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/*

** $Id: ltablib.c,v 1.63 2011/11/28 17:26:30 roberto Exp $

** Library for Table Manipulation

** See Copyright Notice in lua.h

*/

#include 

#define ltablib_c

#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"

#include "lualib.h"

#define aux_getn(L,n)  \

	(luaL_checktype(L, n, LUA_TTABLE), luaL_len(L, n))

#if defined(LUA_COMPAT_MAXN)

static int maxn (lua_State *L) {

  lua_Number max = 0;

  luaL_checktype(L, 1, LUA_TTABLE);

  lua_pushnil(L);  /* first key */

  while (lua_next(L, 1)) {

    lua_pop(L, 1);  /* remove value */

    if (lua_type(L, -1) == LUA_TNUMBER) {

      lua_Number v = lua_tonumber(L, -1);

      if (v > max) max = v;

    }

  }

  lua_pushnumber(L, max);

  return 1;

}

#endif

static int tinsert (lua_State *L) {

  int e = aux_getn(L, 1) + 1;  /* first empty element */

  int pos;  /* where to insert new element */

  switch (lua_gettop(L)) {

    case 2: {  /* called with only 2 arguments */

      pos = e;  /* insert new element at the end */

      break;

    }

    case 3: {

      int i;

      pos = luaL_checkint(L, 2);  /* 2nd argument is the position */

      if (pos > e) e = pos;  /* `grow' array if necessary */

      for (i = e; i > pos; i--) {  /* move up elements */

        lua_rawgeti(L, 1, i-1);

        lua_rawseti(L, 1, i);  /* t[i] = t[i-1] */

      }

      break;

    }

    default: {

      return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));

    }

  }

  lua_rawseti(L, 1, pos);  /* t[pos] = v */

  return 0;

}

static int tremove (lua_State *L) {

  int e = aux_getn(L, 1);

  int pos = luaL_optint(L, 2, e);

  if (!(1 <= pos && pos <= e))  /* position is outside bounds? */

    return 0;  /* nothing to remove */

  lua_rawgeti(L, 1, pos);  /* result = t[pos] */

  for ( ;pos

    lua_rawgeti(L, 1, pos+1);

    lua_rawseti(L, 1, pos);  /* t[pos] = t[pos+1] */

  }

  lua_pushnil(L);

  lua_rawseti(L, 1, e);  /* t[e] = nil */

  return 1;

}

static void addfield (lua_State *L, luaL_Buffer *b, int i) {

  lua_rawgeti(L, 1, i);

  if (!lua_isstring(L, -1))

    luaL_error(L, "invalid value (%s) at index %d in table for "

                  LUA_QL("concat"), luaL_typename(L, -1), i);

  luaL_addvalue(b);

}

static int tconcat (lua_State *L) {

  luaL_Buffer b;

  size_t lsep;

  int i, last;

  const char *sep = luaL_optlstring(L, 2, "", &lsep);

  luaL_checktype(L, 1, LUA_TTABLE);

  i = luaL_optint(L, 3, 1);

  last = luaL_opt(L, luaL_checkint, 4, luaL_len(L, 1));

  luaL_buffinit(L, &b);

  for (; i < last; i++) {

    addfield(L, &b, i);

    luaL_addlstring(&b, sep, lsep);

  }

  if (i == last)  /* add last value (if interval was not empty) */

    addfield(L, &b, i);

  luaL_pushresult(&b);

  return 1;

}

/*

** {======================================================

** Pack/unpack

** =======================================================

*/

static int pack (lua_State *L) {

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

  lua_createtable(L, n, 1);  /* create result table */

  lua_pushinteger(L, n);

  lua_setfield(L, -2, "n");  /* t.n = number of elements */

  if (n > 0) {  /* at least one element? */

    int i;

    lua_pushvalue(L, 1);

    lua_rawseti(L, -2, 1);  /* insert first element */

    lua_replace(L, 1);  /* move table into index 1 */

    for (i = n; i >= 2; i--)  /* assign other elements */

      lua_rawseti(L, 1, i);

  }

  return 1;  /* return table */

}

static int unpack (lua_State *L) {

  int i, e, n;

  luaL_checktype(L, 1, LUA_TTABLE);

  i = luaL_optint(L, 2, 1);

  e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));

  if (i > e) return 0;  /* empty range */

  n = e - i + 1;  /* number of elements */

  if (n <= 0 || !lua_checkstack(L, n))  /* n <= 0 means arith. overflow */

    return luaL_error(L, "too many results to unpack");

  lua_rawgeti(L, 1, i);  /* push arg[i] (avoiding overflow problems) */

  while (i++ < e)  /* push arg[i + 1...e] */

    lua_rawgeti(L, 1, i);

  return n;

}

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

/*

** {======================================================

** Quicksort

** (based on `Algorithms in MODULA-3', Robert Sedgewick;

**  Addison-Wesley, 1993.)

** =======================================================

*/

static void set2 (lua_State *L, int i, int j) {

  lua_rawseti(L, 1, i);

  lua_rawseti(L, 1, j);

}

static int sort_comp (lua_State *L, int a, int b) {

  if (!lua_isnil(L, 2)) {  /* function? */

    int res;

    lua_pushvalue(L, 2);

    lua_pushvalue(L, a-1);  /* -1 to compensate function */

    lua_pushvalue(L, b-2);  /* -2 to compensate function and `a' */

    lua_call(L, 2, 1);

    res = lua_toboolean(L, -1);

    lua_pop(L, 1);

    return res;

  }

  else  /* a < b? */

    return lua_compare(L, a, b, LUA_OPLT);

}

static void auxsort (lua_State *L, int l, int u) {

  while (l < u) {  /* for tail recursion */

    int i, j;

    /* sort elements a[l], a[(l+u)/2] and a[u] */

    lua_rawgeti(L, 1, l);

    lua_rawgeti(L, 1, u);

    if (sort_comp(L, -1, -2))  /* a[u] < a[l]? */

      set2(L, l, u);  /* swap a[l] - a[u] */

    else

      lua_pop(L, 2);

    if (u-l == 1) break;  /* only 2 elements */

    i = (l+u)/2;

    lua_rawgeti(L, 1, i);

    lua_rawgeti(L, 1, l);

    if (sort_comp(L, -2, -1))  /* a[i]

      set2(L, i, l);

    else {

      lua_pop(L, 1);  /* remove a[l] */

      lua_rawgeti(L, 1, u);

      if (sort_comp(L, -1, -2))  /* a[u]

        set2(L, i, u);

      else

        lua_pop(L, 2);

    }

    if (u-l == 2) break;  /* only 3 elements */

    lua_rawgeti(L, 1, i);  /* Pivot */

    lua_pushvalue(L, -1);

    lua_rawgeti(L, 1, u-1);

    set2(L, i, u-1);

    /* a[l] <= P == a[u-1] <= a[u], only need to sort from l+1 to u-2 */

    i = l; j = u-1;

    for (;;) {  /* invariant: a[l..i] <= P <= a[j..u] */

      /* repeat ++i until a[i] >= P */

      while (lua_rawgeti(L, 1, ++i), sort_comp(L, -1, -2)) {

        if (i>=u) luaL_error(L, "invalid order function for sorting");

        lua_pop(L, 1);  /* remove a[i] */

      }

      /* repeat --j until a[j] <= P */

      while (lua_rawgeti(L, 1, --j), sort_comp(L, -3, -1)) {

        if (j<=l) luaL_error(L, "invalid order function for sorting");

        lua_pop(L, 1);  /* remove a[j] */

      }

      if (j

        lua_pop(L, 3);  /* pop pivot, a[i], a[j] */

        break;

      }

      set2(L, i, j);

    }

    lua_rawgeti(L, 1, u-1);

    lua_rawgeti(L, 1, i);

    set2(L, u-1, i);  /* swap pivot (a[u-1]) with a[i] */

    /* a[l..i-1] <= a[i] == P <= a[i+1..u] */

    /* adjust so that smaller half is in [j..i] and larger one in [l..u] */

    if (i-l < u-i) {

      j=l; i=i-1; l=i+2;

    }

    else {

      j=i+1; i=u; u=j-2;

    }

    auxsort(L, j, i);  /* call recursively the smaller one */

  }  /* repeat the routine for the larger one */

}

static int sort (lua_State *L) {

  int n = aux_getn(L, 1);

  luaL_checkstack(L, 40, "");  /* assume array is smaller than 2^40 */

  if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */

    luaL_checktype(L, 2, LUA_TFUNCTION);

  lua_settop(L, 2);  /* make sure there is two arguments */

  auxsort(L, 1, n);

  return 0;

}

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

static const luaL_Reg tab_funcs[] = {

  {"concat", tconcat},

#if defined(LUA_COMPAT_MAXN)

  {"maxn", maxn},

#endif

  {"insert", tinsert},

  {"pack", pack},

  {"unpack", unpack},

  {"remove", tremove},

  {"sort", sort},

  {NULL, NULL}

};

LUAMOD_API int luaopen_table (lua_State *L) {

  luaL_newlib(L, tab_funcs);

#if defined(LUA_COMPAT_UNPACK)

  /* _G.unpack = table.unpack */

  lua_getfield(L, -1, "unpack");

  lua_setglobal(L, "unpack");

#endif

  return 1;

}