[issue20678] re does not allow back references in {} matching operator

Changes by Serhiy Storchaka : -- resolution: -> not a bug stage: -> resolved status: open -> closed ___ Python tracker ___ ___ Pytho

[issue20678] re does not allow back references in {} matching operator

Matthew Barnett added the comment: Yes. If it's not a valid repeat, then it's treated as a literal. Perl does the same. By the way, "\1" isn't a group reference; it's the same as "\x01". You should be either doubling the backslashes ("\\1") or using a raw string literal (r"\1"). --

[issue20678] re does not allow back references in {} matching operator

steven Michalske added the comment: The RE compiler will not error out, with a back reference in there... It treats the {\1} as a literal {\1} in the string. In [180]: re.search("(\d) fo.{\1}", '3 foo{\1}').group(0) Out[180]: '3 foo{\x01}' -- ___ Pyt

[issue20678] re does not allow back references in {} matching operator

Matthew Barnett added the comment: I don't know of any regex implementation that lets you do that. -- type: behavior -> enhancement ___ Python tracker ___ ___

[issue20678] re does not allow back references in {} matching operator

New submission from steven Michalske: When writing a regular expression to match the following text. d = """num interesting lines: 3 1 2 3 foo""" # I only want to match the interesting lines. m = re.match(".+?: (\d+)\n((?:.+\n){\1})", d) print(m) # prints: None # Expected a match object. print