Question

I have a unicode string

 u"\uC3A9\xe9" 

, which I want to convert in PCRE supported regular expression

"\x{c3a9}\x{e9}"

in python.

Is there any module which already does that?

Answer 1

I’m not aware of any modules to do this, but here is one potential solution:

import re

def pcre_escape_repl(match):
    char = match.group(0)
    if ord(char) in range(32, 127):
        # if this is a printable ascii character, use re.escape instead of a \x escape
        return re.escape(char)
    # replace non-ascii (or non-printable) characters with a \x escape
    return r'\x{' + hex(ord(char))[2:] + '}'

def pcre_escape(s):
    regex = re.compile('.', re.DOTALL)
    return regex.sub(pcre_escape_repl, s)

Examples:

>>> print pcre_escape(u"\uC3A9\xe9")
\x{c3a9}\x{e9}
>>> print pcre_escape("[foo]{bar}")
\[foo\]\{bar\}