Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.10/site-packages/django/utils/choices.py: 42%

1from collections.abc import Callable, Iterable, Iterator, Mapping 

2from itertools import islice, tee, zip_longest 

3 

4from django.utils.functional import Promise 

5 

6__all__ = [ 

7 "BaseChoiceIterator", 

8 "BlankChoiceIterator", 

9 "CallableChoiceIterator", 

10 "flatten_choices", 

11 "normalize_choices", 

12] 

13 

14 

15class BaseChoiceIterator: 

16 """Base class for lazy iterators for choices.""" 

17 

18 def __eq__(self, other): 

19 if isinstance(other, Iterable): 

20 return all(a == b for a, b in zip_longest(self, other, fillvalue=object())) 

21 return super().__eq__(other) 

22 

23 def __getitem__(self, index): 

24 if isinstance(index, slice) or index < 0: 

25 # Suboptimally consume whole iterator to handle slices and negative 

26 # indexes. 

27 return list(self)[index] 

28 try: 

29 return next(islice(self, index, index + 1)) 

30 except StopIteration: 

31 raise IndexError("index out of range") from None 

32 

33 def __iter__(self): 

34 raise NotImplementedError( 

35 "BaseChoiceIterator subclasses must implement __iter__()." 

36 ) 

37 

38 

39class BlankChoiceIterator(BaseChoiceIterator): 

40 """Iterator to lazily inject a blank choice.""" 

41 

42 def __init__(self, choices, blank_choice): 

43 self.choices = choices 

44 self.blank_choice = blank_choice 

45 

46 def __iter__(self): 

47 choices, other = tee(self.choices) 

48 if not any(value in ("", None) for value, _ in flatten_choices(other)): 

49 yield from self.blank_choice 

50 yield from choices 

51 

52 

53class CallableChoiceIterator(BaseChoiceIterator): 

54 """Iterator to lazily normalize choices generated by a callable.""" 

55 

56 def __init__(self, func): 

57 self.func = func 

58 

59 def __iter__(self): 

60 yield from normalize_choices(self.func()) 

61 

62 

63def flatten_choices(choices): 

64 """Flatten choices by removing nested values.""" 

65 for value_or_group, label_or_nested in choices or (): 

66 if isinstance(label_or_nested, (list, tuple)): 

67 yield from label_or_nested 

68 else: 

69 yield value_or_group, label_or_nested 

70 

71 

72def normalize_choices(value, *, depth=0): 

73 """Normalize choices values consistently for fields and widgets.""" 

74 # Avoid circular import when importing django.forms. 

75 from django.db.models.enums import ChoicesType 

76 

77 match value: 

78 case BaseChoiceIterator() | Promise() | bytes() | str(): 

79 # Avoid prematurely normalizing iterators that should be lazy. 

80 # Because string-like types are iterable, return early to avoid 

81 # iterating over them in the guard for the Iterable case below. 

82 return value 

83 case ChoicesType(): 

84 # Choices enumeration helpers already output in canonical form. 

85 return value.choices 

86 case Mapping() if depth < 2: 

87 value = value.items() 

88 case Iterator() if depth < 2: 

89 # Although Iterator would be handled by the Iterable case below, 

90 # the iterator would be consumed prematurely while checking that 

91 # its elements are not string-like in the guard, so we handle it 

92 # separately. 

93 pass 

94 case Iterable() if depth < 2 and not any( 

95 isinstance(x, (Promise, bytes, str)) for x in value 

96 ): 

97 # String-like types are iterable, so the guard above ensures that 

98 # they're handled by the default case below. 

99 pass 

100 case Callable() if depth == 0: 

101 # If at the top level, wrap callables to be evaluated lazily. 

102 return CallableChoiceIterator(value) 

103 case Callable() if depth < 2: 

104 value = value() 

105 case _: 

106 return value 

107 

108 try: 

109 # Recursive call to convert any nested values to a list of 2-tuples. 

110 return [(k, normalize_choices(v, depth=depth + 1)) for k, v in value] 

111 except (TypeError, ValueError): 

112 # Return original value for the system check to raise if it has items 

113 # that are not iterable or not 2-tuples: 

114 # - TypeError: cannot unpack non-iterable <type> object 

115 # - ValueError: <not enough / too many> values to unpack 

116 return value