Parse positional and optional arguments from argstr. (var length 'pos & optional arguments' based on 'shlex')

shlex_argparse.py

import re
import shlex

def _until_dh(splited):
    """ Slice until double hyphen """
    i = 0
    for i, s in enumerate(splited):
        if s == "--":
            return splited[:i], i+1
        elif s.startswith("--"):
            return splited[:i], i
    return splited[:], i+1

def shlex_argparse(argstr):
    """ Get positional arguments and optional arguments from argstr.
    
    Example::
    
       parse p1 p2 'p3 three' --o1=one '--o2=two' --o3='3 three' p'4 four' --o4 four Four
       
       as args = ['p1', 'p2', 'p3 three', 'p4 four']
       and kwargs = {'o1':'one', 'o2':'two', 'o3':'3 three', 'o4':['four', 'Four']}
    """

    args = shlex.split(argstr)
    classify = re.compile(r"^(?:(?:--(\w+)=([\s\S]*))|(?:--(\w+))|(\S[\s\S]*))$")

    positional_args = []
    optional_args = {}
    i = 0
    while i < len(args):
        match = classify.match(args[i])
        if match is None:
            raise re.error("Not matched", pattern=classify)
        key, value, var_key, pos = match.groups()
        if pos:
            if pos != "--":
                positional_args.append(pos)
        elif key:
            optional_args[key] = value
        elif var_key:
            optional_args[var_key], j = _until_dh(args[i+1:])
            i += j
        i += 1

    return positional_args, optional_args