Загрузка исходника

installer/dataclasses_json.py

@@ -0,0 +1,70 @@
+"""Implement a tiny subset of dataclasses_json for config."""
+from collections.abc import Mapping, Sequence
+from dataclasses import asdict, fields, is_dataclass
+from typing import Any, Dict, Type
+
+
+class DataClassJsonMixin:
+    """Adds from_dict to dataclass."""
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any]) -> Any:
+        """Parse dataclasses recursively."""
+        kwargs: Dict[str, Any] = {}
+
+        cls_fields = {field.name: field for field in fields(cls)}
+        for key, value in data.items():
+            if key not in cls_fields:
+                # Skip unknown fields
+                continue
+
+            field = cls_fields[key]
+            if is_dataclass(field.type):
+                assert issubclass(field.type, DataClassJsonMixin), field.type
+                kwargs[key] = field.type.from_dict(value)
+            else:
+                kwargs[key] = _decode(value, field.type)
+
+        # Fill in optional fields with None
+        for field in cls_fields.values():
+            if (field.name not in kwargs) and _is_optional(field.type):
+                kwargs[field.name] = None
+
+        return cls(**kwargs)
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Alias for asdict."""
+        return asdict(self)
+
+
+def _decode(value: Any, target_type: Type) -> Any:
+    """Decode value using (possibly generic) type."""
+    if is_dataclass(target_type):
+        assert issubclass(target_type, DataClassJsonMixin), target_type
+        return target_type.from_dict(value) if value is not None else None
+
+    if hasattr(target_type, "__args__"):
+        # Optional[T]
+        if type(None) in target_type.__args__:
+            optional_type = target_type.__args__[0]
+            return _decode(value, optional_type)
+
+        # List[T]
+        if isinstance(value, Sequence):
+            list_type = target_type.__args__[0]
+            return [_decode(item, list_type) for item in value]
+
+        # Dict[str, T]
+        if isinstance(value, Mapping):
+            value_type = target_type.__args__[1]
+            return {
+                map_key: _decode(map_value, value_type)
+                for map_key, map_value in value.items()
+            }
+
+    return value
+
+
+def _is_optional(target_type: Type):
+    """True if type is Optional"""
+    return hasattr(target_type, "__args__") and (type(None) in target_type.__args__)