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ccxt/static_dependencies/marshmallow_dataclass/union_field.py

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+import copy
+import inspect
+from typing import List, Tuple, Any, Optional
+
+import typeguard
+from marshmallow import fields, Schema, ValidationError
+
+try:
+    from typeguard import TypeCheckError  # type: ignore[attr-defined]
+except ImportError:
+    # typeguard < 3
+    TypeCheckError = TypeError  # type: ignore[misc, assignment]
+
+if "argname" not in inspect.signature(typeguard.check_type).parameters:
+
+    def _check_type(value, expected_type, argname: str):
+        return typeguard.check_type(value=value, expected_type=expected_type)
+
+else:
+    # typeguard < 3.0.0rc2
+    def _check_type(value, expected_type, argname: str):
+        return typeguard.check_type(  # type: ignore[call-overload]
+            value=value, expected_type=expected_type, argname=argname
+        )
+
+
+class Union(fields.Field):
+    """A union field, composed other `Field` classes or instances.
+    This field serializes elements based on their type, with one of its child fields.
+
+    Example: ::
+
+        number_or_string = UnionField([
+                    (float, fields.Float()),
+                    (str, fields.Str())
+                ])
+
+    :param union_fields: A list of types and their associated field instance.
+    :param kwargs: The same keyword arguments that :class:`Field` receives.
+    """
+
+    def __init__(self, union_fields: List[Tuple[type, fields.Field]], **kwargs):
+        super().__init__(**kwargs)
+        self.union_fields = union_fields
+
+    def _bind_to_schema(self, field_name: str, schema: Schema) -> None:
+        super()._bind_to_schema(field_name, schema)
+        new_union_fields = []
+        for typ, field in self.union_fields:
+            field = copy.deepcopy(field)
+            field._bind_to_schema(field_name, self)
+            new_union_fields.append((typ, field))
+
+        self.union_fields = new_union_fields
+
+    def _serialize(self, value: Any, attr: Optional[str], obj, **kwargs) -> Any:
+        errors = []
+        if value is None:
+            return value
+        for typ, field in self.union_fields:
+            try:
+                _check_type(value=value, expected_type=typ, argname=attr or "anonymous")
+                return field._serialize(value, attr, obj, **kwargs)
+            except TypeCheckError as e:
+                errors.append(e)
+        raise TypeError(
+            f"Unable to serialize value with any of the fields in the union: {errors}"
+        )
+
+    def _deserialize(self, value: Any, attr: Optional[str], data, **kwargs) -> Any:
+        errors = []
+        for typ, field in self.union_fields:
+            try:
+                result = field.deserialize(value, **kwargs)
+                _check_type(
+                    value=result, expected_type=typ, argname=attr or "anonymous"
+                )
+                return result
+            except (TypeCheckError, ValidationError) as e:
+                errors.append(e)
+
+        raise ValidationError(errors)