This adds a mechanism for running generic operations at specific points
of the frame execution. This can be used by any part of the code an not
just Lua since it simply executes std::functions. It also adds an
"execution context" concept that specifies in which situation an
operation should be executed.
This is then used by the Lua Coroutines code for resuming coroutines at
specific points instead of always when the awaited promise resolves.
This will ensure that Lua functions will always be executed in the
correct Lua state. Since we now have multiple threads (which are
different lua_State objects) it is possible that the current code could
execute a Lua function in the main state instead of the thread that is
currently executing. This can lead to weird behavior and probably also
to issues inside Lua.
This adds a Lua API for representing asynchronous operations and running
coroutines based on those operations comfortably. This is very similar
to features other languages have introduced such as C# or JavaScript. In
fact, the whole "promise" thing is derived from how JavaScript
represents these operations.
This is the initial and very basic system for supporting async
coroutines in Lua. There is no native support for running these
operations at specific points (they run whenever the awaited promise
resolved) or making sure they do not leak through different game states.
asarium