ltablib.c
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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 
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 static 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 
90 static 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 */
114 static 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 
146 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
147  lua_geti(L, 1, i);
148  if (!lua_isstring(L, -1))
149  luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
150  luaL_typename(L, -1), i);
151  luaL_addvalue(b);
152 }
153 
154 
155 static 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 
180 static 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 
193 static 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 (n >= (unsigned int)INT_MAX || !lua_checkstack(L, (int)(++n)))
200  return luaL_error(L, "too many results to unpack");
201  for (; i < e; i++) { /* push arg[i..e - 1] (to avoid overflows) */
202  lua_geti(L, 1, i);
203  }
204  lua_geti(L, 1, e); /* push last element */
205  return (int)n;
206 }
207 
208 /* }====================================================== */
209 
210 
211 
212 /*
213 ** {======================================================
214 ** Quicksort
215 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
216 ** Addison-Wesley, 1993.)
217 ** =======================================================
218 */
219 
220 
221 /* type for array indices */
222 typedef unsigned int IdxT;
223 
224 
225 /*
226 ** Produce a "random" 'unsigned int' to randomize pivot choice. This
227 ** macro is used only when 'sort' detects a big imbalance in the result
228 ** of a partition. (If you don't want/need this "randomness", ~0 is a
229 ** good choice.)
230 */
231 #if !defined(l_randomizePivot) /* { */
232 
233 #include <time.h>
234 
235 /* size of 'e' measured in number of 'unsigned int's */
236 #define sof(e) (sizeof(e) / sizeof(unsigned int))
237 
238 /*
239 ** Use 'time' and 'clock' as sources of "randomness". Because we don't
240 ** know the types 'clock_t' and 'time_t', we cannot cast them to
241 ** anything without risking overflows. A safe way to use their values
242 ** is to copy them to an array of a known type and use the array values.
243 */
244 static unsigned int l_randomizePivot (void) {
245  clock_t c = clock();
246  time_t t = time(NULL);
247  unsigned int buff[sof(c) + sof(t)];
248  unsigned int i, rnd = 0;
249  memcpy(buff, &c, sof(c) * sizeof(unsigned int));
250  memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
251  for (i = 0; i < sof(buff); i++)
252  rnd += buff[i];
253  return rnd;
254 }
255 
256 #endif /* } */
257 
258 
259 /* arrays larger than 'RANLIMIT' may use randomized pivots */
260 #define RANLIMIT 100u
261 
262 
263 static void set2 (lua_State *L, IdxT i, IdxT j) {
264  lua_seti(L, 1, i);
265  lua_seti(L, 1, j);
266 }
267 
268 
269 /*
270 ** Return true iff value at stack index 'a' is less than the value at
271 ** index 'b' (according to the order of the sort).
272 */
273 static int sort_comp (lua_State *L, int a, int b) {
274  if (lua_isnil(L, 2)) /* no function? */
275  return lua_compare(L, a, b, LUA_OPLT); /* a < b */
276  else { /* function */
277  int res;
278  lua_pushvalue(L, 2); /* push function */
279  lua_pushvalue(L, a-1); /* -1 to compensate function */
280  lua_pushvalue(L, b-2); /* -2 to compensate function and 'a' */
281  lua_call(L, 2, 1); /* call function */
282  res = lua_toboolean(L, -1); /* get result */
283  lua_pop(L, 1); /* pop result */
284  return res;
285  }
286 }
287 
288 
289 /*
290 ** Does the partition: Pivot P is at the top of the stack.
291 ** precondition: a[lo] <= P == a[up-1] <= a[up],
292 ** so it only needs to do the partition from lo + 1 to up - 2.
293 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
294 ** returns 'i'.
295 */
296 static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
297  IdxT i = lo; /* will be incremented before first use */
298  IdxT j = up - 1; /* will be decremented before first use */
299  /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
300  for (;;) {
301  /* next loop: repeat ++i while a[i] < P */
302  while ((void)lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
303  if (i == up - 1) /* a[i] < P but a[up - 1] == P ?? */
304  luaL_error(L, "invalid order function for sorting");
305  lua_pop(L, 1); /* remove a[i] */
306  }
307  /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
308  /* next loop: repeat --j while P < a[j] */
309  while ((void)lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
310  if (j < i) /* j < i but a[j] > P ?? */
311  luaL_error(L, "invalid order function for sorting");
312  lua_pop(L, 1); /* remove a[j] */
313  }
314  /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
315  if (j < i) { /* no elements out of place? */
316  /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
317  lua_pop(L, 1); /* pop a[j] */
318  /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
319  set2(L, up - 1, i);
320  return i;
321  }
322  /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
323  set2(L, i, j);
324  }
325 }
326 
327 
328 /*
329 ** Choose an element in the middle (2nd-3th quarters) of [lo,up]
330 ** "randomized" by 'rnd'
331 */
332 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
333  IdxT r4 = (up - lo) / 4; /* range/4 */
334  IdxT p = rnd % (r4 * 2) + (lo + r4);
335  lua_assert(lo + r4 <= p && p <= up - r4);
336  return p;
337 }
338 
339 
340 /*
341 ** Quicksort algorithm (recursive function)
342 */
343 static void auxsort (lua_State *L, IdxT lo, IdxT up,
344  unsigned int rnd) {
345  while (lo < up) { /* loop for tail recursion */
346  IdxT p; /* Pivot index */
347  IdxT n; /* to be used later */
348  /* sort elements 'lo', 'p', and 'up' */
349  lua_geti(L, 1, lo);
350  lua_geti(L, 1, up);
351  if (sort_comp(L, -1, -2)) /* a[up] < a[lo]? */
352  set2(L, lo, up); /* swap a[lo] - a[up] */
353  else
354  lua_pop(L, 2); /* remove both values */
355  if (up - lo == 1) /* only 2 elements? */
356  return; /* already sorted */
357  if (up - lo < RANLIMIT || rnd == 0) /* small interval or no randomize? */
358  p = (lo + up)/2; /* middle element is a good pivot */
359  else /* for larger intervals, it is worth a random pivot */
360  p = choosePivot(lo, up, rnd);
361  lua_geti(L, 1, p);
362  lua_geti(L, 1, lo);
363  if (sort_comp(L, -2, -1)) /* a[p] < a[lo]? */
364  set2(L, p, lo); /* swap a[p] - a[lo] */
365  else {
366  lua_pop(L, 1); /* remove a[lo] */
367  lua_geti(L, 1, up);
368  if (sort_comp(L, -1, -2)) /* a[up] < a[p]? */
369  set2(L, p, up); /* swap a[up] - a[p] */
370  else
371  lua_pop(L, 2);
372  }
373  if (up - lo == 2) /* only 3 elements? */
374  return; /* already sorted */
375  lua_geti(L, 1, p); /* get middle element (Pivot) */
376  lua_pushvalue(L, -1); /* push Pivot */
377  lua_geti(L, 1, up - 1); /* push a[up - 1] */
378  set2(L, p, up - 1); /* swap Pivot (a[p]) with a[up - 1] */
379  p = partition(L, lo, up);
380  /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
381  if (p - lo < up - p) { /* lower interval is smaller? */
382  auxsort(L, lo, p - 1, rnd); /* call recursively for lower interval */
383  n = p - lo; /* size of smaller interval */
384  lo = p + 1; /* tail call for [p + 1 .. up] (upper interval) */
385  }
386  else {
387  auxsort(L, p + 1, up, rnd); /* call recursively for upper interval */
388  n = up - p; /* size of smaller interval */
389  up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */
390  }
391  if ((up - lo) / 128 > n) /* partition too imbalanced? */
392  rnd = l_randomizePivot(); /* try a new randomization */
393  } /* tail call auxsort(L, lo, up, rnd) */
394 }
395 
396 
397 static int sort (lua_State *L) {
398  lua_Integer n = aux_getn(L, 1, TAB_RW);
399  if (n > 1) { /* non-trivial interval? */
400  luaL_argcheck(L, n < INT_MAX, 1, "array too big");
401  if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
402  luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */
403  lua_settop(L, 2); /* make sure there are two arguments */
404  auxsort(L, 1, (IdxT)n, 0);
405  }
406  return 0;
407 }
408 
409 /* }====================================================== */
410 
411 
412 static const luaL_Reg tab_funcs[] = {
413  {"concat", tconcat},
414  {"insert", tinsert},
415  {"pack", tpack},
416  {"unpack", tunpack},
417  {"remove", tremove},
418  {"move", tmove},
419  {"sort", sort},
420  {NULL, NULL}
421 };
422 
423 
424 LUAMOD_API int luaopen_table (lua_State *L) {
425  luaL_newlib(L, tab_funcs);
426  return 1;
427 }
428 
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LUA_API int lua_isstring(lua_State *L, int idx)
Definition: lapi.c:292
lua_isnoneornil
#define lua_isnoneornil(L, n)
Definition: lua.h:379
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static IdxT partition(lua_State *L, IdxT lo, IdxT up)
Definition: ltablib.c:296
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static void addfield(lua_State *L, luaL_Buffer *b, lua_Integer i)
Definition: ltablib.c:146
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LUA_API int lua_rawget(lua_State *L, int idx)
Definition: lapi.c:698
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Definition: ltablib.c:263
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static int sort_comp(lua_State *L, int a, int b)
Definition: ltablib.c:273
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static int tpack(lua_State *L)
Definition: ltablib.c:180
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Definition: lapi.c:473
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Definition: lapi.c:375
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Definition: lapi.c:843
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#define TAB_RW
Definition: ltablib.c:30
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LUA_API void lua_setfield(lua_State *L, int idx, const char *k)
Definition: lapi.c:837
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Definition: lapi.c:327
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Definition: ltablib.c:90
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Definition: lauxlib.h:141
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Definition: ltablib.c:155
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Definition: lua.h:71
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Definition: lauxlib.c:620
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Definition: ltablib.c:36
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Definition: lauxlib.c:570
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Definition: lapi.c:661
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Definition: lapi.c:246
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Definition: lapi.c:173
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Definition: lapi.c:741
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Definition: ltablib.c:424
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Definition: lua.h:94
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Definition: ltablib.c:332
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Definition: lua.h:65
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Definition: lauxlib.h:151
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Definition: lauxlib.c:584
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Definition: ltablib.c:46
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Definition: ltablib.c:61
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Definition: lauxlib.c:409
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Definition: ltablib.c:397
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Definition: lauxlib.c:849
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Definition: lauxlib.c:442
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Definition: core.h:1656
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Definition: lapi.c:260
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Definition: lapi.c:728
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Definition: lauxlib.c:234
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Definition: ltablib.c:193
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Definition: ltablib.c:236
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Definition: ltablib.c:412
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Definition: ltablib.c:27
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Definition: ltablib.c:260
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Definition: ltablib.c:28
IdxT
unsigned int IdxT
Definition: ltablib.c:222
LUA_TTABLE
#define LUA_TTABLE
Definition: lua.h:70
auxsort
static void auxsort(lua_State *L, IdxT lo, IdxT up, unsigned int rnd)
Definition: ltablib.c:343
TAB_L
#define TAB_L
Definition: ltablib.c:29
tmove
static int tmove(lua_State *L)
Definition: ltablib.c:114
LUA_OPEQ
#define LUA_OPEQ
Definition: lua.h:222
l_randomizePivot
static unsigned int l_randomizePivot(void)
Definition: ltablib.c:244
luaL_Buffer
Definition: lauxlib.h:166
lua_checkstack
LUA_API int lua_checkstack(lua_State *L, int n)
Definition: lapi.c:98
lua_gettop
LUA_API int lua_gettop(lua_State *L)
Definition: lapi.c:168

plotjuggler
Author(s): Davide Faconti
autogenerated on Sun Dec 6 2020 03:48:09