What is the proper regular expression to match all utf-8/unicode lowercase letter forms

Question

I would like to match all lowercase letter forms in the Latin block. The trivial '[a-z]' only matches characters between U+0061 and U+007A, and not all the other lowercase forms.

I would like to match all lowercase letters, most importantly, all the accented lowercase letters in the Latin block used in EFIGS languages.

[a-zà-ý] is a start, but there are still tons of other lowercase characters (see http://www.unicode.org/charts/PDF/U0000.pdf). Is there a recommended way of doing this?

FYI I'm using Python, but I suspect that this problem is cross-language.

Python's builtin "islower()" method seems to do the right checking:

lower = '' for c in xrange(0,2**16):    if unichr(c).islower():      lower += unichr(c)  print lower  

Answer 1

Python does not currently support Unicode properties in regular expressions. See this answer for a link to the Ponyguruma library which does support them.

Using such a library, you could use \p{Ll} to match any lowercase letter in a Unicode string.

Every character in the Unicode standard is in exactly one category. \p{Ll} is the category of lowercase letters, while \p{L} comprises all the characters in one of the "Letter" categories (Letter, uppercase; Letter, lowercase; Letter, titlecase; Letter, modifier; and Letter, other). For more information see the Character Properties chapter of the Unicode Standard. Or see this page for a good explanation on use of Unicode in regular expressions.

Answer 2

Looks as though this recipe posted back in the old 2005

import sys, re  uppers = [u'[']  for i in xrange(sys.maxunicode):    c = unichr(i)    if c.isupper(): uppers.append(c)  uppers.append(u']')  uppers = u"".join(uppers)  uppers_re = re.compile(uppers)   print uppers_re.match('A') 

is still relevant.