+
+/**
+ * Constructs an XPath expression in the form:
+ *    /root/child[3]/grandchild[2] ...
+ *
+ * @author <a href="mailto:ltheussl@apache.org">Lukas Theussl</a>
+ */
+
+public class XPathLocationTracker extends XMLFilterImpl
+{
+
+    private State state;
+    private static final Integer[] ints = new Integer[]
+    {
+        new Integer(0),
+        new Integer(1),
+        new Integer(2),
+        new Integer(3),
+        new Integer(4)
+    };
+
+    /**
+     * Constructor: sets the ContentHandler.
+     * @param handler The ContentHandler
+     */
+    public XPathLocationTracker( ContentHandler handler )
+    {
+        setContentHandler(handler);
+    }
+
+    /**
+     * Overriding ContentHandler.
+     * @throws SAXException SAXException
+     */
+    public void startDocument() throws SAXException
+    {
+        state = new State(null);
+        super.startDocument();
+    }
+
+    /**
+     * Overriding ContentHandler.
+     * @throws SAXException SAXException
+     */
+    public void endDocument() throws SAXException
+    {
+        super.endDocument();
+        state = null;
+    }
+
+    /**
+     * Overriding ContentHandler.
+     * @param uri uri
+     * @param localName localName
+     * @param qName qName
+     * @param atts atts
+     * @throws SAXException SAXException
+     */
+    public void startElement(String uri, String localName,
+            String qName, Attributes atts) throws SAXException
+    {
+        state = state.push(qName);
+        super.startElement(uri, localName, qName, atts);
+    }
+
+    /**
+     * Overriding ContentHandler.
+     * @param uri uri
+     * @param localName localName
+     * @param qName qName
+     * @throws SAXException SAXException
+     */
+    public void endElement(String uri, String localName, String qName)
+            throws SAXException
+    {
+        super.endElement(uri, localName, qName);
+        state = state.pop();
+    }
+
+    /**
+     * Gets the XPath expression that points to the current location.
+     * Throws a new IllegalStateException if the component is not
+     * parsing a document.
+     * @return The XPath expression
+     */
+    public final String getXPath()
+    {
+        if ( state == null )
+        {
+            throw new IllegalStateException(
+                "startDocument event is not invoked");
+        }
+        return state.getXPath();
+    }
+
+    private static Integer getInt(int i)
+    {
+        if ( i < ints.length )
+        {
+            return ints[i];
+        } else {
+            return new Integer(i);
+        }
+    }
+
+    private static final class State
+    {
+
+        private final Map counter = new HashMap();
+        private final State parent;
+        private State child;
+        private String currentName;
+
+        State( State newParent )
+        {
+            this.parent = newParent;
+        }
+
+        protected State push( String rawName )
+        {
+            count(rawName);
+            currentName = rawName;
+            if ( child == null )
+            {
+                child = new State(this);
+            } else {
+                child.reset();
+            }
+            return child;
+        }
+
+        protected State pop()
+        {
+            parent.currentName = null;
+            return parent;
+        }
+
+        private void count( String rawName )
+        {
+            Integer i = (Integer) counter.get(rawName);
+            if ( i == null )
+            {
+                i = getInt(1);
+            } else {
+                i = getInt(i.intValue() + 1);
+            }
+            counter.put(rawName, i);
+        }
+
+        private void reset()
+        {
+            counter.clear();
+            currentName = null;
+        }
+
+        private String getXPath()
+        {
+            String xPath;
+            if ( parent == null ) // root
+            {
+                xPath = "/";
+                if ( currentName != null)
+                {
+                    xPath += currentName;
+                }
+            } else { // child node
+                xPath = parent.getXPath();
+                if ( currentName != null )
+                {
+                    xPath += '/' + currentName;
+                    Integer i = (Integer) counter.get(currentName);
+                    xPath += '[' + i.toString() + ']';
+                }
+            }
+            return xPath;
+        }
+
+    }
+
+}