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ltablib.cpp
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1 /*
2 ** $Id: ltablib.c,v 1.93 2016/02/25 19:41:54 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 
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 */
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)
62 static int maxn (lua_State *L) {
63  lua_Number max = 0;
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 
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 
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 */
128 static int tmove (lua_State *L) {
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 
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 
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 
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 
207 static int unpack (lua_State *L) {
208  lua_Unsigned n;
209  lua_Integer i = luaL_optinteger(L, 2, 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 */
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 
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 */
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 */
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 */
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 */
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 
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 
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 
#define lua_isnoneornil(L, n)
Definition: lua.h:359
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Definition: ltablib.cpp:46
LUA_NUMBER lua_Number
Definition: lua.h:89
LUA_API const char * lua_pushstring(lua_State *L, const char *s)
Definition: lapi.cpp:491
LUA_API void lua_setfield(lua_State *L, int idx, const char *k)
Definition: lapi.cpp:776
LUA_API int lua_next(lua_State *L, int idx)
Definition: lapi.cpp:1122
#define LUA_OPEQ
Definition: lua.h:213
static void auxsort(lua_State *L, IdxT lo, IdxT up, unsigned int rnd)
Definition: ltablib.cpp:357
LUA_API void lua_seti(lua_State *L, int idx, lua_Integer n)
Definition: lapi.cpp:782