1 /* $NetBSD: ltablib.c,v 1.11 2023/06/08 21:12:08 nikita Exp $ */ 2 3 /* 4 ** Id: ltablib.c 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 static int tinsert (lua_State *L) { 66 lua_Integer pos; /* where to insert new element */ 67 lua_Integer e = aux_getn(L, 1, TAB_RW); 68 e = luaL_intop(+, e, 1); /* first empty element */ 69 switch (lua_gettop(L)) { 70 case 2: { /* called with only 2 arguments */ 71 pos = e; /* insert new element at the end */ 72 break; 73 } 74 case 3: { 75 lua_Integer i; 76 pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */ 77 /* check whether 'pos' is in [1, e] */ 78 luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2, 79 "position out of bounds"); 80 for (i = e; i > pos; i--) { /* move up elements */ 81 lua_geti(L, 1, i - 1); 82 lua_seti(L, 1, i); /* t[i] = t[i - 1] */ 83 } 84 break; 85 } 86 default: { 87 return luaL_error(L, "wrong number of arguments to 'insert'"); 88 } 89 } 90 lua_seti(L, 1, pos); /* t[pos] = v */ 91 return 0; 92 } 93 94 95 static int tremove (lua_State *L) { 96 lua_Integer size = aux_getn(L, 1, TAB_RW); 97 lua_Integer pos = luaL_optinteger(L, 2, size); 98 if (pos != size) /* validate 'pos' if given */ 99 /* check whether 'pos' is in [1, size + 1] */ 100 luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 2, 101 "position out of bounds"); 102 lua_geti(L, 1, pos); /* result = t[pos] */ 103 for ( ; pos < size; pos++) { 104 lua_geti(L, 1, pos + 1); 105 lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */ 106 } 107 lua_pushnil(L); 108 lua_seti(L, 1, pos); /* remove entry t[pos] */ 109 return 1; 110 } 111 112 113 /* 114 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever 115 ** possible, copy in increasing order, which is better for rehashing. 116 ** "possible" means destination after original range, or smaller 117 ** than origin, or copying to another table. 118 */ 119 static int tmove (lua_State *L) { 120 lua_Integer f = luaL_checkinteger(L, 2); 121 lua_Integer e = luaL_checkinteger(L, 3); 122 lua_Integer t = luaL_checkinteger(L, 4); 123 int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */ 124 checktab(L, 1, TAB_R); 125 checktab(L, tt, TAB_W); 126 if (e >= f) { /* otherwise, nothing to move */ 127 lua_Integer n, i; 128 luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3, 129 "too many elements to move"); 130 n = e - f + 1; /* number of elements to move */ 131 luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4, 132 "destination wrap around"); 133 if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) { 134 for (i = 0; i < n; i++) { 135 lua_geti(L, 1, f + i); 136 lua_seti(L, tt, t + i); 137 } 138 } 139 else { 140 for (i = n - 1; i >= 0; i--) { 141 lua_geti(L, 1, f + i); 142 lua_seti(L, tt, t + i); 143 } 144 } 145 } 146 lua_pushvalue(L, tt); /* return destination table */ 147 return 1; 148 } 149 150 151 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) { 152 lua_geti(L, 1, i); 153 if (l_unlikely(!lua_isstring(L, -1))) 154 luaL_error(L, "invalid value (%s) at index %I in table for 'concat'", 155 luaL_typename(L, -1), (LUAI_UACINT)i); 156 luaL_addvalue(b); 157 } 158 159 160 static int tconcat (lua_State *L) { 161 luaL_Buffer b; 162 lua_Integer last = aux_getn(L, 1, TAB_R); 163 size_t lsep; 164 const char *sep = luaL_optlstring(L, 2, "", &lsep); 165 lua_Integer i = luaL_optinteger(L, 3, 1); 166 last = luaL_optinteger(L, 4, last); 167 luaL_buffinit(L, &b); 168 for (; i < last; i++) { 169 addfield(L, &b, i); 170 luaL_addlstring(&b, sep, lsep); 171 } 172 if (i == last) /* add last value (if interval was not empty) */ 173 addfield(L, &b, i); 174 luaL_pushresult(&b); 175 return 1; 176 } 177 178 179 /* 180 ** {====================================================== 181 ** Pack/unpack 182 ** ======================================================= 183 */ 184 185 static int tpack (lua_State *L) { 186 int i; 187 int n = lua_gettop(L); /* number of elements to pack */ 188 lua_createtable(L, n, 1); /* create result table */ 189 lua_insert(L, 1); /* put it at index 1 */ 190 for (i = n; i >= 1; i--) /* assign elements */ 191 lua_seti(L, 1, i); 192 lua_pushinteger(L, n); 193 lua_setfield(L, 1, "n"); /* t.n = number of elements */ 194 return 1; /* return table */ 195 } 196 197 198 static int tunpack (lua_State *L) { 199 lua_Unsigned n; 200 lua_Integer i = luaL_optinteger(L, 2, 1); 201 lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1)); 202 if (i > e) return 0; /* empty range */ 203 n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */ 204 if (l_unlikely(n >= (unsigned int)INT_MAX || 205 !lua_checkstack(L, (int)(++n)))) 206 return luaL_error(L, "too many results to unpack"); 207 for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */ 208 lua_geti(L, 1, i); 209 } 210 lua_geti(L, 1, e); /* push last element */ 211 return (int)n; 212 } 213 214 /* }====================================================== */ 215 216 217 218 /* 219 ** {====================================================== 220 ** Quicksort 221 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick; 222 ** Addison-Wesley, 1993.) 223 ** ======================================================= 224 */ 225 226 227 /* type for array indices */ 228 typedef unsigned int IdxT; 229 230 231 /* 232 ** Produce a "random" 'unsigned int' to randomize pivot choice. This 233 ** macro is used only when 'sort' detects a big imbalance in the result 234 ** of a partition. (If you don't want/need this "randomness", ~0 is a 235 ** good choice.) 236 */ 237 #if !defined(l_randomizePivot) /* { */ 238 239 #include <time.h> 240 241 /* size of 'e' measured in number of 'unsigned int's */ 242 #define sof(e) (sizeof(e) / sizeof(unsigned int)) 243 244 /* 245 ** Use 'time' and 'clock' as sources of "randomness". Because we don't 246 ** know the types 'clock_t' and 'time_t', we cannot cast them to 247 ** anything without risking overflows. A safe way to use their values 248 ** is to copy them to an array of a known type and use the array values. 249 */ 250 static unsigned int l_randomizePivot (void) { 251 clock_t c = clock(); 252 time_t t = time(NULL); 253 unsigned int buff[sof(c) + sof(t)]; 254 unsigned int i, rnd = 0; 255 memcpy(buff, &c, sof(c) * sizeof(unsigned int)); 256 memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int)); 257 for (i = 0; i < sof(buff); i++) 258 rnd += buff[i]; 259 return rnd; 260 } 261 262 #endif /* } */ 263 264 265 /* arrays larger than 'RANLIMIT' may use randomized pivots */ 266 #define RANLIMIT 100u 267 268 269 static void set2 (lua_State *L, IdxT i, IdxT j) { 270 lua_seti(L, 1, i); 271 lua_seti(L, 1, j); 272 } 273 274 275 /* 276 ** Return true iff value at stack index 'a' is less than the value at 277 ** index 'b' (according to the order of the sort). 278 */ 279 static int sort_comp (lua_State *L, int a, int b) { 280 if (lua_isnil(L, 2)) /* no function? */ 281 return lua_compare(L, a, b, LUA_OPLT); /* a < b */ 282 else { /* function */ 283 int res; 284 lua_pushvalue(L, 2); /* push function */ 285 lua_pushvalue(L, a-1); /* -1 to compensate function */ 286 lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */ 287 lua_call(L, 2, 1); /* call function */ 288 res = lua_toboolean(L, -1); /* get result */ 289 lua_pop(L, 1); /* pop result */ 290 return res; 291 } 292 } 293 294 295 /* 296 ** Does the partition: Pivot P is at the top of the stack. 297 ** precondition: a[lo] <= P == a[up-1] <= a[up], 298 ** so it only needs to do the partition from lo + 1 to up - 2. 299 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up] 300 ** returns 'i'. 301 */ 302 static IdxT partition (lua_State *L, IdxT lo, IdxT up) { 303 IdxT i = lo; /* will be incremented before first use */ 304 IdxT j = up - 1; /* will be decremented before first use */ 305 /* loop invariant: a[lo .. i] <= P <= a[j .. up] */ 306 for (;;) { 307 /* next loop: repeat ++i while a[i] < P */ 308 while ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) { 309 if (l_unlikely(i == up - 1)) /* a[i] < P but a[up - 1] == P ?? */ 310 luaL_error(L, "invalid order function for sorting"); 311 lua_pop(L, 1); /* remove a[i] */ 312 } 313 /* after the loop, a[i] >= P and a[lo .. i - 1] < P */ 314 /* next loop: repeat --j while P < a[j] */ 315 while ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) { 316 if (l_unlikely(j < i)) /* j < i but a[j] > P ?? */ 317 luaL_error(L, "invalid order function for sorting"); 318 lua_pop(L, 1); /* remove a[j] */ 319 } 320 /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */ 321 if (j < i) { /* no elements out of place? */ 322 /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */ 323 lua_pop(L, 1); /* pop a[j] */ 324 /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */ 325 set2(L, up - 1, i); 326 return i; 327 } 328 /* otherwise, swap a[i] - a[j] to restore invariant and repeat */ 329 set2(L, i, j); 330 } 331 } 332 333 334 /* 335 ** Choose an element in the middle (2nd-3th quarters) of [lo,up] 336 ** "randomized" by 'rnd' 337 */ 338 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) { 339 IdxT r4 = (up - lo) / 4; /* range/4 */ 340 IdxT p = rnd % (r4 * 2) + (lo + r4); 341 lua_assert(lo + r4 <= p && p <= up - r4); 342 return p; 343 } 344 345 346 /* 347 ** Quicksort algorithm (recursive function) 348 */ 349 static void auxsort (lua_State *L, IdxT lo, IdxT up, 350 unsigned int rnd) { 351 while (lo < up) { /* loop for tail recursion */ 352 IdxT p; /* Pivot index */ 353 IdxT n; /* to be used later */ 354 /* sort elements 'lo', 'p', and 'up' */ 355 lua_geti(L, 1, lo); 356 lua_geti(L, 1, up); 357 if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */ 358 set2(L, lo, up); /* swap a[lo] - a[up] */ 359 else 360 lua_pop(L, 2); /* remove both values */ 361 if (up - lo == 1) /* only 2 elements? */ 362 return; /* already sorted */ 363 if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */ 364 p = (lo + up)/2; /* middle element is a good pivot */ 365 else /* for larger intervals, it is worth a random pivot */ 366 p = choosePivot(lo, up, rnd); 367 lua_geti(L, 1, p); 368 lua_geti(L, 1, lo); 369 if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */ 370 set2(L, p, lo); /* swap a[p] - a[lo] */ 371 else { 372 lua_pop(L, 1); /* remove a[lo] */ 373 lua_geti(L, 1, up); 374 if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */ 375 set2(L, p, up); /* swap a[up] - a[p] */ 376 else 377 lua_pop(L, 2); 378 } 379 if (up - lo == 2) /* only 3 elements? */ 380 return; /* already sorted */ 381 lua_geti(L, 1, p); /* get middle element (Pivot) */ 382 lua_pushvalue(L, -1); /* push Pivot */ 383 lua_geti(L, 1, up - 1); /* push a[up - 1] */ 384 set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */ 385 p = partition(L, lo, up); 386 /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */ 387 if (p - lo < up - p) { /* lower interval is smaller? */ 388 auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */ 389 n = p - lo; /* size of smaller interval */ 390 lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */ 391 } 392 else { 393 auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */ 394 n = up - p; /* size of smaller interval */ 395 up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */ 396 } 397 if ((up - lo) / 128 > n) /* partition too imbalanced? */ 398 rnd = l_randomizePivot(); /* try a new randomization */ 399 } /* tail call auxsort(L, lo, up, rnd) */ 400 } 401 402 403 static int sort (lua_State *L) { 404 lua_Integer n = aux_getn(L, 1, TAB_RW); 405 if (n > 1) { /* non-trivial interval? */ 406 luaL_argcheck(L, n < INT_MAX, 1, "array too big"); 407 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */ 408 luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */ 409 lua_settop(L, 2); /* make sure there are two arguments */ 410 auxsort(L, 1, (IdxT)n, 0); 411 } 412 return 0; 413 } 414 415 /* }====================================================== */ 416 417 418 static const luaL_Reg tab_funcs[] = { 419 {"concat", tconcat}, 420 {"insert", tinsert}, 421 {"pack", tpack}, 422 {"unpack", tunpack}, 423 {"remove", tremove}, 424 {"move", tmove}, 425 {"sort", sort}, 426 {NULL, NULL} 427 }; 428 429 430 LUAMOD_API int luaopen_table (lua_State *L) { 431 luaL_newlib(L, tab_funcs); 432 return 1; 433 } 434 435