lua: native C-API coroutine sample

end.lua

print('load end.lua')

Makefile

INCDIR = $(HOME)/opt/local/include/luajit-2.0
LIBDIR = $(HOME)/opt/local/lib
LIB = -lluajit-51

all: native

native:
	cc --std=c99 -o native-co native.c -I$(INCDIR) -L$(LIBDIR) $(LIB) -pagezero_size 10000 -image_base 100000000

clean:
	rm native-co

.PHONY: clean native

native.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <lua.h>
#include <lauxlib.h>

#define STACK_DUMP(L, Name) stack_dump(L, Name)


bool running;


void error(lua_State *L, const char *fmt, ...) {
  va_list argp;
  va_start(argp, fmt);
  vfprintf(stderr, fmt, argp);
  va_end(argp);
  lua_close(L);
  exit(EXIT_FAILURE);
}

static void stack_dump(lua_State *L, const char *stackname) {
  int i;
  int top = lua_gettop(L);
  printf("--------------- %s STACK ---------------\n", stackname);
  for (i = top; i >= 1; i--) {
    int t = lua_type(L, i);
    printf("[%2d - %8s] : ", i, lua_typename(L, t));
    switch (t) {
      case LUA_TSTRING:
        printf("%s", lua_tostring(L, i));
        break;
      case LUA_TBOOLEAN:
        printf(lua_toboolean(L, i) ? "true" : "false");
        break;
      case LUA_TNUMBER:
        printf("%g", lua_tonumber(L, i));
        break;
      case LUA_TNIL:
        printf("nil");
        break;
      case LUA_TNONE:
        printf("none");
        break;
      case LUA_TFUNCTION:
        printf("<function %p>", lua_topointer(L, i));
        break;
      case LUA_TTABLE:
        printf("<table %p>", lua_topointer(L, i));
        break;
      case LUA_TTHREAD:
        printf("<thread %p>", lua_topointer(L, i));
        break;
      case LUA_TUSERDATA:
        printf("<userdata %p>", lua_topointer(L, i));
        break;
      case LUA_TLIGHTUSERDATA:
        printf("<lightuserdata %p>", lua_topointer(L, i));
        break;
      default:
        printf("unknown %s", lua_typename(L, t));
        break;
    }
    printf("\n");
  }
  printf("--------------- %s STACK ---------------\n", stackname);
}

static int lua_cb(lua_State *L) {
  printf("called lua_cb\n");
  return 0;
}

static int lua_mynext(lua_State *L) {
  printf("called lua_mynext\n");
  lua_pushnumber(L, 1);
  lua_pushnumber(L, 2);
  lua_pushcfunction(L, lua_cb);
  return lua_yield(L, 3);
}

int main (void) {
  int status = 0;
  int result = 0;
  lua_State *L = luaL_newstate();
  luaL_openlibs(L);

  status = luaL_loadfile(L, "start.lua"); /* L[ function ] */
  if (status) {
    fprintf(stderr, "could not load start.lua: %s\n", lua_tostring(L, -1));
    exit(1);
  }

  result = lua_pcall(L, 0, LUA_MULTRET, 0); /* L[ ] */
  if (result) {
    fprintf(stderr, "failed to run start.lua script: %s\n", lua_tostring(L, -1));
    exit(1);
  }

  lua_State *L1 = lua_newthread(L);
  luaL_openlibs(L1);
  lua_register(L1, "next", lua_mynext);

  luaL_dofile(L1, "proc.lua"); 
  lua_getglobal(L1, "step");

  do {
    lua_pushnumber(L1, 1);
    lua_pushstring(L1, "hello");
    status = lua_resume(L1, 2);
    printf("lua_resume: %d\n", status);
    if (status == LUA_YIELD) {
      lua_CFunction f = lua_tocfunction(L1, -1);
      f(L1);
    }    
  } while (status == LUA_YIELD);

  status = luaL_loadfile(L, "end.lua");
  if (status) {
    fprintf(stderr, "could not load end.lua: %s\n", lua_tostring(L, -1));
    exit(1);
  }

  result = lua_pcall(L, 0, LUA_MULTRET, 0);
  if (result) {
    fprintf(stderr, "failed to run end.lua script: %s\n", lua_tostring(L, -1));
    exit(1);
  }

  lua_close(L);
  return 0;
}

proc.lua

--[[
local i = 0
while true do
  print('iterate', i)
  sleep(1000000)
  i = i + 1
  if i == 4 then
    print('bkrea!')
    break
  end
end
--]]

function step ()
  print('next', next(1))
  print('next', next('hello', 2))
  print('next', next(function () end))
end

--finish()
print('load proc.lua')

start.lua

print('load start.lua')