Fixed #14 by tolerating dangling headers and short patch < 4 lines

cdiff.py

         """
         self._stream = stream
 
-        flag = 0
-        for line in self._stream.read_stream_header(100):
-            line = decode(line)
-            if line.startswith('--- '):
-                flag |= 1
-            elif line.startswith('+++ '):
-                flag |= 2
-            elif line.startswith('@@ ') or line.startswith('## '):
-                flag |= 4
-            if (flag & 7) == 7:
+        header = self._stream.read_stream_header(100)
+        size = len(header)
+        for n in range(size):
+            if decode(header[n]).startswith('--- ') and (n < size - 1) and \
+                    decode(header[n+1]).startswith('+++ '):
                 self._type = 'udiff'
                 break
         else:
-            raise RuntimeError('unknown diff type')
+            if size < 4:
+                # It's safe to consider as udiff if patch stream contains no
+                # more than 3 lines, happens with `git diff` on a file that
+                # only has perm bits changes
+                #
+                self._type = 'udiff'
+            else:
+                raise RuntimeError('unknown diff type')
 
     def get_diff_generator(self):
         """parse all diff lines, construct a list of Diff objects"""
                 #
                 headers.append(line)
 
-        if headers:
-            raise RuntimeError('dangling header(s):\n%s' % ''.join(headers))
-
         # Validate and yield the last patch set if it is not yielded yet
         if diff._old_path:
             assert diff._new_path is not None
-            assert len(diff._hunks) > 0
             if diff._hunks:
                 assert len(diff._hunks[-1]._hunk_meta) > 0
                 assert len(diff._hunks[-1]._hunk_list) > 0
             yield diff
 
+        if headers:
+            # Tolerate dangling headers, just yield a Diff object with only
+            # header lines
+            #
+            yield Diff(headers, '', '', [])
+
 
 class DiffMarkup(object):
 

tests/git-perm/in.diff

+diff --git a/CHANGES b/CHANGES
+old mode 100644
+new mode 100755

tests/git-perm/out.normal

+diff --git a/CHANGES b/CHANGES
+old mode 100644
+new mode 100755
+

tests/git-perm/out.side-by-side

+diff --git a/CHANGES b/CHANGES
+old mode 100644
+new mode 100755
+

tests/git-perm/out.w70

+diff --git a/CHANGES b/CHANGES
+old mode 100644
+new mode 100755
+

tests/svn-merge/in.diff

+Index: .
+==================================================================
+--- .   (revision 10)
++++ .   (working copy)
+
+Property changes on: .
+___________________________________________________________________
+Modified: svn:mergeinfo
+   Merged /repository/foo/branches/foo-bar:r4-9
+   Merged /repository/foo/trunk/foo:r2-3

tests/svn-merge/out.normal

+Index: .
+==================================================================
+--- .   (revision 10)
++++ .   (working copy)
+
+Property changes on: .
+___________________________________________________________________
+Modified: svn:mergeinfo
+   Merged /repository/foo/branches/foo-bar:r4-9
+   Merged /repository/foo/trunk/foo:r2-3
+

tests/svn-merge/out.side-by-side

+Index: .
+==================================================================
+--- .   (revision 10)
++++ .   (working copy)
+
+Property changes on: .
+___________________________________________________________________
+Modified: svn:mergeinfo
+   Merged /repository/foo/branches/foo-bar:r4-9
+   Merged /repository/foo/trunk/foo:r2-3
+

tests/svn-merge/out.w70

+Index: .
+==================================================================
+--- .   (revision 10)
++++ .   (working copy)
+
+Property changes on: .
+___________________________________________________________________
+Modified: svn:mergeinfo
+   Merged /repository/foo/branches/foo-bar:r4-9
+   Merged /repository/foo/trunk/foo:r2-3
+

tests/test_cdiff.py

         patch = r"""\
 spam
 --- a
-+++ b
 spam
++++ b
 """
         items = patch.splitlines(True)
         stream = cdiff.PatchStream(Sequential(items))
         items = patch.splitlines(True)
         stream = cdiff.PatchStream(Sequential(items))
         parser = cdiff.DiffParser(stream)
-        self.assertRaises(RuntimeError, list, parser.get_diff_generator())
+
+        out = list(parser.get_diff_generator())
+        self.assertEqual(len(out), 2)
+        self.assertEqual(len(out[1]._headers), 1)
+        self.assertEqual(out[1]._headers[0], 'spam\n')
+        self.assertEqual(out[1]._old_path, '')
+        self.assertEqual(out[1]._new_path, '')
+        self.assertEqual(len(out[1]._hunks), 0)
 
     def test_parse_missing_new_path(self):
         patch = r"""\
         items = patch.splitlines(True)
         stream = cdiff.PatchStream(Sequential(items))
         parser = cdiff.DiffParser(stream)
-        self.assertRaises(AssertionError, list, parser.get_diff_generator())
+
+        out = list(parser.get_diff_generator())
+        self.assertEqual(len(out), 2)
+        self.assertEqual(len(out[1]._headers), 0)
+        self.assertEqual(out[1]._old_path, '--- c\n')
+        self.assertEqual(out[1]._new_path, '+++ d\n')
+        self.assertEqual(len(out[1]._hunks), 0)
 
     def test_parse_missing_hunk_list(self):
         patch = r"""\