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ltablib.c (13162B)


      1 /*
      2 ** $Id: ltablib.c $
      3 ** Library for Table Manipulation
      4 ** See Copyright Notice in lua.h
      5 */
      6 
      7 #define ltablib_c
      8 #define LUA_LIB
      9 
     10 #include "lprefix.h"
     11 
     12 
     13 #include <limits.h>
     14 #include <stddef.h>
     15 #include <string.h>
     16 
     17 #include "lua.h"
     18 
     19 #include "lauxlib.h"
     20 #include "lualib.h"
     21 #include "llimits.h"
     22 
     23 
     24 /*
     25 ** Operations that an object must define to mimic a table
     26 ** (some functions only need some of them)
     27 */
     28 #define TAB_R	1			/* read */
     29 #define TAB_W	2			/* write */
     30 #define TAB_L	4			/* length */
     31 #define TAB_RW	(TAB_R | TAB_W)		/* read/write */
     32 
     33 
     34 #define aux_getn(L,n,w)	(checktab(L, n, (w) | TAB_L), luaL_len(L, n))
     35 
     36 
     37 static int checkfield (lua_State *L, const char *key, int n) {
     38   lua_pushstring(L, key);
     39   return (lua_rawget(L, -n) != LUA_TNIL);
     40 }
     41 
     42 
     43 /*
     44 ** Check that 'arg' either is a table or can behave like one (that is,
     45 ** has a metatable with the required metamethods)
     46 */
     47 static void checktab (lua_State *L, int arg, int what) {
     48   if (lua_type(L, arg) != LUA_TTABLE) {  /* is it not a table? */
     49     int n = 1;  /* number of elements to pop */
     50     if (lua_getmetatable(L, arg) &&  /* must have metatable */
     51         (!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
     52         (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
     53         (!(what & TAB_L) || checkfield(L, "__len", ++n))) {
     54       lua_pop(L, n);  /* pop metatable and tested metamethods */
     55     }
     56     else
     57       luaL_checktype(L, arg, LUA_TTABLE);  /* force an error */
     58   }
     59 }
     60 
     61 
     62 static int tcreate (lua_State *L) {
     63   lua_Unsigned sizeseq = (lua_Unsigned)luaL_checkinteger(L, 1);
     64   lua_Unsigned sizerest = (lua_Unsigned)luaL_optinteger(L, 2, 0);
     65   luaL_argcheck(L, sizeseq <= cast_uint(INT_MAX), 1, "out of range");
     66   luaL_argcheck(L, sizerest <= cast_uint(INT_MAX), 2, "out of range");
     67   lua_createtable(L, cast_int(sizeseq), cast_int(sizerest));
     68   return 1;
     69 }
     70 
     71 
     72 static int tinsert (lua_State *L) {
     73   lua_Integer pos;  /* where to insert new element */
     74   lua_Integer e = aux_getn(L, 1, TAB_RW);
     75   e = luaL_intop(+, e, 1);  /* first empty element */
     76   switch (lua_gettop(L)) {
     77     case 2: {  /* called with only 2 arguments */
     78       pos = e;  /* insert new element at the end */
     79       break;
     80     }
     81     case 3: {
     82       lua_Integer i;
     83       pos = luaL_checkinteger(L, 2);  /* 2nd argument is the position */
     84       /* check whether 'pos' is in [1, e] */
     85       luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2,
     86                        "position out of bounds");
     87       for (i = e; i > pos; i--) {  /* move up elements */
     88         lua_geti(L, 1, i - 1);
     89         lua_seti(L, 1, i);  /* t[i] = t[i - 1] */
     90       }
     91       break;
     92     }
     93     default: {
     94       return luaL_error(L, "wrong number of arguments to 'insert'");
     95     }
     96   }
     97   lua_seti(L, 1, pos);  /* t[pos] = v */
     98   return 0;
     99 }
    100 
    101 
    102 static int tremove (lua_State *L) {
    103   lua_Integer size = aux_getn(L, 1, TAB_RW);
    104   lua_Integer pos = luaL_optinteger(L, 2, size);
    105   if (pos != size)  /* validate 'pos' if given */
    106     /* check whether 'pos' is in [1, size + 1] */
    107     luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 2,
    108                      "position out of bounds");
    109   lua_geti(L, 1, pos);  /* result = t[pos] */
    110   for ( ; pos < size; pos++) {
    111     lua_geti(L, 1, pos + 1);
    112     lua_seti(L, 1, pos);  /* t[pos] = t[pos + 1] */
    113   }
    114   lua_pushnil(L);
    115   lua_seti(L, 1, pos);  /* remove entry t[pos] */
    116   return 1;
    117 }
    118 
    119 
    120 /*
    121 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
    122 ** possible, copy in increasing order, which is better for rehashing.
    123 ** "possible" means destination after original range, or smaller
    124 ** than origin, or copying to another table.
    125 */
    126 static int tmove (lua_State *L) {
    127   lua_Integer f = luaL_checkinteger(L, 2);
    128   lua_Integer e = luaL_checkinteger(L, 3);
    129   lua_Integer t = luaL_checkinteger(L, 4);
    130   int tt = !lua_isnoneornil(L, 5) ? 5 : 1;  /* destination table */
    131   checktab(L, 1, TAB_R);
    132   checktab(L, tt, TAB_W);
    133   if (e >= f) {  /* otherwise, nothing to move */
    134     lua_Integer n, i;
    135     luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
    136                   "too many elements to move");
    137     n = e - f + 1;  /* number of elements to move */
    138     luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
    139                   "destination wrap around");
    140     if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
    141       for (i = 0; i < n; i++) {
    142         lua_geti(L, 1, f + i);
    143         lua_seti(L, tt, t + i);
    144       }
    145     }
    146     else {
    147       for (i = n - 1; i >= 0; i--) {
    148         lua_geti(L, 1, f + i);
    149         lua_seti(L, tt, t + i);
    150       }
    151     }
    152   }
    153   lua_pushvalue(L, tt);  /* return destination table */
    154   return 1;
    155 }
    156 
    157 
    158 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
    159   lua_geti(L, 1, i);
    160   if (l_unlikely(!lua_isstring(L, -1)))
    161     luaL_error(L, "invalid value (%s) at index %I in table for 'concat'",
    162                   luaL_typename(L, -1), (LUAI_UACINT)i);
    163   luaL_addvalue(b);
    164 }
    165 
    166 
    167 static int tconcat (lua_State *L) {
    168   luaL_Buffer b;
    169   lua_Integer last = aux_getn(L, 1, TAB_R);
    170   size_t lsep;
    171   const char *sep = luaL_optlstring(L, 2, "", &lsep);
    172   lua_Integer i = luaL_optinteger(L, 3, 1);
    173   last = luaL_optinteger(L, 4, last);
    174   luaL_buffinit(L, &b);
    175   for (; i < last; i++) {
    176     addfield(L, &b, i);
    177     luaL_addlstring(&b, sep, lsep);
    178   }
    179   if (i == last)  /* add last value (if interval was not empty) */
    180     addfield(L, &b, i);
    181   luaL_pushresult(&b);
    182   return 1;
    183 }
    184 
    185 
    186 /*
    187 ** {======================================================
    188 ** Pack/unpack
    189 ** =======================================================
    190 */
    191 
    192 static int tpack (lua_State *L) {
    193   int i;
    194   int n = lua_gettop(L);  /* number of elements to pack */
    195   lua_createtable(L, n, 1);  /* create result table */
    196   lua_insert(L, 1);  /* put it at index 1 */
    197   for (i = n; i >= 1; i--)  /* assign elements */
    198     lua_seti(L, 1, i);
    199   lua_pushinteger(L, n);
    200   lua_setfield(L, 1, "n");  /* t.n = number of elements */
    201   return 1;  /* return table */
    202 }
    203 
    204 
    205 static int tunpack (lua_State *L) {
    206   lua_Unsigned n;
    207   lua_Integer i = luaL_optinteger(L, 2, 1);
    208   lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
    209   if (i > e) return 0;  /* empty range */
    210   n = l_castS2U(e) - l_castS2U(i);  /* number of elements minus 1 */
    211   if (l_unlikely(n >= (unsigned int)INT_MAX  ||
    212                  !lua_checkstack(L, (int)(++n))))
    213     return luaL_error(L, "too many results to unpack");
    214   for (; i < e; i++) {  /* push arg[i..e - 1] (to avoid overflows) */
    215     lua_geti(L, 1, i);
    216   }
    217   lua_geti(L, 1, e);  /* push last element */
    218   return (int)n;
    219 }
    220 
    221 /* }====================================================== */
    222 
    223 
    224 
    225 /*
    226 ** {======================================================
    227 ** Quicksort
    228 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
    229 **  Addison-Wesley, 1993.)
    230 ** =======================================================
    231 */
    232 
    233 
    234 /*
    235 ** Type for array indices. These indices are always limited by INT_MAX,
    236 ** so it is safe to cast them to lua_Integer even for Lua 32 bits.
    237 */
    238 typedef unsigned int IdxT;
    239 
    240 
    241 /* Versions of lua_seti/lua_geti specialized for IdxT */
    242 #define geti(L,idt,idx)	lua_geti(L, idt, l_castU2S(idx))
    243 #define seti(L,idt,idx)	lua_seti(L, idt, l_castU2S(idx))
    244 
    245 
    246 /*
    247 ** Produce a "random" 'unsigned int' to randomize pivot choice. This
    248 ** macro is used only when 'sort' detects a big imbalance in the result
    249 ** of a partition. (If you don't want/need this "randomness", ~0 is a
    250 ** good choice.)
    251 */
    252 #if !defined(l_randomizePivot)
    253 #define l_randomizePivot(L)	luaL_makeseed(L)
    254 #endif					/* } */
    255 
    256 
    257 /* arrays larger than 'RANLIMIT' may use randomized pivots */
    258 #define RANLIMIT	100u
    259 
    260 
    261 static void set2 (lua_State *L, IdxT i, IdxT j) {
    262   seti(L, 1, i);
    263   seti(L, 1, j);
    264 }
    265 
    266 
    267 /*
    268 ** Return true iff value at stack index 'a' is less than the value at
    269 ** index 'b' (according to the order of the sort).
    270 */
    271 static int sort_comp (lua_State *L, int a, int b) {
    272   if (lua_isnil(L, 2))  /* no function? */
    273     return lua_compare(L, a, b, LUA_OPLT);  /* a < b */
    274   else {  /* function */
    275     int res;
    276     lua_pushvalue(L, 2);    /* push function */
    277     lua_pushvalue(L, a-1);  /* -1 to compensate function */
    278     lua_pushvalue(L, b-2);  /* -2 to compensate function and 'a' */
    279     lua_call(L, 2, 1);      /* call function */
    280     res = lua_toboolean(L, -1);  /* get result */
    281     lua_pop(L, 1);          /* pop result */
    282     return res;
    283   }
    284 }
    285 
    286 
    287 /*
    288 ** Does the partition: Pivot P is at the top of the stack.
    289 ** precondition: a[lo] <= P == a[up-1] <= a[up],
    290 ** so it only needs to do the partition from lo + 1 to up - 2.
    291 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
    292 ** returns 'i'.
    293 */
    294 static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
    295   IdxT i = lo;  /* will be incremented before first use */
    296   IdxT j = up - 1;  /* will be decremented before first use */
    297   /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
    298   for (;;) {
    299     /* next loop: repeat ++i while a[i] < P */
    300     while ((void)geti(L, 1, ++i), sort_comp(L, -1, -2)) {
    301       if (l_unlikely(i == up - 1))  /* a[up - 1] < P == a[up - 1] */
    302         luaL_error(L, "invalid order function for sorting");
    303       lua_pop(L, 1);  /* remove a[i] */
    304     }
    305     /* after the loop, a[i] >= P and a[lo .. i - 1] < P  (a) */
    306     /* next loop: repeat --j while P < a[j] */
    307     while ((void)geti(L, 1, --j), sort_comp(L, -3, -1)) {
    308       if (l_unlikely(j < i))  /* j <= i - 1 and a[j] > P, contradicts (a) */
    309         luaL_error(L, "invalid order function for sorting");
    310       lua_pop(L, 1);  /* remove a[j] */
    311     }
    312     /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
    313     if (j < i) {  /* no elements out of place? */
    314       /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
    315       lua_pop(L, 1);  /* pop a[j] */
    316       /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
    317       set2(L, up - 1, i);
    318       return i;
    319     }
    320     /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
    321     set2(L, i, j);
    322   }
    323 }
    324 
    325 
    326 /*
    327 ** Choose an element in the middle (2nd-3th quarters) of [lo,up]
    328 ** "randomized" by 'rnd'
    329 */
    330 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
    331   IdxT r4 = (up - lo) / 4;  /* range/4 */
    332   IdxT p = (rnd ^ lo ^ up) % (r4 * 2) + (lo + r4);
    333   lua_assert(lo + r4 <= p && p <= up - r4);
    334   return p;
    335 }
    336 
    337 
    338 /*
    339 ** Quicksort algorithm (recursive function)
    340 */
    341 static void auxsort (lua_State *L, IdxT lo, IdxT up, unsigned rnd) {
    342   while (lo < up) {  /* loop for tail recursion */
    343     IdxT p;  /* Pivot index */
    344     IdxT n;  /* to be used later */
    345     /* sort elements 'lo', 'p', and 'up' */
    346     geti(L, 1, lo);
    347     geti(L, 1, up);
    348     if (sort_comp(L, -1, -2))  /* a[up] < a[lo]? */
    349       set2(L, lo, up);  /* swap a[lo] - a[up] */
    350     else
    351       lua_pop(L, 2);  /* remove both values */
    352     if (up - lo == 1)  /* only 2 elements? */
    353       return;  /* already sorted */
    354     if (up - lo < RANLIMIT || rnd == 0)  /* small interval or no randomize? */
    355       p = (lo + up)/2;  /* middle element is a good pivot */
    356     else  /* for larger intervals, it is worth a random pivot */
    357       p = choosePivot(lo, up, rnd);
    358     geti(L, 1, p);
    359     geti(L, 1, lo);
    360     if (sort_comp(L, -2, -1))  /* a[p] < a[lo]? */
    361       set2(L, p, lo);  /* swap a[p] - a[lo] */
    362     else {
    363       lua_pop(L, 1);  /* remove a[lo] */
    364       geti(L, 1, up);
    365       if (sort_comp(L, -1, -2))  /* a[up] < a[p]? */
    366         set2(L, p, up);  /* swap a[up] - a[p] */
    367       else
    368         lua_pop(L, 2);
    369     }
    370     if (up - lo == 2)  /* only 3 elements? */
    371       return;  /* already sorted */
    372     geti(L, 1, p);  /* get middle element (Pivot) */
    373     lua_pushvalue(L, -1);  /* push Pivot */
    374     geti(L, 1, up - 1);  /* push a[up - 1] */
    375     set2(L, p, up - 1);  /* swap Pivot (a[p]) with a[up - 1] */
    376     p = partition(L, lo, up);
    377     /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
    378     if (p - lo < up - p) {  /* lower interval is smaller? */
    379       auxsort(L, lo, p - 1, rnd);  /* call recursively for lower interval */
    380       n = p - lo;  /* size of smaller interval */
    381       lo = p + 1;  /* tail call for [p + 1 .. up] (upper interval) */
    382     }
    383     else {
    384       auxsort(L, p + 1, up, rnd);  /* call recursively for upper interval */
    385       n = up - p;  /* size of smaller interval */
    386       up = p - 1;  /* tail call for [lo .. p - 1]  (lower interval) */
    387     }
    388     if ((up - lo) / 128 > n) /* partition too imbalanced? */
    389       rnd = l_randomizePivot(L);  /* try a new randomization */
    390   }  /* tail call auxsort(L, lo, up, rnd) */
    391 }
    392 
    393 
    394 static int sort (lua_State *L) {
    395   lua_Integer n = aux_getn(L, 1, TAB_RW);
    396   if (n > 1) {  /* non-trivial interval? */
    397     luaL_argcheck(L, n < INT_MAX, 1, "array too big");
    398     if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
    399       luaL_checktype(L, 2, LUA_TFUNCTION);  /* must be a function */
    400     lua_settop(L, 2);  /* make sure there are two arguments */
    401     auxsort(L, 1, (IdxT)n, 0);
    402   }
    403   return 0;
    404 }
    405 
    406 /* }====================================================== */
    407 
    408 
    409 static const luaL_Reg tab_funcs[] = {
    410   {"concat", tconcat},
    411   {"create", tcreate},
    412   {"insert", tinsert},
    413   {"pack", tpack},
    414   {"unpack", tunpack},
    415   {"remove", tremove},
    416   {"move", tmove},
    417   {"sort", sort},
    418   {NULL, NULL}
    419 };
    420 
    421 
    422 LUAMOD_API int luaopen_table (lua_State *L) {
    423   luaL_newlib(L, tab_funcs);
    424   return 1;
    425 }
    426