lua

lcorolib.c (4877B)

---

 /*
 ** $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"
 #include "llimits.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_closethread(co, L);  /* 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_closethread(co, L);
       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;
 }