Simple argument parser that works in Jython

argparser.py

import sys
import re

def parse_args(args_def):
    """
    Simple argument parser. args_def is a dict in the following format.
    The multi property can be used to parse comma separated values.
    
    args_def = {
        "user"        : { "required": False, "default": "weblogic" }, 
        "password"    : { "required": True },
        "command"     : { "required": True, "validation": r"start|shutdown" },
        "server_names": { "required": True, "multi": True },
        "rolling"     : { "required": False, "default": False, "type": bool } 
    }
    """
    i = 1; args = {}; add_next = False; prev_key = None
    
    # parse arguments
    while i < len(sys.argv):
        key = sys.argv[i]
        arg_def = args_def.get(key[1:], None)
        
        if key[0] == "-" and arg_def:
            value = sys.argv[i + 1]
            if arg_def.get("type", str) == bool:
                if value not in ["True", "False", "true", "false"]:
                    raise Exception("Argument " + key + " has invalid boolean value: " + value)
                value = value in ["True", "true"] 
            
            add_next = arg_def.get("multi", False)
            if not add_next:
                args[key[1:]] = value
            else:
                # "multi" arguments' value must be a list
                args[key[1:]] = [value]
            prev_key = key[1:]
            i += 2
        else:
            if add_next:
                args[prev_key].append(sys.argv[i])
                i += 1
            else:
                raise Exception("Invalid command line argument: " + \
                    key + ". The valid arguments are " + str(args_def))
    
    # check all required args are present, set the defaults
    for key in args_def.keys():
        value = args_def[key]
        if not args.get(key):
            if value.get("required", False):
                raise Exception("The command line argument " + key + " is required!")
            if value.get("default", None):
                args[key] = value["default"]
        
        if value.get("validation") and not(re.match(value.get("validation"), args[key])):
            raise Exception("The command line argument " + key + " has an invalid value " + args[key] + ". " + \
                "The validation pattern is: " + value.get("validation"))
    
    return args