Merge "Extract positional XML parser into common and fix encoding issues"

14 files changed, 745 insertions, 0 deletions

diff --git a/common/src/com/android/io/FileWrapper.java b/common/src/com/android/io/FileWrapper.java
index 2859c0d..84a1f3e 100644
--- a/common/src/com/android/io/FileWrapper.java
+++ b/common/src/com/android/io/FileWrapper.java
@@ -85,6 +85,7 @@ public class FileWrapper extends File implements IAbstractFile {
         super(uri);
     }
 
+    @Override
     public InputStream getContents() throws StreamException {
         try {
             return new FileInputStream(this);
@@ -93,6 +94,7 @@ public class FileWrapper extends File implements IAbstractFile {
         }
     }
 
+    @Override
     public void setContents(InputStream source) throws StreamException {
         FileOutputStream fos = null;
         try {
@@ -116,6 +118,7 @@ public class FileWrapper extends File implements IAbstractFile {
         }
     }
 
+    @Override
     public OutputStream getOutputStream() throws StreamException {
         try {
             return new FileOutputStream(this);
@@ -124,10 +127,12 @@ public class FileWrapper extends File implements IAbstractFile {
         }
     }
 
+    @Override
     public PreferredWriteMode getPreferredWriteMode() {
         return PreferredWriteMode.OUTPUTSTREAM;
     }
 
+    @Override
     public String getOsLocation() {
         return getAbsolutePath();
     }
@@ -137,10 +142,12 @@ public class FileWrapper extends File implements IAbstractFile {
         return isFile();
     }
 
+    @Override
     public long getModificationStamp() {
         return lastModified();
     }
 
+    @Override
     public IAbstractFolder getParentFolder() {
         String p = this.getParent();
         if (p == null) {
diff --git a/common/src/com/android/io/FolderWrapper.java b/common/src/com/android/io/FolderWrapper.java
index 26ed9cf..c29c934 100644
--- a/common/src/com/android/io/FolderWrapper.java
+++ b/common/src/com/android/io/FolderWrapper.java
@@ -81,6 +81,7 @@ public class FolderWrapper extends File implements IAbstractFolder {
         super(file.getAbsolutePath());
     }
 
+    @Override
     public IAbstractResource[] listMembers() {
         File[] files = listFiles();
         final int count = files == null ? 0 : files.length;
@@ -100,8 +101,10 @@ public class FolderWrapper extends File implements IAbstractFolder {
         return afiles;
     }
 
+    @Override
     public boolean hasFile(final String name) {
         String[] match = list(new FilenameFilter() {
+            @Override
             public boolean accept(IAbstractFolder dir, String filename) {
                 return name.equals(filename);
             }
@@ -110,14 +113,17 @@ public class FolderWrapper extends File implements IAbstractFolder {
         return match.length > 0;
     }
 
+    @Override
     public IAbstractFile getFile(String name) {
         return new FileWrapper(this, name);
     }
 
+    @Override
     public IAbstractFolder getFolder(String name) {
         return new FolderWrapper(this, name);
     }
 
+    @Override
     public IAbstractFolder getParentFolder() {
         String p = this.getParent();
         if (p == null) {
@@ -126,6 +132,7 @@ public class FolderWrapper extends File implements IAbstractFolder {
         return new FolderWrapper(p);
     }
 
+    @Override
     public String getOsLocation() {
         return getAbsolutePath();
     }
@@ -135,6 +142,7 @@ public class FolderWrapper extends File implements IAbstractFolder {
         return isDirectory();
     }
 
+    @Override
     public String[] list(FilenameFilter filter) {
         File[] files = listFiles();
         if (files != null && files.length > 0) {
diff --git a/common/src/com/android/resources/Density.java b/common/src/com/android/resources/Density.java
index f838de4..610789a 100644
--- a/common/src/com/android/resources/Density.java
+++ b/common/src/com/android/resources/Density.java
@@ -72,6 +72,7 @@ public enum Density implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
@@ -88,10 +89,12 @@ public enum Density implements ResourceEnum {
         return "";
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mDisplayValue;
     }
@@ -120,10 +123,12 @@ public enum Density implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return this != NODPI; // nodpi is not a valid config for devices.
     }
diff --git a/common/src/com/android/resources/Keyboard.java b/common/src/com/android/resources/Keyboard.java
index eb99f9b..d6bc80a 100644
--- a/common/src/com/android/resources/Keyboard.java
+++ b/common/src/com/android/resources/Keyboard.java
@@ -53,14 +53,17 @@ public enum Keyboard implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -89,10 +92,12 @@ public enum Keyboard implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/KeyboardState.java b/common/src/com/android/resources/KeyboardState.java
index e3333f5..2eb7e00 100644
--- a/common/src/com/android/resources/KeyboardState.java
+++ b/common/src/com/android/resources/KeyboardState.java
@@ -50,14 +50,17 @@ public enum KeyboardState implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -86,10 +89,12 @@ public enum KeyboardState implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/Navigation.java b/common/src/com/android/resources/Navigation.java
index d5d9541..f857e5f 100644
--- a/common/src/com/android/resources/Navigation.java
+++ b/common/src/com/android/resources/Navigation.java
@@ -51,14 +51,17 @@ public enum Navigation implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -87,10 +90,12 @@ public enum Navigation implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/NavigationState.java b/common/src/com/android/resources/NavigationState.java
index 266d9da..63b8fea 100644
--- a/common/src/com/android/resources/NavigationState.java
+++ b/common/src/com/android/resources/NavigationState.java
@@ -49,14 +49,17 @@ public enum NavigationState implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -85,10 +88,12 @@ public enum NavigationState implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/NightMode.java b/common/src/com/android/resources/NightMode.java
index 2d64316..8fe1dd9 100644
--- a/common/src/com/android/resources/NightMode.java
+++ b/common/src/com/android/resources/NightMode.java
@@ -49,14 +49,17 @@ public enum NightMode implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -85,10 +88,12 @@ public enum NightMode implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/ScreenOrientation.java b/common/src/com/android/resources/ScreenOrientation.java
index 56f907b..b18753d 100644
--- a/common/src/com/android/resources/ScreenOrientation.java
+++ b/common/src/com/android/resources/ScreenOrientation.java
@@ -50,14 +50,17 @@ public enum ScreenOrientation implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -87,10 +90,12 @@ public enum ScreenOrientation implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/ScreenRatio.java b/common/src/com/android/resources/ScreenRatio.java
index 2794b6e..bb575b0 100644
--- a/common/src/com/android/resources/ScreenRatio.java
+++ b/common/src/com/android/resources/ScreenRatio.java
@@ -49,14 +49,17 @@ public enum ScreenRatio implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -86,10 +89,12 @@ public enum ScreenRatio implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/ScreenSize.java b/common/src/com/android/resources/ScreenSize.java
index b6ffc50..4def540 100644
--- a/common/src/com/android/resources/ScreenSize.java
+++ b/common/src/com/android/resources/ScreenSize.java
@@ -51,14 +51,17 @@ public enum ScreenSize implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -88,10 +91,12 @@ public enum ScreenSize implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/TouchScreen.java b/common/src/com/android/resources/TouchScreen.java
index 7ee1f0f..7eeeb08 100644
--- a/common/src/com/android/resources/TouchScreen.java
+++ b/common/src/com/android/resources/TouchScreen.java
@@ -50,14 +50,17 @@ public enum TouchScreen implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mShortDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mLongDisplayValue;
     }
@@ -87,10 +90,12 @@ public enum TouchScreen implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return false;
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return true;
     }
diff --git a/common/src/com/android/resources/UiMode.java b/common/src/com/android/resources/UiMode.java
index 36c903b..d1ddbc8 100644
--- a/common/src/com/android/resources/UiMode.java
+++ b/common/src/com/android/resources/UiMode.java
@@ -49,14 +49,17 @@ public enum UiMode implements ResourceEnum {
         return null;
     }
 
+    @Override
     public String getResourceValue() {
         return mValue;
     }
 
+    @Override
     public String getShortDisplayValue() {
         return mDisplayValue;
     }
 
+    @Override
     public String getLongDisplayValue() {
         return mDisplayValue;
     }
@@ -85,10 +88,12 @@ public enum UiMode implements ResourceEnum {
         return null;
     }
 
+    @Override
     public boolean isFakeValue() {
         return this == NORMAL; // NORMAL is not a real enum. it's used for internal state only.
     }
 
+    @Override
     public boolean isValidValueForDevice() {
         return this != NORMAL;
     }
diff --git a/common/src/com/android/util/PositionXmlParser.java b/common/src/com/android/util/PositionXmlParser.java
new file mode 100644
index 0000000..bfe8075
--- /dev/null
+++ b/common/src/com/android/util/PositionXmlParser.java
@@ -0,0 +1,675 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package com.android.util;
+
+import com.android.annotations.NonNull;
+import com.android.annotations.Nullable;
+
+import org.w3c.dom.Attr;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.Text;
+import org.xml.sax.Attributes;
+import org.xml.sax.InputSource;
+import org.xml.sax.Locator;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringReader;
+import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+/**
+ * A simple DOM XML parser which can retrieve exact beginning and end offsets
+ * (and line and column numbers) for element nodes as well as attribute nodes.
+ */
+public class PositionXmlParser {
+    private static final String UTF_8 = "UTF-8";                 //$NON-NLS-1$
+    private static final String UTF_16 = "UTF_16";               //$NON-NLS-1$
+    private static final String UTF_16LE = "UTF_16LE";           //$NON-NLS-1$
+    private static final String CONTENT_KEY = "contents";        //$NON-NLS-1$
+    private final static String POS_KEY = "offsets";             //$NON-NLS-1$
+    private static final String NAMESPACE_PREFIX_FEATURE =
+            "http://xml.org/sax/features/namespace-prefixes";    //$NON-NLS-1$
+    private static final String NAMESPACE_FEATURE =
+            "http://xml.org/sax/features/namespaces";            //$NON-NLS-1$
+    /** See http://www.w3.org/TR/REC-xml/#NT-EncodingDecl */
+    private static final Pattern ENCODING_PATTERN =
+            Pattern.compile("encoding=['\"](\\S*)['\"]");//$NON-NLS-1$
+
+    /**
+     * Parses the XML content from the given input stream.
+     *
+     * @param input the input stream containing the XML to be parsed
+     * @return the corresponding document
+     * @throws ParserConfigurationException if a SAX parser is not available
+     * @throws SAXException if the document contains a parsing error
+     * @throws IOException if something is seriously wrong. This should not
+     *             happen since the input source is known to be constructed from
+     *             a string.
+     */
+    @Nullable
+    public Document parse(@NonNull InputStream input)
+            throws ParserConfigurationException, SAXException, IOException {
+        // Read in all the data
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        byte[] buf = new byte[1024];
+        while (true) {
+          int r = input.read(buf);
+          if (r == -1) {
+            break;
+          }
+          out.write(buf, 0, r);
+        }
+        input.close();
+        return parse(out.toByteArray());
+    }
+
+    /**
+     * Parses the XML content from the given byte array
+     *
+     * @param data the raw XML data (with unknown encoding)
+     * @return the corresponding document
+     * @throws ParserConfigurationException if a SAX parser is not available
+     * @throws SAXException if the document contains a parsing error
+     * @throws IOException if something is seriously wrong. This should not
+     *             happen since the input source is known to be constructed from
+     *             a string.
+     */
+    @Nullable
+    public Document parse(@NonNull byte[] data)
+            throws ParserConfigurationException, SAXException, IOException {
+        String xml = getXmlString(data);
+        return parse(xml, new InputSource(new StringReader(xml)), true);
+    }
+
+    /**
+     * Parses the given XML content.
+     *
+     * @param xml the XML string to be parsed. This must be in the correct
+     *     encoding already.
+     * @return the corresponding document
+     * @throws ParserConfigurationException if a SAX parser is not available
+     * @throws SAXException if the document contains a parsing error
+     * @throws IOException if something is seriously wrong. This should not
+     *             happen since the input source is known to be constructed from
+     *             a string.
+     */
+    @Nullable
+    public Document parse(@NonNull String xml)
+            throws ParserConfigurationException, SAXException, IOException {
+        return parse(xml, new InputSource(new StringReader(xml)), true);
+    }
+
+    @NonNull
+    private Document parse(@NonNull String xml, @NonNull InputSource input, boolean checkBom)
+            throws ParserConfigurationException, SAXException, IOException {
+        try {
+            SAXParserFactory factory = SAXParserFactory.newInstance();
+            factory.setFeature(NAMESPACE_FEATURE, true);
+            factory.setFeature(NAMESPACE_PREFIX_FEATURE, true);
+            SAXParser parser = factory.newSAXParser();
+            DomBuilder handler = new DomBuilder(xml);
+            parser.parse(input, handler);
+            return handler.getDocument();
+        } catch (SAXException e) {
+            if (checkBom && e.getMessage().contains("Content is not allowed in prolog")) {
+                // Byte order mark in the string? Skip it. There are many markers
+                // (see http://en.wikipedia.org/wiki/Byte_order_mark) so here we'll
+                // just skip those up to the XML prolog beginning character, <
+                xml = xml.replaceFirst("^([\\W]+)<","<");  //$NON-NLS-1$ //$NON-NLS-2$
+                return parse(xml, null, false);
+            }
+            throw e;
+        }
+    }
+
+    /**
+     * Returns the String corresponding to the given byte array of XML data
+     * (with unknown encoding). This method attempts to guess the encoding based
+     * on the XML prologue.
+     * @param data the XML data to be decoded into a string
+     * @return a string corresponding to the XML data
+     */
+    public static String getXmlString(byte[] data) {
+        int offset = 0;
+
+        String defaultCharset = UTF_8;
+        String charset = null;
+        // Look for the byte order mark, to see if we need to remove bytes from
+        // the input stream (and to determine whether files are big endian or little endian) etc
+        // for files which do not specify the encoding.
+        // See http://unicode.org/faq/utf_bom.html#BOM for more.
+        if (data.length > 4) {
+            if (data[0] == (byte)0xef && data[1] == (byte)0xbb && data[2] == (byte)0xbf) {
+                // UTF-8
+                defaultCharset = charset = UTF_8;
+                offset += 3;
+            } else if (data[0] == (byte)0xfe && data[1] == (byte)0xff) {
+                //  UTF-16, big-endian
+                defaultCharset = charset = UTF_16;
+                offset += 2;
+            } else if (data[0] == (byte)0x0 && data[1] == (byte)0x0
+                    && data[2] == (byte)0xfe && data[3] == (byte)0xff) {
+                // UTF-32, big-endian
+                defaultCharset = charset = "UTF_32";    //$NON-NLS-1$
+                offset += 4;
+            } else if (data[0] == (byte)0xff && data[1] == (byte)0xfe
+                    && data[2] == (byte)0x0 && data[3] == (byte)0x0) {
+                // UTF-32, little-endian. We must check for this *before* looking for
+                // UTF_16LE since UTF_32LE has the same prefix!
+                defaultCharset = charset = "UTF_32LE";  //$NON-NLS-1$
+                offset += 4;
+            } else if (data[0] == (byte)0xff && data[1] == (byte)0xfe) {
+                //  UTF-16, little-endian
+                defaultCharset = charset = UTF_16LE;
+                offset += 2;
+            }
+        }
+        int length = data.length - offset;
+
+        // Guess encoding by searching for an encoding= entry in the first line.
+        // The prologue, and the encoding names, will always be in ASCII - which means
+        // we don't need to worry about strange character encodings for the prologue characters.
+        // However, one wrinkle is that the whole file may be encoded in something like UTF-16
+        // where there are two bytes per character, so we can't just look for
+        //  ['e','n','c','o','d','i','n','g'] etc in the byte array since there could be
+        // multiple bytes for each character. However, since again the prologue is in ASCII,
+        // we can just drop the zeroes.
+        boolean seenOddZero = false;
+        boolean seenEvenZero = false;
+        int prologueStart = -1;
+        for (int lineEnd = offset; lineEnd < data.length; lineEnd++) {
+            if (data[lineEnd] == 0) {
+                if ((lineEnd - offset) % 1 == 0) {
+                    seenEvenZero = true;
+                } else {
+                    seenOddZero = true;
+                }
+            } else if (data[lineEnd] == '\n') {
+                break;
+            } else if (data[lineEnd] == '<') {
+                prologueStart = lineEnd;
+            } else if (data[lineEnd] == '>') {
+                // End of prologue. Quick check to see if this is a utf-8 file since that's
+                // common
+                for (int i = lineEnd - 4; i >= 0; i--) {
+                    if ((data[i] == 'u' || data[i] == 'U')
+                            && (data[i + 1] == 't' || data[i + 1] == 'T')
+                            && (data[i + 2] == 'f' || data[i + 2] == 'F')
+                            && (data[i + 3] == '-' || data[i + 3] == '_')
+                            && (data[i + 4] == '8')
+                            ) {
+                        charset = UTF_8;
+                        break;
+                    }
+                }
+
+                if (charset == null) {
+                    StringBuilder sb = new StringBuilder();
+                    for (int i = prologueStart; i <= lineEnd; i++) {
+                        if (data[i] != 0) {
+                            sb.append((char) data[i]);
+                        }
+                    }
+                    String prologue = sb.toString();
+                    int encodingIndex = prologue.indexOf("encoding"); //$NON-NLS-1$
+                    if (encodingIndex != -1) {
+                        Matcher matcher = ENCODING_PATTERN.matcher(prologue);
+                        if (matcher.find(encodingIndex)) {
+                            charset = matcher.group(1);
+                        }
+                    }
+                }
+
+                break;
+            }
+        }
+
+        // No prologue on the first line, and no byte order mark: Assume UTF-8/16
+        if (charset == null) {
+            charset = seenOddZero ? UTF_16 : seenEvenZero ? UTF_16LE : UTF_8;
+        }
+
+        String xml = null;
+        try {
+            xml = new String(data, offset, length, charset);
+        } catch (UnsupportedEncodingException e) {
+            try {
+                if (charset != defaultCharset) {
+                    xml = new String(data, offset, length, defaultCharset);
+                }
+            } catch (UnsupportedEncodingException u) {
+                // Just use the default encoding below
+            }
+        }
+        if (xml == null) {
+            xml = new String(data, offset, length);
+        }
+        return xml;
+    }
+
+    /**
+     * Returns the position for the given node. This is the start position. The
+     * end position can be obtained via {@link Position#getEnd()}.
+     *
+     * @param node the node to look up position for
+     * @return the position, or null if the node type is not supported for
+     *         position info
+     */
+    @Nullable
+    public Position getPosition(@NonNull Node node) {
+        // Look up the position information stored while parsing for the given node.
+        // Note however that we only store position information for elements (because
+        // there is no SAX callback for individual attributes).
+        // Therefore, this method special cases this:
+        //  -- First, it looks at the owner element and uses its position
+        //     information as a first approximation.
+        //  -- Second, it uses that, as well as the original XML text, to search
+        //     within the node range for an exact text match on the attribute name
+        //     and if found uses that as the exact node offsets instead.
+        if (node instanceof Attr) {
+            Attr attr = (Attr) node;
+            Position pos = (Position) attr.getOwnerElement().getUserData(POS_KEY);
+            if (pos != null) {
+                int startOffset = pos.getOffset();
+                int endOffset = pos.getEnd().getOffset();
+
+                // Find attribute in the text
+                String contents = (String) node.getOwnerDocument().getUserData(CONTENT_KEY);
+                if (contents == null) {
+                    return null;
+                }
+
+                // Locate the name=value attribute in the source text
+                // Fast string check first for the common occurrence
+                String name = attr.getName();
+                Pattern pattern = Pattern.compile(
+                        String.format("%1$s\\s*=\\s*[\"'].*[\"']", name)); //$NON-NLS-1$
+                Matcher matcher = pattern.matcher(contents);
+                if (matcher.find(startOffset) && matcher.start() <= endOffset) {
+                    int index = matcher.start();
+                    // Adjust the line and column to this new offset
+                    int line = pos.getLine();
+                    int column = pos.getColumn();
+                    for (int offset = pos.getOffset(); offset < index; offset++) {
+                        char t = contents.charAt(offset);
+                        if (t == '\n') {
+                            line++;
+                            column = 0;
+                        } else {
+                            column++;
+                        }
+                    }
+
+                    Position attributePosition = createPosition(line, column, index);
+                    // Also set end range for retrieval in getLocation
+                    attributePosition.setEnd(createPosition(line, column, matcher.end()));
+                    return attributePosition;
+                } else {
+                    // No regexp match either: just fall back to element position
+                    return pos;
+                }
+            }
+        } else if (node instanceof Text) {
+            // Position of parent element, if any
+            Position pos = null;
+            if (node.getPreviousSibling() != null) {
+                pos = (Position) node.getPreviousSibling().getUserData(POS_KEY);
+            }
+            if (pos == null) {
+                pos = (Position) node.getParentNode().getUserData(POS_KEY);
+            }
+            if (pos != null) {
+                // Attempt to point forward to the actual text node
+                int startOffset = pos.getOffset();
+                int endOffset = pos.getEnd().getOffset();
+                int line = pos.getLine();
+                int column = pos.getColumn();
+
+                // Find attribute in the text
+                String contents = (String) node.getOwnerDocument().getUserData(CONTENT_KEY);
+                if (contents == null || contents.length() < endOffset) {
+                    return null;
+                }
+
+                boolean inAttribute = false;
+                for (int offset = startOffset; offset <= endOffset; offset++) {
+                    char c = contents.charAt(offset);
+                    if (c == '>' && !inAttribute) {
+                        // Found the end of the element open tag: this is where the
+                        // text begins.
+
+                        // Skip >
+                        offset++;
+
+                        // Skip text whitespace prefix, if the text node contains non-whitespace
+                        // characters
+                        String text = node.getNodeValue();
+                        int textIndex = 0;
+                        int textLength = text.length();
+                        int newLine = line;
+                        int newColumn = column;
+                        for (; textIndex < text.length(); textIndex++) {
+                            char t = text.charAt(textIndex);
+                            if (t == '\n') {
+                                newLine++;
+                                newColumn = 0;
+                            } else {
+                                newColumn++;
+                            }
+                            if (!Character.isWhitespace(t)) {
+                                break;
+                            }
+                        }
+                        if (textIndex == textLength) {
+                            textIndex = 0; // Whitespace node
+                        } else {
+                            line = newLine;
+                            column = newColumn;
+                        }
+
+                        Position attributePosition = createPosition(line, column,
+                                offset);
+                        // Also set end range for retrieval in getLocation
+                        attributePosition.setEnd(createPosition(line, column,
+                                offset + textLength));
+                        return attributePosition;
+                    } else if (c == '"') {
+                        inAttribute = !inAttribute;
+                    } else if (c == '\n') {
+                        line++;
+                        column = -1; // pre-subtract column added below
+                    }
+                    column++;
+                }
+
+                return pos;
+            }
+        }
+
+        return (Position) node.getUserData(POS_KEY);
+    }
+
+    /**
+     * SAX parser handler which incrementally builds up a DOM document as we go
+     * along, and updates position information along the way. Position
+     * information is attached to the DOM nodes by setting user data with the
+     * {@link POS_KEY} key.
+     */
+    private final class DomBuilder extends DefaultHandler {
+        private final String mXml;
+        private final Document mDocument;
+        private Locator mLocator;
+        private int mCurrentLine = 0;
+        private int mCurrentOffset;
+        private int mCurrentColumn;
+        private final List<Element> mStack = new ArrayList<Element>();
+        private final StringBuilder mPendingText = new StringBuilder();
+
+        private DomBuilder(String xml) throws ParserConfigurationException {
+            mXml = xml;
+
+            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+            factory.setNamespaceAware(true);
+            factory.setValidating(false);
+            DocumentBuilder docBuilder = factory.newDocumentBuilder();
+            mDocument = docBuilder.newDocument();
+            mDocument.setUserData(CONTENT_KEY, xml, null);
+        }
+
+        /** Returns the document parsed by the handler */
+        Document getDocument() {
+            return mDocument;
+        }
+
+        @Override
+        public void setDocumentLocator(Locator locator) {
+            this.mLocator = locator;
+        }
+
+        @Override
+        public void startElement(String uri, String localName, String qName,
+                Attributes attributes) throws SAXException {
+            flushText();
+            Element element = mDocument.createElement(qName);
+            for (int i = 0; i < attributes.getLength(); i++) {
+                if (attributes.getURI(i) != null && attributes.getURI(i).length() > 0) {
+                    Attr attr = mDocument.createAttributeNS(attributes.getURI(i),
+                            attributes.getQName(i));
+                    attr.setValue(attributes.getValue(i));
+                    element.setAttributeNodeNS(attr);
+                    assert attr.getOwnerElement() == element;
+                } else {
+                    Attr attr = mDocument.createAttribute(attributes.getQName(i));
+                    attr.setValue(attributes.getValue(i));
+                    element.setAttributeNode(attr);
+                    assert attr.getOwnerElement() == element;
+                }
+            }
+
+            Position pos = getCurrentPosition();
+
+            // The starting position reported to us by SAX is really the END of the
+            // open tag in an element, when all the attributes have been processed.
+            // We have to scan backwards to find the real beginning. We'll do that
+            // by scanning backwards.
+            // -1: Make sure that when we have <foo></foo> we don't consider </foo>
+            // the beginning since pos.offset will typically point to the first character
+            // AFTER the element open tag, which could be a closing tag or a child open
+            // tag
+
+            for (int offset = pos.getOffset() - 1; offset >= 0; offset--) {
+                char c = mXml.charAt(offset);
+                // < cannot appear in attribute values or anywhere else within
+                // an element open tag, so we know the first occurrence is the real
+                // element start
+                if (c == '<') {
+                    // Adjust line position
+                    int line = pos.getLine();
+                    for (int i = offset, n = pos.getOffset(); i < n; i++) {
+                        if (mXml.charAt(i) == '\n') {
+                            line--;
+                        }
+                    }
+
+                    // Compute new column position
+                    int column = 0;
+                    for (int i = offset; i >= 0; i--, column++) {
+                        if (mXml.charAt(i) == '\n') {
+                            break;
+                        }
+                    }
+
+                    pos = createPosition(line, column, offset);
+                    break;
+                }
+            }
+
+            element.setUserData(POS_KEY, pos, null);
+            mStack.add(element);
+        }
+
+        @Override
+        public void endElement(String uri, String localName, String qName) {
+            flushText();
+            Element element = mStack.remove(mStack.size() - 1);
+
+            Position pos = (Position) element.getUserData(POS_KEY);
+            assert pos != null;
+            pos.setEnd(getCurrentPosition());
+
+            if (mStack.isEmpty()) {
+                mDocument.appendChild(element);
+            } else {
+                Element parent = mStack.get(mStack.size() - 1);
+                parent.appendChild(element);
+            }
+        }
+
+        /**
+         * Returns a position holder for the current position. The most
+         * important part of this function is to incrementally compute the
+         * offset as well, by counting forwards until it reaches the new line
+         * number and column position of the XML parser, counting characters as
+         * it goes along.
+         */
+        private Position getCurrentPosition() {
+            int line = mLocator.getLineNumber() - 1;
+            int column = mLocator.getColumnNumber() - 1;
+
+            // Compute offset incrementally now that we have the new line and column
+            // numbers
+            while (mCurrentLine < line) {
+                char c = mXml.charAt(mCurrentOffset);
+                if (c == '\r' && mCurrentOffset < mXml.length() - 1) {
+                    if (mXml.charAt(mCurrentOffset + 1) != '\n') {
+                        mCurrentLine++;
+                        mCurrentColumn = 0;
+                    }
+                } else if (c == '\n') {
+                    mCurrentLine++;
+                    mCurrentColumn = 0;
+                } else {
+                    mCurrentColumn++;
+                }
+                mCurrentOffset++;
+            }
+
+            mCurrentOffset += column - mCurrentColumn;
+            mCurrentColumn = column;
+
+            return createPosition(mCurrentLine, mCurrentColumn, mCurrentOffset);
+        }
+
+        @Override
+        public void characters(char c[], int start, int length) throws SAXException {
+            mPendingText.append(c, start, length);
+        }
+
+        private void flushText() {
+            if (mPendingText.length() > 0 && !mStack.isEmpty()) {
+                Element element = mStack.get(mStack.size() - 1);
+                Node textNode = mDocument.createTextNode(mPendingText.toString());
+                element.appendChild(textNode);
+                mPendingText.setLength(0);
+            }
+        }
+    }
+
+    /**
+     * Creates a position while constructing the DOM document. This method
+     * allows a subclass to create a custom implementation of the position
+     * class.
+     *
+     * @param line the line number for the position
+     * @param column the column number for the position
+     * @param offset the character offset
+     * @return a new position
+     */
+    @NonNull
+    protected Position createPosition(int line, int column, int offset) {
+        return new DefaultPosition(line, column, offset);
+    }
+
+    protected interface Position {
+        /**
+         * Linked position: for a begin position this will point to the
+         * corresponding end position. For an end position this will be null.
+         *
+         * @return the end position, or null
+         */
+        @Nullable
+        public Position getEnd();
+
+        /**
+         * Linked position: for a begin position this will point to the
+         * corresponding end position. For an end position this will be null.
+         *
+         * @param end the end position
+         */
+        public void setEnd(@NonNull Position end);
+
+        /** @return the line number, 0-based */
+        public int getLine();
+
+        /** @return the offset number, 0-based */
+        public int getOffset();
+
+        /** @return the column number, 0-based, and -1 if the column number if not known */
+        public int getColumn();
+    }
+
+    protected static class DefaultPosition implements Position {
+        /** The line number (0-based where the first line is line 0) */
+        private final int mLine;
+        private final int mColumn;
+        private final int mOffset;
+        private Position mEnd;
+
+        /**
+         * Creates a new {@link Position}
+         *
+         * @param line the 0-based line number, or -1 if unknown
+         * @param column the 0-based column number, or -1 if unknown
+         * @param offset the offset, or -1 if unknown
+         */
+        public DefaultPosition(int line, int column, int offset) {
+            this.mLine = line;
+            this.mColumn = column;
+            this.mOffset = offset;
+        }
+
+        @Override
+        public int getLine() {
+            return mLine;
+        }
+
+        @Override
+        public int getOffset() {
+            return mOffset;
+        }
+
+        @Override
+        public int getColumn() {
+            return mColumn;
+        }
+
+        @Override
+        public Position getEnd() {
+            return mEnd;
+        }
+
+        @Override
+        public void setEnd(Position end) {
+            mEnd = end;
+        }
+    }
+}