replace to nf7:yield() from a custom type of Node::Lambda in Lua script

common/luajit.cc

@@ -368,43 +368,6 @@ void PushMutableVector(lua_State* L, std::vector<uint8_t>&& v) noexcept {
   lua_setmetatable(L, -2);
 }
 
-void PushNodeLambda(lua_State* L,
-                    const std::shared_ptr<nf7::Node::Lambda>& callee,
-                    const std::weak_ptr<nf7::Node::Lambda>& caller) noexcept {
-  constexpr auto kTypeName = "nf7::Node::Lambda";
-  struct Data {
-    std::shared_ptr<nf7::Node::Lambda> callee;
-    std::weak_ptr<nf7::Node::Lambda>   caller;
-  };
-  new (lua_newuserdata(L, sizeof(Data))) Data { .callee = callee, .caller = caller };
-
-  if (luaL_newmetatable(L, kTypeName)) {
-    lua_pushcfunction(L, [](auto L) {
-      const auto& d = *reinterpret_cast<Data*>(luaL_checkudata(L, 1, kTypeName));
-
-      auto caller = d.caller.lock();
-      if (!caller) return luaL_error(L, "caller expired");
-
-      std::string n = luaL_checkstring(L, 2);
-      auto        v = nf7::luajit::CheckValue(L, 3);
-
-      auto callee = d.callee;
-      callee->env().ExecSub(callee, [callee, caller, n = std::move(n), v = std::move(v)]() {
-        callee->Handle(n, v, caller);
-      });
-      return 0;
-    });
-    lua_setfield(L, -2, "__call");
-
-    lua_pushcfunction(L, [](auto L) {
-      reinterpret_cast<Data*>(luaL_checkudata(L, 1, kTypeName))->~Data();
-      return 0;
-    });
-    lua_setfield(L, -2, "__gc");
-  }
-  lua_setmetatable(L, -2);
-}
-
 
 std::optional<nf7::Value> ToValue(lua_State* L, int idx) noexcept {
   if (lua_isnoneornil(L, idx)) {

common/luajit.hh

@@ -9,7 +9,6 @@
 
 #include <lua.hpp>
 
-#include "common/node.hh"
 #include "common/value.hh"
 
 
@@ -20,9 +19,6 @@ void PushImmEnv(lua_State*) noexcept;
 void PushValue(lua_State*, const nf7::Value&) noexcept;
 void PushVector(lua_State*, const nf7::Value::ConstVector&) noexcept;
 void PushMutableVector(lua_State*, std::vector<uint8_t>&&) noexcept;
-void PushNodeLambda(lua_State*,
-                    const std::shared_ptr<nf7::Node::Lambda>& callee,
-                    const std::weak_ptr<nf7::Node::Lambda>& caller) noexcept;
 
 std::optional<nf7::Value> ToValue(lua_State*, int) noexcept;
 std::optional<nf7::Value::ConstVector> ToVector(lua_State*, int) noexcept;

common/luajit_thread.cc

@@ -147,9 +147,6 @@ static void PushMeta(lua_State* L) noexcept {
 
       // nf7:yield(results...)
       lua_pushcfunction(L, [](auto L) {
-        auto th = Thread::GetPtr(L, 1);
-        th->ExecResume(L);
-        th->ExpectYield(L);
         return lua_yield(L, lua_gettop(L)-1);
       });
       lua_setfield(L, -2, "yield");

common/luajit_thread.hh

@@ -5,6 +5,7 @@
 #include <functional>
 #include <memory>
 #include <optional>
+#include <string>
 #include <type_traits>
 #include <utility>
 #include <vector>
@@ -17,6 +18,7 @@
 #include "common/logger_ref.hh"
 #include "common/luajit.hh"
 #include "common/luajit_ref.hh"
+#include "common/node.hh"
 
 
 namespace nf7::luajit {
@@ -40,9 +42,14 @@ class Thread final : public std::enable_shared_from_this<Thread> {
 
   // Creates a handler to finalize a promise.
   template <typename T>
-  static Handler CreatePromiseHandler(
+  static inline Handler CreatePromiseHandler(
       nf7::Future<T>::Promise& pro, std::function<T(lua_State*)>&&) noexcept;
 
+  // Creates a handler to emit yielded value to Node::Lambda.
+  static inline Handler CreateNodeLambdaHandler(
+      const std::shared_ptr<nf7::Node::Lambda>& caller,
+      const std::shared_ptr<nf7::Node::Lambda>& callee) noexcept;
+
   // must be called on luajit thread
   static std::shared_ptr<Thread> GetPtr(lua_State* L, int idx) {
     auto th = CheckWeakPtr<Thread>(L, idx, kTypeName);
@@ -176,4 +183,42 @@ Thread::Handler Thread::CreatePromiseHandler(
   };
 }
 
+Thread::Handler Thread::CreateNodeLambdaHandler(
+    const std::shared_ptr<nf7::Node::Lambda>& caller,
+    const std::shared_ptr<nf7::Node::Lambda>& callee) noexcept {
+  return [caller, callee](auto& th, auto L) {
+    switch (th.state()) {
+    case nf7::luajit::Thread::kPaused:
+      switch (lua_gettop(L)) {
+      case 0:
+        th.ExecResume(L);
+        return;
+      case 2: {
+        auto k = luaL_checkstring(L, 1);
+        auto v = nf7::luajit::CheckValue(L, 2);
+        caller->env().ExecSub(
+            caller, [caller, callee, k = std::string {k}, v = std::move(v)]() {
+              caller->Handle(k, v, callee);
+            });
+      } return;
+      default:
+        if (auto log = th.logger()) {
+          log->Warn("invalid use of yield, nf7:yield() or nf7:yield(name, value)");
+        }
+        th.Resume(L, 0);
+        return;
+      }
+
+    case nf7::luajit::Thread::kFinished:
+      return;
+
+    default:
+      if (auto log = th.logger()) {
+        log->Warn(std::string {"luajit execution error: "}+lua_tostring(L, -1));
+      }
+      return;
+    }
+  };
+}
+
 }  // namespace nf7::luajit