Get the patience diff module compiling and loading

setup/extensions.py

@@ -89,6 +89,10 @@ extensions = [
         ['calibre/utils/speedup.c'],
         ),
 
+    Extension('_patiencediff_c',
+        ['calibre/utils/diff/_patiencediff_c.c'],
+        ),
+
     Extension('icu',
         ['calibre/utils/icu.c'],
         libraries=icu_libs,

src/calibre/constants.py

@@ -141,6 +141,7 @@ class Plugins(collections.Mapping):
                 'qt_hack',
                 '_regex',
                 'hunspell',
+                '_patiencediff_c',
             ]
         if iswindows:
             plugins.extend(['winutil', 'wpd', 'winfonts'])

src/calibre/utils/diff/__init__.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+# vim:fileencoding=utf-8
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__ = 'GPL v3'
+__copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
+
+from calibre.constants import plugins
+
+def load_patience_module():
+    p, err = plugins['_patiencediff_c']
+    if err is not None:
+        raise ImportError('Failed to import the PatienceDiff C module with error: %s' % err)
+    return p
+
+def get_sequence_matcher():
+    return load_patience_module().PatienceSequenceMatcher_c
+

src/calibre/utils/diff/_patiencediff_c.c

@@ -23,11 +23,11 @@
 */
 
 
+#include <Python.h>
 #include <stdlib.h>
 #include <string.h>
-#include <Python.h>
 
-#include "python-compat.h"
+/* #include "python-compat.h" Commented out by Kovid as nothing defined in it is needed for this module */
 
 
 #if defined(__GNUC__)