Utilities for running nested event loops, asking them to return, and
keeping track of which ones are still running.
Process the current thread’s event queue, calling event handlers until
a call to exitNestedEventLoop, below, asks us to return.
The name ‘enterNestedEventLoop’ may be misleading if read too literally.
This method loops calling event handlers until one asks it to stop, and
then returns. So by that point, the nested event loop has been not only
entered, but also run and exited.
When enterNestedEventLoop calls an event handler, that handler may itself
call enterNestedEventLoop, and so on, so that there may be arbitrarily
many such calls on the stack at the same time.
We say an enterNestedEventLoop call is “running” if it has not yet been
asked to return, or “stopped” if it has been asked to return once it has
finished processing the current event.
(Note that not all calls still on the stack are
necessary running; exitNestedEventLoop can ask any
number of enterNestedEventLoop calls to return.)
| requestor | A token of the caller's choice to identify this event loop. |
| depth The number of running enterNestedEventLoop calls remaining, now that this one has returned. |
Stop the youngest running enterNestedEventLoop call, asking it to return
once it has finished processing the current event.
The name ‘exitNestedEventLoop’ may be misleading if read too literally.
The affected event loop does not return immediately when this method is
called. Rather, this method simply returns to its caller; the affected
loop’s current event handler is allowed to run to completion; and then
that loop returns without processing any more events.
This method ignores loops that have already been stopped, and operates on
the youngest loop that is still running. Each call to this method stops
another running loop.
@throws NS_ERROR_FAILURE if there are no running enterNestedEventLoop calls.
| depth The number of running enterNestedEventLoop calls remaining, now that one has been stopped. |
The number of running enterNestedEventLoop calls on the stack.
This count does not include stopped enterNestedEventLoop calls.
The |requestor| value that was passed to the youngest running
enterNestedEventLoop call.