Hi!
I want lua code to be running as a single coroutine. For example,
imagine C/C++ GUI application with logic written in lua. GUI event
loop runs in C/C++, and lua code needs to drop back to it when it
needs input from the user (it can't get user input by calling C/C++
function, as this would not resume event loop). I'm trying to use a
single lua coroutine for it, but I'm confused about whether I can
call lua_resume on a lua_State returned by lua_open, not lua_newthread,
cause lua_resume documentation says "To start a coroutine, you first
create a new thread".
This test code works, but I want to be sure that there is no errors
or undefined behaviour in it:
---
#include<lua.h>
#include<lualib.h>
#include<lauxlib.h>
#include<stdio.h>
#include<assert.h>
int my_func(lua_State* lua) {
fprintf(stderr, "[LUA] Hello from lua!\n");
return 0;
}
int my_yield(lua_State* lua) {
fprintf(stderr, "[LUA] Now yielding...\n");
return lua_yield(lua, 0);
}
int main() {
int ret;
/* create lua state */
lua_State* lua = lua_open();
assert(lua != NULL);
/* register own lua functions */
lua_register(lua, "my_func", my_func);
lua_register(lua, "my_yield", my_yield);
/* load lua code */
ret = luaL_dostring(lua, "function main() my_func(\"Hello, world!\"); my_yield(); for i = 1,9 do my_func(i); if i % 3 == 0 then my_yield(); end end my_yield(); my_func(\"Bye!\"); end");
assert(ret == 0);
/* push lua main() function onto the stack */
lua_getglobal(lua, "main");
/* main loop which runs "in parallel" to lua main(), switching back and forth */
fprintf(stderr, "[ C ] Starting mainloop...\n");
while (1) {
fprintf(stderr, "[ C ] Running/resuming lua...\n");
ret = lua_resume(lua, 0);
if (ret == LUA_YIELD) {
fprintf(stderr, "[ C ] Lua has yielded!\n");
} else if (ret == 0) {
fprintf(stderr, "[ C ] Lua has finished!\n");
break;
} else {
assert(0); /* something gone wrong */
}
fprintf(stderr, "[ C ] Hello from C!\n");
}
fprintf(stderr, "[ C ] We're done!\n");
lua_close(lua);
return 0;
}
---
