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
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
61#if defined(LUA_COMPAT_MAXN)
62static 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
79static 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
106static 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*/
128static 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
160static 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
169static 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
194static 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
207static 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 */
236typedef 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*/
258static 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
277static 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*/
287static 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*/
310static 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*/
346static 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*/
357static 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
411static 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
426static 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
441LUAMOD_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