49 lines
1.6 KiB
Python
49 lines
1.6 KiB
Python
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import inspect
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from .sync import iscoroutinefunction
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def is_double_callable(application):
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"""
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Tests to see if an application is a legacy-style (double-callable) application.
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"""
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# Look for a hint on the object first
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if getattr(application, "_asgi_single_callable", False):
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return False
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if getattr(application, "_asgi_double_callable", False):
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return True
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# Uninstanted classes are double-callable
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if inspect.isclass(application):
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return True
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# Instanted classes depend on their __call__
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if hasattr(application, "__call__"):
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# We only check to see if its __call__ is a coroutine function -
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# if it's not, it still might be a coroutine function itself.
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if iscoroutinefunction(application.__call__):
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return False
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# Non-classes we just check directly
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return not iscoroutinefunction(application)
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def double_to_single_callable(application):
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"""
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Transforms a double-callable ASGI application into a single-callable one.
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"""
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async def new_application(scope, receive, send):
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instance = application(scope)
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return await instance(receive, send)
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return new_application
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def guarantee_single_callable(application):
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"""
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Takes either a single- or double-callable application and always returns it
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in single-callable style. Use this to add backwards compatibility for ASGI
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2.0 applications to your server/test harness/etc.
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"""
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if is_double_callable(application):
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application = double_to_single_callable(application)
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return application
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