ltablib.c
(5.4.7)
/*
** $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 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 <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 (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;
}