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- /*
- ** $Id: ltablib.c $
- ** Library for Table Manipulation
- ** See Copyright Notice in lua.h
- */
- #define ltablib_c
- #define LUA_LIB
- #include "lprefix.h"
- #include <limits.h>
- #include <stddef.h>
- #include <string.h>
- #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 e = aux_getn(L, 1, TAB_RW) + 1; /* first empty element */
- lua_Integer pos; /* where to insert new 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, 1,
- "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 (!lua_isstring(L, -1))
- luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
- luaL_typename(L, -1), 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 (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 <time.h>
- /* 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 (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 (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;
- }
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