How to tell if one regular expression matches a subset of another regular expression?

Question

I\'m just wondering if it\'s possible to use one regular expression to match another, that is some sort of:

[\'a-z\'].match([\'b-x\'])
True

[\'m-n\'].match(         


        

Answer 1

pip3 install https://github.com/leafstorm/lexington/archive/master.zip
python3
>>> from lexington.regex import Regex as R
>>> from lexington.regex import Null
>>> from functools import reduce
>>> from string import ascii_lowercase, digits
>>> a_z = reduce(lambda a, b: a | R(b), ascii_lowercase, Null)
>>> b_x = reduce(lambda a, b: a | R(b), ascii_lowercase[1:-2], Null)
>>> a_z | b_x == a_z
True
>>> m_n = R("m") | R("n")
>>> zero_nine = reduce(lambda a, b: a | R(b), digits, Null)
>>> m_n | zero_nine == m_n
False

Also tested successfully with Python 2. See also how to do it with a different library.

Alternatively, pip3 install https://github.com/ferno/greenery/archive/master.zip and:

from greenery.lego import parse as p
a_z = p("[a-z]")
b_x = p("[b-x]")
assert a_z | b_x == a_z
m_n = p("m|n")
zero_nine = p("[0-9]")
assert not m_n | zero_nine == m_n