mirror of
https://github.com/lua/lua
synced 2024-11-23 05:11:45 +03:00
d12262068d
Checks of the form '1 <= x && x <= M' were rewritten in the form '(unsigned)x - 1 < (unsigned)M', which is usually more efficient. (Other similar checks have similar translations.) Although some compilers do these optimizations, that does not happen for all compilers or all cases.
429 lines
13 KiB
C
429 lines
13 KiB
C
/*
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** $Id: ltablib.c $
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** Library for Table Manipulation
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** See Copyright Notice in lua.h
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*/
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#define ltablib_c
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#define LUA_LIB
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#include "lprefix.h"
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#include <limits.h>
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#include <stddef.h>
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#include <string.h>
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#include "lua.h"
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#include "lauxlib.h"
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#include "lualib.h"
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/*
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** Operations that an object must define to mimic a table
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** (some functions only need some of them)
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*/
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#define TAB_R 1 /* read */
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#define TAB_W 2 /* write */
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#define TAB_L 4 /* length */
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#define TAB_RW (TAB_R | TAB_W) /* read/write */
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#define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n))
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static int checkfield (lua_State *L, const char *key, int n) {
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lua_pushstring(L, key);
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return (lua_rawget(L, -n) != LUA_TNIL);
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}
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/*
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** Check that 'arg' either is a table or can behave like one (that is,
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** has a metatable with the required metamethods)
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*/
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static void checktab (lua_State *L, int arg, int what) {
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if (lua_type(L, arg) != LUA_TTABLE) { /* is it not a table? */
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int n = 1; /* number of elements to pop */
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if (lua_getmetatable(L, arg) && /* must have metatable */
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(!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
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(!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
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(!(what & TAB_L) || checkfield(L, "__len", ++n))) {
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lua_pop(L, n); /* pop metatable and tested metamethods */
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}
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else
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luaL_checktype(L, arg, LUA_TTABLE); /* force an error */
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}
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}
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static int tinsert (lua_State *L) {
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lua_Integer e = aux_getn(L, 1, TAB_RW) + 1; /* first empty element */
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lua_Integer pos; /* where to insert new element */
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switch (lua_gettop(L)) {
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case 2: { /* called with only 2 arguments */
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pos = e; /* insert new element at the end */
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break;
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}
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case 3: {
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lua_Integer i;
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pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */
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/* check whether 'pos' is in [1, e] */
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luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2,
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"position out of bounds");
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for (i = e; i > pos; i--) { /* move up elements */
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lua_geti(L, 1, i - 1);
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lua_seti(L, 1, i); /* t[i] = t[i - 1] */
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}
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break;
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}
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default: {
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return luaL_error(L, "wrong number of arguments to 'insert'");
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}
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}
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lua_seti(L, 1, pos); /* t[pos] = v */
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return 0;
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}
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static int tremove (lua_State *L) {
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lua_Integer size = aux_getn(L, 1, TAB_RW);
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lua_Integer pos = luaL_optinteger(L, 2, size);
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if (pos != size) /* validate 'pos' if given */
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/* check whether 'pos' is in [1, size + 1] */
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luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 1,
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"position out of bounds");
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lua_geti(L, 1, pos); /* result = t[pos] */
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for ( ; pos < size; pos++) {
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lua_geti(L, 1, pos + 1);
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lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */
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}
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lua_pushnil(L);
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lua_seti(L, 1, pos); /* remove entry t[pos] */
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return 1;
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}
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/*
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** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
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** possible, copy in increasing order, which is better for rehashing.
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** "possible" means destination after original range, or smaller
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** than origin, or copying to another table.
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*/
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static int tmove (lua_State *L) {
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lua_Integer f = luaL_checkinteger(L, 2);
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lua_Integer e = luaL_checkinteger(L, 3);
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lua_Integer t = luaL_checkinteger(L, 4);
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int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */
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checktab(L, 1, TAB_R);
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checktab(L, tt, TAB_W);
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if (e >= f) { /* otherwise, nothing to move */
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lua_Integer n, i;
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luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
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"too many elements to move");
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n = e - f + 1; /* number of elements to move */
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luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
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"destination wrap around");
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if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
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for (i = 0; i < n; i++) {
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lua_geti(L, 1, f + i);
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lua_seti(L, tt, t + i);
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}
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}
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else {
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for (i = n - 1; i >= 0; i--) {
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lua_geti(L, 1, f + i);
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lua_seti(L, tt, t + i);
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}
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}
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}
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lua_pushvalue(L, tt); /* return destination table */
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return 1;
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}
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static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
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lua_geti(L, 1, i);
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if (!lua_isstring(L, -1))
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luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
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luaL_typename(L, -1), i);
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luaL_addvalue(b);
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}
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static int tconcat (lua_State *L) {
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luaL_Buffer b;
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lua_Integer last = aux_getn(L, 1, TAB_R);
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size_t lsep;
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const char *sep = luaL_optlstring(L, 2, "", &lsep);
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lua_Integer i = luaL_optinteger(L, 3, 1);
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last = luaL_optinteger(L, 4, last);
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luaL_buffinit(L, &b);
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for (; i < last; i++) {
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addfield(L, &b, i);
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luaL_addlstring(&b, sep, lsep);
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}
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if (i == last) /* add last value (if interval was not empty) */
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addfield(L, &b, i);
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luaL_pushresult(&b);
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return 1;
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}
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/*
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** {======================================================
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** Pack/unpack
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** =======================================================
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*/
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static int tpack (lua_State *L) {
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int i;
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int n = lua_gettop(L); /* number of elements to pack */
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lua_createtable(L, n, 1); /* create result table */
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lua_insert(L, 1); /* put it at index 1 */
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for (i = n; i >= 1; i--) /* assign elements */
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lua_seti(L, 1, i);
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lua_pushinteger(L, n);
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lua_setfield(L, 1, "n"); /* t.n = number of elements */
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return 1; /* return table */
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}
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static int tunpack (lua_State *L) {
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lua_Unsigned n;
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lua_Integer i = luaL_optinteger(L, 2, 1);
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lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
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if (i > e) return 0; /* empty range */
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n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */
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if (n >= (unsigned int)INT_MAX || !lua_checkstack(L, (int)(++n)))
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return luaL_error(L, "too many results to unpack");
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for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */
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lua_geti(L, 1, i);
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}
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lua_geti(L, 1, e); /* push last element */
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return (int)n;
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}
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/* }====================================================== */
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/*
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** {======================================================
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** Quicksort
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** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
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** Addison-Wesley, 1993.)
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** =======================================================
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*/
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/* type for array indices */
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typedef unsigned int IdxT;
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/*
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** Produce a "random" 'unsigned int' to randomize pivot choice. This
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** macro is used only when 'sort' detects a big imbalance in the result
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** of a partition. (If you don't want/need this "randomness", ~0 is a
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** good choice.)
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*/
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#if !defined(l_randomizePivot) /* { */
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#include <time.h>
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/* size of 'e' measured in number of 'unsigned int's */
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#define sof(e) (sizeof(e) / sizeof(unsigned int))
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/*
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** Use 'time' and 'clock' as sources of "randomness". Because we don't
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** know the types 'clock_t' and 'time_t', we cannot cast them to
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** anything without risking overflows. A safe way to use their values
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** is to copy them to an array of a known type and use the array values.
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*/
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static unsigned int l_randomizePivot (void) {
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clock_t c = clock();
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time_t t = time(NULL);
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unsigned int buff[sof(c) + sof(t)];
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unsigned int i, rnd = 0;
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memcpy(buff, &c, sof(c) * sizeof(unsigned int));
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memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
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for (i = 0; i < sof(buff); i++)
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rnd += buff[i];
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return rnd;
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}
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#endif /* } */
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/* arrays larger than 'RANLIMIT' may use randomized pivots */
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#define RANLIMIT 100u
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static void set2 (lua_State *L, IdxT i, IdxT j) {
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lua_seti(L, 1, i);
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lua_seti(L, 1, j);
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}
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/*
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** Return true iff value at stack index 'a' is less than the value at
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** index 'b' (according to the order of the sort).
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*/
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static int sort_comp (lua_State *L, int a, int b) {
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if (lua_isnil(L, 2)) /* no function? */
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return lua_compare(L, a, b, LUA_OPLT); /* a < b */
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else { /* function */
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int res;
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lua_pushvalue(L, 2); /* push function */
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lua_pushvalue(L, a-1); /* -1 to compensate function */
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lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */
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lua_call(L, 2, 1); /* call function */
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res = lua_toboolean(L, -1); /* get result */
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lua_pop(L, 1); /* pop result */
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return res;
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}
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}
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/*
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** Does the partition: Pivot P is at the top of the stack.
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** precondition: a[lo] <= P == a[up-1] <= a[up],
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** so it only needs to do the partition from lo + 1 to up - 2.
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** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
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** returns 'i'.
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*/
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static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
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IdxT i = lo; /* will be incremented before first use */
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IdxT j = up - 1; /* will be decremented before first use */
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/* loop invariant: a[lo .. i] <= P <= a[j .. up] */
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for (;;) {
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/* next loop: repeat ++i while a[i] < P */
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while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
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if (i == up - 1) /* a[i] < P but a[up - 1] == P ?? */
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luaL_error(L, "invalid order function for sorting");
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lua_pop(L, 1); /* remove a[i] */
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}
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/* after the loop, a[i] >= P and a[lo .. i - 1] < P */
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/* next loop: repeat --j while P < a[j] */
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while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
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if (j < i) /* j < i but a[j] > P ?? */
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luaL_error(L, "invalid order function for sorting");
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lua_pop(L, 1); /* remove a[j] */
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}
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/* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
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if (j < i) { /* no elements out of place? */
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/* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
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lua_pop(L, 1); /* pop a[j] */
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/* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
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set2(L, up - 1, i);
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return i;
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}
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/* otherwise, swap a[i] - a[j] to restore invariant and repeat */
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set2(L, i, j);
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}
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}
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/*
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** Choose an element in the middle (2nd-3th quarters) of [lo,up]
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** "randomized" by 'rnd'
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*/
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static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
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IdxT r4 = (up - lo) / 4; /* range/4 */
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IdxT p = rnd % (r4 * 2) + (lo + r4);
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lua_assert(lo + r4 <= p && p <= up - r4);
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return p;
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}
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/*
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** QuickSort algorithm (recursive function)
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*/
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static void auxsort (lua_State *L, IdxT lo, IdxT up,
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unsigned int rnd) {
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while (lo < up) { /* loop for tail recursion */
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IdxT p; /* Pivot index */
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IdxT n; /* to be used later */
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/* sort elements 'lo', 'p', and 'up' */
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lua_geti(L, 1, lo);
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lua_geti(L, 1, up);
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if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */
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set2(L, lo, up); /* swap a[lo] - a[up] */
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else
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lua_pop(L, 2); /* remove both values */
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if (up - lo == 1) /* only 2 elements? */
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return; /* already sorted */
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if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */
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p = (lo + up)/2; /* middle element is a good pivot */
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else /* for larger intervals, it is worth a random pivot */
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p = choosePivot(lo, up, rnd);
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lua_geti(L, 1, p);
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lua_geti(L, 1, lo);
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if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */
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set2(L, p, lo); /* swap a[p] - a[lo] */
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else {
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lua_pop(L, 1); /* remove a[lo] */
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lua_geti(L, 1, up);
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if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */
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set2(L, p, up); /* swap a[up] - a[p] */
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else
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lua_pop(L, 2);
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}
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if (up - lo == 2) /* only 3 elements? */
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return; /* already sorted */
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lua_geti(L, 1, p); /* get middle element (Pivot) */
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lua_pushvalue(L, -1); /* push Pivot */
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lua_geti(L, 1, up - 1); /* push a[up - 1] */
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set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */
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p = partition(L, lo, up);
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/* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
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if (p - lo < up - p) { /* lower interval is smaller? */
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auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */
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n = p - lo; /* size of smaller interval */
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lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */
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}
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else {
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auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */
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n = up - p; /* size of smaller interval */
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up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */
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}
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if ((up - lo) / 128 > n) /* partition too imbalanced? */
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rnd = l_randomizePivot(); /* try a new randomization */
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} /* tail call auxsort(L, lo, up, rnd) */
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}
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static int sort (lua_State *L) {
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lua_Integer n = aux_getn(L, 1, TAB_RW);
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if (n > 1) { /* non-trivial interval? */
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luaL_argcheck(L, n < INT_MAX, 1, "array too big");
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if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
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luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */
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lua_settop(L, 2); /* make sure there are two arguments */
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auxsort(L, 1, (IdxT)n, 0);
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}
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return 0;
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}
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/* }====================================================== */
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static const luaL_Reg tab_funcs[] = {
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{"concat", tconcat},
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{"insert", tinsert},
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{"pack", tpack},
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{"unpack", tunpack},
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{"remove", tremove},
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{"move", tmove},
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{"sort", sort},
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{NULL, NULL}
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};
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LUAMOD_API int luaopen_table (lua_State *L) {
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luaL_newlib(L, tab_funcs);
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return 1;
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}
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