Function _MakeParseFn

fire/core.py:699–754

Creates a parse function for fn. Args: fn: The function or class to create the parse function for. metadata: Additional metadata about the component the parse function is for. Returns: A parse function for fn. The parse function accepts a list of arguments and returns (varargs,

(fn, metadata)

def _MakeParseFn(fn, metadata):
  """Creates a parse function for fn.

  Args:
    fn: The function or class to create the parse function for.
    metadata: Additional metadata about the component the parse function is for.
  Returns:
    A parse function for fn. The parse function accepts a list of arguments
    and returns (varargs, kwargs), remaining_args. The original function fn
    can then be called with fn(*varargs, **kwargs). The remaining_args are
    the leftover args from the arguments to the parse function.
  """
  fn_spec = inspectutils.GetFullArgSpec(fn)

  # Note: num_required_args is the number of positional arguments without
  # default values. All of these arguments are required.
  num_required_args = len(fn_spec.args) - len(fn_spec.defaults)
  required_kwonly = set(fn_spec.kwonlyargs) - set(fn_spec.kwonlydefaults)

  def _ParseFn(args):
    """Parses the list of `args` into (varargs, kwargs), remaining_args."""
    kwargs, remaining_kwargs, remaining_args = _ParseKeywordArgs(args, fn_spec)

    # Note: _ParseArgs modifies kwargs.
    parsed_args, kwargs, remaining_args, capacity = _ParseArgs(
        fn_spec.args, fn_spec.defaults, num_required_args, kwargs,
        remaining_args, metadata)

    if fn_spec.varargs or fn_spec.varkw:
      # If we're allowed *varargs or **kwargs, there's always capacity.
      capacity = True

    extra_kw = set(kwargs) - set(fn_spec.kwonlyargs)
    if fn_spec.varkw is None and extra_kw:
      raise FireError('Unexpected kwargs present:', extra_kw)

    missing_kwonly = set(required_kwonly) - set(kwargs)
    if missing_kwonly:
      raise FireError('Missing required flags:', missing_kwonly)

    # If we accept *varargs, then use all remaining arguments for *varargs.
    if fn_spec.varargs is not None:
      varargs, remaining_args = remaining_args, []
    else:
      varargs = []

    for index, value in enumerate(varargs):
      varargs[index] = _ParseValue(value, None, None, metadata)

    varargs = parsed_args + varargs
    remaining_args += remaining_kwargs

    consumed_args = args[:len(args) - len(remaining_args)]
    return (varargs, kwargs), consumed_args, remaining_args, capacity

  return _ParseFn