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