1/*
2** $Id: ltablib.c $
3** Library for Table Manipulation
4** See Copyright Notice in lua.h
5*/
6
7#define ltablib_c
8#define LUA_LIB
9
10#include "lprefix.h"
11
12
13#include <limits.h>
14#include <stddef.h>
15#include <string.h>
16
17#include "lua.h"
18
19#include "lauxlib.h"
20#include "lualib.h"
21
22
23/*
24** Operations that an object must define to mimic a table
25** (some functions only need some of them)
26*/
27#define TAB_R 1 /* read */
28#define TAB_W 2 /* write */
29#define TAB_L 4 /* length */
30#define TAB_RW (TAB_R | TAB_W) /* read/write */
31
32
33#define aux_getn(L,n,w) (checktab(L, n, (w) | TAB_L), luaL_len(L, n))
34
35
36static int checkfield (lua_State *L, const char *key, int n) {
37 lua_pushstring(L, key);
38 return (lua_rawget(L, -n) != LUA_TNIL);
39}
40
41
42/*
43** Check that 'arg' either is a table or can behave like one (that is,
44** has a metatable with the required metamethods)
45*/
46static void checktab (lua_State *L, int arg, int what) {
47 if (lua_type(L, arg) != LUA_TTABLE) { /* is it not a table? */
48 int n = 1; /* number of elements to pop */
49 if (lua_getmetatable(L, arg) && /* must have metatable */
50 (!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
51 (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
52 (!(what & TAB_L) || checkfield(L, "__len", ++n))) {
53 lua_pop(L, n); /* pop metatable and tested metamethods */
54 }
55 else
56 luaL_checktype(L, arg, LUA_TTABLE); /* force an error */
57 }
58}
59
60
61static int tinsert (lua_State *L) {
62 lua_Integer pos; /* where to insert new element */
63 lua_Integer e = aux_getn(L, 1, TAB_RW);
64 e = luaL_intop(+, e, 1); /* first empty element */
65 switch (lua_gettop(L)) {
66 case 2: { /* called with only 2 arguments */
67 pos = e; /* insert new element at the end */
68 break;
69 }
70 case 3: {
71 lua_Integer i;
72 pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */
73 /* check whether 'pos' is in [1, e] */
74 luaL_argcheck(L, (lua_Unsigned)pos - 1u < (lua_Unsigned)e, 2,
75 "position out of bounds");
76 for (i = e; i > pos; i--) { /* move up elements */
77 lua_geti(L, 1, i - 1);
78 lua_seti(L, 1, i); /* t[i] = t[i - 1] */
79 }
80 break;
81 }
82 default: {
83 return luaL_error(L, "wrong number of arguments to 'insert'");
84 }
85 }
86 lua_seti(L, 1, pos); /* t[pos] = v */
87 return 0;
88}
89
90
91static int tremove (lua_State *L) {
92 lua_Integer size = aux_getn(L, 1, TAB_RW);
93 lua_Integer pos = luaL_optinteger(L, 2, size);
94 if (pos != size) /* validate 'pos' if given */
95 /* check whether 'pos' is in [1, size + 1] */
96 luaL_argcheck(L, (lua_Unsigned)pos - 1u <= (lua_Unsigned)size, 1,
97 "position out of bounds");
98 lua_geti(L, 1, pos); /* result = t[pos] */
99 for ( ; pos < size; pos++) {
100 lua_geti(L, 1, pos + 1);
101 lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */
102 }
103 lua_pushnil(L);
104 lua_seti(L, 1, pos); /* remove entry t[pos] */
105 return 1;
106}
107
108
109/*
110** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
111** possible, copy in increasing order, which is better for rehashing.
112** "possible" means destination after original range, or smaller
113** than origin, or copying to another table.
114*/
115static int tmove (lua_State *L) {
116 lua_Integer f = luaL_checkinteger(L, 2);
117 lua_Integer e = luaL_checkinteger(L, 3);
118 lua_Integer t = luaL_checkinteger(L, 4);
119 int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */
120 checktab(L, 1, TAB_R);
121 checktab(L, tt, TAB_W);
122 if (e >= f) { /* otherwise, nothing to move */
123 lua_Integer n, i;
124 luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
125 "too many elements to move");
126 n = e - f + 1; /* number of elements to move */
127 luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
128 "destination wrap around");
129 if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
130 for (i = 0; i < n; i++) {
131 lua_geti(L, 1, f + i);
132 lua_seti(L, tt, t + i);
133 }
134 }
135 else {
136 for (i = n - 1; i >= 0; i--) {
137 lua_geti(L, 1, f + i);
138 lua_seti(L, tt, t + i);
139 }
140 }
141 }
142 lua_pushvalue(L, tt); /* return destination table */
143 return 1;
144}
145
146
147static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
148 lua_geti(L, 1, i);
149 if (l_unlikely(!lua_isstring(L, -1)))
150 luaL_error(L, "invalid value (%s) at index %I in table for 'concat'",
151 luaL_typename(L, -1), (LUAI_UACINT)i);
152 luaL_addvalue(b);
153}
154
155
156static int tconcat (lua_State *L) {
157 luaL_Buffer b;
158 lua_Integer last = aux_getn(L, 1, TAB_R);
159 size_t lsep;
160 const char *sep = luaL_optlstring(L, 2, "", &lsep);
161 lua_Integer i = luaL_optinteger(L, 3, 1);
162 last = luaL_optinteger(L, 4, last);
163 luaL_buffinit(L, &b);
164 for (; i < last; i++) {
165 addfield(L, &b, i);
166 luaL_addlstring(&b, sep, lsep);
167 }
168 if (i == last) /* add last value (if interval was not empty) */
169 addfield(L, &b, i);
170 luaL_pushresult(&b);
171 return 1;
172}
173
174
175/*
176** {======================================================
177** Pack/unpack
178** =======================================================
179*/
180
181static int tpack (lua_State *L) {
182 int i;
183 int n = lua_gettop(L); /* number of elements to pack */
184 lua_createtable(L, n, 1); /* create result table */
185 lua_insert(L, 1); /* put it at index 1 */
186 for (i = n; i >= 1; i--) /* assign elements */
187 lua_seti(L, 1, i);
188 lua_pushinteger(L, n);
189 lua_setfield(L, 1, "n"); /* t.n = number of elements */
190 return 1; /* return table */
191}
192
193
194static int tunpack (lua_State *L) {
195 lua_Unsigned n;
196 lua_Integer i = luaL_optinteger(L, 2, 1);
197 lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
198 if (i > e) return 0; /* empty range */
199 n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */
200 if (l_unlikely(n >= (unsigned int)INT_MAX ||
201 !lua_checkstack(L, (int)(++n))))
202 return luaL_error(L, "too many results to unpack");
203 for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */
204 lua_geti(L, 1, i);
205 }
206 lua_geti(L, 1, e); /* push last element */
207 return (int)n;
208}
209
210/* }====================================================== */
211
212
213
214/*
215** {======================================================
216** Quicksort
217** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
218** Addison-Wesley, 1993.)
219** =======================================================
220*/
221
222
223/* type for array indices */
224typedef unsigned int IdxT;
225
226
227/*
228** Produce a "random" 'unsigned int' to randomize pivot choice. This
229** macro is used only when 'sort' detects a big imbalance in the result
230** of a partition. (If you don't want/need this "randomness", ~0 is a
231** good choice.)
232*/
233#if !defined(l_randomizePivot) /* { */
234
235#include <time.h>
236
237/* size of 'e' measured in number of 'unsigned int's */
238#define sof(e) (sizeof(e) / sizeof(unsigned int))
239
240/*
241** Use 'time' and 'clock' as sources of "randomness". Because we don't
242** know the types 'clock_t' and 'time_t', we cannot cast them to
243** anything without risking overflows. A safe way to use their values
244** is to copy them to an array of a known type and use the array values.
245*/
246static unsigned int l_randomizePivot (void) {
247 clock_t c = clock();
248 time_t t = time(NULL);
249 unsigned int buff[sof(c) + sof(t)];
250 unsigned int i, rnd = 0;
251 memcpy(buff, &c, sof(c) * sizeof(unsigned int));
252 memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
253 for (i = 0; i < sof(buff); i++)
254 rnd += buff[i];
255 return rnd;
256}
257
258#endif /* } */
259
260
261/* arrays larger than 'RANLIMIT' may use randomized pivots */
262#define RANLIMIT 100u
263
264
265static void set2 (lua_State *L, IdxT i, IdxT j) {
266 lua_seti(L, 1, i);
267 lua_seti(L, 1, j);
268}
269
270
271/*
272** Return true iff value at stack index 'a' is less than the value at
273** index 'b' (according to the order of the sort).
274*/
275static int sort_comp (lua_State *L, int a, int b) {
276 if (lua_isnil(L, 2)) /* no function? */
277 return lua_compare(L, a, b, LUA_OPLT); /* a < b */
278 else { /* function */
279 int res;
280 lua_pushvalue(L, 2); /* push function */
281 lua_pushvalue(L, a-1); /* -1 to compensate function */
282 lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */
283 lua_call(L, 2, 1); /* call function */
284 res = lua_toboolean(L, -1); /* get result */
285 lua_pop(L, 1); /* pop result */
286 return res;
287 }
288}
289
290
291/*
292** Does the partition: Pivot P is at the top of the stack.
293** precondition: a[lo] <= P == a[up-1] <= a[up],
294** so it only needs to do the partition from lo + 1 to up - 2.
295** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
296** returns 'i'.
297*/
298static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
299 IdxT i = lo; /* will be incremented before first use */
300 IdxT j = up - 1; /* will be decremented before first use */
301 /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
302 for (;;) {
303 /* next loop: repeat ++i while a[i] < P */
304 while ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
305 if (l_unlikely(i == up - 1)) /* a[i] < P but a[up - 1] == P ?? */
306 luaL_error(L, "invalid order function for sorting");
307 lua_pop(L, 1); /* remove a[i] */
308 }
309 /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
310 /* next loop: repeat --j while P < a[j] */
311 while ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
312 if (l_unlikely(j < i)) /* j < i but a[j] > P ?? */
313 luaL_error(L, "invalid order function for sorting");
314 lua_pop(L, 1); /* remove a[j] */
315 }
316 /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
317 if (j < i) { /* no elements out of place? */
318 /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
319 lua_pop(L, 1); /* pop a[j] */
320 /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
321 set2(L, up - 1, i);
322 return i;
323 }
324 /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
325 set2(L, i, j);
326 }
327}
328
329
330/*
331** Choose an element in the middle (2nd-3th quarters) of [lo,up]
332** "randomized" by 'rnd'
333*/
334static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
335 IdxT r4 = (up - lo) / 4; /* range/4 */
336 IdxT p = rnd % (r4 * 2) + (lo + r4);
337 lua_assert(lo + r4 <= p && p <= up - r4);
338 return p;
339}
340
341
342/*
343** Quicksort algorithm (recursive function)
344*/
345static void auxsort (lua_State *L, IdxT lo, IdxT up,
346 unsigned int rnd) {
347 while (lo < up) { /* loop for tail recursion */
348 IdxT p; /* Pivot index */
349 IdxT n; /* to be used later */
350 /* sort elements 'lo', 'p', and 'up' */
351 lua_geti(L, 1, lo);
352 lua_geti(L, 1, up);
353 if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */
354 set2(L, lo, up); /* swap a[lo] - a[up] */
355 else
356 lua_pop(L, 2); /* remove both values */
357 if (up - lo == 1) /* only 2 elements? */
358 return; /* already sorted */
359 if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */
360 p = (lo + up)/2; /* middle element is a good pivot */
361 else /* for larger intervals, it is worth a random pivot */
362 p = choosePivot(lo, up, rnd);
363 lua_geti(L, 1, p);
364 lua_geti(L, 1, lo);
365 if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */
366 set2(L, p, lo); /* swap a[p] - a[lo] */
367 else {
368 lua_pop(L, 1); /* remove a[lo] */
369 lua_geti(L, 1, up);
370 if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */
371 set2(L, p, up); /* swap a[up] - a[p] */
372 else
373 lua_pop(L, 2);
374 }
375 if (up - lo == 2) /* only 3 elements? */
376 return; /* already sorted */
377 lua_geti(L, 1, p); /* get middle element (Pivot) */
378 lua_pushvalue(L, -1); /* push Pivot */
379 lua_geti(L, 1, up - 1); /* push a[up - 1] */
380 set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */
381 p = partition(L, lo, up);
382 /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
383 if (p - lo < up - p) { /* lower interval is smaller? */
384 auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */
385 n = p - lo; /* size of smaller interval */
386 lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */
387 }
388 else {
389 auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */
390 n = up - p; /* size of smaller interval */
391 up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */
392 }
393 if ((up - lo) / 128 > n) /* partition too imbalanced? */
394 rnd = l_randomizePivot(); /* try a new randomization */
395 } /* tail call auxsort(L, lo, up, rnd) */
396}
397
398
399static int sort (lua_State *L) {
400 lua_Integer n = aux_getn(L, 1, TAB_RW);
401 if (n > 1) { /* non-trivial interval? */
402 luaL_argcheck(L, n < INT_MAX, 1, "array too big");
403 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
404 luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */
405 lua_settop(L, 2); /* make sure there are two arguments */
406 auxsort(L, 1, (IdxT)n, 0);
407 }
408 return 0;
409}
410
411/* }====================================================== */
412
413
414static const luaL_Reg tab_funcs[] = {
415 {"concat", tconcat},
416 {"insert", tinsert},
417 {"pack", tpack},
418 {"unpack", tunpack},
419 {"remove", tremove},
420 {"move", tmove},
421 {"sort", sort},
422 {NULL, NULL}
423};
424
425
426LUAMOD_API int luaopen_table (lua_State *L) {
427 luaL_newlib(L, tab_funcs);
428 return 1;
429}
430
431