1 /* 2 ** $Id: ltablib.c,v 1.93.1.1 2017/04/19 17:20:42 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_checktype(L, arg, LUA_TTABLE); /* 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 && !lua_compare(L, 1, tt, LUA_OPEQ))) { 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 destination 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_optinteger(L, 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 /* type for array indices */ 236 typedef unsigned int IdxT; 237 238 239 /* 240 ** Produce a "random" 'unsigned int' to randomize pivot choice. This 241 ** macro is used only when 'sort' detects a big imbalance in the result 242 ** of a partition. (If you don't want/need this "randomness", ~0 is a 243 ** good choice.) 244 */ 245 #if !defined(l_randomizePivot) /* { */ 246 247 #include <time.h> 248 249 /* size of 'e' measured in number of 'unsigned int's */ 250 #define sof(e) (sizeof(e) / sizeof(unsigned int)) 251 252 /* 253 ** Use 'time' and 'clock' as sources of "randomness". Because we don't 254 ** know the types 'clock_t' and 'time_t', we cannot cast them to 255 ** anything without risking overflows. A safe way to use their values 256 ** is to copy them to an array of a known type and use the array values. 257 */ 258 static unsigned int l_randomizePivot (void) { 259 clock_t c = clock(); 260 time_t t = time(NULL); 261 unsigned int buff[sof(c) + sof(t)]; 262 unsigned int i, rnd = 0; 263 memcpy(buff, &c, sof(c) * sizeof(unsigned int)); 264 memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int)); 265 for (i = 0; i < sof(buff); i++) 266 rnd += buff[i]; 267 return rnd; 268 } 269 270 #endif /* } */ 271 272 273 /* arrays larger than 'RANLIMIT' may use randomized pivots */ 274 #define RANLIMIT 100u 275 276 277 static void set2 (lua_State *L, IdxT i, IdxT j) { 278 lua_seti(L, 1, i); 279 lua_seti(L, 1, j); 280 } 281 282 283 /* 284 ** Return true iff value at stack index 'a' is less than the value at 285 ** index 'b' (according to the order of the sort). 286 */ 287 static int sort_comp (lua_State *L, int a, int b) { 288 if (lua_isnil(L, 2)) /* no function? */ 289 return lua_compare(L, a, b, LUA_OPLT); /* a < b */ 290 else { /* function */ 291 int res; 292 lua_pushvalue(L, 2); /* push function */ 293 lua_pushvalue(L, a-1); /* -1 to compensate function */ 294 lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */ 295 lua_call(L, 2, 1); /* call function */ 296 res = lua_toboolean(L, -1); /* get result */ 297 lua_pop(L, 1); /* pop result */ 298 return res; 299 } 300 } 301 302 303 /* 304 ** Does the partition: Pivot P is at the top of the stack. 305 ** precondition: a[lo] <= P == a[up-1] <= a[up], 306 ** so it only needs to do the partition from lo + 1 to up - 2. 307 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up] 308 ** returns 'i'. 309 */ 310 static IdxT partition (lua_State *L, IdxT lo, IdxT up) { 311 IdxT i = lo; /* will be incremented before first use */ 312 IdxT j = up - 1; /* will be decremented before first use */ 313 /* loop invariant: a[lo .. i] <= P <= a[j .. up] */ 314 for (;;) { 315 /* next loop: repeat ++i while a[i] < P */ 316 while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) { 317 if (i == up - 1) /* a[i] < P but a[up - 1] == P ?? */ 318 luaL_error(L, "invalid order function for sorting"); 319 lua_pop(L, 1); /* remove a[i] */ 320 } 321 /* after the loop, a[i] >= P and a[lo .. i - 1] < P */ 322 /* next loop: repeat --j while P < a[j] */ 323 while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) { 324 if (j < i) /* j < i but a[j] > P ?? */ 325 luaL_error(L, "invalid order function for sorting"); 326 lua_pop(L, 1); /* remove a[j] */ 327 } 328 /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */ 329 if (j < i) { /* no elements out of place? */ 330 /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */ 331 lua_pop(L, 1); /* pop a[j] */ 332 /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */ 333 set2(L, up - 1, i); 334 return i; 335 } 336 /* otherwise, swap a[i] - a[j] to restore invariant and repeat */ 337 set2(L, i, j); 338 } 339 } 340 341 342 /* 343 ** Choose an element in the middle (2nd-3th quarters) of [lo,up] 344 ** "randomized" by 'rnd' 345 */ 346 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) { 347 IdxT r4 = (up - lo) / 4; /* range/4 */ 348 IdxT p = rnd % (r4 * 2) + (lo + r4); 349 lua_assert(lo + r4 <= p && p <= up - r4); 350 return p; 351 } 352 353 354 /* 355 ** QuickSort algorithm (recursive function) 356 */ 357 static void auxsort (lua_State *L, IdxT lo, IdxT up, 358 unsigned int rnd) { 359 while (lo < up) { /* loop for tail recursion */ 360 IdxT p; /* Pivot index */ 361 IdxT n; /* to be used later */ 362 /* sort elements 'lo', 'p', and 'up' */ 363 lua_geti(L, 1, lo); 364 lua_geti(L, 1, up); 365 if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */ 366 set2(L, lo, up); /* swap a[lo] - a[up] */ 367 else 368 lua_pop(L, 2); /* remove both values */ 369 if (up - lo == 1) /* only 2 elements? */ 370 return; /* already sorted */ 371 if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */ 372 p = (lo + up)/2; /* middle element is a good pivot */ 373 else /* for larger intervals, it is worth a random pivot */ 374 p = choosePivot(lo, up, rnd); 375 lua_geti(L, 1, p); 376 lua_geti(L, 1, lo); 377 if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */ 378 set2(L, p, lo); /* swap a[p] - a[lo] */ 379 else { 380 lua_pop(L, 1); /* remove a[lo] */ 381 lua_geti(L, 1, up); 382 if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */ 383 set2(L, p, up); /* swap a[up] - a[p] */ 384 else 385 lua_pop(L, 2); 386 } 387 if (up - lo == 2) /* only 3 elements? */ 388 return; /* already sorted */ 389 lua_geti(L, 1, p); /* get middle element (Pivot) */ 390 lua_pushvalue(L, -1); /* push Pivot */ 391 lua_geti(L, 1, up - 1); /* push a[up - 1] */ 392 set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */ 393 p = partition(L, lo, up); 394 /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */ 395 if (p - lo < up - p) { /* lower interval is smaller? */ 396 auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */ 397 n = p - lo; /* size of smaller interval */ 398 lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */ 399 } 400 else { 401 auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */ 402 n = up - p; /* size of smaller interval */ 403 up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */ 404 } 405 if ((up - lo) / 128 > n) /* partition too imbalanced? */ 406 rnd = l_randomizePivot(); /* try a new randomization */ 407 } /* tail call auxsort(L, lo, up, rnd) */ 408 } 409 410 411 static int sort (lua_State *L) { 412 lua_Integer n = aux_getn(L, 1, TAB_RW); 413 if (n > 1) { /* non-trivial interval? */ 414 luaL_argcheck(L, n < INT_MAX, 1, "array too big"); 415 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */ 416 luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */ 417 lua_settop(L, 2); /* make sure there are two arguments */ 418 auxsort(L, 1, (IdxT)n, 0); 419 } 420 return 0; 421 } 422 423 /* }====================================================== */ 424 425 426 static const luaL_Reg tab_funcs[] = { 427 {"concat", tconcat}, 428 #if defined(LUA_COMPAT_MAXN) 429 {"maxn", maxn}, 430 #endif 431 {"insert", tinsert}, 432 {"pack", pack}, 433 {"unpack", unpack}, 434 {"remove", tremove}, 435 {"move", tmove}, 436 {"sort", sort}, 437 {NULL, NULL} 438 }; 439 440 441 LUAMOD_API int luaopen_table (lua_State *L) { 442 luaL_newlib(L, tab_funcs); 443 #if defined(LUA_COMPAT_UNPACK) 444 /* _G.unpack = table.unpack */ 445 lua_getfield(L, -1, "unpack"); 446 lua_setglobal(L, "unpack"); 447 #endif 448 return 1; 449 } 450 451