Sorry if this post is a bit confusing to read this is my first post on this site and this is a hard question to ask, I have tried my best. I have also tried googling and i can not find anything.
I am trying to make my own command line like application in python and i would like to know how to split a string if a "\\" is not in front of a space and to delete the backslash.
This is what i mean.
>>> c = "play song I\ Want\ To\ Break\ Free"
>>> print c.split(" ")
['play', 'song', 'I\\', 'Want\\', 'To\\', 'Break\\', 'Free']
When I split c
with a space it keeps the backslash however it removes the space. This is how I want it to be like:
>>> c = "play song I\ Want\ To\ Break\ Free"
>>> print c.split(" ")
['play', 'song', 'I ', 'Want ', 'To ', 'Break ', 'Free']
If someone can help me that would be great!
Also if it needs Regular expressions could you please explain it more because I have never used them before.
Edit : Now this has been solved i forgot to ask is there a way on how to detect if the backslash has been escaped or not too?
It looks like you're writing a commandline parser. If that's the case, may I recommend shlex.split
? It properly splits a command string according to shell lexing rules, and handles escapes properly. Example:
>>> import shlex
>>> shlex.split('play song I\ Want\ To\ Break\ Free')
['play', 'song', 'I Want To Break Free']
Just split on the space, then replace any string ending with a backslash with with one ending in a space instead:
[s[:-1] + ' ' if s.endswith('\\') else s for s in c.split(' ')]
This is a list comprehension; c
is split on spaces, and each resulting string is examined for a trailing \\
backslash at the end; if so, the last character is removed and a space is added.
One slight disadvantage: if the original string ends with a backslash (no space), that last backslash is also replaced by a space.
Demo:
>>> c = r"play song I\ Want\ To\ Break\ Free"
>>> [s[:-1] + ' ' if s.endswith('\\') else s for s in c.split(' ')]
['play', 'song', 'I ', 'Want ', 'To ', 'Break ', 'Free']
To handle escaped backslashes, you'd count the number of backslashes. An even number means the backslash is escaped:
[s[:-1] + ' ' if s.endswith('\\') and (len(s) - len(s.rstrip('\\'))) % 2 == 1 else s
for s in c.split(' ')]
Demo:
>>> c = r"play song I\ Want\ To\ Break\\ Free"
>>> [s[:-1] + ' ' if s.endswith('\\') and (len(s) - len(s.rstrip('\\'))) % 2 == 1 else s
... for s in c.split(' ')]
['play', 'song', 'I ', 'Want ', 'To ', 'Break\\\\', 'Free']
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