mirror of
https://github.com/lua/lua
synced 2024-11-22 04:41:23 +03:00
deac067ed3
Any C function can receive maxinteger as an integer argument, and therefore cannot increment it without some care (e.g., doing unsigned arithmetic as the core does).
431 lines
13 KiB
C
431 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 pos; /* where to insert new element */
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lua_Integer e = aux_getn(L, 1, TAB_RW);
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e = luaL_intop(+, e, 1); /* first empty 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 (l_unlikely(!lua_isstring(L, -1)))
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luaL_error(L, "invalid value (%s) at index %I in table for 'concat'",
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luaL_typename(L, -1), (LUAI_UACINT)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 (l_unlikely(n >= (unsigned int)INT_MAX ||
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!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 ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
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if (l_unlikely(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 ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
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if (l_unlikely(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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