1 /* $NetBSD: ltablib.c,v 1.9 2018/08/04 17:30:01 alnsn Exp $ */ 2 3 /* 4 ** Id: ltablib.c,v 1.93.1.1 2017/04/19 17:20:42 roberto Exp 5 ** Library for Table Manipulation 6 ** See Copyright Notice in lua.h 7 */ 8 9 #define ltablib_c 10 #define LUA_LIB 11 12 #include "lprefix.h" 13 14 15 #ifndef _KERNEL 16 #include <limits.h> 17 #include <stddef.h> 18 #include <string.h> 19 #endif /* _KERNEL */ 20 21 #include "lua.h" 22 23 #include "lauxlib.h" 24 #include "lualib.h" 25 26 27 /* 28 ** Operations that an object must define to mimic a table 29 ** (some functions only need some of them) 30 */ 31 #define TAB_R 1 /* read */ 32 #define TAB_W 2 /* write */ 33 #define TAB_L 4 /* length */ 34 #define TAB_RW (TAB_R | TAB_W) /* read/write */ 35 36 37 #define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n)) 38 39 40 static int checkfield (lua_State *L, const char *key, int n) { 41 lua_pushstring(L, key); 42 return (lua_rawget(L, -n) != LUA_TNIL); 43 } 44 45 46 /* 47 ** Check that 'arg' either is a table or can behave like one (that is, 48 ** has a metatable with the required metamethods) 49 */ 50 static void checktab (lua_State *L, int arg, int what) { 51 if (lua_type(L, arg) != LUA_TTABLE) { /* is it not a table? */ 52 int n = 1; /* number of elements to pop */ 53 if (lua_getmetatable(L, arg) && /* must have metatable */ 54 (!(what & TAB_R) || checkfield(L, "__index", ++n)) && 55 (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) && 56 (!(what & TAB_L) || checkfield(L, "__len", ++n))) { 57 lua_pop(L, n); /* pop metatable and tested metamethods */ 58 } 59 else 60 luaL_checktype(L, arg, LUA_TTABLE); /* force an error */ 61 } 62 } 63 64 65 #if defined(LUA_COMPAT_MAXN) 66 static int maxn (lua_State *L) { 67 lua_Number max = 0; 68 luaL_checktype(L, 1, LUA_TTABLE); 69 lua_pushnil(L); /* first key */ 70 while (lua_next(L, 1)) { 71 lua_pop(L, 1); /* remove value */ 72 if (lua_type(L, -1) == LUA_TNUMBER) { 73 lua_Number v = lua_tonumber(L, -1); 74 if (v > max) max = v; 75 } 76 } 77 lua_pushnumber(L, max); 78 return 1; 79 } 80 #endif 81 82 83 static int tinsert (lua_State *L) { 84 lua_Integer e = aux_getn(L, 1, TAB_RW) + 1; /* first empty element */ 85 lua_Integer pos; /* where to insert new element */ 86 switch (lua_gettop(L)) { 87 case 2: { /* called with only 2 arguments */ 88 pos = e; /* insert new element at the end */ 89 break; 90 } 91 case 3: { 92 lua_Integer i; 93 pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */ 94 luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds"); 95 for (i = e; i > pos; i--) { /* move up elements */ 96 lua_geti(L, 1, i - 1); 97 lua_seti(L, 1, i); /* t[i] = t[i - 1] */ 98 } 99 break; 100 } 101 default: { 102 return luaL_error(L, "wrong number of arguments to 'insert'"); 103 } 104 } 105 lua_seti(L, 1, pos); /* t[pos] = v */ 106 return 0; 107 } 108 109 110 static int tremove (lua_State *L) { 111 lua_Integer size = aux_getn(L, 1, TAB_RW); 112 lua_Integer pos = luaL_optinteger(L, 2, size); 113 if (pos != size) /* validate 'pos' if given */ 114 luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds"); 115 lua_geti(L, 1, pos); /* result = t[pos] */ 116 for ( ; pos < size; pos++) { 117 lua_geti(L, 1, pos + 1); 118 lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */ 119 } 120 lua_pushnil(L); 121 lua_seti(L, 1, pos); /* t[pos] = nil */ 122 return 1; 123 } 124 125 126 /* 127 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever 128 ** possible, copy in increasing order, which is better for rehashing. 129 ** "possible" means destination after original range, or smaller 130 ** than origin, or copying to another table. 131 */ 132 static int tmove (lua_State *L) { 133 lua_Integer f = luaL_checkinteger(L, 2); 134 lua_Integer e = luaL_checkinteger(L, 3); 135 lua_Integer t = luaL_checkinteger(L, 4); 136 int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */ 137 checktab(L, 1, TAB_R); 138 checktab(L, tt, TAB_W); 139 if (e >= f) { /* otherwise, nothing to move */ 140 lua_Integer n, i; 141 luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3, 142 "too many elements to move"); 143 n = e - f + 1; /* number of elements to move */ 144 luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4, 145 "destination wrap around"); 146 if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) { 147 for (i = 0; i < n; i++) { 148 lua_geti(L, 1, f + i); 149 lua_seti(L, tt, t + i); 150 } 151 } 152 else { 153 for (i = n - 1; i >= 0; i--) { 154 lua_geti(L, 1, f + i); 155 lua_seti(L, tt, t + i); 156 } 157 } 158 } 159 lua_pushvalue(L, tt); /* return destination table */ 160 return 1; 161 } 162 163 164 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) { 165 lua_geti(L, 1, i); 166 if (!lua_isstring(L, -1)) 167 luaL_error(L, "invalid value (%s) at index %d in table for 'concat'", 168 luaL_typename(L, -1), i); 169 luaL_addvalue(b); 170 } 171 172 173 static int tconcat (lua_State *L) { 174 luaL_Buffer b; 175 lua_Integer last = aux_getn(L, 1, TAB_R); 176 size_t lsep; 177 const char *sep = luaL_optlstring(L, 2, "", &lsep); 178 lua_Integer i = luaL_optinteger(L, 3, 1); 179 last = luaL_optinteger(L, 4, last); 180 luaL_buffinit(L, &b); 181 for (; i < last; i++) { 182 addfield(L, &b, i); 183 luaL_addlstring(&b, sep, lsep); 184 } 185 if (i == last) /* add last value (if interval was not empty) */ 186 addfield(L, &b, i); 187 luaL_pushresult(&b); 188 return 1; 189 } 190 191 192 /* 193 ** {====================================================== 194 ** Pack/unpack 195 ** ======================================================= 196 */ 197 198 static int pack (lua_State *L) { 199 int i; 200 int n = lua_gettop(L); /* number of elements to pack */ 201 lua_createtable(L, n, 1); /* create result table */ 202 lua_insert(L, 1); /* put it at index 1 */ 203 for (i = n; i >= 1; i--) /* assign elements */ 204 lua_seti(L, 1, i); 205 lua_pushinteger(L, n); 206 lua_setfield(L, 1, "n"); /* t.n = number of elements */ 207 return 1; /* return table */ 208 } 209 210 211 static int unpack (lua_State *L) { 212 lua_Unsigned n; 213 lua_Integer i = luaL_optinteger(L, 2, 1); 214 lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1)); 215 if (i > e) return 0; /* empty range */ 216 n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */ 217 if (n >= (unsigned int)INT_MAX || !lua_checkstack(L, (int)(++n))) 218 return luaL_error(L, "too many results to unpack"); 219 for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */ 220 lua_geti(L, 1, i); 221 } 222 lua_geti(L, 1, e); /* push last element */ 223 return (int)n; 224 } 225 226 /* }====================================================== */ 227 228 229 230 /* 231 ** {====================================================== 232 ** Quicksort 233 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick; 234 ** Addison-Wesley, 1993.) 235 ** ======================================================= 236 */ 237 238 239 /* type for array indices */ 240 typedef unsigned int IdxT; 241 242 243 /* 244 ** Produce a "random" 'unsigned int' to randomize pivot choice. This 245 ** macro is used only when 'sort' detects a big imbalance in the result 246 ** of a partition. (If you don't want/need this "randomness", ~0 is a 247 ** good choice.) 248 */ 249 #if !defined(l_randomizePivot) /* { */ 250 251 #include <time.h> 252 253 /* size of 'e' measured in number of 'unsigned int's */ 254 #define sof(e) (sizeof(e) / sizeof(unsigned int)) 255 256 /* 257 ** Use 'time' and 'clock' as sources of "randomness". Because we don't 258 ** know the types 'clock_t' and 'time_t', we cannot cast them to 259 ** anything without risking overflows. A safe way to use their values 260 ** is to copy them to an array of a known type and use the array values. 261 */ 262 static unsigned int l_randomizePivot (void) { 263 clock_t c = clock(); 264 time_t t = time(NULL); 265 unsigned int buff[sof(c) + sof(t)]; 266 unsigned int i, rnd = 0; 267 memcpy(buff, &c, sof(c) * sizeof(unsigned int)); 268 memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int)); 269 for (i = 0; i < sof(buff); i++) 270 rnd += buff[i]; 271 return rnd; 272 } 273 274 #endif /* } */ 275 276 277 /* arrays larger than 'RANLIMIT' may use randomized pivots */ 278 #define RANLIMIT 100u 279 280 281 static void set2 (lua_State *L, IdxT i, IdxT j) { 282 lua_seti(L, 1, i); 283 lua_seti(L, 1, j); 284 } 285 286 287 /* 288 ** Return true iff value at stack index 'a' is less than the value at 289 ** index 'b' (according to the order of the sort). 290 */ 291 static int sort_comp (lua_State *L, int a, int b) { 292 if (lua_isnil(L, 2)) /* no function? */ 293 return lua_compare(L, a, b, LUA_OPLT); /* a < b */ 294 else { /* function */ 295 int res; 296 lua_pushvalue(L, 2); /* push function */ 297 lua_pushvalue(L, a-1); /* -1 to compensate function */ 298 lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */ 299 lua_call(L, 2, 1); /* call function */ 300 res = lua_toboolean(L, -1); /* get result */ 301 lua_pop(L, 1); /* pop result */ 302 return res; 303 } 304 } 305 306 307 /* 308 ** Does the partition: Pivot P is at the top of the stack. 309 ** precondition: a[lo] <= P == a[up-1] <= a[up], 310 ** so it only needs to do the partition from lo + 1 to up - 2. 311 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up] 312 ** returns 'i'. 313 */ 314 static IdxT partition (lua_State *L, IdxT lo, IdxT up) { 315 IdxT i = lo; /* will be incremented before first use */ 316 IdxT j = up - 1; /* will be decremented before first use */ 317 /* loop invariant: a[lo .. i] <= P <= a[j .. up] */ 318 for (;;) { 319 /* next loop: repeat ++i while a[i] < P */ 320 while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) { 321 if (i == up - 1) /* a[i] < P but a[up - 1] == P ?? */ 322 luaL_error(L, "invalid order function for sorting"); 323 lua_pop(L, 1); /* remove a[i] */ 324 } 325 /* after the loop, a[i] >= P and a[lo .. i - 1] < P */ 326 /* next loop: repeat --j while P < a[j] */ 327 while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) { 328 if (j < i) /* j < i but a[j] > P ?? */ 329 luaL_error(L, "invalid order function for sorting"); 330 lua_pop(L, 1); /* remove a[j] */ 331 } 332 /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */ 333 if (j < i) { /* no elements out of place? */ 334 /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */ 335 lua_pop(L, 1); /* pop a[j] */ 336 /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */ 337 set2(L, up - 1, i); 338 return i; 339 } 340 /* otherwise, swap a[i] - a[j] to restore invariant and repeat */ 341 set2(L, i, j); 342 } 343 } 344 345 346 /* 347 ** Choose an element in the middle (2nd-3th quarters) of [lo,up] 348 ** "randomized" by 'rnd' 349 */ 350 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) { 351 IdxT r4 = (up - lo) / 4; /* range/4 */ 352 IdxT p = rnd % (r4 * 2) + (lo + r4); 353 lua_assert(lo + r4 <= p && p <= up - r4); 354 return p; 355 } 356 357 358 /* 359 ** QuickSort algorithm (recursive function) 360 */ 361 static void auxsort (lua_State *L, IdxT lo, IdxT up, 362 unsigned int rnd) { 363 while (lo < up) { /* loop for tail recursion */ 364 IdxT p; /* Pivot index */ 365 IdxT n; /* to be used later */ 366 /* sort elements 'lo', 'p', and 'up' */ 367 lua_geti(L, 1, lo); 368 lua_geti(L, 1, up); 369 if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */ 370 set2(L, lo, up); /* swap a[lo] - a[up] */ 371 else 372 lua_pop(L, 2); /* remove both values */ 373 if (up - lo == 1) /* only 2 elements? */ 374 return; /* already sorted */ 375 if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */ 376 p = (lo + up)/2; /* middle element is a good pivot */ 377 else /* for larger intervals, it is worth a random pivot */ 378 p = choosePivot(lo, up, rnd); 379 lua_geti(L, 1, p); 380 lua_geti(L, 1, lo); 381 if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */ 382 set2(L, p, lo); /* swap a[p] - a[lo] */ 383 else { 384 lua_pop(L, 1); /* remove a[lo] */ 385 lua_geti(L, 1, up); 386 if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */ 387 set2(L, p, up); /* swap a[up] - a[p] */ 388 else 389 lua_pop(L, 2); 390 } 391 if (up - lo == 2) /* only 3 elements? */ 392 return; /* already sorted */ 393 lua_geti(L, 1, p); /* get middle element (Pivot) */ 394 lua_pushvalue(L, -1); /* push Pivot */ 395 lua_geti(L, 1, up - 1); /* push a[up - 1] */ 396 set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */ 397 p = partition(L, lo, up); 398 /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */ 399 if (p - lo < up - p) { /* lower interval is smaller? */ 400 auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */ 401 n = p - lo; /* size of smaller interval */ 402 lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */ 403 } 404 else { 405 auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */ 406 n = up - p; /* size of smaller interval */ 407 up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */ 408 } 409 if ((up - lo) / 128 > n) /* partition too imbalanced? */ 410 rnd = l_randomizePivot(); /* try a new randomization */ 411 } /* tail call auxsort(L, lo, up, rnd) */ 412 } 413 414 415 static int sort (lua_State *L) { 416 lua_Integer n = aux_getn(L, 1, TAB_RW); 417 if (n > 1) { /* non-trivial interval? */ 418 luaL_argcheck(L, n < INT_MAX, 1, "array too big"); 419 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */ 420 luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */ 421 lua_settop(L, 2); /* make sure there are two arguments */ 422 auxsort(L, 1, (IdxT)n, 0); 423 } 424 return 0; 425 } 426 427 /* }====================================================== */ 428 429 430 static const luaL_Reg tab_funcs[] = { 431 {"concat", tconcat}, 432 #if defined(LUA_COMPAT_MAXN) 433 {"maxn", maxn}, 434 #endif 435 {"insert", tinsert}, 436 {"pack", pack}, 437 {"unpack", unpack}, 438 {"remove", tremove}, 439 {"move", tmove}, 440 {"sort", sort}, 441 {NULL, NULL} 442 }; 443 444 445 LUAMOD_API int luaopen_table (lua_State *L) { 446 luaL_newlib(L, tab_funcs); 447 #if defined(LUA_COMPAT_UNPACK) 448 /* _G.unpack = table.unpack */ 449 lua_getfield(L, -1, "unpack"); 450 lua_setglobal(L, "unpack"); 451 #endif 452 return 1; 453 } 454 455