Python Regex

**Quirky Quantum** · January 24th, 2011, 05:22 PM

So, I'm working on a program, and am trying to use regular expressions to check some input to a commandline type system.

I've gotten pretty close to nailing it, but something is wrong.

Code:

^([a-zA-Z]{1,}) ?(?:(?:-((?:[a-zA-Z0-9]){1,}) ?){,})?$

For anyone who actually does look through that, here's my problem:

When I enter something, say "commandname", it works, and returns commandname as a group (due to being enclosed in parentheses).

When I try to enter something with arguments ( commandname -arg -arg -arg ...), it returns only the last argument.

Here's the function in question:

Code:

    def ProcessCommand(command):
        temp = '^([a-zA-Z]{1,}) ?(?:(?:-((?:[a-zA-Z0-9]){1,}) ?){,})?$'
        m = re.match(temp,com)
        if m == None:
            print('Not a recognized command.')
            return
        command = m.groups()
        name = command[0]
        # args should be in the rest of the "command" tuple

Thanks for the help!

**TheCanadian** · January 24th, 2011, 05:35 PM

I don't know python but I do know regex so I could maybe help you if you help me understand what exactly your trying to do.

**Quirky Quantum** · January 24th, 2011, 05:49 PM

Originally Posted by TheCanadian

I don't know python but I do know regex so I could maybe help you if you help me understand what exactly your trying to do.

Alright, so, here we go

I ask for input, call it the var "command".
I then am trying to do two things,

1st:
Check to make sure "command" follows a pattern:

Code:

commandname -arg1 -arg2 (as many args as you'd like, named whatever)

2nd:
Python has a function groups(), which returns a set of the data grouped in the Regular Expression. Out of this I want to get the command name, and a subset containing the supplied arguments (if any).

Tell me if you need more!
Thanks for the speedy response.

**TheCanadian** · January 24th, 2011, 06:02 PM

So "commandname -arg1 -arg2" is your string and all arguments are preceded by a hyphen and commandname can be any alpha-numeric word?

**Quirky Quantum** · January 24th, 2011, 06:19 PM

Originally Posted by TheCanadian

So "commandname -arg1 -arg2" is your string and all arguments are preceded by a hyphen and commandname can be any alpha-numeric word?

Yup, looks right. The spaces between arguments are also optional.

**TheCanadian** · January 24th, 2011, 07:07 PM

I don't know if that's possible just due to how regular expressions work but you could find the arguments in a separate regex. Something like this should work: /-\w+/g

Also, I think this regex does the same thing as yours but it's a little bit simpler:
/^([a-z]+) *(-\w+ *)+$/i

**Quirky Quantum** · January 24th, 2011, 09:28 PM

Originally Posted by TheCanadian

I don't know if that's possible just due to how regular expressions work but you could find the arguments in a separate regex. Something like this should work: /-\w+/g

Also, I think this regex does the same thing as yours but it's a little bit simpler:
/^([a-z]+) *(-\w+ *)+$/i

Alright, I was wondering if two regular expressions was the way to go.

Thanks for your help!