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- """Client middleware support."""
- from collections.abc import Awaitable, Callable, Sequence
- from .client_reqrep import ClientRequest, ClientResponse
- __all__ = ("ClientMiddlewareType", "ClientHandlerType", "build_client_middlewares")
- # Type alias for client request handlers - functions that process requests and return responses
- ClientHandlerType = Callable[[ClientRequest], Awaitable[ClientResponse]]
- # Type for client middleware - similar to server but uses ClientRequest/ClientResponse
- ClientMiddlewareType = Callable[
- [ClientRequest, ClientHandlerType], Awaitable[ClientResponse]
- ]
- def build_client_middlewares(
- handler: ClientHandlerType,
- middlewares: Sequence[ClientMiddlewareType],
- ) -> ClientHandlerType:
- """
- Apply middlewares to request handler.
- The middlewares are applied in reverse order, so the first middleware
- in the list wraps all subsequent middlewares and the handler.
- This implementation avoids using partial/update_wrapper to minimize overhead
- and doesn't cache to avoid holding references to stateful middleware.
- """
- # Optimize for single middleware case
- if len(middlewares) == 1:
- middleware = middlewares[0]
- async def single_middleware_handler(req: ClientRequest) -> ClientResponse:
- return await middleware(req, handler)
- return single_middleware_handler
- # Build the chain for multiple middlewares
- current_handler = handler
- for middleware in reversed(middlewares):
- # Create a new closure that captures the current state
- def make_wrapper(
- mw: ClientMiddlewareType, next_h: ClientHandlerType
- ) -> ClientHandlerType:
- async def wrapped(req: ClientRequest) -> ClientResponse:
- return await mw(req, next_h)
- return wrapped
- current_handler = make_wrapper(middleware, current_handler)
- return current_handler
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