+def get_format_from_string(txt):
+ """
+ Returns the SourceFormat class that corresponds to the specified .changes
+ Format value. If the string does not match any class, UnknownFormatError
+ is raised.
+ """
+
+ for format in srcformats:
+ if format.re_format.match(txt):
+ return format
+
+ raise UnknownFormatError, "Unknown format %r" % txt
+
+def parse_format(txt):
+ """
+ Parse a .changes Format string into a tuple representation for easy
+ comparison.
+
+ >>> parse_format('1.0')
+ (1, 0)
+ >>> parse_format('8.4 (hardy)')
+ (8, 4, 'hardy')
+
+ If the format doesn't match these forms, raises UnknownFormatError.
+ """
+
+ format = re_verwithext.search(txt)
+
+ if format is None:
+ raise UnknownFormatError, txt
+
+ format = format.groups()
+
+ if format[1] is None:
+ format = int(float(format[0])), 0, format[2]
+ else:
+ format = int(format[0]), int(format[1]), format[2]
+
+ if format[2] is None:
+ format = format[:2]
+
+ return format
+