Coverage for /pythoncovmergedfiles/medio/medio/src/jupyter_server/jupyter_server/base/call_context.py: 56%

1"""Provides access to variables pertaining to specific call contexts.""" 

2# Copyright (c) Jupyter Development Team. 

3# Distributed under the terms of the Modified BSD License. 

4 

5from contextvars import Context, ContextVar, copy_context 

6from typing import Any 

7 

8 

9class CallContext: 

10 """CallContext essentially acts as a namespace for managing context variables. 

11 

12 Although not required, it is recommended that any "file-spanning" context variable 

13 names (i.e., variables that will be set or retrieved from multiple files or services) be 

14 added as constants to this class definition. 

15 """ 

16 

17 # Add well-known (file-spanning) names here. 

18 #: Provides access to the current request handler once set. 

19 JUPYTER_HANDLER: str = "JUPYTER_HANDLER" 

20 

21 # A map of variable name to value is maintained as the single ContextVar. This also enables 

22 # easier management over maintaining a set of ContextVar instances, since the Context is a 

23 # map of ContextVar instances to their values, and the "name" is no longer a lookup key. 

24 _NAME_VALUE_MAP = "_name_value_map" 

25 _name_value_map: ContextVar[dict[str, Any]] = ContextVar(_NAME_VALUE_MAP) 

26 

27 @classmethod 

28 def get(cls, name: str) -> Any: 

29 """Returns the value corresponding the named variable relative to this context. 

30 

31 If the named variable doesn't exist, None will be returned. 

32 

33 Parameters 

34 ---------- 

35 name : str 

36 The name of the variable to get from the call context 

37 

38 Returns 

39 ------- 

40 value: Any 

41 The value associated with the named variable for this call context 

42 """ 

43 name_value_map = CallContext._get_map() 

44 

45 if name in name_value_map: 

46 return name_value_map[name] 

47 return None # TODO: should this raise `LookupError` (or a custom error derived from said) 

48 

49 @classmethod 

50 def set(cls, name: str, value: Any) -> None: 

51 """Sets the named variable to the specified value in the current call context. 

52 

53 Parameters 

54 ---------- 

55 name : str 

56 The name of the variable to store into the call context 

57 value : Any 

58 The value of the variable to store into the call context 

59 

60 Returns 

61 ------- 

62 None 

63 """ 

64 name_value_map = CallContext._get_map() 

65 name_value_map[name] = value 

66 

67 @classmethod 

68 def context_variable_names(cls) -> list[str]: 

69 """Returns a list of variable names set for this call context. 

70 

71 Returns 

72 ------- 

73 names: List[str] 

74 A list of variable names set for this call context. 

75 """ 

76 name_value_map = CallContext._get_map() 

77 return list(name_value_map.keys()) 

78 

79 @classmethod 

80 def _get_map(cls) -> dict[str, Any]: 

81 """Get the map of names to their values from the _NAME_VALUE_MAP context var. 

82 

83 If the map does not exist in the current context, an empty map is created and returned. 

84 """ 

85 ctx: Context = copy_context() 

86 if CallContext._name_value_map not in ctx: 

87 CallContext._name_value_map.set({}) 

88 return CallContext._name_value_map.get()