Probe context diff for #15

cdiff.py

@@ -429,6 +429,10 @@ class UnifiedDiff(Diff):
         return re.match('^Binary files .* differ$', line.rstrip())
 
 
+class ContextDiff(Diff):
+    pass
+
+
 class PatchStream(object):
 
     def __init__(self, diff_hdl):
@@ -474,6 +478,14 @@ class DiffParser(object):
                   self._stream.read_stream_header(100)]
         size = len(header)
 
+        if size >= 4 and (header[0].startswith('*** ') and
+                          header[1].startswith('--- ') and
+                          header[2] == '***************\n' and
+                          header[3].startswith('*** ') and
+                          header[3].endswith(' ****\n')):
+            self._type = 'context'
+            return
+
         for n in range(size):
             if header[n].startswith('--- ') and (n < size - 1) and \
                     header[n+1].startswith('+++ '):

tests/test_cdiff.py

@@ -423,7 +423,7 @@ class UnifiedDiffTest(unittest.TestCase):
 
 class DiffParserTest(unittest.TestCase):
 
-    def test_type_detect(self):
+    def test_type_detect_unified(self):
         patch = """\
 spam
 --- a
@@ -435,6 +435,21 @@ spam
         parser = cdiff.DiffParser(stream)
         self.assertEqual(parser._type, 'unified')
 
+    def test_type_detect_context(self):
+        patch = """\
+*** /path/to/original timestamp
+--- /path/to/new timestamp
+***************
+*** 1,1 ****
+--- 1,2 ----
++ This is an important
+  This part of the
+"""
+        items = patch.splitlines(True)
+        stream = cdiff.PatchStream(Sequential(items))
+        parser = cdiff.DiffParser(stream)
+        self.assertEqual(parser._type, 'context')
+
     def test_type_detect_neg(self):
         patch = """\
 spam