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  1. /*
  2. ** $Id: lcorolib.c $
  3. ** Coroutine Library
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7. #define lcorolib_c
  8. #define LUA_LIB
  9.  
  10. #include "lprefix.h"
  11.  
  12.  
  13. #include <stdlib.h>
  14.  
  15. #include "lua.h"
  16.  
  17. #include "lauxlib.h"
  18. #include "lualib.h"
  19.  
  20.  
  21. static lua_State *getco (lua_State *L) {
  22.   lua_State *co = lua_tothread(L, 1);
  23.   luaL_argexpected(L, co, 1, "thread");
  24.   return co;
  25. }
  26.  
  27.  
  28. /*
  29. ** Resumes a coroutine. Returns the number of results for non-error
  30. ** cases or -1 for errors.
  31. */
  32. static int auxresume (lua_State *L, lua_State *co, int narg) {
  33.   int status, nres;
  34.   if (l_unlikely(!lua_checkstack(co, narg))) {
  35.     lua_pushliteral(L, "too many arguments to resume");
  36.     return -1;  /* error flag */
  37.   }
  38.   lua_xmove(L, co, narg);
  39.   status = lua_resume(co, L, narg, &nres);
  40.   if (l_likely(status == LUA_OK || status == LUA_YIELD)) {
  41.     if (l_unlikely(!lua_checkstack(L, nres + 1))) {
  42.       lua_pop(co, nres);  /* remove results anyway */
  43.       lua_pushliteral(L, "too many results to resume");
  44.       return -1;  /* error flag */
  45.     }
  46.     lua_xmove(co, L, nres);  /* move yielded values */
  47.     return nres;
  48.   }
  49.   else {
  50.     lua_xmove(co, L, 1);  /* move error message */
  51.     return -1;  /* error flag */
  52.   }
  53. }
  54.  
  55.  
  56. static int luaB_coresume (lua_State *L) {
  57.   lua_State *co = getco(L);
  58.   int r;
  59.   r = auxresume(L, co, lua_gettop(L) - 1);
  60.   if (l_unlikely(r < 0)) {
  61.     lua_pushboolean(L, 0);
  62.     lua_insert(L, -2);
  63.     return 2;  /* return false + error message */
  64.   }
  65.   else {
  66.     lua_pushboolean(L, 1);
  67.     lua_insert(L, -(r + 1));
  68.     return r + 1;  /* return true + 'resume' returns */
  69.   }
  70. }
  71.  
  72.  
  73. static int luaB_auxwrap (lua_State *L) {
  74.   lua_State *co = lua_tothread(L, lua_upvalueindex(1));
  75.   int r = auxresume(L, co, lua_gettop(L));
  76.   if (l_unlikely(r < 0)) {  /* error? */
  77.     int stat = lua_status(co);
  78.     if (stat != LUA_OK && stat != LUA_YIELD) {  /* error in the coroutine? */
  79.       stat = lua_resetthread(co);  /* close its tbc variables */
  80.       lua_assert(stat != LUA_OK);
  81.       lua_xmove(co, L, 1);  /* move error message to the caller */
  82.     }
  83.     if (stat != LUA_ERRMEM &&  /* not a memory error and ... */
  84.         lua_type(L, -1) == LUA_TSTRING) {  /* ... error object is a string? */
  85.       luaL_where(L, 1);  /* add extra info, if available */
  86.       lua_insert(L, -2);
  87.       lua_concat(L, 2);
  88.     }
  89.     return lua_error(L);  /* propagate error */
  90.   }
  91.   return r;
  92. }
  93.  
  94.  
  95. static int luaB_cocreate (lua_State *L) {
  96.   lua_State *NL;
  97.   luaL_checktype(L, 1, LUA_TFUNCTION);
  98.   NL = lua_newthread(L);
  99.   lua_pushvalue(L, 1);  /* move function to top */
  100.   lua_xmove(L, NL, 1);  /* move function from L to NL */
  101.   return 1;
  102. }
  103.  
  104.  
  105. static int luaB_cowrap (lua_State *L) {
  106.   luaB_cocreate(L);
  107.   lua_pushcclosure(L, luaB_auxwrap, 1);
  108.   return 1;
  109. }
  110.  
  111.  
  112. static int luaB_yield (lua_State *L) {
  113.   return lua_yield(L, lua_gettop(L));
  114. }
  115.  
  116.  
  117. #define COS_RUN         0
  118. #define COS_DEAD        1
  119. #define COS_YIELD       2
  120. #define COS_NORM        3
  121.  
  122.  
  123. static const char *const statname[] =
  124.   {"running", "dead", "suspended", "normal"};
  125.  
  126.  
  127. static int auxstatus (lua_State *L, lua_State *co) {
  128.   if (L == co) return COS_RUN;
  129.   else {
  130.     switch (lua_status(co)) {
  131.       case LUA_YIELD:
  132.         return COS_YIELD;
  133.       case LUA_OK: {
  134.         lua_Debug ar;
  135.         if (lua_getstack(co, 0, &ar))  /* does it have frames? */
  136.           return COS_NORM;  /* it is running */
  137.         else if (lua_gettop(co) == 0)
  138.             return COS_DEAD;
  139.         else
  140.           return COS_YIELD;  /* initial state */
  141.       }
  142.       default:  /* some error occurred */
  143.         return COS_DEAD;
  144.     }
  145.   }
  146. }
  147.  
  148.  
  149. static int luaB_costatus (lua_State *L) {
  150.   lua_State *co = getco(L);
  151.   lua_pushstring(L, statname[auxstatus(L, co)]);
  152.   return 1;
  153. }
  154.  
  155.  
  156. static int luaB_yieldable (lua_State *L) {
  157.   lua_State *co = lua_isnone(L, 1) ? L : getco(L);
  158.   lua_pushboolean(L, lua_isyieldable(co));
  159.   return 1;
  160. }
  161.  
  162.  
  163. static int luaB_corunning (lua_State *L) {
  164.   int ismain = lua_pushthread(L);
  165.   lua_pushboolean(L, ismain);
  166.   return 2;
  167. }
  168.  
  169.  
  170. static int luaB_close (lua_State *L) {
  171.   lua_State *co = getco(L);
  172.   int status = auxstatus(L, co);
  173.   switch (status) {
  174.     case COS_DEAD: case COS_YIELD: {
  175.       status = lua_resetthread(co);
  176.       if (status == LUA_OK) {
  177.         lua_pushboolean(L, 1);
  178.         return 1;
  179.       }
  180.       else {
  181.         lua_pushboolean(L, 0);
  182.         lua_xmove(co, L, 1);  /* move error message */
  183.         return 2;
  184.       }
  185.     }
  186.     default:  /* normal or running coroutine */
  187.       return luaL_error(L, "cannot close a %s coroutine", statname[status]);
  188.   }
  189. }
  190.  
  191.  
  192. static const luaL_Reg co_funcs[] = {
  193.   {"create", luaB_cocreate},
  194.   {"resume", luaB_coresume},
  195.   {"running", luaB_corunning},
  196.   {"status", luaB_costatus},
  197.   {"wrap", luaB_cowrap},
  198.   {"yield", luaB_yield},
  199.   {"isyieldable", luaB_yieldable},
  200.   {"close", luaB_close},
  201.   {NULL, NULL}
  202. };
  203.  
  204.  
  205.  
  206. LUAMOD_API int luaopen_coroutine (lua_State *L) {
  207.   luaL_newlib(L, co_funcs);
  208.   return 1;
  209. }
  210.  
  211.