lbaselib.c

Lua 语言解释器源码

    case LUA_TBOOLEAN:
      lua_pushstring(L, (lua_toboolean(L, 1) ? "true" : "false"));
      return 1;
    case LUA_TTABLE:
      sprintf(buff, "table: %p", lua_topointer(L, 1));
      break;
    case LUA_TFUNCTION:
      sprintf(buff, "function: %p", lua_topointer(L, 1));
      break;
    case LUA_TUSERDATA:
    case LUA_TLIGHTUSERDATA:
      sprintf(buff, "userdata: %p", lua_touserdata(L, 1));
      break;
    case LUA_TTHREAD:
      sprintf(buff, "thread: %p", (void *)lua_tothread(L, 1));
      break;
    case LUA_TNIL:
      lua_pushliteral(L, "nil");
      return 1;
  }
  lua_pushstring(L, buff);
  return 1;
}


static int luaB_newproxy (lua_State *L) {
  lua_settop(L, 1);
  lua_newuserdata(L, 0);  /* create proxy */
  if (lua_toboolean(L, 1) == 0)
    return 1;  /* no metatable */
  else if (lua_isboolean(L, 1)) {
    lua_newtable(L);  /* create a new metatable `m' ... */
    lua_pushvalue(L, -1);  /* ... and mark `m' as a valid metatable */
    lua_pushboolean(L, 1);
    lua_rawset(L, lua_upvalueindex(1));  /* weaktable[m] = true */
  }
  else {
    int validproxy = 0;  /* to check if weaktable[metatable(u)] == true */
    if (lua_getmetatable(L, 1)) {
      lua_rawget(L, lua_upvalueindex(1));
      validproxy = lua_toboolean(L, -1);
      lua_pop(L, 1);  /* remove value */
    }
    luaL_argcheck(L, validproxy, 1, "boolean or proxy expected");
    lua_getmetatable(L, 1);  /* metatable is valid; get it */
  }
  lua_setmetatable(L, 2);
  return 1;
}


/*
** {======================================================
** `require' function
** =======================================================
*/


/* name of global that holds table with loaded packages */
#define REQTAB		"_LOADED"

/* name of global that holds the search path for packages */
#define LUA_PATH	"LUA_PATH"

#ifndef LUA_PATH_SEP
#define LUA_PATH_SEP	';'
#endif

#ifndef LUA_PATH_MARK
#define LUA_PATH_MARK	'?'
#endif

#ifndef LUA_PATH_DEFAULT
#define LUA_PATH_DEFAULT	"?;?.lua"
#endif


static const char *getpath (lua_State *L) {
  const char *path;
  lua_getglobal(L, LUA_PATH);  /* try global variable */
  path = lua_tostring(L, -1);
  lua_pop(L, 1);
  if (path) return path;
  path = getenv(LUA_PATH);  /* else try environment variable */
  if (path) return path;
  return LUA_PATH_DEFAULT;  /* else use default */
}


static const char *pushnextpath (lua_State *L, const char *path) {
  const char *l;
  if (*path == '\0') return NULL;  /* no more paths */
  if (*path == LUA_PATH_SEP) path++;  /* skip separator */
  l = strchr(path, LUA_PATH_SEP);  /* find next separator */
  if (l == NULL) l = path+strlen(path);
  lua_pushlstring(L, path, l - path);  /* directory name */
  return l;
}


static void pushcomposename (lua_State *L) {
  const char *path = lua_tostring(L, -1);
  const char *wild;
  int n = 1;
  while ((wild = strchr(path, LUA_PATH_MARK)) != NULL) {
    /* is there stack space for prefix, name, and eventual last sufix? */
    luaL_checkstack(L, 3, "too many marks in a path component");
    lua_pushlstring(L, path, wild - path);  /* push prefix */
    lua_pushvalue(L, 1);  /* push package name (in place of MARK) */
    path = wild + 1;  /* continue after MARK */
    n += 2;
  }
  lua_pushstring(L, path);  /* push last sufix (`n' already includes this) */
  lua_concat(L, n);
}


static int luaB_require (lua_State *L) {
  const char *path;
  int status = LUA_ERRFILE;  /* not found (yet) */
  luaL_checkstring(L, 1);
  lua_settop(L, 1);
  lua_getglobal(L, REQTAB);
  if (!lua_istable(L, 2)) return luaL_error(L, "`" REQTAB "' is not a table");
  path = getpath(L);
  lua_pushvalue(L, 1);  /* check package's name in book-keeping table */
  lua_rawget(L, 2);
  if (lua_toboolean(L, -1))  /* is it there? */
    return 1;  /* package is already loaded; return its result */
  else {  /* must load it */
    while (status == LUA_ERRFILE) {
      lua_settop(L, 3);  /* reset stack position */
      if ((path = pushnextpath(L, path)) == NULL) break;
      pushcomposename(L);
      status = luaL_loadfile(L, lua_tostring(L, -1));  /* try to load it */
    }
  }
  switch (status) {
    case 0: {
      lua_getglobal(L, "_REQUIREDNAME");  /* save previous name */
      lua_insert(L, -2);  /* put it below function */
      lua_pushvalue(L, 1);
      lua_setglobal(L, "_REQUIREDNAME");  /* set new name */
      lua_call(L, 0, 1);  /* run loaded module */
      lua_insert(L, -2);  /* put result below previous name */
      lua_setglobal(L, "_REQUIREDNAME");  /* reset to previous name */
      if (lua_isnil(L, -1)) {  /* no/nil return? */
        lua_pushboolean(L, 1);
        lua_replace(L, -2);  /* replace to true */
      }
      lua_pushvalue(L, 1);
      lua_pushvalue(L, -2);
      lua_rawset(L, 2);  /* mark it as loaded */
      return 1;  /* return value */
    }
    case LUA_ERRFILE: {  /* file not found */
      return luaL_error(L, "could not load package `%s' from path `%s'",
                            lua_tostring(L, 1), getpath(L));
    }
    default: {
      return luaL_error(L, "error loading package `%s' (%s)",
                           lua_tostring(L, 1), lua_tostring(L, -1));
    }
  }
}

/* }====================================================== */


static const luaL_reg base_funcs[] = {
  {"error", luaB_error},
  {"getmetatable", luaB_getmetatable},
  {"setmetatable", luaB_setmetatable},
  {"getfenv", luaB_getfenv},
  {"setfenv", luaB_setfenv},
  {"next", luaB_next},
  {"ipairs", luaB_ipairs},
  {"pairs", luaB_pairs},
  {"print", luaB_print},
  {"tonumber", luaB_tonumber},
  {"tostring", luaB_tostring},
  {"type", luaB_type},
  {"assert", luaB_assert},
  {"unpack", luaB_unpack},
  {"rawequal", luaB_rawequal},
  {"rawget", luaB_rawget},
  {"rawset", luaB_rawset},
  {"pcall", luaB_pcall},
  {"xpcall", luaB_xpcall},
  {"collectgarbage", luaB_collectgarbage},
  {"gcinfo", luaB_gcinfo},
  {"loadfile", luaB_loadfile},
  {"dofile", luaB_dofile},
  {"loadstring", luaB_loadstring},
  {"require", luaB_require},
  {NULL, NULL}
};


/*
** {======================================================
** Coroutine library
** =======================================================
*/

static int auxresume (lua_State *L, lua_State *co, int narg) {
  int status;
  if (!lua_checkstack(co, narg))
    luaL_error(L, "too many arguments to resume");
  lua_xmove(L, co, narg);
  status = lua_resume(co, narg);
  if (status == 0) {
    int nres = lua_gettop(co);
    if (!lua_checkstack(L, nres))
      luaL_error(L, "too many results to resume");
    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 = lua_tothread(L, 1);
  int r;
  luaL_argcheck(L, co, 1, "coroutine expected");
  r = auxresume(L, co, lua_gettop(L) - 1);
  if (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 (r < 0) {
    if (lua_isstring(L, -1)) {  /* error object is a string? */
      luaL_where(L, 1);  /* add extra info */
      lua_insert(L, -2);
      lua_concat(L, 2);
    }
    lua_error(L);  /* propagate error */
  }
  return r;
}


static int luaB_cocreate (lua_State *L) {
  lua_State *NL = lua_newthread(L);
  luaL_argcheck(L, lua_isfunction(L, 1) && !lua_iscfunction(L, 1), 1,
    "Lua function expected");
  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));
}


static int luaB_costatus (lua_State *L) {
  lua_State *co = lua_tothread(L, 1);
  luaL_argcheck(L, co, 1, "coroutine expected");
  if (L == co) lua_pushliteral(L, "running");
  else {
    lua_Debug ar;
    if (lua_getstack(co, 0, &ar) == 0 && lua_gettop(co) == 0)
      lua_pushliteral(L, "dead");
    else
      lua_pushliteral(L, "suspended");
  }
  return 1;
}


static const luaL_reg co_funcs[] = {
  {"create", luaB_cocreate},
  {"wrap", luaB_cowrap},
  {"resume", luaB_coresume},
  {"yield", luaB_yield},
  {"status", luaB_costatus},
  {NULL, NULL}
};

/* }====================================================== */



static void base_open (lua_State *L) {
  lua_pushliteral(L, "_G");
  lua_pushvalue(L, LUA_GLOBALSINDEX);
  luaL_openlib(L, NULL, base_funcs, 0);  /* open lib into global table */
  lua_pushliteral(L, "_VERSION");
  lua_pushliteral(L, LUA_VERSION);
  lua_rawset(L, -3);  /* set global _VERSION */
  /* `newproxy' needs a weaktable as upvalue */
  lua_pushliteral(L, "newproxy");
  lua_newtable(L);  /* new table `w' */
  lua_pushvalue(L, -1);  /* `w' will be its own metatable */
  lua_setmetatable(L, -2);
  lua_pushliteral(L, "__mode");
  lua_pushliteral(L, "k");
  lua_rawset(L, -3);  /* metatable(w).__mode = "k" */
  lua_pushcclosure(L, luaB_newproxy, 1);
  lua_rawset(L, -3);  /* set global `newproxy' */
  lua_rawset(L, -1);  /* set global _G */
}


LUALIB_API int luaopen_base (lua_State *L) {
  base_open(L);
  luaL_openlib(L, LUA_COLIBNAME, co_funcs, 0);
  lua_newtable(L);
  lua_setglobal(L, REQTAB);
  return 0;
}