liblua/lcorolib.c

   1 /*
   2 ** $Id: lcorolib.c,v 1.5 2013/02/21 13:44:53 roberto Exp $
   3 ** Coroutine Library
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdlib.h>
   9
  10
  11 #define lcorolib_c
  12 #define LUA_LIB
  13
  14 #include "lua.h"
  15
  16 #include "lauxlib.h"
  17 #include "lualib.h"
  18
  19
  20 static int auxresume (lua_State *L, lua_State *co, int narg) {
  21   int status;
  22   if (!lua_checkstack(co, narg)) {
  23     lua_pushliteral(L, "too many arguments to resume");
  24     return -1;  /* error flag */
  25   }
  26   if (lua_status(co) == LUA_OK && lua_gettop(co) == 0) {
  27     lua_pushliteral(L, "cannot resume dead coroutine");
  28     return -1;  /* error flag */
  29   }
  30   lua_xmove(L, co, narg);
  31   status = lua_resume(co, L, narg);
  32   if (status == LUA_OK || status == LUA_YIELD) {
  33     int nres = lua_gettop(co);
  34     if (!lua_checkstack(L, nres + 1)) {
  35       lua_pop(co, nres);  /* remove results anyway */
  36       lua_pushliteral(L, "too many results to resume");
  37       return -1;  /* error flag */
  38     }
  39     lua_xmove(co, L, nres);  /* move yielded values */
  40     return nres;
  41   }
  42   else {
  43     lua_xmove(co, L, 1);  /* move error message */
  44     return -1;  /* error flag */
  45   }
  46 }
  47
  48
  49 static int luaB_coresume (lua_State *L) {
  50   lua_State *co = lua_tothread(L, 1);
  51   int r;
  52   luaL_argcheck(L, co, 1, "coroutine expected");
  53   r = auxresume(L, co, lua_gettop(L) - 1);
  54   if (r < 0) {
  55     lua_pushboolean(L, 0);
  56     lua_insert(L, -2);
  57     return 2;  /* return false + error message */
  58   }
  59   else {
  60     lua_pushboolean(L, 1);
  61     lua_insert(L, -(r + 1));
  62     return r + 1;  /* return true + `resume' returns */
  63   }
  64 }
  65
  66
  67 static int luaB_auxwrap (lua_State *L) {
  68   lua_State *co = lua_tothread(L, lua_upvalueindex(1));
  69   int r = auxresume(L, co, lua_gettop(L));
  70   if (r < 0) {
  71     if (lua_isstring(L, -1)) {  /* error object is a string? */
  72       luaL_where(L, 1);  /* add extra info */
  73       lua_insert(L, -2);
  74       lua_concat(L, 2);
  75     }
  76     return lua_error(L);  /* propagate error */
  77   }
  78   return r;
  79 }
  80
  81
  82 static int luaB_cocreate (lua_State *L) {
  83   lua_State *NL;
  84   luaL_checktype(L, 1, LUA_TFUNCTION);
  85   NL = lua_newthread(L);
  86   lua_pushvalue(L, 1);  /* move function to top */
  87   lua_xmove(L, NL, 1);  /* move function from L to NL */
  88   return 1;
  89 }
  90
  91
  92 static int luaB_cowrap (lua_State *L) {
  93   luaB_cocreate(L);
  94   lua_pushcclosure(L, luaB_auxwrap, 1);
  95   return 1;
  96 }
  97
  98
  99 static int luaB_yield (lua_State *L) {
 100   return lua_yield(L, lua_gettop(L));
 101 }
 102
 103
 104 static int luaB_costatus (lua_State *L) {
 105   lua_State *co = lua_tothread(L, 1);
 106   luaL_argcheck(L, co, 1, "coroutine expected");
 107   if (L == co) lua_pushliteral(L, "running");
 108   else {
 109     switch (lua_status(co)) {
 110       case LUA_YIELD:
 111         lua_pushliteral(L, "suspended");
 112         break;
 113       case LUA_OK: {
 114         lua_Debug ar;
 115         if (lua_getstack(co, 0, &ar) > 0)  /* does it have frames? */
 116           lua_pushliteral(L, "normal");  /* it is running */
 117         else if (lua_gettop(co) == 0)
 118             lua_pushliteral(L, "dead");
 119         else
 120           lua_pushliteral(L, "suspended");  /* initial state */
 121         break;
 122       }
 123       default:  /* some error occurred */
 124         lua_pushliteral(L, "dead");
 125         break;
 126     }
 127   }
 128   return 1;
 129 }
 130
 131
 132 static int luaB_corunning (lua_State *L) {
 133   int ismain = lua_pushthread(L);
 134   lua_pushboolean(L, ismain);
 135   return 2;
 136 }
 137
 138
 139 static const luaL_Reg co_funcs[] = {
 140   {"create", luaB_cocreate},
 141   {"resume", luaB_coresume},
 142   {"running", luaB_corunning},
 143   {"status", luaB_costatus},
 144   {"wrap", luaB_cowrap},
 145   {"yield", luaB_yield},
 146   {NULL, NULL}
 147 };
 148
 149
 150
 151 LUAMOD_API int luaopen_coroutine (lua_State *L) {
 152   luaL_newlib(L, co_funcs);
 153   return 1;
 154 }
 155