This is a patch for Trac 0.12.2 (Debian package 'trac').
Tested with Ubuntu Oneiric (11.10), package version 0.12.2-1
Also tested in Trac 0.12.3dev-r10806 on freetz.org (2011-10-30)

(C) 2011 Alexander Kriegisch (http://scrum-master.de)

Purpose: enable Trac to determine MIME types for syntax highlighting not just
simply by file extension, but more powerfully by regex file name matching.
This is done by introducing a new trac.ini parameter 'mime_map_patterns' in
section [mimeviewer].

How to apply:
  - Install Trac and connect it with a source code repository (e.g. SVN)
  - Apply patch with sudo or as root (attention: your Trac location might
    be somewhere else, so you might have to adjust the -p parameter and the
    working directory):
    sudo patch -p 0 < mime_map_patterns.trac.patch

How to test:
  - Add this to trac.ini, section [mimeviewer]:
    mime_map_patterns = text/x-python:.*_py_.*
  - Add a Python source file to your source code repository, but rename it to
    something containing '_py_' *without* the defauly '.py' extension, e.g.
    'test_py_file'
  - Restart Trac
  - Check in a web browser if your new repository file is correctly highlighted
    as a Python file

This patch was initially developed for the Freetz project (http://freetz.org)
in order to enable its Trac system to easier highlight Kconfig files by adding
this to trac.ini in connection with a Pygments patch (Kconfig lexer):

mime_map_patterns = text/x-kconfig:.*Config.in.*|external.in.*

The patch helps us get rid of manually setting svn:mime-type for each Kconfig
file in order to get syntax highlighting. We want highlighting to be
independent of the SCM system underneath (svn, git or whatever). Now it is. :)


--- /usr/share/pyshared/trac/mimeview/api.py	2011-01-31 23:05:46.000000000 +0100
+++ /usr/share/pyshared/trac/mimeview/api.py	2011-10-30 14:46:11.000000000 +0100
@@ -389,7 +389,7 @@
     | vim:.*?(?:syntax|filetype|ft)=(\w+)   # 4. look for VIM's syntax=<n>
     """, re.VERBOSE)
 
-def get_mimetype(filename, content=None, mime_map=MIME_MAP):
+def get_mimetype(filename, content=None, mime_map=MIME_MAP, mime_map_patterns={}):
     """Guess the most probable MIME type of a file with the given name.
 
     `filename` is either a filename (the lookup will then use the suffix)
@@ -421,6 +421,10 @@
                 if is_binary(content):
                     # 4) mimetype from the content, using`is_binary`
                     return 'application/octet-stream'
+        # 5) mimetype from filename pattern
+        for type, pattern in mime_map_patterns.iteritems():
+            if pattern.match(filename):
+                return type
         return mimetype
 
 def ct_mimetype(content_type):
@@ -625,6 +629,12 @@
         there's a colon (":") separated list of associated keywords
         or file extensions. (''since 0.10'')""")
 
+    mime_map_patterns = ListOption('mimeviewer', 'mime_map_patterns',
+        'text/plain:README|INSTALL|COPYING.*',
+        doc="""List of additional MIME types and regex(!) filename patterns.
+        Mappings are comma-separated, and for each MIME type,
+        there's a colon (":") separated regex filename pattern (''since 0.12.###'')""")
+
     treat_as_binary = ListOption('mimeviewer', 'treat_as_binary',
         'application/octet-stream,application/pdf,application/postscript,'
         'application/msword,application/rtf,',
@@ -633,6 +643,7 @@
 
     def __init__(self):
         self._mime_map = None
+        self._mime_map_patterns = None
 
     # Public API
 
@@ -904,7 +915,7 @@
         or `None` if detection failed.
         """
 
-        mimetype = get_mimetype(filename, content, self.mime_map)
+        mimetype = get_mimetype(filename, content, self.mime_map, self.mime_map_patterns)
         charset = None
         if mimetype:
             charset = self.get_charset(content, mimetype)
@@ -912,6 +923,16 @@
             mimetype += '; charset=' + charset
         return mimetype
 
+    @property
+    def mime_map_patterns(self):
+        if not self._mime_map_patterns:
+            self._mime_map_patterns = {}
+            for mapping in self.config['mimeviewer'].getlist('mime_map_patterns'):
+                if ':' in mapping:
+                    assocations = mapping.split(':')
+                    self._mime_map_patterns[assocations[0]] = re.compile((r'%s' % assocations[1]))
+        return self._mime_map_patterns
+
     def is_binary(self, mimetype=None, filename=None, content=None):
         """Check if a file must be considered as binary."""
         if not mimetype and filename: