def __init__(self, data, fieldnames=None):
first_value, iterator = iterpeek(data)
if isinstance(first_value, dict):
if not fieldnames:
fieldnames = list(first_value.keys())
super(DataSource, self).__init__(iterator, fieldnames)
else:
if fieldnames:
iterator = itertools.chain([fieldnames], iterator)
super(DataSource, self).__init__(iterator)
def _require_callable(data, function):
if data is NOVALUE:
return Invalid(None) # <- EXIT!
def wrapped(element):
try:
if isinstance(element, BaseElement):
returned_value = function(element)
else:
returned_value = function(*element)
except Exception:
returned_value = False # Raised errors count as False.
if returned_value == True:
return None # <- EXIT!
if returned_value == False:
return Invalid(element) # <- EXIT!
if isinstance(returned_value, BaseDifference):
return returned_value # <- EXIT!
callable_name = function.__name__
message = \
'{0!r} returned {1!r}, should return True, False or a difference instance'
raise TypeError(message.format(callable_name, returned_value))
if isinstance(data, BaseElement):
return wrapped(data) # <- EXIT!
results = (wrapped(elem) for elem in data)
diffs = (diff for diff in results if diff)
first_element, diffs = iterpeek(diffs)
if first_element: # If not empty, return diffs.
return diffs
return None