src/mdis/walker.py

   1 __all__ = [
   2     "Walker",
   3     "WalkerMeta",
   4 ]
   5
   6 import enum
   7 import dataclasses
   8
   9 from . import dispatcher
  10
  11
  12 class WalkerMeta(dispatcher.DispatcherMeta):
  13     pass
  14
  15
  16 class GenericPath:
  17     def __init__(self, path):
  18         self.__path = path
  19         return super().__init__()
  20
  21     def __str__(self):
  22         return self.__path.__str__()
  23
  24     def __repr__(self):
  25         return f"{self.__class__.__name__}({str(self)})"
  26
  27     @property
  28     def path(self):
  29         return self.__path
  30
  31
  32 class IndexPath(GenericPath):
  33     def __str__(self):
  34         return f"[{self.path}]"
  35
  36
  37 class AttributePath(GenericPath):
  38     def __str__(self):
  39         return f".{self.path}]"
  40
  41
  42 class HashPath(GenericPath):
  43     def __str__(self):
  44         return f"{{{self.path}}}"
  45
  46
  47 class Walker(dispatcher.Dispatcher, metaclass=WalkerMeta):
  48     @dispatcher.Hook(tuple, list)
  49     def dispatch_ordered_sequence(self, instance):
  50         for (index, item) in enumerate(instance):
  51             yield (item, instance, index, IndexPath)
  52             yield from self(item)
  53
  54     @dispatcher.Hook(set, frozenset)
  55     def dispatch_unordered_sequence(self, instance):
  56         for item in instance:
  57             yield (item, instance, item, HashPath)
  58             yield from self(item)
  59
  60     @dispatcher.Hook(dataclasses.is_dataclass)
  61     def dispatch_dataclass(self, instance):
  62         for field in dataclasses.fields(instance):
  63             key = field.name
  64             value = getattr(instance, key)
  65             yield (value, instance, key, AttributePath)
  66             yield from self(value)
  67
  68     @dispatcher.Hook(dict)
  69     def dispatch_mapping(self, instance):
  70         for (key, value) in instance.items():
  71             yield (key, instance, key, HashPath)
  72             yield from self(key)
  73             yield (value, instance, key, IndexPath)
  74             yield from self(value)
  75
  76     @dispatcher.Hook(object)
  77     def dispatch_object(self, instance, path=()):
  78         yield from ()