/*
** $Id: lcorolib.c $
** Coroutine Library
** See Copyright Notice in lua.h
*/
#define lcorolib_c
#define LUA_LIB
#include "lprefix.h"
#include <stdlib.h>
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
static lua_State *getco (lua_State *L) {
lua_State *co = lua_tothread(L, 1);
luaL_argexpected(L, co, 1, "thread");
return co;
}
/*
** Resumes a coroutine. Returns the number of results for non-error
** cases or -1 for errors.
*/
static int auxresume (lua_State *L, lua_State *co, int narg) {
int status, nres;
if (l_unlikely(!lua_checkstack(co, narg))) {
lua_pushliteral(L, "too many arguments to resume");
return -1; /* error flag */
}
lua_xmove(L, co, narg);
status = lua_resume(co, L, narg, &nres);
if (l_likely(status == LUA_OK || status == LUA_YIELD)) {
if (l_unlikely(!lua_checkstack(L, nres + 1))) {
lua_pop(co, nres); /* remove results anyway */
lua_pushliteral(L, "too many results to resume");
return -1; /* error flag */
}
lua_xmove(co, L, nres); /* move yielded values */
return nres;
}
else {
lua_xmove(co, L, 1); /* move error message */
return -1; /* error flag */
}
}
static int luaB_coresume (lua_State *L) {
lua_State *co = getco(L);
int r;
r = auxresume(L, co, lua_gettop(L) - 1);
if (l_unlikely(r < 0)) {
lua_pushboolean(L, 0);
lua_insert(L, -2);
return 2; /* return false + error message */
}
else {
lua_pushboolean(L, 1);
lua_insert(L, -(r + 1));
return r + 1; /* return true + 'resume' returns */
}
}
static int luaB_auxwrap (lua_State *L) {
lua_State *co = lua_tothread(L, lua_upvalueindex(1));
int r = auxresume(L, co, lua_gettop(L));
if (l_unlikely(r < 0)) { /* error? */
int stat = lua_status(co);
if (stat != LUA_OK && stat != LUA_YIELD) { /* error in the coroutine? */
stat = lua_resetthread(co); /* close its tbc variables */
lua_assert(stat != LUA_OK);
lua_xmove(co, L, 1); /* move error message to the caller */
}
if (stat != LUA_ERRMEM && /* not a memory error and ... */
lua_type(L, -1) == LUA_TSTRING) { /* ... error object is a string? */
luaL_where(L, 1); /* add extra info, if available */
lua_insert(L, -2);
lua_concat(L, 2);
}
return lua_error(L); /* propagate error */
}
return r;
}
static int luaB_cocreate (lua_State *L) {
lua_State *NL;
luaL_checktype(L, 1, LUA_TFUNCTION);
NL = lua_newthread(L);
lua_pushvalue(L, 1); /* move function to top */
lua_xmove(L, NL, 1); /* move function from L to NL */
return 1;
}
static int luaB_cowrap (lua_State *L) {
luaB_cocreate(L);
lua_pushcclosure(L, luaB_auxwrap, 1);
return 1;
}
static int luaB_yield (lua_State *L) {
return lua_yield(L, lua_gettop(L));
}
#define COS_RUN 0
#define COS_DEAD 1
#define COS_YIELD 2
#define COS_NORM 3
static const char *const statname[] =
{"running", "dead", "suspended", "normal"};
static int auxstatus (lua_State *L, lua_State *co) {
if (L == co) return COS_RUN;
else {
switch (lua_status(co)) {
case LUA_YIELD:
return COS_YIELD;
case LUA_OK: {
lua_Debug ar;
if (lua_getstack(co, 0, &ar)) /* does it have frames? */
return COS_NORM; /* it is running */
else if (lua_gettop(co) == 0)
return COS_DEAD;
else
return COS_YIELD; /* initial state */
}
default: /* some error occurred */
return COS_DEAD;
}
}
}
static int luaB_costatus (lua_State *L) {
lua_State *co = getco(L);
lua_pushstring(L, statname[auxstatus(L, co)]);
return 1;
}
static int luaB_yieldable (lua_State *L) {
lua_State *co = lua_isnone(L, 1) ? L : getco(L);
lua_pushboolean(L, lua_isyieldable(co));
return 1;
}
static int luaB_corunning (lua_State *L) {
int ismain = lua_pushthread(L);
lua_pushboolean(L, ismain);
return 2;
}
static int luaB_close (lua_State *L) {
lua_State *co = getco(L);
int status = auxstatus(L, co);
switch (status) {
case COS_DEAD: case COS_YIELD: {
status = lua_resetthread(co);
if (status == LUA_OK) {
lua_pushboolean(L, 1);
return 1;
}
else {
lua_pushboolean(L, 0);
lua_xmove(co, L, 1); /* move error message */
return 2;
}
}
default: /* normal or running coroutine */
return luaL_error(L, "cannot close a %s coroutine", statname[status]);
}
}
static const luaL_Reg co_funcs[] = {
{"create", luaB_cocreate},
{"resume", luaB_coresume},
{"running", luaB_corunning},
{"status", luaB_costatus},
{"wrap", luaB_cowrap},
{"yield", luaB_yield},
{"isyieldable", luaB_yieldable},
{"close", luaB_close},
{NULL, NULL}
};
LUAMOD_API int luaopen_coroutine (lua_State *L) {
luaL_newlib(L, co_funcs);
return 1;
}