diff --git a/pylons_app/lib/differ.py b/pylons_app/lib/differ.py
new file mode 100644
--- /dev/null
+++ b/pylons_app/lib/differ.py
@@ -0,0 +1,209 @@
+# -*- coding: utf-8 -*-
+# original copyright: 2007-2008 by Armin Ronacher
+# licensed under the BSD license.
+
+import re, difflib
+
+def render_udiff(udiff, differ='udiff'):
+    """Renders the udiff into multiple chunks of nice looking tables.
+    The return value is a list of those tables.
+    """
+    return DiffProcessor(udiff, differ).prepare()
+
+class DiffProcessor(object):
+    """Give it a unified diff and it returns a list of the files that were
+    mentioned in the diff together with a dict of meta information that
+    can be used to render it in a HTML template.
+    """
+    _chunk_re = re.compile(r'@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@(.*)')
+
+    def __init__(self, udiff, differ):
+        """
+        :param udiff:   a text in udiff format
+        """
+        if isinstance(udiff, basestring):
+            udiff = udiff.splitlines(1)
+        
+        self.lines = map(self.escaper, udiff)
+        
+        # Select a differ.
+        if differ == 'difflib':
+            self.differ = self._highlight_line_difflib
+        else:
+            self.differ = self._highlight_line_udiff
+            
+
+    def escaper(self, string):
+        return string.replace('<', '&lt;').replace('>', '&gt;')
+
+    def _extract_rev(self, line1, line2):
+        """Extract the filename and revision hint from a line."""
+        try:
+            if line1.startswith('--- ') and line2.startswith('+++ '):
+                filename, old_rev = line1[4:].split(None, 1)
+                new_rev = line2[4:].split(None, 1)[1]
+                return filename, 'old', 'new'
+        except (ValueError, IndexError):
+            pass
+        return None, None, None
+
+    def _highlight_line_difflib(self, line, next):
+        """Highlight inline changes in both lines."""
+        
+        if line['action'] == 'del':
+            old, new = line, next
+        else:
+            old, new = next, line
+        
+        oldwords = re.split(r'(\W)', old['line'])
+        newwords = re.split(r'(\W)', new['line'])
+        
+        sequence = difflib.SequenceMatcher(None, oldwords, newwords)
+        
+        oldfragments, newfragments = [], []
+        for tag, i1, i2, j1, j2 in sequence.get_opcodes():
+            oldfrag = ''.join(oldwords[i1:i2])
+            newfrag = ''.join(newwords[j1:j2])
+            if tag != 'equal':
+                if oldfrag:
+                    oldfrag = '<del>%s</del>' % oldfrag
+                if newfrag:
+                    newfrag = '<ins>%s</ins>' % newfrag
+            oldfragments.append(oldfrag)
+            newfragments.append(newfrag)
+        
+        old['line'] = "".join(oldfragments)
+        new['line'] = "".join(newfragments)
+
+    def _highlight_line_udiff(self, line, next):
+        """Highlight inline changes in both lines."""
+        start = 0
+        limit = min(len(line['line']), len(next['line']))
+        while start < limit and line['line'][start] == next['line'][start]:
+            start += 1
+        end = -1
+        limit -= start
+        while - end <= limit and line['line'][end] == next['line'][end]:
+            end -= 1
+        end += 1
+        if start or end:
+            def do(l):
+                last = end + len(l['line'])
+                if l['action'] == 'add':
+                    tag = 'ins'
+                else:
+                    tag = 'del'
+                l['line'] = '%s<%s>%s</%s>%s' % (
+                    l['line'][:start],
+                    tag,
+                    l['line'][start:last],
+                    tag,
+                    l['line'][last:]
+                )
+            do(line)
+            do(next)
+
+    def _parse_udiff(self):
+        """Parse the diff an return data for the template."""
+        lineiter = iter(self.lines)
+        files = []
+        try:
+            line = lineiter.next()
+            while 1:
+                # continue until we found the old file
+                if not line.startswith('--- '):
+                    line = lineiter.next()
+                    continue
+
+                chunks = []
+                filename, old_rev, new_rev = \
+                    self._extract_rev(line, lineiter.next())
+                files.append({
+                    'filename':         filename,
+                    'old_revision':     old_rev,
+                    'new_revision':     new_rev,
+                    'chunks':           chunks
+                })
+
+                line = lineiter.next()
+                while line:
+                    match = self._chunk_re.match(line)
+                    if not match:
+                        break
+
+                    lines = []
+                    chunks.append(lines)
+
+                    old_line, old_end, new_line, new_end = \
+                        [int(x or 1) for x in match.groups()[:-1]]
+                    old_line -= 1
+                    new_line -= 1
+                    context = match.groups()[-1]
+                    old_end += old_line
+                    new_end += new_line
+
+                    if context:
+                        lines.append({
+                            'old_lineno': None,
+                            'new_lineno': None,
+                            'action': 'context',
+                            'line': line,
+                        })
+
+                    line = lineiter.next()
+
+                    while old_line < old_end or new_line < new_end:
+                        if line:
+                            command, line = line[0], line[1:]
+                        else:
+                            command = ' '
+                        affects_old = affects_new = False
+
+                        # ignore those if we don't expect them
+                        if command in '#@':
+                            continue
+                        elif command == '+':
+                            affects_new = True
+                            action = 'add'
+                        elif command == '-':
+                            affects_old = True
+                            action = 'del'
+                        else:
+                            affects_old = affects_new = True
+                            action = 'unmod'
+
+                        old_line += affects_old
+                        new_line += affects_new
+                        lines.append({
+                            'old_lineno':   affects_old and old_line or '',
+                            'new_lineno':   affects_new and new_line or '',
+                            'action':       action,
+                            'line':         line
+                        })
+                        line = lineiter.next()
+
+        except StopIteration:
+            pass
+
+        # highlight inline changes
+        for file in files:
+            for chunk in chunks:
+                lineiter = iter(chunk)
+                first = True
+                try:
+                    while 1:
+                        line = lineiter.next()
+                        if line['action'] != 'unmod':
+                            nextline = lineiter.next()
+                            if nextline['action'] == 'unmod' or \
+                               nextline['action'] == line['action']:
+                                continue
+                            self.differ(line, nextline)
+                except StopIteration:
+                    pass
+
+        return files
+
+    def prepare(self):
+        """Prepare the passed udiff for HTML rendering."""
+        return self._parse_udiff()