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