1 /*
2 ** $Id: ltablib.c,v 1.93.1.1 2017/04/19 17:20:42 roberto Exp $
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
checkfield(lua_State * L,const char * key,int n)36 static 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 */
checktab(lua_State * L,int arg,int what)46 static 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
61 #if defined(LUA_COMPAT_MAXN)
maxn(lua_State * L)62 static int maxn (lua_State *L) {
63 lua_Number max = 0;
64 luaL_checktype(L, 1, LUA_TTABLE);
65 lua_pushnil(L); /* first key */
66 while (lua_next(L, 1)) {
67 lua_pop(L, 1); /* remove value */
68 if (lua_type(L, -1) == LUA_TNUMBER) {
69 lua_Number v = lua_tonumber(L, -1);
70 if (v > max) max = v;
71 }
72 }
73 lua_pushnumber(L, max);
74 return 1;
75 }
76 #endif
77
78
tinsert(lua_State * L)79 static int tinsert (lua_State *L) {
80 lua_Integer e = aux_getn(L, 1, TAB_RW) + 1; /* first empty element */
81 lua_Integer pos; /* where to insert new element */
82 switch (lua_gettop(L)) {
83 case 2: { /* called with only 2 arguments */
84 pos = e; /* insert new element at the end */
85 break;
86 }
87 case 3: {
88 lua_Integer i;
89 pos = luaL_checkinteger(L, 2); /* 2nd argument is the position */
90 luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
91 for (i = e; i > pos; i--) { /* move up elements */
92 lua_geti(L, 1, i - 1);
93 lua_seti(L, 1, i); /* t[i] = t[i - 1] */
94 }
95 break;
96 }
97 default: {
98 return luaL_error(L, "wrong number of arguments to 'insert'");
99 }
100 }
101 lua_seti(L, 1, pos); /* t[pos] = v */
102 return 0;
103 }
104
105
tremove(lua_State * L)106 static int tremove (lua_State *L) {
107 lua_Integer size = aux_getn(L, 1, TAB_RW);
108 lua_Integer pos = luaL_optinteger(L, 2, size);
109 if (pos != size) /* validate 'pos' if given */
110 luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds");
111 lua_geti(L, 1, pos); /* result = t[pos] */
112 for ( ; pos < size; pos++) {
113 lua_geti(L, 1, pos + 1);
114 lua_seti(L, 1, pos); /* t[pos] = t[pos + 1] */
115 }
116 lua_pushnil(L);
117 lua_seti(L, 1, pos); /* t[pos] = nil */
118 return 1;
119 }
120
121
122 /*
123 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
124 ** possible, copy in increasing order, which is better for rehashing.
125 ** "possible" means destination after original range, or smaller
126 ** than origin, or copying to another table.
127 */
tmove(lua_State * L)128 static int tmove (lua_State *L) {
129 lua_Integer f = luaL_checkinteger(L, 2);
130 lua_Integer e = luaL_checkinteger(L, 3);
131 lua_Integer t = luaL_checkinteger(L, 4);
132 int tt = !lua_isnoneornil(L, 5) ? 5 : 1; /* destination table */
133 checktab(L, 1, TAB_R);
134 checktab(L, tt, TAB_W);
135 if (e >= f) { /* otherwise, nothing to move */
136 lua_Integer n, i;
137 luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
138 "too many elements to move");
139 n = e - f + 1; /* number of elements to move */
140 luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
141 "destination wrap around");
142 if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
143 for (i = 0; i < n; i++) {
144 lua_geti(L, 1, f + i);
145 lua_seti(L, tt, t + i);
146 }
147 }
148 else {
149 for (i = n - 1; i >= 0; i--) {
150 lua_geti(L, 1, f + i);
151 lua_seti(L, tt, t + i);
152 }
153 }
154 }
155 lua_pushvalue(L, tt); /* return destination table */
156 return 1;
157 }
158
159
addfield(lua_State * L,luaL_Buffer * b,lua_Integer i)160 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
161 lua_geti(L, 1, i);
162 if (!lua_isstring(L, -1))
163 luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
164 luaL_typename(L, -1), i);
165 luaL_addvalue(b);
166 }
167
168
tconcat(lua_State * L)169 static int tconcat (lua_State *L) {
170 luaL_Buffer b;
171 lua_Integer last = aux_getn(L, 1, TAB_R);
172 size_t lsep;
173 const char *sep = luaL_optlstring(L, 2, "", &lsep);
174 lua_Integer i = luaL_optinteger(L, 3, 1);
175 last = luaL_optinteger(L, 4, last);
176 luaL_buffinit(L, &b);
177 for (; i < last; i++) {
178 addfield(L, &b, i);
179 luaL_addlstring(&b, sep, lsep);
180 }
181 if (i == last) /* add last value (if interval was not empty) */
182 addfield(L, &b, i);
183 luaL_pushresult(&b);
184 return 1;
185 }
186
187
188 /*
189 ** {======================================================
190 ** Pack/unpack
191 ** =======================================================
192 */
193
pack(lua_State * L)194 static int pack (lua_State *L) {
195 int i;
196 int n = lua_gettop(L); /* number of elements to pack */
197 lua_createtable(L, n, 1); /* create result table */
198 lua_insert(L, 1); /* put it at index 1 */
199 for (i = n; i >= 1; i--) /* assign elements */
200 lua_seti(L, 1, i);
201 lua_pushinteger(L, n);
202 lua_setfield(L, 1, "n"); /* t.n = number of elements */
203 return 1; /* return table */
204 }
205
206
unpack(lua_State * L)207 static int unpack (lua_State *L) {
208 lua_Unsigned n;
209 lua_Integer i = luaL_optinteger(L, 2, 1);
210 lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
211 if (i > e) return 0; /* empty range */
212 n = (lua_Unsigned)e - i; /* number of elements minus 1 (avoid overflows) */
213 if (n >= (unsigned int)INT_MAX || !lua_checkstack(L, (int)(++n)))
214 return luaL_error(L, "too many results to unpack");
215 for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */
216 lua_geti(L, 1, i);
217 }
218 lua_geti(L, 1, e); /* push last element */
219 return (int)n;
220 }
221
222 /* }====================================================== */
223
224
225
226 /*
227 ** {======================================================
228 ** Quicksort
229 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
230 ** Addison-Wesley, 1993.)
231 ** =======================================================
232 */
233
234
235 /* type for array indices */
236 typedef unsigned int IdxT;
237
238
239 /*
240 ** Produce a "random" 'unsigned int' to randomize pivot choice. This
241 ** macro is used only when 'sort' detects a big imbalance in the result
242 ** of a partition. (If you don't want/need this "randomness", ~0 is a
243 ** good choice.)
244 */
245 #if !defined(l_randomizePivot) /* { */
246
247 #include <time.h>
248
249 /* size of 'e' measured in number of 'unsigned int's */
250 #define sof(e) (sizeof(e) / sizeof(unsigned int))
251
252 /*
253 ** Use 'time' and 'clock' as sources of "randomness". Because we don't
254 ** know the types 'clock_t' and 'time_t', we cannot cast them to
255 ** anything without risking overflows. A safe way to use their values
256 ** is to copy them to an array of a known type and use the array values.
257 */
l_randomizePivot(void)258 static unsigned int l_randomizePivot (void) {
259 clock_t c = clock();
260 time_t t = time(NULL);
261 unsigned int buff[sof(c) + sof(t)];
262 unsigned int i, rnd = 0;
263 memcpy(buff, &c, sof(c) * sizeof(unsigned int));
264 memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
265 for (i = 0; i < sof(buff); i++)
266 rnd += buff[i];
267 return rnd;
268 }
269
270 #endif /* } */
271
272
273 /* arrays larger than 'RANLIMIT' may use randomized pivots */
274 #define RANLIMIT 100u
275
276
set2(lua_State * L,IdxT i,IdxT j)277 static void set2 (lua_State *L, IdxT i, IdxT j) {
278 lua_seti(L, 1, i);
279 lua_seti(L, 1, j);
280 }
281
282
283 /*
284 ** Return true iff value at stack index 'a' is less than the value at
285 ** index 'b' (according to the order of the sort).
286 */
sort_comp(lua_State * L,int a,int b)287 static int sort_comp (lua_State *L, int a, int b) {
288 if (lua_isnil(L, 2)) /* no function? */
289 return lua_compare(L, a, b, LUA_OPLT); /* a < b */
290 else { /* function */
291 int res;
292 lua_pushvalue(L, 2); /* push function */
293 lua_pushvalue(L, a-1); /* -1 to compensate function */
294 lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */
295 lua_call(L, 2, 1); /* call function */
296 res = lua_toboolean(L, -1); /* get result */
297 lua_pop(L, 1); /* pop result */
298 return res;
299 }
300 }
301
302
303 /*
304 ** Does the partition: Pivot P is at the top of the stack.
305 ** precondition: a[lo] <= P == a[up-1] <= a[up],
306 ** so it only needs to do the partition from lo + 1 to up - 2.
307 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
308 ** returns 'i'.
309 */
partition(lua_State * L,IdxT lo,IdxT up)310 static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
311 IdxT i = lo; /* will be incremented before first use */
312 IdxT j = up - 1; /* will be decremented before first use */
313 /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
314 for (;;) {
315 /* next loop: repeat ++i while a[i] < P */
316 while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
317 if (i == up - 1) /* a[i] < P but a[up - 1] == P ?? */
318 luaL_error(L, "invalid order function for sorting");
319 lua_pop(L, 1); /* remove a[i] */
320 }
321 /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
322 /* next loop: repeat --j while P < a[j] */
323 while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
324 if (j < i) /* j < i but a[j] > P ?? */
325 luaL_error(L, "invalid order function for sorting");
326 lua_pop(L, 1); /* remove a[j] */
327 }
328 /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
329 if (j < i) { /* no elements out of place? */
330 /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
331 lua_pop(L, 1); /* pop a[j] */
332 /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
333 set2(L, up - 1, i);
334 return i;
335 }
336 /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
337 set2(L, i, j);
338 }
339 }
340
341
342 /*
343 ** Choose an element in the middle (2nd-3th quarters) of [lo,up]
344 ** "randomized" by 'rnd'
345 */
choosePivot(IdxT lo,IdxT up,unsigned int rnd)346 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
347 IdxT r4 = (up - lo) / 4; /* range/4 */
348 IdxT p = rnd % (r4 * 2) + (lo + r4);
349 lua_assert(lo + r4 <= p && p <= up - r4);
350 return p;
351 }
352
353
354 /*
355 ** QuickSort algorithm (recursive function)
356 */
auxsort(lua_State * L,IdxT lo,IdxT up,unsigned int rnd)357 static void auxsort (lua_State *L, IdxT lo, IdxT up,
358 unsigned int rnd) {
359 while (lo < up) { /* loop for tail recursion */
360 IdxT p; /* Pivot index */
361 IdxT n; /* to be used later */
362 /* sort elements 'lo', 'p', and 'up' */
363 lua_geti(L, 1, lo);
364 lua_geti(L, 1, up);
365 if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */
366 set2(L, lo, up); /* swap a[lo] - a[up] */
367 else
368 lua_pop(L, 2); /* remove both values */
369 if (up - lo == 1) /* only 2 elements? */
370 return; /* already sorted */
371 if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */
372 p = (lo + up)/2; /* middle element is a good pivot */
373 else /* for larger intervals, it is worth a random pivot */
374 p = choosePivot(lo, up, rnd);
375 lua_geti(L, 1, p);
376 lua_geti(L, 1, lo);
377 if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */
378 set2(L, p, lo); /* swap a[p] - a[lo] */
379 else {
380 lua_pop(L, 1); /* remove a[lo] */
381 lua_geti(L, 1, up);
382 if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */
383 set2(L, p, up); /* swap a[up] - a[p] */
384 else
385 lua_pop(L, 2);
386 }
387 if (up - lo == 2) /* only 3 elements? */
388 return; /* already sorted */
389 lua_geti(L, 1, p); /* get middle element (Pivot) */
390 lua_pushvalue(L, -1); /* push Pivot */
391 lua_geti(L, 1, up - 1); /* push a[up - 1] */
392 set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */
393 p = partition(L, lo, up);
394 /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
395 if (p - lo < up - p) { /* lower interval is smaller? */
396 auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */
397 n = p - lo; /* size of smaller interval */
398 lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */
399 }
400 else {
401 auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */
402 n = up - p; /* size of smaller interval */
403 up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */
404 }
405 if ((up - lo) / 128 > n) /* partition too imbalanced? */
406 rnd = l_randomizePivot(); /* try a new randomization */
407 } /* tail call auxsort(L, lo, up, rnd) */
408 }
409
410
sort(lua_State * L)411 static int sort (lua_State *L) {
412 lua_Integer n = aux_getn(L, 1, TAB_RW);
413 if (n > 1) { /* non-trivial interval? */
414 luaL_argcheck(L, n < INT_MAX, 1, "array too big");
415 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
416 luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */
417 lua_settop(L, 2); /* make sure there are two arguments */
418 auxsort(L, 1, (IdxT)n, 0);
419 }
420 return 0;
421 }
422
423 /* }====================================================== */
424
425
426 static const luaL_Reg tab_funcs[] = {
427 {"concat", tconcat},
428 #if defined(LUA_COMPAT_MAXN)
429 {"maxn", maxn},
430 #endif
431 {"insert", tinsert},
432 {"pack", pack},
433 {"unpack", unpack},
434 {"remove", tremove},
435 {"move", tmove},
436 {"sort", sort},
437 {NULL, NULL}
438 };
439
440
luaopen_table(lua_State * L)441 LUAMOD_API int luaopen_table (lua_State *L) {
442 luaL_newlib(L, tab_funcs);
443 #if defined(LUA_COMPAT_UNPACK)
444 /* _G.unpack = table.unpack */
445 lua_getfield(L, -1, "unpack");
446 lua_setglobal(L, "unpack");
447 #endif
448 return 1;
449 }
450
451