Use a separate EvalContext structure for holding some state.

1 files changed, 15 insertions, 1 deletions

diff --git a/aisa/eval.h b/aisa/eval.h
index 30dc617..a301e93 100644
--- a/aisa/eval.h
+++ b/aisa/eval.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <coroutine>
+#include <memory>
 #include <optional>
 #include <utility>
 #include <vector>
@@ -11,6 +12,12 @@
 namespace aisa {
 
     template<typename CRTP> struct EvalState {
+        struct EvalContext {
+            task<void> coroutine;
+
+            bool resume() { return coroutine(); }
+        };
+
         CRTP & crtp() noexcept { return static_cast<CRTP &>(*this); }
 
         task<regval_t> async_load_reg(regnum_t rn)
@@ -31,7 +38,7 @@ namespace aisa {
             }
         }
 
-        task<void> eval(const Step &step)
+        task<void> async_evaluate(EvalContext &contex, const Step &step)
         {
             if (step.predicate.has_value()) {
                 regval_t pval = co_await async_load_reg(step.predicate->first);
@@ -46,6 +53,13 @@ namespace aisa {
             for (unsigned int i = 0; i < step.destination_regs.size(); ++i)
                 co_await async_store_reg(step.destination_regs[i], destination_vals[i]);
         }
+
+        std::unique_ptr<EvalContext> operator()(const Step &step)
+        {
+            auto context = std::make_unique<EvalContext>();
+            context->coroutine = async_evaluate(*context, step);
+            return context;
+        }
     };
 
 }