/* ** $Id: ltablib.c $ ** Library for Table Manipulation ** See Copyright Notice in lua.h */ #define ltablib_c #define LUA_LIB #include "lprefix.h" #include #include #include #include "lua.h" #include "lauxlib.h" #include "lualib.h" /* ** Operations that an object must define to mimic a table ** (some functions only need some of them) */ #define TAB_R 1 /* read */ #define TAB_W 2 /* write */ #define TAB_L 4 /* length */ #define TAB_RW (TAB_R | TAB_W) /* read/write */ #define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n)) static int checkfield (lua_State *L, const char *key, int n) { lua_pushstring(L, key); return (lua_rawget(L, -n) != LUA_TNIL); } /* ** Check that 'arg' either is a table or can behave like one (that is, ** has a metatable with the required metamethods) */ static void checktab (lua_State *L, int arg, int what) { if (lua_type(L, arg) != LUA_TTABLE) { /* is it not a table? */ int n = 1; /* number of elements to pop */ if (lua_getmetatable(L, arg) && /* must have metatable */ (!(what & TAB_R) || checkfield(L, "__index", ++n)) && (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) && (!(what & TAB_L) || checkfield(L, "__len", ++n))) { lua_pop(L, n); /* pop metatable and tested metamethods */ } else luaL_checktype(L, arg, LUA_TTABLE); /* force an error */ } } static int tinsert (lua_State *L) { lua_Integer pos; /* where to insert new element */ lua_Integer e = aux_getn(L, 1, TAB_RW); e = luaL_intop(+, e, 1); /* first empty element */ switch (lua_gettop(L)) { case 2: { /* called with only 2 arguments */ pos = e; /* insert new element at the end */ break; } case 3: { lua_Integer i; pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */ /* check whether 'pos' is in [1, e] */ luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2, "position out of bounds"); for (i = e; i > pos; i--) { /* move up elements */ lua_geti(L, 1, i - 1); lua_seti(L, 1, i); /* t[i] = t[i - 1] */ } break; } default: { return luaL_error(L, "wrong number of arguments to 'insert'"); } } lua_seti(L, 1, pos); /* t[pos] = v */ return 0; } static int tremove (lua_State *L) { lua_Integer size = aux_getn(L, 1, TAB_RW); lua_Integer pos = luaL_optinteger(L, 2, size); if (pos != size) /* validate 'pos' if given */ /* check whether 'pos' is in [1, size + 1] */ luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 2, "position out of bounds"); lua_geti(L, 1, pos); /* result = t[pos] */ for ( ; pos < size; pos++) { lua_geti(L, 1, pos + 1); lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */ } lua_pushnil(L); lua_seti(L, 1, pos); /* remove entry t[pos] */ return 1; } /* ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever ** possible, copy in increasing order, which is better for rehashing. ** "possible" means destination after original range, or smaller ** than origin, or copying to another table. */ static int tmove (lua_State *L) { lua_Integer f = luaL_checkinteger(L, 2); lua_Integer e = luaL_checkinteger(L, 3); lua_Integer t = luaL_checkinteger(L, 4); int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */ checktab(L, 1, TAB_R); checktab(L, tt, TAB_W); if (e >= f) { /* otherwise, nothing to move */ lua_Integer n, i; luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3, "too many elements to move"); n = e - f + 1; /* number of elements to move */ luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4, "destination wrap around"); if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) { for (i = 0; i < n; i++) { lua_geti(L, 1, f + i); lua_seti(L, tt, t + i); } } else { for (i = n - 1; i >= 0; i--) { lua_geti(L, 1, f + i); lua_seti(L, tt, t + i); } } } lua_pushvalue(L, tt); /* return destination table */ return 1; } static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) { lua_geti(L, 1, i); if (l_unlikely(!lua_isstring(L, -1))) luaL_error(L, "invalid value (%s) at index %I in table for 'concat'", luaL_typename(L, -1), (LUAI_UACINT)i); luaL_addvalue(b); } static int tconcat (lua_State *L) { luaL_Buffer b; lua_Integer last = aux_getn(L, 1, TAB_R); size_t lsep; const char *sep = luaL_optlstring(L, 2, "", &lsep); lua_Integer i = luaL_optinteger(L, 3, 1); last = luaL_optinteger(L, 4, last); luaL_buffinit(L, &b); for (; i < last; i++) { addfield(L, &b, i); luaL_addlstring(&b, sep, lsep); } if (i == last) /* add last value (if interval was not empty) */ addfield(L, &b, i); luaL_pushresult(&b); return 1; } /* ** {====================================================== ** Pack/unpack ** ======================================================= */ static int tpack (lua_State *L) { int i; int n = lua_gettop(L); /* number of elements to pack */ lua_createtable(L, n, 1); /* create result table */ lua_insert(L, 1); /* put it at index 1 */ for (i = n; i >= 1; i--) /* assign elements */ lua_seti(L, 1, i); lua_pushinteger(L, n); lua_setfield(L, 1, "n"); /* t.n = number of elements */ return 1; /* return table */ } static int tunpack (lua_State *L) { lua_Unsigned n; lua_Integer i = luaL_optinteger(L, 2, 1); lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1)); if (i > e) return 0; /* empty range */ n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */ if (l_unlikely(n >= (unsigned int)INT_MAX || !lua_checkstack(L, (int)(++n)))) return luaL_error(L, "too many results to unpack"); for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */ lua_geti(L, 1, i); } lua_geti(L, 1, e); /* push last element */ return (int)n; } /* }====================================================== */ /* ** {====================================================== ** Quicksort ** (based on 'Algorithms in MODULA-3', Robert Sedgewick; ** Addison-Wesley, 1993.) ** ======================================================= */ /* type for array indices */ typedef unsigned int IdxT; /* ** Produce a "random" 'unsigned int' to randomize pivot choice. This ** macro is used only when 'sort' detects a big imbalance in the result ** of a partition. (If you don't want/need this "randomness", ~0 is a ** good choice.) */ #if !defined(l_randomizePivot) /* { */ #include /* size of 'e' measured in number of 'unsigned int's */ #define sof(e) (sizeof(e) / sizeof(unsigned int)) /* ** Use 'time' and 'clock' as sources of "randomness". Because we don't ** know the types 'clock_t' and 'time_t', we cannot cast them to ** anything without risking overflows. A safe way to use their values ** is to copy them to an array of a known type and use the array values. */ static unsigned int l_randomizePivot (void) { clock_t c = clock(); time_t t = time(NULL); unsigned int buff[sof(c) + sof(t)]; unsigned int i, rnd = 0; memcpy(buff, &c, sof(c) * sizeof(unsigned int)); memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int)); for (i = 0; i < sof(buff); i++) rnd += buff[i]; return rnd; } #endif /* } */ /* arrays larger than 'RANLIMIT' may use randomized pivots */ #define RANLIMIT 100u static void set2 (lua_State *L, IdxT i, IdxT j) { lua_seti(L, 1, i); lua_seti(L, 1, j); } /* ** Return true iff value at stack index 'a' is less than the value at ** index 'b' (according to the order of the sort). */ static int sort_comp (lua_State *L, int a, int b) { if (lua_isnil(L, 2)) /* no function? */ return lua_compare(L, a, b, LUA_OPLT); /* a < b */ else { /* function */ int res; lua_pushvalue(L, 2); /* push function */ lua_pushvalue(L, a-1); /* -1 to compensate function */ lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */ lua_call(L, 2, 1); /* call function */ res = lua_toboolean(L, -1); /* get result */ lua_pop(L, 1); /* pop result */ return res; } } /* ** Does the partition: Pivot P is at the top of the stack. ** precondition: a[lo] <= P == a[up-1] <= a[up], ** so it only needs to do the partition from lo + 1 to up - 2. ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up] ** returns 'i'. */ static IdxT partition (lua_State *L, IdxT lo, IdxT up) { IdxT i = lo; /* will be incremented before first use */ IdxT j = up - 1; /* will be decremented before first use */ /* loop invariant: a[lo .. i] <= P <= a[j .. up] */ for (;;) { /* next loop: repeat ++i while a[i] < P */ while ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) { if (l_unlikely(i == up - 1)) /* a[i] < P but a[up - 1] == P ?? */ luaL_error(L, "invalid order function for sorting"); lua_pop(L, 1); /* remove a[i] */ } /* after the loop, a[i] >= P and a[lo .. i - 1] < P */ /* next loop: repeat --j while P < a[j] */ while ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) { if (l_unlikely(j < i)) /* j < i but a[j] > P ?? */ luaL_error(L, "invalid order function for sorting"); lua_pop(L, 1); /* remove a[j] */ } /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */ if (j < i) { /* no elements out of place? */ /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */ lua_pop(L, 1); /* pop a[j] */ /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */ set2(L, up - 1, i); return i; } /* otherwise, swap a[i] - a[j] to restore invariant and repeat */ set2(L, i, j); } } /* ** Choose an element in the middle (2nd-3th quarters) of [lo,up] ** "randomized" by 'rnd' */ static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) { IdxT r4 = (up - lo) / 4; /* range/4 */ IdxT p = rnd % (r4 * 2) + (lo + r4); lua_assert(lo + r4 <= p && p <= up - r4); return p; } /* ** Quicksort algorithm (recursive function) */ static void auxsort (lua_State *L, IdxT lo, IdxT up, unsigned int rnd) { while (lo < up) { /* loop for tail recursion */ IdxT p; /* Pivot index */ IdxT n; /* to be used later */ /* sort elements 'lo', 'p', and 'up' */ lua_geti(L, 1, lo); lua_geti(L, 1, up); if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */ set2(L, lo, up); /* swap a[lo] - a[up] */ else lua_pop(L, 2); /* remove both values */ if (up - lo == 1) /* only 2 elements? */ return; /* already sorted */ if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */ p = (lo + up)/2; /* middle element is a good pivot */ else /* for larger intervals, it is worth a random pivot */ p = choosePivot(lo, up, rnd); lua_geti(L, 1, p); lua_geti(L, 1, lo); if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */ set2(L, p, lo); /* swap a[p] - a[lo] */ else { lua_pop(L, 1); /* remove a[lo] */ lua_geti(L, 1, up); if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */ set2(L, p, up); /* swap a[up] - a[p] */ else lua_pop(L, 2); } if (up - lo == 2) /* only 3 elements? */ return; /* already sorted */ lua_geti(L, 1, p); /* get middle element (Pivot) */ lua_pushvalue(L, -1); /* push Pivot */ lua_geti(L, 1, up - 1); /* push a[up - 1] */ set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */ p = partition(L, lo, up); /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */ if (p - lo < up - p) { /* lower interval is smaller? */ auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */ n = p - lo; /* size of smaller interval */ lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */ } else { auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */ n = up - p; /* size of smaller interval */ up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */ } if ((up - lo) / 128 > n) /* partition too imbalanced? */ rnd = l_randomizePivot(); /* try a new randomization */ } /* tail call auxsort(L, lo, up, rnd) */ } static int sort (lua_State *L) { lua_Integer n = aux_getn(L, 1, TAB_RW); if (n > 1) { /* non-trivial interval? */ luaL_argcheck(L, n < INT_MAX, 1, "array too big"); if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */ luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */ lua_settop(L, 2); /* make sure there are two arguments */ auxsort(L, 1, (IdxT)n, 0); } return 0; } /* }====================================================== */ static const luaL_Reg tab_funcs[] = { {"concat", tconcat}, {"insert", tinsert}, {"pack", tpack}, {"unpack", tunpack}, {"remove", tremove}, {"move", tmove}, {"sort", sort}, {NULL, NULL} }; LUAMOD_API int luaopen_table (lua_State *L) { luaL_newlib(L, tab_funcs); return 1; }