arg_parser.py

def parse_args(input_args, accept_args):
    """
    >>> parse_args(["main.py"], {'--hoge': (1, 1)})
    Traceback (most recent call last):
    Exception: error: argument --hoge: expected 1 argument(s)
    >>> parse_args(["main.py", "a", "b", "--hoge", "w", "x", "y", "z"], {"--hoge": (2, 2)})
    ({'--hoge': ['w', 'x']}, ['main.py', 'a', 'b', 'y', 'z'])
    >>> parse_args(["main.py", "a", "b", "--hoge", "w", "x", "y", "z"], {"--hoge": (0, 0)})
    ({'--hoge': []}, ['main.py', 'a', 'b', 'w', 'x', 'y', 'z'])
    >>> parse_args(["main.py"], {'--hoge': (1, 1, ["piyo"])})
    ({'--hoge': ['piyo']}, ['main.py'])
    >>> parse_args(["main.py"], {"--hoge": (0, 0)})
    ({}, ['main.py'])
    >>> parse_args(["main.py", "--hoge"], {"--hoge": (0, 0)})
    ({'--hoge': []}, ['main.py'])
    >>> parse_args(["main.py", "--hoge"], {'--hoge': (0, 1)})
    ({'--hoge': []}, ['main.py'])
    >>> parse_args(["main.py", "--hoge", "fuga"], {'--hoge': (0, 1)})
    ({'--hoge': ['fuga']}, ['main.py'])
    >>> parse_args(["main.py", "--hoge"], {'--hoge': (1, 1)})
    Traceback (most recent call last):
    Exception: error: argument --hoge: expected 1 argument(s)
    >>> parse_args(["main.py", "--hoge=fuga"], {"--hoge": (0, 0)})
    Traceback (most recent call last):
    Exception: error: argument --hoge: ignored explicit argument fuga
    """
    input_args = input_args[:]
    options = {}
    right_values = []
    args = []
    while input_args:
        arg = input_args.pop()
        left, sep, right = arg.partition('=')
        if left in accept_args:
            min_length, max_length = accept_args[left][:2]
            if right:
                options[left] = [right]
            else:
                if max_length > 0:
                    options[left] = right_values[-max_length:]
                    options[left].reverse()
                    args.extend(right_values[:-max_length])
                else:
                    options[left] = []
                    args.extend(right_values)
                right_values = []
            if len(options[left]) < min_length:
                raise Exception("error: argument {0}: expected {1} argument(s)".format(left, max_length))
            elif len(options[left]) > max_length:
                raise Exception("error: argument {0}: ignored explicit argument {1}".format(left, options[left][0]))
            del accept_args[left]
        else:
            right_values.append(left)
    for key, value in accept_args.items():
        # When a key was not appeared in arguments
        min_length = value[0]
        if len(value) >= 3:
            # an argument has default value
            options[key] = value[2]
        elif min_length > 0:
            raise Exception("error: argument {0}: expected {1} argument(s)".format(key, min_length))
    args.extend(right_values)
    args.reverse()
    return options, args