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!r}]"
  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, node, *_, **__):
  50         for (index, item) in enumerate(node):
  51             yield (item, node, index, IndexPath)
  52
  53     @dispatcher.Hook(set, frozenset)
  54     def dispatch_unordered_sequence(self, node, *_, **__):
  55         for item in node:
  56             yield (item, node, item, HashPath)
  57
  58     @dispatcher.Hook(dataclasses.is_dataclass)
  59     def dispatch_dataclass(self, node, *_, **__):
  60         for field in dataclasses.fields(node):
  61             key = field.name
  62             value = getattr(node, key)
  63             yield (value, node, key, AttributePath)
  64
  65     @dispatcher.Hook(dict)
  66     def dispatch_mapping(self, node, *_, **__):
  67         for (key, value) in node.items():
  68             yield (key, node, key, HashPath)
  69             yield (value, node, key, IndexPath)
  70
  71     @dispatcher.Hook(object)
  72     def dispatch_object(self, node, *_, **__):
  73         yield from ()