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asarium
ebcf686cf7
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.
94 lines
2.4 KiB
C++
94 lines
2.4 KiB
C++
//
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// Created by marius on 14.05.20.
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//
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#include "promise.h"
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namespace scripting {
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namespace api {
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ADE_OBJ(l_Promise,
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LuaPromise,
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"promise",
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"A promise that represents an operation that will return a value at some point in the future");
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// Can't call this "then" since that is a Lua keyword
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ADE_FUNC(continueWith,
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l_Promise,
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"function(args...)",
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"When the called on promise resolves, this function will be called with the resolved value of the promise.",
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"promise",
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"A promise that will resolve with the return value of the passed function.")
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{
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LuaPromise* promise = nullptr;
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luacpp::LuaFunction thenFunc;
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if (!ade_get_args(L, "ou", l_Promise.GetPtr(&promise), &thenFunc)) {
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return ADE_RETURN_NIL;
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}
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if (!thenFunc.isValid()) {
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LuaError(L, "'continueWith' function is invalid!");
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return ADE_RETURN_NIL;
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}
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if (promise == nullptr || !promise->isValid()) {
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LuaError(L, "Invalid promise detected. This should not happen. Please contact a developer.");
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return ADE_RETURN_NIL;
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}
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return ade_set_args(L, "o", l_Promise.Set(promise->then(thenFunc)));
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}
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ADE_FUNC(isResolved,
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l_Promise,
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nullptr,
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"Checks if the promise is already resolved.",
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"boolean",
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"true if resolved, false if result is still pending.")
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{
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LuaPromise* promise = nullptr;
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if (!ade_get_args(L, "o", l_Promise.GetPtr(&promise))) {
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return ADE_RETURN_NIL;
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}
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if (promise == nullptr || !promise->isValid()) {
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LuaError(L, "Invalid promise detected. This should not happen. Please contact a developer.");
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return ADE_RETURN_NIL;
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}
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return ade_set_args(L, "b", promise->isResolved());
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}
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ADE_FUNC(getValue,
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l_Promise,
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nullptr,
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"Gets the resolved value of this promise. Causes an error when used on an unresolved promise!",
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"unknown",
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"The resolved values.")
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{
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LuaPromise* promise = nullptr;
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if (!ade_get_args(L, "o", l_Promise.GetPtr(&promise))) {
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return ADE_RETURN_NIL;
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}
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if (promise == nullptr || !promise->isValid()) {
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LuaError(L, "Invalid promise detected. This should not happen. Please contact a developer.");
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return ADE_RETURN_NIL;
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}
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if (!promise->isResolved()) {
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LuaError(L, "Tried to get the value of a promise that was not resolved!");
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return ADE_RETURN_NIL;
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}
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// We can't use our usual functions for returning here since we return a variable amount of values
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const auto& retVals = promise->resolveValue();
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for (const auto& retVal : retVals) {
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retVal.pushValue(L);
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}
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return static_cast<int>(retVals.size());
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}
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} // namespace api
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} // namespace scripting
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