From Lua 5.3: Add lua_isyieldable().

Contributed by François Perrad.

src/lj_api.c

@@ -1113,6 +1113,11 @@ LUALIB_API int luaL_callmeta(lua_State *L, int idx, const char *field)
 
 /* -- Coroutine yield and resume ------------------------------------------ */
 
+LUA_API int lua_isyieldable(lua_State *L)
+{
+  return cframe_canyield(L->cframe);
+}
+
 LUA_API int lua_yield(lua_State *L, int nresults)
 {
   void *cf = L->cframe;