♻️ Relax type annotations, refactor custom handler inferences, naming

.gitignore

@@ -105,3 +105,5 @@ venv.bak/
 
 # IDE Settings
 .idea/
+
+.DS_Store

mangum/adapter.py

@@ -1,14 +1,13 @@
-from itertools import chain
 import logging
+from itertools import chain
 from contextlib import ExitStack
 from typing import List, Optional, Type
-import warnings
 
 from mangum.protocols import HTTPCycle, LifespanCycle
 from mangum.handlers import ALB, HTTPGateway, APIGateway, LambdaAtEdge
 from mangum.exceptions import ConfigurationError
 from mangum.types import (
-    ASGIApp,
+    ASGI,
     LifespanMode,
     LambdaConfig,
     LambdaEvent,
@@ -31,7 +30,7 @@
 class Mangum:
     def __init__(
         self,
-        app: ASGIApp,
+        app: ASGI,
         lifespan: LifespanMode = "auto",
         api_gateway_base_path: str = "/",
         custom_handlers: Optional[List[Type[LambdaHandler]]] = None,
@@ -45,27 +44,12 @@ def __init__(
         self.lifespan = lifespan
         self.api_gateway_base_path = api_gateway_base_path or "/"
         self.config = LambdaConfig(api_gateway_base_path=self.api_gateway_base_path)
-
-        if custom_handlers is not None:
-            warnings.warn(  # pragma: no cover
-                "Support for custom event handlers is currently provisional and may "
-                "drastically change (or be removed entirely) in the future.",
-                FutureWarning,
-            )
-
         self.custom_handlers = custom_handlers or []
 
     def infer(self, event: LambdaEvent, context: LambdaContext) -> LambdaHandler:
-        for handler_cls in chain(
-            self.custom_handlers,
-            HANDLERS,
-        ):
-            handler = handler_cls.infer(
-                event,
-                context,
-                self.config,
-            )
-            if handler:
+        for handler_cls in chain(self.custom_handlers, HANDLERS):
+            if handler_cls.infer(event, context, self.config):
+                handler = handler_cls(event, context, self.config)
                 break
         else:
             raise RuntimeError(  # pragma: no cover

mangum/handlers/alb.py

@@ -1,20 +1,18 @@
 from itertools import islice
-from typing import Dict, Generator, List, Optional, Tuple
+from typing import Dict, Generator, List, Tuple
 from urllib.parse import urlencode, unquote, unquote_plus
 
-
 from mangum.handlers.utils import (
     get_server_and_port,
     handle_base64_response_body,
     maybe_encode_body,
 )
 from mangum.types import (
-    HTTPResponse,
-    HTTPScope,
+    Response,
+    Scope,
     LambdaConfig,
     LambdaEvent,
     LambdaContext,
-    LambdaHandler,
     QueryParams,
 )
 
@@ -86,11 +84,8 @@ class ALB:
     @classmethod
     def infer(
         cls, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
-    ) -> Optional[LambdaHandler]:
-        if "requestContext" in event and "elb" in event["requestContext"]:
-            return cls(event, context, config)
-
-        return None
+    ) -> bool:
+        return "requestContext" in event and "elb" in event["requestContext"]
 
     def __init__(
         self, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
@@ -107,7 +102,7 @@ def body(self) -> bytes:
         )
 
     @property
-    def scope(self) -> HTTPScope:
+    def scope(self) -> Scope:
 
         headers = transform_headers(self.event)
         list_headers = [list(x) for x in headers]
@@ -129,7 +124,7 @@ def scope(self) -> HTTPScope:
         server = get_server_and_port(uq_headers)
         client = (source_ip, 0)
 
-        scope: HTTPScope = {
+        scope: Scope = {
             "type": "http",
             "method": http_method,
             "http_version": "1.1",
@@ -148,7 +143,7 @@ def scope(self) -> HTTPScope:
 
         return scope
 
-    def __call__(self, response: HTTPResponse) -> dict:
+    def __call__(self, response: Response) -> dict:
         multi_value_headers: Dict[str, List[str]] = {}
         for key, value in response["headers"]:
             lower_key = key.decode().lower()

mangum/handlers/api_gateway.py

@@ -1,4 +1,4 @@
-from typing import Dict, List, Optional, Tuple
+from typing import Dict, List, Tuple
 from urllib.parse import urlencode
 
 from mangum.handlers.utils import (
@@ -9,14 +9,13 @@
     strip_api_gateway_path,
 )
 from mangum.types import (
-    HTTPResponse,
+    Response,
     LambdaConfig,
     Headers,
     LambdaEvent,
     LambdaContext,
-    LambdaHandler,
     QueryParams,
-    HTTPScope,
+    Scope,
 )
 
 
@@ -68,11 +67,8 @@ class APIGateway:
     @classmethod
     def infer(
         cls, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
-    ) -> Optional[LambdaHandler]:
-        if "resource" in event and "requestContext" in event:
-            return cls(event, context, config)
-
-        return None
+    ) -> bool:
+        return "resource" in event and "requestContext" in event
 
     def __init__(
         self, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
@@ -89,7 +85,7 @@ def body(self) -> bytes:
         )
 
     @property
-    def scope(self) -> HTTPScope:
+    def scope(self) -> Scope:
         headers = _handle_multi_value_headers_for_request(self.event)
         return {
             "type": "http",
@@ -114,7 +110,7 @@ def scope(self) -> HTTPScope:
             "aws.context": self.context,
         }
 
-    def __call__(self, response: HTTPResponse) -> dict:
+    def __call__(self, response: Response) -> dict:
         finalized_headers, multi_value_headers = handle_multi_value_headers(
             response["headers"]
         )
@@ -135,11 +131,8 @@ class HTTPGateway:
     @classmethod
     def infer(
         cls, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
-    ) -> Optional[LambdaHandler]:
-        if "version" in event and "requestContext" in event:
-            return cls(event, context, config)
-
-        return None
+    ) -> bool:
+        return "version" in event and "requestContext" in event
 
     def __init__(
         self, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
@@ -156,7 +149,7 @@ def body(self) -> bytes:
         )
 
     @property
-    def scope(self) -> HTTPScope:
+    def scope(self) -> Scope:
         request_context = self.event["requestContext"]
         event_version = self.event["version"]
 
@@ -203,7 +196,7 @@ def scope(self) -> HTTPScope:
             "aws.context": self.context,
         }
 
-    def __call__(self, response: HTTPResponse) -> dict:
+    def __call__(self, response: Response) -> dict:
         if self.scope["aws.event"]["version"] == "2.0":
             finalized_headers, cookies = _combine_headers_v2(response["headers"])
 

mangum/handlers/lambda_at_edge.py

@@ -1,35 +1,27 @@
-from typing import Dict, List, Optional
+from typing import Dict, List
 
 from mangum.handlers.utils import (
     handle_base64_response_body,
     handle_multi_value_headers,
     maybe_encode_body,
 )
-from mangum.types import (
-    HTTPScope,
-    HTTPResponse,
-    LambdaConfig,
-    LambdaEvent,
-    LambdaContext,
-    LambdaHandler,
-)
+from mangum.types import Scope, Response, LambdaConfig, LambdaEvent, LambdaContext
 
 
 class LambdaAtEdge:
     @classmethod
     def infer(
         cls, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
-    ) -> Optional[LambdaHandler]:
-        if (
+    ) -> bool:
+        return (
             "Records" in event
             and len(event["Records"]) > 0
             and "cf" in event["Records"][0]
-        ):
-            return cls(event, context, config)
+        )
 
         # FIXME: Since this is the last in the chain it doesn't get coverage by default,
-        # just ignoring it for now.
-        return None  # pragma: nocover
+        # # just ignoring it for now.
+        # return None  # pragma: nocover
 
     def __init__(
         self, event: LambdaEvent, context: LambdaContext, config: LambdaConfig
@@ -47,7 +39,7 @@ def body(self) -> bytes:
         )
 
     @property
-    def scope(self) -> HTTPScope:
+    def scope(self) -> Scope:
         cf_request = self.event["Records"][0]["cf"]["request"]
         scheme_header = cf_request["headers"].get("cloudfront-forwarded-proto", [{}])
         scheme = scheme_header[0].get("value", "https")
@@ -84,7 +76,7 @@ def scope(self) -> HTTPScope:
             "aws.context": self.context,
         }
 
-    def __call__(self, response: HTTPResponse) -> dict:
+    def __call__(self, response: Response) -> dict:
         multi_value_headers, _ = handle_multi_value_headers(response["headers"])
         response_body, is_base64_encoded = handle_base64_response_body(
             response["body"], multi_value_headers

mangum/protocols/http.py

@@ -3,15 +3,7 @@
 import logging
 from io import BytesIO
 
-
-from mangum.types import (
-    ASGIApp,
-    ASGIReceiveEvent,
-    ASGISendEvent,
-    HTTPDisconnectEvent,
-    HTTPScope,
-    HTTPResponse,
-)
+from mangum.types import ASGI, Message, Scope, Response
 from mangum.exceptions import UnexpectedMessage
 
 
@@ -35,12 +27,12 @@ class HTTPCycleState(enum.Enum):
 
 
 class HTTPCycle:
-    def __init__(self, scope: HTTPScope, body: bytes) -> None:
+    def __init__(self, scope: Scope, body: bytes) -> None:
         self.scope = scope
         self.buffer = BytesIO()
         self.state = HTTPCycleState.REQUEST
         self.logger = logging.getLogger("mangum.http")
-        self.app_queue: asyncio.Queue[ASGIReceiveEvent] = asyncio.Queue()
+        self.app_queue: asyncio.Queue[Message] = asyncio.Queue()
         self.app_queue.put_nowait(
             {
                 "type": "http.request",
@@ -49,7 +41,7 @@ def __init__(self, scope: HTTPScope, body: bytes) -> None:
             }
         )
 
-    def __call__(self, app: ASGIApp) -> HTTPResponse:
+    def __call__(self, app: ASGI) -> Response:
         asgi_instance = self.run(app)
         loop = asyncio.get_event_loop()
         asgi_task = loop.create_task(asgi_instance)
@@ -61,7 +53,7 @@ def __call__(self, app: ASGIApp) -> HTTPResponse:
             "body": self.body,
         }
 
-    async def run(self, app: ASGIApp) -> None:
+    async def run(self, app: ASGI) -> None:
         try:
             await app(self.scope, self.receive, self.send)
         except BaseException:
@@ -86,10 +78,10 @@ async def run(self, app: ASGIApp) -> None:
                 self.body = b"Internal Server Error"
                 self.headers = [[b"content-type", b"text/plain; charset=utf-8"]]
 
-    async def receive(self) -> ASGIReceiveEvent:
+    async def receive(self) -> Message:
         return await self.app_queue.get()  # pragma: no cover
 
-    async def send(self, message: ASGISendEvent) -> None:
+    async def send(self, message: Message) -> None:
         if (
             self.state is HTTPCycleState.REQUEST
             and message["type"] == "http.response.start"
@@ -110,7 +102,7 @@ async def send(self, message: ASGISendEvent) -> None:
                 self.buffer.close()
 
                 self.state = HTTPCycleState.COMPLETE
-                await self.app_queue.put(HTTPDisconnectEvent(type="http.disconnect"))
+                await self.app_queue.put({"type": "http.disconnect"})
 
                 self.logger.info(
                     "%s %s %s",