ceph/src/lua/src/ltablib.c

   1 /*
   2 ** $Id: ltablib.c,v 1.90 2015/11/25 12:48:57 roberto Exp $
   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
  22
  23 /*
  24 ** Operations that an object must define to mimic a table
  25 ** (some functions only need some of them)
  26 */
  27 #define TAB_R   1                       /* read */
  28 #define TAB_W   2                       /* write */
  29 #define TAB_L   4                       /* length */
  30 #define TAB_RW  (TAB_R | TAB_W)         /* read/write */
  31
  32
  33 #define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n))
  34
  35
  36 static int checkfield (lua_State *L, const char *key, int n) {
  37   lua_pushstring(L, key);
  38   return (lua_rawget(L, -n) != LUA_TNIL);
  39 }
  40
  41
  42 /*
  43 ** Check that 'arg' either is a table or can behave like one (that is,
  44 ** has a metatable with the required metamethods)
  45 */
  46 static void checktab (lua_State *L, int arg, int what) {
  47   if (lua_type(L, arg) != LUA_TTABLE) {  /* is it not a table? */
  48     int n = 1;  /* number of elements to pop */
  49     if (lua_getmetatable(L, arg) &&  /* must have metatable */
  50         (!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
  51         (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
  52         (!(what & TAB_L) || checkfield(L, "__len", ++n))) {
  53       lua_pop(L, n);  /* pop metatable and tested metamethods */
  54     }
  55     else
  56       luaL_argerror(L, arg, "table expected");  /* force an error */
  57   }
  58 }
  59
  60
  61 #if defined(LUA_COMPAT_MAXN)
  62 static int maxn (lua_State *L) {
  63   lua_Number max = 0;
  64   luaL_checktype(L, 1, LUA_TTABLE);
  65   lua_pushnil(L);  /* first key */
  66   while (lua_next(L, 1)) {
  67     lua_pop(L, 1);  /* remove value */
  68     if (lua_type(L, -1) == LUA_TNUMBER) {
  69       lua_Number v = lua_tonumber(L, -1);
  70       if (v > max) max = v;
  71     }
  72   }
  73   lua_pushnumber(L, max);
  74   return 1;
  75 }
  76 #endif
  77
  78
  79 static int tinsert (lua_State *L) {
  80   lua_Integer e = aux_getn(L, 1, TAB_RW) + 1;  /* first empty element */
  81   lua_Integer pos;  /* where to insert new element */
  82   switch (lua_gettop(L)) {
  83     case 2: {  /* called with only 2 arguments */
  84       pos = e;  /* insert new element at the end */
  85       break;
  86     }
  87     case 3: {
  88       lua_Integer i;
  89       pos = luaL_checkinteger(L, 2);  /* 2nd argument is the position */
  90       luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
  91       for (i = e; i > pos; i--) {  /* move up elements */
  92         lua_geti(L, 1, i - 1);
  93         lua_seti(L, 1, i);  /* t[i] = t[i - 1] */
  94       }
  95       break;
  96     }
  97     default: {
  98       return luaL_error(L, "wrong number of arguments to 'insert'");
  99     }
 100   }
 101   lua_seti(L, 1, pos);  /* t[pos] = v */
 102   return 0;
 103 }
 104
 105
 106 static int tremove (lua_State *L) {
 107   lua_Integer size = aux_getn(L, 1, TAB_RW);
 108   lua_Integer pos = luaL_optinteger(L, 2, size);
 109   if (pos != size)  /* validate 'pos' if given */
 110     luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds");
 111   lua_geti(L, 1, pos);  /* result = t[pos] */
 112   for ( ; pos < size; pos++) {
 113     lua_geti(L, 1, pos + 1);
 114     lua_seti(L, 1, pos);  /* t[pos] = t[pos + 1] */
 115   }
 116   lua_pushnil(L);
 117   lua_seti(L, 1, pos);  /* t[pos] = nil */
 118   return 1;
 119 }
 120
 121
 122 /*
 123 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
 124 ** possible, copy in increasing order, which is better for rehashing.
 125 ** "possible" means destination after original range, or smaller
 126 ** than origin, or copying to another table.
 127 */
 128 static int tmove (lua_State *L) {
 129   lua_Integer f = luaL_checkinteger(L, 2);
 130   lua_Integer e = luaL_checkinteger(L, 3);
 131   lua_Integer t = luaL_checkinteger(L, 4);
 132   int tt = !lua_isnoneornil(L, 5) ? 5 : 1;  /* destination table */
 133   checktab(L, 1, TAB_R);
 134   checktab(L, tt, TAB_W);
 135   if (e >= f) {  /* otherwise, nothing to move */
 136     lua_Integer n, i;
 137     luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
 138                   "too many elements to move");
 139     n = e - f + 1;  /* number of elements to move */
 140     luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
 141                   "destination wrap around");
 142     if (t > e || t <= f || tt != 1) {
 143       for (i = 0; i < n; i++) {
 144         lua_geti(L, 1, f + i);
 145         lua_seti(L, tt, t + i);
 146       }
 147     }
 148     else {
 149       for (i = n - 1; i >= 0; i--) {
 150         lua_geti(L, 1, f + i);
 151         lua_seti(L, tt, t + i);
 152       }
 153     }
 154   }
 155   lua_pushvalue(L, tt);  /* return "to table" */
 156   return 1;
 157 }
 158
 159
 160 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
 161   lua_geti(L, 1, i);
 162   if (!lua_isstring(L, -1))
 163     luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
 164                   luaL_typename(L, -1), i);
 165   luaL_addvalue(b);
 166 }
 167
 168
 169 static int tconcat (lua_State *L) {
 170   luaL_Buffer b;
 171   lua_Integer last = aux_getn(L, 1, TAB_R);
 172   size_t lsep;
 173   const char *sep = luaL_optlstring(L, 2, "", &lsep);
 174   lua_Integer i = luaL_optinteger(L, 3, 1);
 175   last = luaL_opt(L, luaL_checkinteger, 4, last);
 176   luaL_buffinit(L, &b);
 177   for (; i < last; i++) {
 178     addfield(L, &b, i);
 179     luaL_addlstring(&b, sep, lsep);
 180   }
 181   if (i == last)  /* add last value (if interval was not empty) */
 182     addfield(L, &b, i);
 183   luaL_pushresult(&b);
 184   return 1;
 185 }
 186
 187
 188 /*
 189 ** {======================================================
 190 ** Pack/unpack
 191 ** =======================================================
 192 */
 193
 194 static int pack (lua_State *L) {
 195   int i;
 196   int n = lua_gettop(L);  /* number of elements to pack */
 197   lua_createtable(L, n, 1);  /* create result table */
 198   lua_insert(L, 1);  /* put it at index 1 */
 199   for (i = n; i >= 1; i--)  /* assign elements */
 200     lua_seti(L, 1, i);
 201   lua_pushinteger(L, n);
 202   lua_setfield(L, 1, "n");  /* t.n = number of elements */
 203   return 1;  /* return table */
 204 }
 205
 206
 207 static int unpack (lua_State *L) {
 208   lua_Unsigned n;
 209   lua_Integer i = luaL_optinteger(L, 2, 1);
 210   lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
 211   if (i > e) return 0;  /* empty range */
 212   n = (lua_Unsigned)e - i;  /* number of elements minus 1 (avoid overflows) */
 213   if (n >= (unsigned int)INT_MAX  || !lua_checkstack(L, (int)(++n)))
 214     return luaL_error(L, "too many results to unpack");
 215   for (; i < e; i++) {  /* push arg[i..e - 1] (to avoid overflows) */
 216     lua_geti(L, 1, i);
 217   }
 218   lua_geti(L, 1, e);  /* push last element */
 219   return (int)n;
 220 }
 221
 222 /* }====================================================== */
 223
 224
 225
 226 /*
 227 ** {======================================================
 228 ** Quicksort
 229 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
 230 **  Addison-Wesley, 1993.)
 231 ** =======================================================
 232 */
 233
 234
 235 /*
 236 ** Produce a "random" 'unsigned int' to randomize pivot choice. This
 237 ** macro is used only when 'sort' detects a big imbalance in the result
 238 ** of a partition. (If you don't want/need this "randomness", ~0 is a
 239 ** good choice.)
 240 */
 241 #if !defined(l_randomizePivot)          /* { */
 242
 243 #include <time.h>
 244
 245 /* size of 'e' measured in number of 'unsigned int's */
 246 #define sof(e)          (sizeof(e) / sizeof(unsigned int))
 247
 248 /*
 249 ** Use 'time' and 'clock' as sources of "randomness". Because we don't
 250 ** know the types 'clock_t' and 'time_t', we cannot cast them to
 251 ** anything without risking overflows. A safe way to use their values
 252 ** is to copy them to an array of a known type and use the array values.
 253 */
 254 static unsigned int l_randomizePivot (void) {
 255   clock_t c = clock();
 256   time_t t = time(NULL);
 257   unsigned int buff[sof(c) + sof(t)];
 258   unsigned int i, rnd = 0;
 259   memcpy(buff, &c, sof(c) * sizeof(unsigned int));
 260   memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
 261   for (i = 0; i < sof(buff); i++)
 262     rnd += buff[i];
 263   return rnd;
 264 }
 265
 266 #endif                                  /* } */
 267
 268
 269 /* arrays larger than 'RANLIMIT' may use randomized pivots */
 270 #define RANLIMIT        100u
 271
 272
 273 static void set2 (lua_State *L, unsigned int i, unsigned int j) {
 274   lua_seti(L, 1, i);
 275   lua_seti(L, 1, j);
 276 }
 277
 278
 279 /*
 280 ** Return true iff value at stack index 'a' is less than the value at
 281 ** index 'b' (according to the order of the sort).
 282 */
 283 static int sort_comp (lua_State *L, int a, int b) {
 284   if (lua_isnil(L, 2))  /* no function? */
 285     return lua_compare(L, a, b, LUA_OPLT);  /* a < b */
 286   else {  /* function */
 287     int res;
 288     lua_pushvalue(L, 2);    /* push function */
 289     lua_pushvalue(L, a-1);  /* -1 to compensate function */
 290     lua_pushvalue(L, b-2);  /* -2 to compensate function and 'a' */
 291     lua_call(L, 2, 1);      /* call function */
 292     res = lua_toboolean(L, -1);  /* get result */
 293     lua_pop(L, 1);          /* pop result */
 294     return res;
 295   }
 296 }
 297
 298
 299 /*
 300 ** Does the partition: Pivot P is at the top of the stack.
 301 ** precondition: a[lo] <= P == a[up-1] <= a[up],
 302 ** so it only needs to do the partition from lo + 1 to up - 2.
 303 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
 304 ** returns 'i'.
 305 */
 306 static unsigned int partition (lua_State *L, unsigned int lo,
 307                                              unsigned int up) {
 308   unsigned int i = lo;  /* will be incremented before first use */
 309   unsigned int j = up - 1;  /* will be decremented before first use */
 310   /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
 311   for (;;) {
 312     /* next loop: repeat ++i while a[i] < P */
 313     while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
 314       if (i == up - 1)  /* a[i] < P  but a[up - 1] == P  ?? */
 315         luaL_error(L, "invalid order function for sorting");
 316       lua_pop(L, 1);  /* remove a[i] */
 317     }
 318     /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
 319     /* next loop: repeat --j while P < a[j] */
 320     while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
 321       if (j < i)  /* j < i  but  a[j] > P ?? */
 322         luaL_error(L, "invalid order function for sorting");
 323       lua_pop(L, 1);  /* remove a[j] */
 324     }
 325     /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
 326     if (j < i) {  /* no elements out of place? */
 327       /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
 328       lua_pop(L, 1);  /* pop a[j] */
 329       /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
 330       set2(L, up - 1, i);
 331       return i;
 332     }
 333     /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
 334     set2(L, i, j);
 335   }
 336 }
 337
 338
 339 /*
 340 ** Choose an element in the middle (2nd-3th quarters) of [lo,up]
 341 ** "randomized" by 'rnd'
 342 */
 343 static unsigned int choosePivot (unsigned int lo, unsigned int up,
 344                                  unsigned int rnd) {
 345   unsigned int r4 = (unsigned int)(up - lo) / 4u;  /* range/4 */
 346   unsigned int p = rnd % (r4 * 2) + (lo + r4);
 347   lua_assert(lo + r4 <= p && p <= up - r4);
 348   return p;
 349 }
 350
 351
 352 /*
 353 ** QuickSort algorithm (recursive function)
 354 */
 355 static void auxsort (lua_State *L, unsigned int lo, unsigned int up,
 356                                    unsigned int rnd) {
 357   while (lo < up) {  /* loop for tail recursion */
 358     unsigned int p;  /* Pivot index */
 359     unsigned int n;  /* to be used later */
 360     /* sort elements 'lo', 'p', and 'up' */
 361     lua_geti(L, 1, lo);
 362     lua_geti(L, 1, up);
 363     if (sort_comp(L, -1, -2))  /* a[up] < a[lo]? */
 364       set2(L, lo, up);  /* swap a[lo] - a[up] */
 365     else
 366       lua_pop(L, 2);  /* remove both values */
 367     if (up - lo == 1)  /* only 2 elements? */
 368       return;  /* already sorted */
 369     if (up - lo < RANLIMIT || rnd == 0)  /* small interval or no randomize? */
 370       p = (lo + up)/2;  /* middle element is a good pivot */
 371     else  /* for larger intervals, it is worth a random pivot */
 372       p = choosePivot(lo, up, rnd);
 373     lua_geti(L, 1, p);
 374     lua_geti(L, 1, lo);
 375     if (sort_comp(L, -2, -1))  /* a[p] < a[lo]? */
 376       set2(L, p, lo);  /* swap a[p] - a[lo] */
 377     else {
 378       lua_pop(L, 1);  /* remove a[lo] */
 379       lua_geti(L, 1, up);
 380       if (sort_comp(L, -1, -2))  /* a[up] < a[p]? */
 381         set2(L, p, up);  /* swap a[up] - a[p] */
 382       else
 383         lua_pop(L, 2);
 384     }
 385     if (up - lo == 2)  /* only 3 elements? */
 386       return;  /* already sorted */
 387     lua_geti(L, 1, p);  /* get middle element (Pivot) */
 388     lua_pushvalue(L, -1);  /* push Pivot */
 389     lua_geti(L, 1, up - 1);  /* push a[up - 1] */
 390     set2(L, p, up - 1);  /* swap Pivot (a[p]) with a[up - 1] */
 391     p = partition(L, lo, up);
 392     /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
 393     if (p - lo < up - p) {  /* lower interval is smaller? */
 394       auxsort(L, lo, p - 1, rnd);  /* call recursively for lower interval */
 395       n = p - lo;  /* size of smaller interval */
 396       lo = p + 1;  /* tail call for [p + 1 .. up] (upper interval) */
 397     }
 398     else {
 399       auxsort(L, p + 1, up, rnd);  /* call recursively for upper interval */
 400       n = up - p;  /* size of smaller interval */
 401       up = p - 1;  /* tail call for [lo .. p - 1]  (lower interval) */
 402     }
 403     if ((up - lo) / 128u > n) /* partition too imbalanced? */
 404       rnd = l_randomizePivot();  /* try a new randomization */
 405   }  /* tail call auxsort(L, lo, up, rnd) */
 406 }
 407
 408
 409 static int sort (lua_State *L) {
 410   lua_Integer n = aux_getn(L, 1, TAB_RW);
 411   if (n > 1) {  /* non-trivial interval? */
 412     luaL_argcheck(L, n < INT_MAX, 1, "array too big");
 413     luaL_checkstack(L, 40, "");  /* assume array is smaller than 2^40 */
 414     if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
 415       luaL_checktype(L, 2, LUA_TFUNCTION);  /* must be a function */
 416     lua_settop(L, 2);  /* make sure there are two arguments */
 417     auxsort(L, 1, (unsigned int)n, 0u);
 418   }
 419   return 0;
 420 }
 421
 422 /* }====================================================== */
 423
 424
 425 static const luaL_Reg tab_funcs[] = {
 426   {"concat", tconcat},
 427 #if defined(LUA_COMPAT_MAXN)
 428   {"maxn", maxn},
 429 #endif
 430   {"insert", tinsert},
 431   {"pack", pack},
 432   {"unpack", unpack},
 433   {"remove", tremove},
 434   {"move", tmove},
 435   {"sort", sort},
 436   {NULL, NULL}
 437 };
 438
 439
 440 LUAMOD_API int luaopen_table (lua_State *L) {
 441   luaL_newlib(L, tab_funcs);
 442 #if defined(LUA_COMPAT_UNPACK)
 443   /* _G.unpack = table.unpack */
 444   lua_getfield(L, -1, "unpack");
 445   lua_setglobal(L, "unpack");
 446 #endif
 447   return 1;
 448 }
 449