lbaselib.c

/*
** $Id: lbaselib.c $
** Basic library
** See Copyright Notice in lua.h
*/

#define lbaselib_c
#define LUA_LIB

#include "lprefix.h"


#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


static int luaB_print (lua_State *L) {
  int n = lua_gettop(L);  /* number of arguments */
  int i;
  for (i = 1; i <= n; i++) {  /* for each argument */
    size_t l;
    const char *s = luaL_tolstring(L, i, &l);  /* convert it to string */
    if (i > 1)  /* not the first element? */
      lua_writestring("\t", 1);  /* add a tab before it */
    lua_writestring(s, l);  /* print it */
    lua_pop(L, 1);  /* pop result */
  }
  lua_writeline();
  return 0;
}


/*
** Creates a warning with all given arguments.
** Check first for errors; otherwise an error may interrupt
** the composition of a warning, leaving it unfinished.
*/
static int luaB_warn (lua_State *L) {
  int n = lua_gettop(L);  /* number of arguments */
  int i;
  luaL_checkstring(L, 1);  /* at least one argument */
  for (i = 2; i <= n; i++)
    luaL_checkstring(L, i);  /* make sure all arguments are strings */
  for (i = 1; i < n; i++)  /* compose warning */
    lua_warning(L, lua_tostring(L, i), 1);
  lua_warning(L, lua_tostring(L, n), 0);  /* close warning */
  return 0;
}


#define SPACECHARS	" \f\n\r\t\v"

static const char *b_str2int (const char *s, int base, lua_Integer *pn) {
  lua_Unsigned n = 0;
  int neg = 0;
  s += strspn(s, SPACECHARS);  /* skip initial spaces */
  if (*s == '-') { s++; neg = 1; }  /* handle sign */
  else if (*s == '+') s++;
  if (!isalnum((unsigned char)*s))  /* no digit? */
    return NULL;
  do {
    int digit = (isdigit((unsigned char)*s)) ? *s - '0'
                   : (toupper((unsigned char)*s) - 'A') + 10;
    if (digit >= base) return NULL;  /* invalid numeral */
    n = n * base + digit;
    s++;
  } while (isalnum((unsigned char)*s));
  s += strspn(s, SPACECHARS);  /* skip trailing spaces */
  *pn = (lua_Integer)((neg) ? (0u - n) : n);
  return s;
}


static int luaB_tonumber (lua_State *L) {
  if (lua_isnoneornil(L, 2)) {  /* standard conversion? */
    if (lua_type(L, 1) == LUA_TNUMBER) {  /* already a number? */
      lua_settop(L, 1);  /* yes; return it */
      return 1;
    }
    else {
      size_t l;
      const char *s = lua_tolstring(L, 1, &l);
      if (s != NULL && lua_stringtonumber(L, s) == l + 1)
        return 1;  /* successful conversion to number */
      /* else not a number */
      luaL_checkany(L, 1);  /* (but there must be some parameter) */
    }
  }
  else {
    size_t l;
    const char *s;
    lua_Integer n = 0;  /* to avoid warnings */
    lua_Integer base = luaL_checkinteger(L, 2);
    luaL_checktype(L, 1, LUA_TSTRING);  /* no numbers as strings */
    s = lua_tolstring(L, 1, &l);
    luaL_argcheck(L, 2 <= base && base <= 36, 2, "base out of range");
    if (b_str2int(s, (int)base, &n) == s + l) {
      lua_pushinteger(L, n);
      return 1;
    }  /* else not a number */
  }  /* else not a number */
  luaL_pushfail(L);  /* not a number */
  return 1;
}


static int luaB_error (lua_State *L) {
  int level = (int)luaL_optinteger(L, 2, 1);
  lua_settop(L, 1);
  if (lua_type(L, 1) == LUA_TSTRING && level > 0) {
    luaL_where(L, level);   /* add extra information */
    lua_pushvalue(L, 1);
    lua_concat(L, 2);
  }
  return lua_error(L);
}


static int luaB_getmetatable (lua_State *L) {
  luaL_checkany(L, 1);
  if (!lua_getmetatable(L, 1)) {
    lua_pushnil(L);
    return 1;  /* no metatable */
  }
  luaL_getmetafield(L, 1, "__metatable");
  return 1;  /* returns either __metatable field (if present) or metatable */
}


static int luaB_setmetatable (lua_State *L) {
  int t = lua_type(L, 2);
  luaL_checktype(L, 1, LUA_TTABLE);
  luaL_argexpected(L, t == LUA_TNIL || t == LUA_TTABLE, 2, "nil or table");
  if (luaL_getmetafield(L, 1, "__metatable") != LUA_TNIL)
    return luaL_error(L, "cannot change a protected metatable");
  lua_settop(L, 2);
  lua_setmetatable(L, 1);
  return 1;
}


static int luaB_rawequal (lua_State *L) {
  luaL_checkany(L, 1);
  luaL_checkany(L, 2);
  lua_pushboolean(L, lua_rawequal(L, 1, 2));
  return 1;
}


static int luaB_rawlen (lua_State *L) {
  int t = lua_type(L, 1);
  luaL_argexpected(L, t == LUA_TTABLE || t == LUA_TSTRING, 1,
                      "table or string");
  lua_pushinteger(L, lua_rawlen(L, 1));
  return 1;
}


static int luaB_rawget (lua_State *L) {
  luaL_checktype(L, 1, LUA_TTABLE);
  luaL_checkany(L, 2);
  lua_settop(L, 2);
  lua_rawget(L, 1);
  return 1;
}

static int luaB_rawset (lua_State *L) {
  luaL_checktype(L, 1, LUA_TTABLE);
  luaL_checkany(L, 2);
  luaL_checkany(L, 3);
  lua_settop(L, 3);
  lua_rawset(L, 1);
  return 1;
}


static int pushmode (lua_State *L, int oldmode) {
  lua_pushstring(L, (oldmode == LUA_GCINC) ? "incremental" : "generational");
  return 1;
}


static int luaB_collectgarbage (lua_State *L) {
  static const char *const opts[] = {"stop", "restart", "collect",
    "count", "step", "setpause", "setstepmul",
    "isrunning", "generational", "incremental", NULL};
  static const int optsnum[] = {LUA_GCSTOP, LUA_GCRESTART, LUA_GCCOLLECT,
    LUA_GCCOUNT, LUA_GCSTEP, LUA_GCSETPAUSE, LUA_GCSETSTEPMUL,
    LUA_GCISRUNNING, LUA_GCGEN, LUA_GCINC};
  int o = optsnum[luaL_checkoption(L, 1, "collect", opts)];
  switch (o) {
    case LUA_GCCOUNT: {
      int k = lua_gc(L, o);
      int b = lua_gc(L, LUA_GCCOUNTB);
      lua_pushnumber(L, (lua_Number)k + ((lua_Number)b/1024));
      return 1;
    }
    case LUA_GCSTEP: {
      int step = (int)luaL_optinteger(L, 2, 0);
      int res = lua_gc(L, o, step);
      lua_pushboolean(L, res);
      return 1;
    }
    case LUA_GCSETPAUSE:
    case LUA_GCSETSTEPMUL: {
      int p = (int)luaL_optinteger(L, 2, 0);
      int previous = lua_gc(L, o, p);
      lua_pushinteger(L, previous);
      return 1;
    }
    case LUA_GCISRUNNING: {
      int res = lua_gc(L, o);
      lua_pushboolean(L, res);
      return 1;
    }
    case LUA_GCGEN: {
      int minormul = (int)luaL_optinteger(L, 2, 0);
      int majormul = (int)luaL_optinteger(L, 3, 0);
      return pushmode(L, lua_gc(L, o, minormul, majormul));
    }
    case LUA_GCINC: {
      int pause = (int)luaL_optinteger(L, 2, 0);
      int stepmul = (int)luaL_optinteger(L, 3, 0);
      int stepsize = (int)luaL_optinteger(L, 4, 0);
      return pushmode(L, lua_gc(L, o, pause, stepmul, stepsize));
    }
    default: {
      int res = lua_gc(L, o);
      lua_pushinteger(L, res);
      return 1;
    }
  }
}


static int luaB_type (lua_State *L) {
  int t = lua_type(L, 1);
  luaL_argcheck(L, t != LUA_TNONE, 1, "value expected");
  lua_pushstring(L, lua_typename(L, t));
  return 1;
}


static int luaB_next (lua_State *L) {
  luaL_checktype(L, 1, LUA_TTABLE);
  lua_settop(L, 2);  /* create a 2nd argument if there isn't one */
  if (lua_next(L, 1))
    return 2;
  else {
    lua_pushnil(L);
    return 1;
  }
}


static int luaB_pairs (lua_State *L) {
  luaL_checkany(L, 1);
  if (luaL_getmetafield(L, 1, "__pairs") == LUA_TNIL) {  /* no metamethod? */
    lua_pushcfunction(L, luaB_next);  /* will return generator, */
    lua_pushvalue(L, 1);  /* state, */
    lua_pushnil(L);  /* and initial value */
  }
  else {
    lua_pushvalue(L, 1);  /* argument 'self' to metamethod */
    lua_call(L, 1, 3);  /* get 3 values from metamethod */
  }
  return 3;
}


/*
** Traversal function for 'ipairs'
*/
static int ipairsaux (lua_State *L) {
  lua_Integer i = luaL_checkinteger(L, 2) + 1;
  lua_pushinteger(L, i);
  return (lua_geti(L, 1, i) == LUA_TNIL) ? 1 : 2;
}


/*
** 'ipairs' function. Returns 'ipairsaux', given "table", 0.
** (The given "table" may not be a table.)
*/
static int luaB_ipairs (lua_State *L) {
  luaL_checkany(L, 1);
  lua_pushcfunction(L, ipairsaux);  /* iteration function */
  lua_pushvalue(L, 1);  /* state */
  lua_pushinteger(L, 0);  /* initial value */
  return 3;
}


static int load_aux (lua_State *L, int status, int envidx) {
  if (status == LUA_OK) {
    if (envidx != 0) {  /* 'env' parameter? */
      lua_pushvalue(L, envidx);  /* environment for loaded function */
      if (!lua_setupvalue(L, -2, 1))  /* set it as 1st upvalue */
        lua_pop(L, 1);  /* remove 'env' if not used by previous call */
    }
    return 1;
  }
  else {  /* error (message is on top of the stack) */
    luaL_pushfail(L);
    lua_insert(L, -2);  /* put before error message */
    return 2;  /* return fail plus error message */
  }
}


static int luaB_loadfile (lua_State *L) {
  const char *fname = luaL_optstring(L, 1, NULL);
  const char *mode = luaL_optstring(L, 2, NULL);
  int env = (!lua_isnone(L, 3) ? 3 : 0);  /* 'env' index or 0 if no 'env' */
  int status = luaL_loadfilex(L, fname, mode);
  return load_aux(L, status, env);
}


/*
** {======================================================
** Generic Read function
** =======================================================
*/


/*
** reserved slot, above all arguments, to hold a copy of the returned
** string to avoid it being collected while parsed. 'load' has four
** optional arguments (chunk, source name, mode, and environment).
*/
#define RESERVEDSLOT	5


/*
** Reader for generic 'load' function: 'lua_load' uses the
** stack for internal stuff, so the reader cannot change the
** stack top. Instead, it keeps its resulting string in a
** reserved slot inside the stack.
*/
static const char *generic_reader (lua_State *L, void *ud, size_t *size) {
  (void)(ud);  /* not used */
  luaL_checkstack(L, 2, "too many nested functions");
  lua_pushvalue(L, 1);  /* get function */
  lua_call(L, 0, 1);  /* call it */
  if (lua_isnil(L, -1)) {
    lua_pop(L, 1);  /* pop result */
    *size = 0;
    return NULL;
  }
  else if (!lua_isstring(L, -1))
    luaL_error(L, "reader function must return a string");
  lua_replace(L, RESERVEDSLOT);  /* save string in reserved slot */
  return lua_tolstring(L, RESERVEDSLOT, size);
}


static int luaB_load (lua_State *L) {
  int status;
  size_t l;
  const char *s = lua_tolstring(L, 1, &l);
  const char *mode = luaL_optstring(L, 3, "bt");
  int env = (!lua_isnone(L, 4) ? 4 : 0);  /* 'env' index or 0 if no 'env' */
  if (s != NULL) {  /* loading a string? */
    const char *chunkname = luaL_optstring(L, 2, s);
    status = luaL_loadbufferx(L, s, l, chunkname, mode);
  }
  else {  /* loading from a reader function */
    const char *chunkname = luaL_optstring(L, 2, "=(load)");
    luaL_checktype(L, 1, LUA_TFUNCTION);
    lua_settop(L, RESERVEDSLOT);  /* create reserved slot */
    status = lua_load(L, generic_reader, NULL, chunkname, mode);
  }
  return load_aux(L, status, env);
}

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


static int dofilecont (lua_State *L, int d1, lua_KContext d2) {
  (void)d1;  (void)d2;  /* only to match 'lua_Kfunction' prototype */
  return lua_gettop(L) - 1;
}


static int luaB_dofile (lua_State *L) {
  const char *fname = luaL_optstring(L, 1, NULL);
  lua_settop(L, 1);
  if (luaL_loadfile(L, fname) != LUA_OK)
    return lua_error(L);
  lua_callk(L, 0, LUA_MULTRET, 0, dofilecont);
  return dofilecont(L, 0, 0);
}


static int luaB_assert (lua_State *L) {
  if (lua_toboolean(L, 1))  /* condition is true? */
    return lua_gettop(L);  /* return all arguments */
  else {  /* error */
    luaL_checkany(L, 1);  /* there must be a condition */
    lua_remove(L, 1);  /* remove it */
    lua_pushliteral(L, "assertion failed!");  /* default message */
    lua_settop(L, 1);  /* leave only message (default if no other one) */
    return luaB_error(L);  /* call 'error' */
  }
}


static int luaB_select (lua_State *L) {
  int n = lua_gettop(L);
  if (lua_type(L, 1) == LUA_TSTRING && *lua_tostring(L, 1) == '#') {
    lua_pushinteger(L, n-1);
    return 1;
  }
  else {
    lua_Integer i = luaL_checkinteger(L, 1);
    if (i < 0) i = n + i;
    else if (i > n) i = n;
    luaL_argcheck(L, 1 <= i, 1, "index out of range");
    return n - (int)i;
  }
}


/*
** Continuation function for 'pcall' and 'xpcall'. Both functions
** already pushed a 'true' before doing the call, so in case of success
** 'finishpcall' only has to return everything in the stack minus
** 'extra' values (where 'extra' is exactly the number of items to be
** ignored).
*/
static int finishpcall (lua_State *L, int status, lua_KContext extra) {
  if (status != LUA_OK && status != LUA_YIELD) {  /* error? */
    lua_pushboolean(L, 0);  /* first result (false) */
    lua_pushvalue(L, -2);  /* error message */
    return 2;  /* return false, msg */
  }
  else
    return lua_gettop(L) - (int)extra;  /* return all results */
}


static int luaB_pcall (lua_State *L) {
  int status;
  luaL_checkany(L, 1);
  lua_pushboolean(L, 1);  /* first result if no errors */
  lua_insert(L, 1);  /* put it in place */
  status = lua_pcallk(L, lua_gettop(L) - 2, LUA_MULTRET, 0, 0, finishpcall);
  return finishpcall(L, status, 0);
}


/*
** Do a protected call with error handling. After 'lua_rotate', the
** stack will have <f, err, true, f, [args...]>; so, the function passes
** 2 to 'finishpcall' to skip the 2 first values when returning results.
*/
static int luaB_xpcall (lua_State *L) {
  int status;
  int n = lua_gettop(L);
  luaL_checktype(L, 2, LUA_TFUNCTION);  /* check error function */
  lua_pushboolean(L, 1);  /* first result */
  lua_pushvalue(L, 1);  /* function */
  lua_rotate(L, 3, 2);  /* move them below function's arguments */
  status = lua_pcallk(L, n - 2, LUA_MULTRET, 2, 2, finishpcall);
  return finishpcall(L, status, 2);
}


static int luaB_tostring (lua_State *L) {
  luaL_checkany(L, 1);
  luaL_tolstring(L, 1, NULL);
  return 1;
}


/*
function locals()
    local vars = {}
    local idx = 1
    while true do
        local ln, lv = debug.getlocal(2, idx)
        if ln == nil then break end
        vars[ln] = lv
        idx = idx + 1
    end
    return vars
end
*/
static int luaB_locals (lua_State *L) {
    lua_Debug ar;
    const char *name;
    int nvar = 1;  /* local-variable index */
    if (!lua_getstack(L, 1, &ar))  /* out of range? */
        return luaL_argerror(L, 1, "level out of range");

    lua_newtable(L);
    while (name = lua_getlocal(L, &ar, nvar++))
        lua_setfield(L, -2, name);

    return 1;
}


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 auxresume (lua_State *L, lua_State *co, int narg) {
    int status, nres;
    if (!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 (status == LUA_OK || status == LUA_YIELD) {
        if (!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_auxwrap (lua_State *L) {
    lua_State *co = lua_tothread(L, lua_upvalueindex(1));
    int r = auxresume(L, co, lua_gettop(L));
    if (r < 0) {
        int stat = lua_status(co);
        if (stat != LUA_OK && stat != LUA_YIELD)
            lua_resetthread(co);  /* close variables in case of errors */
        if (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 generate_retf (lua_State *L) {
    int hidx = lua_upvalueindex(1);
    int n = (int)luaL_checkinteger(L, lua_upvalueindex(2));
    int i;

    lua_pop(L, lua_gettop(L)); //在for循环中会有两个nil的参数

    lua_pushvalue(L, lua_upvalueindex(3));

    if (n > 0) { //只在第一次运行时使用参数
        lua_pushinteger(L, 0);
        lua_replace(L, lua_upvalueindex(2));
        for (i = 1; i <= n; i++)
            lua_geti(L, hidx, i);
    }

    lua_call(L, n, -1);
    return lua_gettop(L);
}


static int generate_func (lua_State *L) {
    int n = lua_gettop(L);  /* number of elements to pack */
    int i;

    lua_createtable(L, n, 1);  /* create result table */
    lua_insert(L, 1);  /* put it at index 1 */
    for (i = n; i >= 1; i--)  /* assign elements */
        lua_seti(L, 1, i);

    lua_pushinteger(L, n);

    lua_pushvalue(L, lua_upvalueindex(1));
    lua_insert(L, 1);
    luaB_cocreate(L);
    lua_pushcclosure(L, luaB_auxwrap, 1);
    
    lua_pushcclosure(L, generate_retf, 3);

    return 1;
}


/*
function generate(func)
    return function(...)
        local args = {...}
        local bfunc = coroutine.wrap(func)
        return function()
            return bfunc(table.unpack(args))
        end
    end
end
*/
static int luaB_generate (lua_State *L) {
    lua_pushcclosure(L, generate_func, 1);
    return 1;
}


static int luaB_yield (lua_State *L) {
    return lua_yield(L, lua_gettop(L));
}


static int iter_table (lua_State *L) {
    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(2));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(2));

    lua_geti(L, lua_upvalueindex(1), index);
    return 1;
}


static int iter_string (lua_State *L) {
    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(2));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(2));
    
    const char *s = luaL_checkstring(L, lua_upvalueindex(1));
    if (!s[index])
        lua_pushnil(L);
    else
        lua_pushlstring(L, s + index, 1);
    return 1;
}


static int iter_iter (lua_State *L) {
    lua_pop(L, lua_gettop(L));
    lua_pushvalue(L, lua_upvalueindex(1));

    lua_call(L, 0, -1);
    return lua_gettop(L);
}


/*
iter = generate(function(data)
    local index = 1
    local val
    if type(data) == "function" then
        while true do
            val = data()
            if val == nil then return nil end
            yield(val)
            index = index + 1
        end
    elseif type(data) == "table" then
        while true do
            val = data[index]
            if val == nil then return nil end
            yield(val)
            index = index + 1
        end
    elseif type(data) == "string" then
        while true do
            val = string.sub(data, index, index)
            if val == "" then return nil end
            yield(val)
            index = index + 1
        end
    end
end)
*/
static int luaB_iter (lua_State *L) {
    lua_pop(L, lua_gettop(L) - 1); //只保留第一个参数，如io.lines("xxx")的栈大小为4
    switch (lua_type(L, 1))
    {
    case LUA_TLIST: case LUA_TTABLE:
        lua_pushinteger(L, 1);
        lua_pushcclosure(L, iter_table, 2);
        break;
    case LUA_TSTRING:
        lua_pushinteger(L, 0);
        lua_pushcclosure(L, iter_string, 2);
        break;
    case LUA_TFUNCTION:
        lua_pushcclosure(L, iter_iter, 1);
        break;
    }

    return 1;
}


static int enumerate_table (lua_State *L) {
    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(2));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(2));

    lua_len(L, lua_upvalueindex(1));
    lua_Integer n = luaL_checkinteger(L, -1);
    if (index > n)
    {
        lua_pushnil(L);
        return 1;
    }
    lua_pushinteger(L, index);
    lua_geti(L, lua_upvalueindex(1), index);
    return 2;
}


static int enumerate_string (lua_State *L) {
    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(2));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(2));

    const char *s = luaL_checkstring(L, lua_upvalueindex(1));
    if (!s[index])
    {
        lua_pushnil(L);
        return 1;
    }

    lua_pushinteger(L, index + 1);
    lua_pushlstring(L, s + index, 1);    
    return 2;
}


static int enumerate_iter (lua_State *L) {
    lua_pop(L, lua_gettop(L));
    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(2));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(2));

    lua_pushvalue(L, lua_upvalueindex(1));

    lua_call(L, 0, -1);

    if (!lua_gettop(L) || lua_isnil(L, 1))
    {
        lua_pushnil(L);
        return 1;
    }
    lua_pushinteger(L, index);
    lua_insert(L, 1);
    return lua_gettop(L);
}


/*
enumerate = generate(function(data)
    local index = 1
    local it = iter(data)
    local val
    while true do
        val = it()
        if val == nil then return nil end
        yield(index, val)
        index = index + 1
    end
end)
*/
static int luaB_enumerate (lua_State *L) {
    lua_pop(L, lua_gettop(L) - 1);
    switch (lua_type(L, 1))
    {
    case LUA_TLIST: case LUA_TTABLE:
        lua_pushinteger(L, 1);
        lua_pushcclosure(L, enumerate_table, 2);
        break;
    case LUA_TSTRING:
        lua_pushinteger(L, 0);
        lua_pushcclosure(L, enumerate_string, 2);
        break;
    case LUA_TFUNCTION:
        lua_pushinteger(L, 1);
        lua_pushcclosure(L, enumerate_iter, 2);
        break;
    }

    return 1;
}


static int zip_func (lua_State *L) {
    int hidx = lua_upvalueindex(1);
    int n = (int)luaL_checkinteger(L, lua_upvalueindex(2));
    int i;

    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(3));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(3));

    lua_pop(L, lua_gettop(L)); //在for循环中会有两个nil的参数

    for (i = 1; i <= n; i++)
        lua_geti(L, hidx, i);

    for (i = 1; i <= n; i++)
    {
        switch (lua_type(L, i))
        {
        case LUA_TLIST: case LUA_TTABLE: {
            lua_geti(L, i, index);
            if (lua_isnil(L, -1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        case LUA_TSTRING: {
            const char *s = luaL_checkstring(L, i);
            if (!s[index - 1]) {
                lua_pushnil(L);
                return 1;
            }
            lua_pushlstring(L, s + index - 1, 1);
            break;
        }
        case LUA_TFUNCTION: {
            int t = lua_gettop(L);
            lua_pushvalue(L, i);
            lua_call(L, 0, -1);
            if (!(lua_gettop(L) - t) || lua_isnil(L, t + 1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        }
    }
    return lua_gettop(L) - n;
}


/*
function zip(...)
    local gargs = {}
    for i, v in ipairs({...}) do
        gargs[i] = iter(v)
    end
    return function()
        local r = {}
        for i, v in ipairs(gargs) do
            r[i] = v()
            if r[i] == nil then return nil end
        end
        return table.unpack(r)
    end
end
*/
static int luaB_zip (lua_State *L) {
    int n = lua_gettop(L);  /* number of elements to pack */
    int i;

    lua_createtable(L, n, 1);  /* create result table */
    lua_insert(L, 1);  /* put it at index 1 */
    for (i = n; i >= 1; i--)  /* assign elements */
        lua_seti(L, 1, i);

    lua_pushinteger(L, n);
    lua_pushinteger(L, 1);
    lua_pushcclosure(L, zip_func, 3);
    return 1;
}


static int map_func (lua_State *L) {
    int hidx = lua_upvalueindex(1);
    int fidx = lua_upvalueindex(2);
    int n = (int)luaL_checkinteger(L, lua_upvalueindex(3));
    int i;

    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(4));
    lua_pushinteger(L, index + 1);
    lua_replace(L, lua_upvalueindex(4));

    lua_pop(L, lua_gettop(L)); //在for循环中会有两个nil的参数

    for (i = 1; i <= n; i++)
        lua_geti(L, hidx, i);

    lua_pushvalue(L, fidx);

    for (i = 1; i <= n; i++)
    {
        switch (lua_type(L, i))
        {
        case LUA_TLIST: case LUA_TTABLE: {
            lua_geti(L, i, index);
            if (lua_isnil(L, -1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        case LUA_TSTRING: {
            const char *s = luaL_checkstring(L, i);
            if (!s[index - 1]) {
                lua_pushnil(L);
                return 1;
            }
            lua_pushlstring(L, s + index - 1, 1);
            break;
        }
        case LUA_TFUNCTION: {
            int t = lua_gettop(L);
            lua_pushvalue(L, i);
            lua_call(L, 0, -1);
            if (!(lua_gettop(L) - t) || lua_isnil(L, t + 1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        }
    }

    lua_call(L, lua_gettop(L) - n - 1, -1);
    return lua_gettop(L) - n;
}


/*
function map(func, ...)
    local gargs = {}
    for i, v in ipairs({...}) do
        gargs[i] = iter(v)
    end
    return function()
        local r = {}
        for i, v in ipairs(gargs) do
            r[i] = v()
            if r[i] == nil then return nil end
        end
        return func(table.unpack(r))
    end
end
*/
static int luaB_map (lua_State *L) {
    luaL_checktype(L, 1, LUA_TFUNCTION);

    int n = lua_gettop(L) - 1;  /* number of elements to pack */
    int i;

    lua_createtable(L, n, 1);  /* create result table */
    lua_insert(L, 1);  /* put it at index 1 */
    for (i = n; i >= 1; i--)  /* assign elements */
        lua_seti(L, 1, i);

    lua_pushinteger(L, n);
    lua_pushinteger(L, 1);
    lua_pushcclosure(L, map_func, 4);
    return 1;
}


/*
function reduce(func, data, init)
    local s = init
    local e
    for v in iter(data) do
        e = v
        if s == nil then
            s = e
        else
            s = func(s, e)
        end
    end
    return s
end
*/
static int luaB_reduce (lua_State *L) {
    luaL_checktype(L, 1, LUA_TFUNCTION);

    int n = lua_gettop(L);  /* number of elements to pack */
    int i = 1;

    switch (lua_type(L, 2))
    {
    case LUA_TLIST: case LUA_TTABLE: {
        if (n >= 3)
            lua_pushvalue(L, 3);
        else {
            lua_geti(L, 2, i++);
            if (lua_isnil(L, -1))
                return 1;
        }
        while (1) {
            lua_geti(L, 2, i++);
            if (lua_isnil(L, -1)) {
                lua_pop(L, 1);
                return 1;
            }

            lua_pushvalue(L, 1);
            lua_insert(L, -3);
            lua_call(L, 2, 1);
        }
        break;
    }
    case LUA_TSTRING: {
        i--;
        const char *s = luaL_checkstring(L, 2);
        if (n >= 3)
            lua_pushvalue(L, 3);
        else {
            if (!s[i])
                return 1;
            lua_pushlstring(L, s + i++, 1);
        }
        
        while (1) {
            if (!s[i])
                return 1;
            lua_pushlstring(L, s + i++, 1);

            lua_pushvalue(L, 1);
            lua_insert(L, -3);
            lua_call(L, 2, 1);
        }
        break;
    }
    case LUA_TFUNCTION: {
        if (n >= 3)
            lua_pushvalue(L, 3);
        else {
            lua_pushvalue(L, 2);
            lua_call(L, 0, 1);
            if (lua_isnil(L, -1))
                return 1;
        }
        while (1) {
            lua_pushvalue(L, 2);
            lua_call(L, 0, 1);
            if (lua_isnil(L, -1)) {
                lua_pop(L, 1);
                return 1;
            }

            lua_pushvalue(L, 1);
            lua_insert(L, -3);
            lua_call(L, 2, 1);
        }
        break;
    }
    default:
        lua_pushvalue(L, 2);
    }

    return 1;
}


static int filter_func (lua_State *L) {
    lua_pop(L, lua_gettop(L)); //在for循环中会有两个nil的参数

    lua_Integer index = luaL_checkinteger(L, lua_upvalueindex(3));
    lua_pushvalue(L, lua_upvalueindex(2));

    while (1) {
        switch (lua_type(L, 1))
        {
        case LUA_TLIST: case LUA_TTABLE: {
            lua_geti(L, 1, index);
            if (lua_isnil(L, -1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        case LUA_TSTRING: {
            const char *s = luaL_checkstring(L, 1);
            if (!s[index - 1]) {
                lua_pushnil(L);
                return 1;
            }
            lua_pushlstring(L, s + index - 1, 1);
            break;
        }
        case LUA_TFUNCTION: {
            lua_pushvalue(L, 1);
            lua_call(L, 0, 1);
            if (lua_gettop(L) != 2 || lua_isnil(L, -1)) {
                lua_pushnil(L);
                return 1;
            }
            break;
        }
        }

        index++;
        lua_pushvalue(L, lua_upvalueindex(1));
        lua_pushvalue(L, -2);  /* copy data */

        lua_call(L, 1, 1);
        if (lua_toboolean(L, -1))
            break;
        lua_pop(L, 2);
    }
    lua_pop(L, 1);  /* pop result */

    lua_pushinteger(L, index);
    lua_replace(L, lua_upvalueindex(3));

    return 1;
}


static int luaB_filter (lua_State *L) {
    luaL_checktype(L, 1, LUA_TFUNCTION);
    lua_pushinteger(L, 1);
    lua_pushcclosure(L, filter_func, 3);
    return 1;
}


static const luaL_Reg base_funcs[] = {
  {"assert", luaB_assert},
  {"collectgarbage", luaB_collectgarbage},
  {"dofile", luaB_dofile},
  {"error", luaB_error},
  {"getmetatable", luaB_getmetatable},
  {"ipairs", luaB_ipairs},
  {"loadfile", luaB_loadfile},
  {"load", luaB_load},
  {"next", luaB_next},
  {"pairs", luaB_pairs},
  {"pcall", luaB_pcall},
  {"print", luaB_print},
  {"warn", luaB_warn},
  {"rawequal", luaB_rawequal},
  {"rawlen", luaB_rawlen},
  {"rawget", luaB_rawget},
  {"rawset", luaB_rawset},
  {"select", luaB_select},
  {"setmetatable", luaB_setmetatable},
  {"tonumber", luaB_tonumber},
  {"tostring", luaB_tostring},
  {"type", luaB_type},
  {"xpcall", luaB_xpcall},
  {"locals", luaB_locals},
  {"generate", luaB_generate},
  {"yield", luaB_yield},
  {"iter", luaB_iter},
  {"enumerate", luaB_enumerate},
  {"zip", luaB_zip},
  {"map", luaB_map},
  {"reduce", luaB_reduce},
  {"filter", luaB_filter},
  /* placeholders */
  {LUA_GNAME, NULL},
  {"_VERSION", NULL},
  {NULL, NULL}
};


LUAMOD_API int luaopen_base (lua_State *L) {
  /* open lib into global table */
  lua_pushglobaltable(L);
  luaL_setfuncs(L, base_funcs, 0);
  /* set global _G */
  lua_pushvalue(L, -1);
  lua_setfield(L, -2, LUA_GNAME);
  /* set global _VERSION */
  lua_pushliteral(L, LUA_VERSION);
  lua_setfield(L, -2, "_VERSION");
  return 1;
}