Line data Source code
1 : /*
2 : ** $Id: ltable.c,v 2.32.1.2 2007/12/28 15:32:23 roberto Exp $
3 : ** Lua tables (hash)
4 : ** See Copyright Notice in lua.h
5 : */
6 :
7 :
8 : /*
9 : ** Implementation of tables (aka arrays, objects, or hash tables).
10 : ** Tables keep its elements in two parts: an array part and a hash part.
11 : ** Non-negative integer keys are all candidates to be kept in the array
12 : ** part. The actual size of the array is the largest `n' such that at
13 : ** least half the slots between 0 and n are in use.
14 : ** Hash uses a mix of chained scatter table with Brent's variation.
15 : ** A main invariant of these tables is that, if an element is not
16 : ** in its main position (i.e. the `original' position that its hash gives
17 : ** to it), then the colliding element is in its own main position.
18 : ** Hence even when the load factor reaches 100%, performance remains good.
19 : */
20 :
21 : #include <math.h>
22 : #include <string.h>
23 :
24 : #define ltable_c
25 : #define LUA_CORE
26 :
27 : #include "lua.h"
28 :
29 : #include "ldebug.h"
30 : #include "ldo.h"
31 : #include "lgc.h"
32 : #include "lmem.h"
33 : #include "lobject.h"
34 : #include "lstate.h"
35 : #include "ltable.h"
36 :
37 :
38 : /*
39 : ** max size of array part is 2^MAXBITS
40 : */
41 : #if LUAI_BITSINT > 26
42 : #define MAXBITS 26
43 : #else
44 : #define MAXBITS (LUAI_BITSINT-2)
45 : #endif
46 :
47 : #define MAXASIZE (1 << MAXBITS)
48 :
49 :
50 : #define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))
51 :
52 : #define hashstr(t,str) hashpow2(t, (str)->tsv.hash)
53 : #define hashboolean(t,p) hashpow2(t, p)
54 :
55 :
56 : /*
57 : ** for some types, it is better to avoid modulus by power of 2, as
58 : ** they tend to have many 2 factors.
59 : */
60 : #define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))
61 :
62 :
63 : #define hashpointer(t,p) hashmod(t, IntPoint(p))
64 :
65 :
66 : /*
67 : ** number of ints inside a lua_Number
68 : */
69 : #define numints cast_int(sizeof(lua_Number)/sizeof(int))
70 :
71 :
72 :
73 : #define dummynode (&dummynode_)
74 :
75 : static const Node dummynode_ = {
76 : {{NULL}, LUA_TNIL}, /* value */
77 : {{{NULL}, LUA_TNIL, NULL}} /* key */
78 : };
79 :
80 :
81 : /*
82 : ** hash for lua_Numbers
83 : */
84 56796 : static Node *hashnum (const Table *t, lua_Number n) {
85 : unsigned int a[numints];
86 : int i;
87 56796 : if (luai_numeq(n, 0)) /* avoid problems with -0 */
88 3031 : return gnode(t, 0);
89 53765 : memcpy(a, &n, sizeof(a));
90 107530 : for (i = 1; i < numints; i++) a[0] += a[i];
91 53765 : return hashmod(t, a[0]);
92 : }
93 :
94 :
95 :
96 : /*
97 : ** returns the `main' position of an element in a table (that is, the index
98 : ** of its hash value)
99 : */
100 174954 : static Node *mainposition (const Table *t, const TValue *key) {
101 174954 : switch (ttype(key)) {
102 28329 : case LUA_TNUMBER:
103 28329 : return hashnum(t, nvalue(key));
104 145130 : case LUA_TSTRING:
105 145130 : return hashstr(t, rawtsvalue(key));
106 819 : case LUA_TBOOLEAN:
107 819 : return hashboolean(t, bvalue(key));
108 499 : case LUA_TLIGHTUSERDATA:
109 499 : return hashpointer(t, pvalue(key));
110 177 : default:
111 177 : return hashpointer(t, gcvalue(key));
112 : }
113 : }
114 :
115 :
116 : /*
117 : ** returns the index for `key' if `key' is an appropriate key to live in
118 : ** the array part of the table, -1 otherwise.
119 : */
120 90635 : static int arrayindex (const TValue *key) {
121 90635 : if (ttisnumber(key)) {
122 25828 : lua_Number n = nvalue(key);
123 : int k;
124 25828 : lua_number2int(k, n);
125 25828 : if (luai_numeq(cast_num(k), n))
126 25676 : return k;
127 : }
128 64959 : return -1; /* `key' did not match some condition */
129 : }
130 :
131 :
132 : /*
133 : ** returns the index of a `key' for table traversals. First goes all
134 : ** elements in the array part, then elements in the hash part. The
135 : ** beginning of a traversal is signalled by -1.
136 : */
137 57 : static int findindex (lua_State *L, Table *t, StkId key) {
138 : int i;
139 57 : if (ttisnil(key)) return -1; /* first iteration */
140 41 : i = arrayindex(key);
141 41 : if (0 < i && i <= t->sizearray) /* is `key' inside array part? */
142 25 : return i-1; /* yes; that's the index (corrected to C) */
143 : else {
144 16 : Node *n = mainposition(t, key);
145 : do { /* check whether `key' is somewhere in the chain */
146 : /* key may be dead already, but it is ok to use it in `next' */
147 19 : if (luaO_rawequalObj(key2tval(n), key) ||
148 4 : (ttype(gkey(n)) == LUA_TDEADKEY && iscollectable(key) &&
149 0 : gcvalue(gkey(n)) == gcvalue(key))) {
150 15 : i = cast_int(n - gnode(t, 0)); /* key index in hash table */
151 : /* hash elements are numbered after array ones */
152 15 : return i + t->sizearray;
153 : }
154 4 : else n = gnext(n);
155 4 : } while (n);
156 1 : luaG_runerror(L, "invalid key to " LUA_QL("next")); /* key not found */
157 0 : return 0; /* to avoid warnings */
158 : }
159 : }
160 :
161 :
162 57 : int luaH_next (lua_State *L, Table *t, StkId key) {
163 57 : int i = findindex(L, t, key); /* find original element */
164 56 : for (i++; i < t->sizearray; i++) { /* try first array part */
165 24 : if (!ttisnil(&t->array[i])) { /* a non-nil value? */
166 24 : setnvalue(key, cast_num(i+1));
167 24 : setobj2s(L, key+1, &t->array[i]);
168 24 : return 1;
169 : }
170 : }
171 45 : for (i -= t->sizearray; i < sizenode(t); i++) { /* then hash part */
172 28 : if (!ttisnil(gval(gnode(t, i)))) { /* a non-nil value? */
173 15 : setobj2s(L, key, key2tval(gnode(t, i)));
174 15 : setobj2s(L, key+1, gval(gnode(t, i)));
175 15 : return 1;
176 : }
177 : }
178 17 : return 0; /* no more elements */
179 : }
180 :
181 :
182 : /*
183 : ** {=============================================================
184 : ** Rehash
185 : ** ==============================================================
186 : */
187 :
188 :
189 35600 : static int computesizes (int nums[], int *narray) {
190 : int i;
191 : int twotoi; /* 2^i */
192 35600 : int a = 0; /* number of elements smaller than 2^i */
193 35600 : int na = 0; /* number of elements to go to array part */
194 35600 : int n = 0; /* optimal size for array part */
195 71862 : for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {
196 61056 : if (nums[i] > 0) {
197 60757 : a += nums[i];
198 60757 : if (a > twotoi/2) { /* more than half elements present? */
199 60711 : n = twotoi; /* optimal size (till now) */
200 60711 : na = a; /* all elements smaller than n will go to array part */
201 : }
202 : }
203 61056 : if (a == *narray) break; /* all elements already counted */
204 : }
205 35600 : *narray = n;
206 : lua_assert(*narray/2 <= na && na <= *narray);
207 35600 : return na;
208 : }
209 :
210 :
211 90594 : static int countint (const TValue *key, int *nums) {
212 90594 : int k = arrayindex(key);
213 90594 : if (0 < k && k <= MAXASIZE) { /* is `key' an appropriate array index? */
214 24882 : nums[ceillog2(k)]++; /* count as such */
215 24882 : return 1;
216 : }
217 : else
218 65712 : return 0;
219 : }
220 :
221 :
222 35600 : static int numusearray (const Table *t, int *nums) {
223 : int lg;
224 : int ttlg; /* 2^lg */
225 35600 : int ause = 0; /* summation of `nums' */
226 35600 : int i = 1; /* count to traverse all array keys */
227 71984 : for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) { /* for each slice */
228 71984 : int lc = 0; /* counter */
229 71984 : int lim = ttlg;
230 71984 : if (lim > t->sizearray) {
231 35603 : lim = t->sizearray; /* adjust upper limit */
232 35603 : if (i > lim)
233 35600 : break; /* no more elements to count */
234 : }
235 : /* count elements in range (2^(lg-1), 2^lg] */
236 80748 : for (; i <= lim; i++) {
237 44364 : if (!ttisnil(&t->array[i-1]))
238 44293 : lc++;
239 : }
240 36384 : nums[lg] += lc;
241 36384 : ause += lc;
242 : }
243 35600 : return ause;
244 : }
245 :
246 :
247 35600 : static int numusehash (const Table *t, int *nums, int *pnasize) {
248 35600 : int totaluse = 0; /* total number of elements */
249 35600 : int ause = 0; /* summation of `nums' */
250 35600 : int i = sizenode(t);
251 116689 : while (i--) {
252 81089 : Node *n = &t->node[i];
253 81089 : if (!ttisnil(gval(n))) {
254 54994 : ause += countint(key2tval(n), nums);
255 54994 : totaluse++;
256 : }
257 : }
258 35600 : *pnasize += ause;
259 35600 : return totaluse;
260 : }
261 :
262 :
263 35014 : static void setarrayvector (lua_State *L, Table *t, int size) {
264 : int i;
265 35014 : luaM_reallocvector(L, t->array, t->sizearray, size, TValue);
266 85459 : for (i=t->sizearray; i<size; i++)
267 50445 : setnilvalue(&t->array[i]);
268 35014 : t->sizearray = size;
269 35014 : }
270 :
271 :
272 46324 : static void setnodevector (lua_State *L, Table *t, int size) {
273 : int lsize;
274 46324 : if (size == 0) { /* no elements to hash part? */
275 32943 : t->node = cast(Node *, dummynode); /* use common `dummynode' */
276 32943 : lsize = 0;
277 : }
278 : else {
279 : int i;
280 13381 : lsize = ceillog2(size);
281 13381 : if (lsize > MAXBITS)
282 0 : luaG_runerror(L, "table overflow");
283 13381 : size = twoto(lsize);
284 13381 : t->node = luaM_newvector(L, size, Node);
285 133080 : for (i=0; i<size; i++) {
286 119699 : Node *n = gnode(t, i);
287 119699 : gnext(n) = NULL;
288 119699 : setnilvalue(gkey(n));
289 119699 : setnilvalue(gval(n));
290 : }
291 : }
292 46324 : t->lsizenode = cast_byte(lsize);
293 46324 : t->lastfree = gnode(t, size); /* all positions are free */
294 46324 : }
295 :
296 :
297 35813 : static void resize (lua_State *L, Table *t, int nasize, int nhsize) {
298 : int i;
299 35813 : int oldasize = t->sizearray;
300 35813 : int oldhsize = t->lsizenode;
301 35813 : Node *nold = t->node; /* save old hash ... */
302 35813 : if (nasize > oldasize) /* array part must grow? */
303 24503 : setarrayvector(L, t, nasize);
304 : /* create new hash part with appropriate size */
305 35813 : setnodevector(L, t, nhsize);
306 35813 : if (nasize < oldasize) { /* array part must shrink? */
307 0 : t->sizearray = nasize;
308 : /* re-insert elements from vanishing slice */
309 0 : for (i=nasize; i<oldasize; i++) {
310 0 : if (!ttisnil(&t->array[i]))
311 0 : setobjt2t(L, luaH_setnum(L, t, i+1), &t->array[i]);
312 : }
313 : /* shrink array */
314 0 : luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
315 : }
316 : /* re-insert elements from hash part */
317 117115 : for (i = twoto(oldhsize) - 1; i >= 0; i--) {
318 81302 : Node *old = nold+i;
319 81302 : if (!ttisnil(gval(old)))
320 54994 : setobjt2t(L, luaH_set(L, t, key2tval(old)), gval(old));
321 : }
322 35813 : if (nold != dummynode)
323 9507 : luaM_freearray(L, nold, twoto(oldhsize), Node); /* free old array */
324 35813 : }
325 :
326 :
327 213 : void luaH_resizearray (lua_State *L, Table *t, int nasize) {
328 213 : int nsize = (t->node == dummynode) ? 0 : sizenode(t);
329 213 : resize(L, t, nasize, nsize);
330 213 : }
331 :
332 :
333 35600 : static void rehash (lua_State *L, Table *t, const TValue *ek) {
334 : int nasize, na;
335 : int nums[MAXBITS+1]; /* nums[i] = number of keys between 2^(i-1) and 2^i */
336 : int i;
337 : int totaluse;
338 996800 : for (i=0; i<=MAXBITS; i++) nums[i] = 0; /* reset counts */
339 35600 : nasize = numusearray(t, nums); /* count keys in array part */
340 35600 : totaluse = nasize; /* all those keys are integer keys */
341 35600 : totaluse += numusehash(t, nums, &nasize); /* count keys in hash part */
342 : /* count extra key */
343 35600 : nasize += countint(ek, nums);
344 35600 : totaluse++;
345 : /* compute new size for array part */
346 35600 : na = computesizes(nums, &nasize);
347 : /* resize the table to new computed sizes */
348 35600 : resize(L, t, nasize, totaluse - na);
349 35600 : }
350 :
351 :
352 :
353 : /*
354 : ** }=============================================================
355 : */
356 :
357 :
358 10511 : Table *luaH_new (lua_State *L, int narray, int nhash) {
359 10511 : Table *t = luaM_new(L, Table);
360 10511 : luaC_link(L, obj2gco(t), LUA_TTABLE);
361 10511 : t->metatable = NULL;
362 10511 : t->flags = cast_byte(~0);
363 : /* temporary values (kept only if some malloc fails) */
364 10511 : t->array = NULL;
365 10511 : t->sizearray = 0;
366 10511 : t->lsizenode = 0;
367 10511 : t->node = cast(Node *, dummynode);
368 10511 : setarrayvector(L, t, narray);
369 10511 : setnodevector(L, t, nhash);
370 10511 : return t;
371 : }
372 :
373 :
374 10286 : void luaH_free (lua_State *L, Table *t) {
375 10286 : if (t->node != dummynode)
376 3670 : luaM_freearray(L, t->node, sizenode(t), Node);
377 10286 : luaM_freearray(L, t->array, t->sizearray, TValue);
378 10286 : luaM_free(L, t);
379 10286 : }
380 :
381 :
382 72619 : static Node *getfreepos (Table *t) {
383 115822 : while (t->lastfree-- > t->node) {
384 80222 : if (ttisnil(gkey(t->lastfree)))
385 37019 : return t->lastfree;
386 : }
387 35600 : return NULL; /* could not find a free place */
388 : }
389 :
390 :
391 :
392 : /*
393 : ** inserts a new key into a hash table; first, check whether key's main
394 : ** position is free. If not, check whether colliding node is in its main
395 : ** position or not: if it is not, move colliding node to an empty place and
396 : ** put new key in its main position; otherwise (colliding node is in its main
397 : ** position), new key goes to an empty position.
398 : */
399 136590 : static TValue *newkey (lua_State *L, Table *t, const TValue *key) {
400 136590 : Node *mp = mainposition(t, key);
401 136590 : if (!ttisnil(gval(mp)) || mp == dummynode) {
402 : Node *othern;
403 72619 : Node *n = getfreepos(t); /* get a free place */
404 72619 : if (n == NULL) { /* cannot find a free place? */
405 35600 : rehash(L, t, key); /* grow table */
406 35600 : return luaH_set(L, t, key); /* re-insert key into grown table */
407 : }
408 : lua_assert(n != dummynode);
409 37019 : othern = mainposition(t, key2tval(mp));
410 37019 : if (othern != mp) { /* is colliding node out of its main position? */
411 : /* yes; move colliding node into free position */
412 7925 : while (gnext(othern) != mp) othern = gnext(othern); /* find previous */
413 6429 : gnext(othern) = n; /* redo the chain with `n' in place of `mp' */
414 6429 : *n = *mp; /* copy colliding node into free pos. (mp->next also goes) */
415 6429 : gnext(mp) = NULL; /* now `mp' is free */
416 6429 : setnilvalue(gval(mp));
417 : }
418 : else { /* colliding node is in its own main position */
419 : /* new node will go into free position */
420 30590 : gnext(n) = gnext(mp); /* chain new position */
421 30590 : gnext(mp) = n;
422 30590 : mp = n;
423 : }
424 : }
425 100990 : gkey(mp)->value = key->value; gkey(mp)->tt = key->tt;
426 100990 : luaC_barriert(L, t, key);
427 : lua_assert(ttisnil(gval(mp)));
428 100990 : return gval(mp);
429 : }
430 :
431 :
432 : /*
433 : ** search function for integers
434 : */
435 534327 : const TValue *luaH_getnum (Table *t, int key) {
436 : /* (1 <= key && key <= t->sizearray) */
437 534327 : if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))
438 505860 : return &t->array[key-1];
439 : else {
440 28467 : lua_Number nk = cast_num(key);
441 28467 : Node *n = hashnum(t, nk);
442 : do { /* check whether `key' is somewhere in the chain */
443 29460 : if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))
444 1230 : return gval(n); /* that's it */
445 28230 : else n = gnext(n);
446 28230 : } while (n);
447 27237 : return luaO_nilobject;
448 : }
449 : }
450 :
451 :
452 : /*
453 : ** search function for strings
454 : */
455 260098 : const TValue *luaH_getstr (Table *t, TString *key) {
456 260098 : Node *n = hashstr(t, key);
457 : do { /* check whether `key' is somewhere in the chain */
458 302604 : if (ttisstring(gkey(n)) && rawtsvalue(gkey(n)) == key)
459 146309 : return gval(n); /* that's it */
460 156295 : else n = gnext(n);
461 156295 : } while (n);
462 113789 : return luaO_nilobject;
463 : }
464 :
465 :
466 : /*
467 : ** main search function
468 : */
469 351919 : const TValue *luaH_get (Table *t, const TValue *key) {
470 351919 : switch (ttype(key)) {
471 4 : case LUA_TNIL: return luaO_nilobject;
472 197628 : case LUA_TSTRING: return luaH_getstr(t, rawtsvalue(key));
473 153261 : case LUA_TNUMBER: {
474 : int k;
475 153261 : lua_Number n = nvalue(key);
476 153261 : lua_number2int(k, n);
477 153261 : if (luai_numeq(cast_num(k), nvalue(key))) /* index is int? */
478 152958 : return luaH_getnum(t, k); /* use specialized version */
479 : /* else go through */
480 : }
481 : default: {
482 1329 : Node *n = mainposition(t, key);
483 : do { /* check whether `key' is somewhere in the chain */
484 1758 : if (luaO_rawequalObj(key2tval(n), key))
485 681 : return gval(n); /* that's it */
486 1077 : else n = gnext(n);
487 1077 : } while (n);
488 648 : return luaO_nilobject;
489 : }
490 : }
491 : }
492 :
493 :
494 213473 : TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
495 213473 : const TValue *p = luaH_get(t, key);
496 213473 : t->flags = 0;
497 213473 : if (p != luaO_nilobject)
498 105014 : return cast(TValue *, p);
499 : else {
500 108459 : if (ttisnil(key)) luaG_runerror(L, "table index is nil");
501 108457 : else if (ttisnumber(key) && luai_numisnan(nvalue(key)))
502 1 : luaG_runerror(L, "table index is NaN");
503 108456 : return newkey(L, t, key);
504 : }
505 : }
506 :
507 :
508 87918 : TValue *luaH_setnum (lua_State *L, Table *t, int key) {
509 87918 : const TValue *p = luaH_getnum(t, key);
510 87918 : if (p != luaO_nilobject)
511 87471 : return cast(TValue *, p);
512 : else {
513 : TValue k;
514 447 : setnvalue(&k, cast_num(key));
515 447 : return newkey(L, t, &k);
516 : }
517 : }
518 :
519 :
520 54199 : TValue *luaH_setstr (lua_State *L, Table *t, TString *key) {
521 54199 : const TValue *p = luaH_getstr(t, key);
522 54199 : if (p != luaO_nilobject)
523 26512 : return cast(TValue *, p);
524 : else {
525 : TValue k;
526 27687 : setsvalue(L, &k, key);
527 27687 : return newkey(L, t, &k);
528 : }
529 : }
530 :
531 :
532 4 : static int unbound_search (Table *t, unsigned int j) {
533 4 : unsigned int i = j; /* i is zero or a present index */
534 4 : j++;
535 : /* find `i' and `j' such that i is present and j is not */
536 4 : while (!ttisnil(luaH_getnum(t, j))) {
537 0 : i = j;
538 0 : j *= 2;
539 0 : if (j > cast(unsigned int, MAX_INT)) { /* overflow? */
540 : /* table was built with bad purposes: resort to linear search */
541 0 : i = 1;
542 0 : while (!ttisnil(luaH_getnum(t, i))) i++;
543 0 : return i - 1;
544 : }
545 : }
546 : /* now do a binary search between them */
547 4 : while (j - i > 1) {
548 0 : unsigned int m = (i+j)/2;
549 0 : if (ttisnil(luaH_getnum(t, m))) j = m;
550 0 : else i = m;
551 : }
552 4 : return i;
553 : }
554 :
555 :
556 : /*
557 : ** Try to find a boundary in table `t'. A `boundary' is an integer index
558 : ** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
559 : */
560 18581 : int luaH_getn (Table *t) {
561 18581 : unsigned int j = t->sizearray;
562 18581 : if (j > 0 && ttisnil(&t->array[j - 1])) {
563 : /* there is a boundary in the array part: (binary) search for it */
564 17802 : unsigned int i = 0;
565 71011 : while (j - i > 1) {
566 53209 : unsigned int m = (i+j)/2;
567 53209 : if (ttisnil(&t->array[m - 1])) j = m;
568 50632 : else i = m;
569 : }
570 17802 : return i;
571 : }
572 : /* else must find a boundary in hash part */
573 779 : else if (t->node == dummynode) /* hash part is empty? */
574 775 : return j; /* that is easy... */
575 4 : else return unbound_search(t, j);
576 : }
577 :
578 :
579 :
580 : #if defined(LUA_DEBUG)
581 :
582 : Node *luaH_mainposition (const Table *t, const TValue *key) {
583 : return mainposition(t, key);
584 : }
585 :
586 : int luaH_isdummy (Node *n) { return n == dummynode; }
587 :
588 : #endif
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