simplify screws up literal special characters

[iamthad]

simplify turns a literal period into an unescaped period.

>>> import exrex
>>> exrex.simplify(r'\.')
'.'
>>> exrex.simplify('[.]')
'.'

EDIT: This affects any single special character.

[erzvtvhfm-fhjnyfxv]

Issue still exists 😞 Used version is exrex-0.10.5.

$ exrex -s '\..'
..

[vwyu]

It seems that the issue is due to the following lines of sre_to_string method in exrex.py:

elif i[0] == sre_parse.LITERAL:
    ret += unichr(i[1])

The issue appears to be resolved, if we change these lines as follows:

elif i[0] == sre_parse.LITERAL:
    u = unichr(i[1])
    ret += u if u not in sre_parse.SPECIAL_CHARS else '\\{0}'.format(u)

After the change, I get:

>>> import exrex
>>> exrex.simplify(r'\.')
'\\.'
>>> exrex.simplify('[.]')
'\\.'
>>> exrex.simplify('.')
'.'
>>> exrex.simplify(r'\$')
'\\$'
>>> exrex.simplify('[$]')
'\\$'
>>> exrex.simplify('[a]')
'a'

I belive that exrex.simplify('[.]') returning '\\.' and exrex.simplify('[$]') returning '\\$' are correct behaviors, since both cases involve special characters in ranges [].

[iamthad]

@vwyu That does indeed appear to fix the issue. Do you want to make a pull request?

[scopatz]

I am also seeing this on 0.10.5 with [*]