feat: abstract event

Signed-off-by: Alexander Tkachev <sasha64sasha@gmail.com>

cloudevents/sdk/event/abstract_event.py

@@ -0,0 +1,63 @@
+import abc
+import typing
+
+
+class AbstractCloudEvent(abc.ABC):
+    @property
+    def _attributes_read_model(self) -> typing.Dict[str, typing.Any]:
+        raise NotImplementedError()
+
+    @property
+    def data(self) -> typing.Optional[typing.Any]:
+        raise NotImplementedError()
+
+    @data.setter
+    def data(self, value: typing.Optional[typing.Any]) -> None:
+        raise NotImplementedError()
+
+    def __setitem__(self, key: str, value: typing.Any) -> None:
+        raise NotImplementedError()
+
+    def __delitem__(self, key: str) -> None:
+        raise NotImplementedError()
+
+    def __eq__(self, other: typing.Any) -> bool:
+        if isinstance(other, AbstractCloudEvent):
+            return (
+                self.data == other.data
+                and self._attributes_read_model == other._attributes_read_model
+            )
+        return False
+
+    # Data access is handled via `.data` member
+    # Attribute access is managed via Mapping type
+    def __getitem__(self, key: str) -> typing.Any:
+        return self._attributes_read_model[key]
+
+    def get(
+        self, key: str, default: typing.Optional[typing.Any] = None
+    ) -> typing.Optional[typing.Any]:
+        """
+        Retrieves an event attribute value for the given key.
+        Returns the default value if not attribute for the given key exists.
+
+        MUST NOT throw an exception when the key does not exist.
+
+        :param key: The event attribute name.
+        :param default: The default value to be returned when
+            no attribute with the given key exists.
+        :returns: The event attribute value if exists, default value otherwise.
+        """
+        return self._attributes_read_model.get(key, default)
+
+    def __iter__(self) -> typing.Iterator[typing.Any]:
+        return iter(self._attributes_read_model)
+
+    def __len__(self) -> int:
+        return len(self._attributes_read_model)
+
+    def __contains__(self, key: str) -> bool:
+        return key in self._attributes_read_model
+
+    def __repr__(self) -> str:
+        return str({"attributes": self._attributes_read_model, "data": self.data})