Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/django/utils/tree.py: 44%

1""" 

2A class for storing a tree graph. Primarily used for filter constructs in the 

3ORM. 

4""" 

5 

6import copy 

7 

8from django.utils.hashable import make_hashable 

9 

10 

11class Node: 

12 """ 

13 A single internal node in the tree graph. A Node should be viewed as a 

14 connection (the root) with the children being either leaf nodes or other 

15 Node instances. 

16 """ 

17 

18 # Standard connector type. Clients usually won't use this at all and 

19 # subclasses will usually override the value. 

20 default = "DEFAULT" 

21 

22 def __init__(self, children=None, connector=None, negated=False): 

23 """Construct a new Node. If no connector is given, use the default.""" 

24 self.children = children[:] if children else [] 

25 self.connector = connector or self.default 

26 self.negated = negated 

27 

28 @classmethod 

29 def create(cls, children=None, connector=None, negated=False): 

30 """ 

31 Create a new instance using Node() instead of __init__() as some 

32 subclasses, e.g. django.db.models.query_utils.Q, may implement a custom 

33 __init__() with a signature that conflicts with the one defined in 

34 Node.__init__(). 

35 """ 

36 obj = Node(children, connector or cls.default, negated) 

37 obj.__class__ = cls 

38 return obj 

39 

40 def __str__(self): 

41 template = "(NOT (%s: %s))" if self.negated else "(%s: %s)" 

42 return template % (self.connector, ", ".join(str(c) for c in self.children)) 

43 

44 def __repr__(self): 

45 return "<%s: %s>" % (self.__class__.__name__, self) 

46 

47 def __copy__(self): 

48 obj = self.create(connector=self.connector, negated=self.negated) 

49 obj.children = self.children # Don't [:] as .__init__() via .create() does. 

50 return obj 

51 

52 copy = __copy__ 

53 

54 def __deepcopy__(self, memodict): 

55 obj = self.create(connector=self.connector, negated=self.negated) 

56 obj.children = copy.deepcopy(self.children, memodict) 

57 return obj 

58 

59 def __len__(self): 

60 """Return the number of children this node has.""" 

61 return len(self.children) 

62 

63 def __bool__(self): 

64 """Return whether or not this node has children.""" 

65 return bool(self.children) 

66 

67 def __contains__(self, other): 

68 """Return True if 'other' is a direct child of this instance.""" 

69 return other in self.children 

70 

71 def __eq__(self, other): 

72 return ( 

73 self.__class__ == other.__class__ 

74 and self.connector == other.connector 

75 and self.negated == other.negated 

76 and self.children == other.children 

77 ) 

78 

79 def __hash__(self): 

80 return hash( 

81 ( 

82 self.__class__, 

83 self.connector, 

84 self.negated, 

85 *make_hashable(self.children), 

86 ) 

87 ) 

88 

89 def add(self, data, conn_type): 

90 """ 

91 Combine this tree and the data represented by data using the 

92 connector conn_type. The combine is done by squashing the node other 

93 away if possible. 

94 

95 This tree (self) will never be pushed to a child node of the 

96 combined tree, nor will the connector or negated properties change. 

97 

98 Return a node which can be used in place of data regardless if the 

99 node other got squashed or not. 

100 """ 

101 if self.connector != conn_type: 

102 obj = self.copy() 

103 self.connector = conn_type 

104 self.children = [obj, data] 

105 return data 

106 elif ( 

107 isinstance(data, Node) 

108 and not data.negated 

109 and (data.connector == conn_type or len(data) == 1) 

110 ): 

111 # We can squash the other node's children directly into this node. 

112 # We are just doing (AB)(CD) == (ABCD) here, with the addition that 

113 # if the length of the other node is 1 the connector doesn't 

114 # matter. However, for the len(self) == 1 case we don't want to do 

115 # the squashing, as it would alter self.connector. 

116 self.children.extend(data.children) 

117 return self 

118 else: 

119 # We could use perhaps additional logic here to see if some 

120 # children could be used for pushdown here. 

121 self.children.append(data) 

122 return data 

123 

124 def negate(self): 

125 """Negate the sense of the root connector.""" 

126 self.negated = not self.negated