Line data Source code
1 : /*
2 : ** $Id: ltable.c,v 2.72.1.1 2013/04/12 18:48:47 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 <string.h>
22 :
23 : #define ltable_c
24 : #define LUA_CORE
25 :
26 : #include "lua.h"
27 :
28 : #include "ldebug.h"
29 : #include "ldo.h"
30 : #include "lgc.h"
31 : #include "lmem.h"
32 : #include "lobject.h"
33 : #include "lstate.h"
34 : #include "lstring.h"
35 : #include "ltable.h"
36 : #include "lvm.h"
37 :
38 :
39 : /*
40 : ** max size of array part is 2^MAXBITS
41 : */
42 : #if LUAI_BITSINT >= 32
43 : #define MAXBITS 30
44 : #else
45 : #define MAXBITS (LUAI_BITSINT-2)
46 : #endif
47 :
48 : #define MAXASIZE (1 << MAXBITS)
49 :
50 :
51 : #define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))
52 :
53 : #define hashstr(t,str) hashpow2(t, (str)->tsv.hash)
54 : #define hashboolean(t,p) hashpow2(t, p)
55 :
56 :
57 : /*
58 : ** for some types, it is better to avoid modulus by power of 2, as
59 : ** they tend to have many 2 factors.
60 : */
61 : #define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))
62 :
63 :
64 : #define hashpointer(t,p) hashmod(t, IntPoint(p))
65 :
66 :
67 : #define dummynode (&dummynode_)
68 :
69 : #define isdummy(n) ((n) == dummynode)
70 :
71 : static const Node dummynode_ = {
72 : {NILCONSTANT}, /* value */
73 : {{NILCONSTANT, NULL}} /* key */
74 : };
75 :
76 :
77 : /*
78 : ** hash for lua_Numbers
79 : */
80 53555 : static Node *hashnum (const Table *t, lua_Number n) {
81 : int i;
82 53555 : luai_hashnum(i, n);
83 53555 : if (i < 0) {
84 760 : if (cast(unsigned int, i) == 0u - i) /* use unsigned to avoid overflows */
85 0 : i = 0; /* handle INT_MIN */
86 760 : i = -i; /* must be a positive value */
87 : }
88 53555 : return hashmod(t, i);
89 : }
90 :
91 :
92 :
93 : /*
94 : ** returns the `main' position of an element in a table (that is, the index
95 : ** of its hash value)
96 : */
97 180280 : static Node *mainposition (const Table *t, const TValue *key) {
98 180280 : switch (ttype(key)) {
99 26710 : case LUA_TNUMBER:
100 26710 : return hashnum(t, nvalue(key));
101 1345 : case LUA_TLNGSTR: {
102 1345 : TString *s = rawtsvalue(key);
103 1345 : if (s->tsv.extra == 0) { /* no hash? */
104 310 : s->tsv.hash = luaS_hash(getstr(s), s->tsv.len, s->tsv.hash);
105 310 : s->tsv.extra = 1; /* now it has its hash */
106 : }
107 1345 : return hashstr(t, rawtsvalue(key));
108 : }
109 151069 : case LUA_TSHRSTR:
110 151069 : return hashstr(t, rawtsvalue(key));
111 726 : case LUA_TBOOLEAN:
112 726 : return hashboolean(t, bvalue(key));
113 0 : case LUA_TLIGHTUSERDATA:
114 0 : return hashpointer(t, pvalue(key));
115 5 : case LUA_TLCF:
116 5 : return hashpointer(t, fvalue(key));
117 425 : default:
118 425 : return hashpointer(t, gcvalue(key));
119 : }
120 : }
121 :
122 :
123 : /*
124 : ** returns the index for `key' if `key' is an appropriate key to live in
125 : ** the array part of the table, -1 otherwise.
126 : */
127 93215 : static int arrayindex (const TValue *key) {
128 93215 : if (ttisnumber(key)) {
129 24982 : lua_Number n = nvalue(key);
130 : int k;
131 24982 : lua_number2int(k, n);
132 24982 : if (luai_numeq(cast_num(k), n))
133 24830 : return k;
134 : }
135 68385 : return -1; /* `key' did not match some condition */
136 : }
137 :
138 :
139 : /*
140 : ** returns the index of a `key' for table traversals. First goes all
141 : ** elements in the array part, then elements in the hash part. The
142 : ** beginning of a traversal is signaled by -1.
143 : */
144 1112 : static int findindex (lua_State *L, Table *t, StkId key) {
145 : int i;
146 1112 : if (ttisnil(key)) return -1; /* first iteration */
147 1047 : i = arrayindex(key);
148 1047 : if (0 < i && i <= t->sizearray) /* is `key' inside array part? */
149 22 : return i-1; /* yes; that's the index (corrected to C) */
150 : else {
151 1025 : Node *n = mainposition(t, key);
152 : for (;;) { /* check whether `key' is somewhere in the chain */
153 : /* key may be dead already, but it is ok to use it in `next' */
154 1348 : if (luaV_rawequalobj(gkey(n), key) ||
155 324 : (ttisdeadkey(gkey(n)) && iscollectable(key) &&
156 0 : deadvalue(gkey(n)) == gcvalue(key))) {
157 1024 : i = cast_int(n - gnode(t, 0)); /* key index in hash table */
158 : /* hash elements are numbered after array ones */
159 1024 : return i + t->sizearray;
160 : }
161 324 : else n = gnext(n);
162 324 : if (n == NULL)
163 1 : luaG_runerror(L, "invalid key to " LUA_QL("next")); /* key not found */
164 : }
165 : }
166 : }
167 :
168 :
169 1112 : int luaH_next (lua_State *L, Table *t, StkId key) {
170 1112 : int i = findindex(L, t, key); /* find original element */
171 1111 : for (i++; i < t->sizearray; i++) { /* try first array part */
172 21 : if (!ttisnil(&t->array[i])) { /* a non-nil value? */
173 21 : setnvalue(key, cast_num(i+1));
174 21 : setobj2s(L, key+1, &t->array[i]);
175 21 : return 1;
176 : }
177 : }
178 1585 : for (i -= t->sizearray; i < sizenode(t); i++) { /* then hash part */
179 1519 : if (!ttisnil(gval(gnode(t, i)))) { /* a non-nil value? */
180 1024 : setobj2s(L, key, gkey(gnode(t, i)));
181 1024 : setobj2s(L, key+1, gval(gnode(t, i)));
182 1024 : return 1;
183 : }
184 : }
185 66 : return 0; /* no more elements */
186 : }
187 :
188 :
189 : /*
190 : ** {=============================================================
191 : ** Rehash
192 : ** ==============================================================
193 : */
194 :
195 :
196 35953 : static int computesizes (int nums[], int *narray) {
197 : int i;
198 : int twotoi; /* 2^i */
199 35953 : int a = 0; /* number of elements smaller than 2^i */
200 35953 : int na = 0; /* number of elements to go to array part */
201 35953 : int n = 0; /* optimal size for array part */
202 72461 : for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {
203 61477 : if (nums[i] > 0) {
204 61184 : a += nums[i];
205 61184 : if (a > twotoi/2) { /* more than half elements present? */
206 61139 : n = twotoi; /* optimal size (till now) */
207 61139 : na = a; /* all elements smaller than n will go to array part */
208 : }
209 : }
210 61477 : if (a == *narray) break; /* all elements already counted */
211 : }
212 35953 : *narray = n;
213 : lua_assert(*narray/2 <= na && na <= *narray);
214 35953 : return na;
215 : }
216 :
217 :
218 92168 : static int countint (const TValue *key, int *nums) {
219 92168 : int k = arrayindex(key);
220 92168 : if (0 < k && k <= MAXASIZE) { /* is `key' an appropriate array index? */
221 24714 : nums[luaO_ceillog2(k)]++; /* count as such */
222 24714 : return 1;
223 : }
224 : else
225 67454 : return 0;
226 : }
227 :
228 :
229 35953 : static int numusearray (const Table *t, int *nums) {
230 : int lg;
231 : int ttlg; /* 2^lg */
232 35953 : int ause = 0; /* summation of `nums' */
233 35953 : int i = 1; /* count to traverse all array keys */
234 72931 : for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) { /* for each slice */
235 72931 : int lc = 0; /* counter */
236 72931 : int lim = ttlg;
237 72931 : if (lim > t->sizearray) {
238 35956 : lim = t->sizearray; /* adjust upper limit */
239 35956 : if (i > lim)
240 35953 : break; /* no more elements to count */
241 : }
242 : /* count elements in range (2^(lg-1), 2^lg] */
243 81930 : for (; i <= lim; i++) {
244 44952 : if (!ttisnil(&t->array[i-1]))
245 44883 : lc++;
246 : }
247 36978 : nums[lg] += lc;
248 36978 : ause += lc;
249 : }
250 35953 : return ause;
251 : }
252 :
253 :
254 35953 : static int numusehash (const Table *t, int *nums, int *pnasize) {
255 35953 : int totaluse = 0; /* total number of elements */
256 35953 : int ause = 0; /* summation of `nums' */
257 35953 : int i = sizenode(t);
258 118453 : while (i--) {
259 82500 : Node *n = &t->node[i];
260 82500 : if (!ttisnil(gval(n))) {
261 56215 : ause += countint(gkey(n), nums);
262 56215 : totaluse++;
263 : }
264 : }
265 35953 : *pnasize += ause;
266 35953 : return totaluse;
267 : }
268 :
269 :
270 24671 : static void setarrayvector (lua_State *L, Table *t, int size) {
271 : int i;
272 24671 : luaM_reallocvector(L, t->array, t->sizearray, size, TValue);
273 75165 : for (i=t->sizearray; i<size; i++)
274 50494 : setnilvalue(&t->array[i]);
275 24671 : t->sizearray = size;
276 24671 : }
277 :
278 :
279 48073 : static void setnodevector (lua_State *L, Table *t, int size) {
280 : int lsize;
281 48073 : if (size == 0) { /* no elements to hash part? */
282 34734 : t->node = cast(Node *, dummynode); /* use common `dummynode' */
283 34734 : lsize = 0;
284 : }
285 : else {
286 : int i;
287 13339 : lsize = luaO_ceillog2(size);
288 13339 : if (lsize > MAXBITS)
289 0 : luaG_runerror(L, "table overflow");
290 13339 : size = twoto(lsize);
291 13339 : t->node = luaM_newvector(L, size, Node);
292 136281 : for (i=0; i<size; i++) {
293 122942 : Node *n = gnode(t, i);
294 122942 : gnext(n) = NULL;
295 122942 : setnilvalue(gkey(n));
296 122942 : setnilvalue(gval(n));
297 : }
298 : }
299 48073 : t->lsizenode = cast_byte(lsize);
300 48073 : t->lastfree = gnode(t, size); /* all positions are free */
301 48073 : }
302 :
303 :
304 37628 : void luaH_resize (lua_State *L, Table *t, int nasize, int nhsize) {
305 : int i;
306 37628 : int oldasize = t->sizearray;
307 37628 : int oldhsize = t->lsizenode;
308 37628 : Node *nold = t->node; /* save old hash ... */
309 37628 : if (nasize > oldasize) /* array part must grow? */
310 24671 : setarrayvector(L, t, nasize);
311 : /* create new hash part with appropriate size */
312 37628 : setnodevector(L, t, nhsize);
313 37628 : if (nasize < oldasize) { /* array part must shrink? */
314 0 : t->sizearray = nasize;
315 : /* re-insert elements from vanishing slice */
316 0 : for (i=nasize; i<oldasize; i++) {
317 0 : if (!ttisnil(&t->array[i]))
318 0 : luaH_setint(L, t, i + 1, &t->array[i]);
319 : }
320 : /* shrink array */
321 0 : luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
322 : }
323 : /* re-insert elements from hash part */
324 121803 : for (i = twoto(oldhsize) - 1; i >= 0; i--) {
325 84175 : Node *old = nold+i;
326 84175 : if (!ttisnil(gval(old))) {
327 : /* doesn't need barrier/invalidate cache, as entry was
328 : already present in the table */
329 56215 : setobjt2t(L, luaH_set(L, t, gkey(old)), gval(old));
330 : }
331 : }
332 37628 : if (!isdummy(nold))
333 9668 : luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old array */
334 37628 : }
335 :
336 :
337 219 : void luaH_resizearray (lua_State *L, Table *t, int nasize) {
338 219 : int nsize = isdummy(t->node) ? 0 : sizenode(t);
339 219 : luaH_resize(L, t, nasize, nsize);
340 219 : }
341 :
342 :
343 35953 : static void rehash (lua_State *L, Table *t, const TValue *ek) {
344 : int nasize, na;
345 : int nums[MAXBITS+1]; /* nums[i] = number of keys with 2^(i-1) < k <= 2^i */
346 : int i;
347 : int totaluse;
348 1150496 : for (i=0; i<=MAXBITS; i++) nums[i] = 0; /* reset counts */
349 35953 : nasize = numusearray(t, nums); /* count keys in array part */
350 35953 : totaluse = nasize; /* all those keys are integer keys */
351 35953 : totaluse += numusehash(t, nums, &nasize); /* count keys in hash part */
352 : /* count extra key */
353 35953 : nasize += countint(ek, nums);
354 35953 : totaluse++;
355 : /* compute new size for array part */
356 35953 : na = computesizes(nums, &nasize);
357 : /* resize the table to new computed sizes */
358 35953 : luaH_resize(L, t, nasize, totaluse - na);
359 35953 : }
360 :
361 :
362 :
363 : /*
364 : ** }=============================================================
365 : */
366 :
367 :
368 10445 : Table *luaH_new (lua_State *L) {
369 10445 : Table *t = &luaC_newobj(L, LUA_TTABLE, sizeof(Table), NULL, 0)->h;
370 10445 : t->metatable = NULL;
371 10445 : t->flags = cast_byte(~0);
372 10445 : t->array = NULL;
373 10445 : t->sizearray = 0;
374 10445 : setnodevector(L, t, 0);
375 10445 : return t;
376 : }
377 :
378 :
379 10150 : void luaH_free (lua_State *L, Table *t) {
380 10150 : if (!isdummy(t->node))
381 3421 : luaM_freearray(L, t->node, cast(size_t, sizenode(t)));
382 10150 : luaM_freearray(L, t->array, t->sizearray);
383 10150 : luaM_free(L, t);
384 10150 : }
385 :
386 :
387 73943 : static Node *getfreepos (Table *t) {
388 119084 : while (t->lastfree > t->node) {
389 83131 : t->lastfree--;
390 83131 : if (ttisnil(gkey(t->lastfree)))
391 37990 : return t->lastfree;
392 : }
393 35953 : return NULL; /* could not find a free place */
394 : }
395 :
396 :
397 :
398 : /*
399 : ** inserts a new key into a hash table; first, check whether key's main
400 : ** position is free. If not, check whether colliding node is in its main
401 : ** position or not: if it is not, move colliding node to an empty place and
402 : ** put new key in its main position; otherwise (colliding node is in its main
403 : ** position), new key goes to an empty position.
404 : */
405 139471 : TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
406 : Node *mp;
407 139471 : if (ttisnil(key)) luaG_runerror(L, "table index is nil");
408 139469 : else if (ttisnumber(key) && luai_numisnan(L, nvalue(key)))
409 1 : luaG_runerror(L, "table index is NaN");
410 139468 : mp = mainposition(t, key);
411 139468 : if (!ttisnil(gval(mp)) || isdummy(mp)) { /* main position is taken? */
412 : Node *othern;
413 73943 : Node *n = getfreepos(t); /* get a free place */
414 73943 : if (n == NULL) { /* cannot find a free place? */
415 35953 : rehash(L, t, key); /* grow table */
416 : /* whatever called 'newkey' take care of TM cache and GC barrier */
417 35953 : return luaH_set(L, t, key); /* insert key into grown table */
418 : }
419 : lua_assert(!isdummy(n));
420 37990 : othern = mainposition(t, gkey(mp));
421 37990 : if (othern != mp) { /* is colliding node out of its main position? */
422 : /* yes; move colliding node into free position */
423 8375 : while (gnext(othern) != mp) othern = gnext(othern); /* find previous */
424 7021 : gnext(othern) = n; /* redo the chain with `n' in place of `mp' */
425 7021 : *n = *mp; /* copy colliding node into free pos. (mp->next also goes) */
426 7021 : gnext(mp) = NULL; /* now `mp' is free */
427 7021 : setnilvalue(gval(mp));
428 : }
429 : else { /* colliding node is in its own main position */
430 : /* new node will go into free position */
431 30969 : gnext(n) = gnext(mp); /* chain new position */
432 30969 : gnext(mp) = n;
433 30969 : mp = n;
434 : }
435 : }
436 103515 : setobj2t(L, gkey(mp), key);
437 103515 : luaC_barrierback(L, obj2gco(t), key);
438 : lua_assert(ttisnil(gval(mp)));
439 103515 : return gval(mp);
440 : }
441 :
442 :
443 : /*
444 : ** search function for integers
445 : */
446 536472 : const TValue *luaH_getint (Table *t, int key) {
447 : /* (1 <= key && key <= t->sizearray) */
448 536472 : if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))
449 509627 : return &t->array[key-1];
450 : else {
451 26845 : lua_Number nk = cast_num(key);
452 26845 : Node *n = hashnum(t, nk);
453 : do { /* check whether `key' is somewhere in the chain */
454 27714 : if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))
455 920 : return gval(n); /* that's it */
456 26794 : else n = gnext(n);
457 26794 : } while (n);
458 25925 : return luaO_nilobject;
459 : }
460 : }
461 :
462 :
463 : /*
464 : ** search function for short strings
465 : */
466 263529 : const TValue *luaH_getstr (Table *t, TString *key) {
467 263529 : Node *n = hashstr(t, key);
468 : lua_assert(key->tsv.tt == LUA_TSHRSTR);
469 : do { /* check whether `key' is somewhere in the chain */
470 303072 : if (ttisshrstring(gkey(n)) && eqshrstr(rawtsvalue(gkey(n)), key))
471 146913 : return gval(n); /* that's it */
472 156159 : else n = gnext(n);
473 156159 : } while (n);
474 116616 : return luaO_nilobject;
475 : }
476 :
477 :
478 : /*
479 : ** main search function
480 : */
481 408250 : const TValue *luaH_get (Table *t, const TValue *key) {
482 408250 : switch (ttype(key)) {
483 255088 : case LUA_TSHRSTR: return luaH_getstr(t, rawtsvalue(key));
484 4 : case LUA_TNIL: return luaO_nilobject;
485 151670 : case LUA_TNUMBER: {
486 : int k;
487 151670 : lua_Number n = nvalue(key);
488 151670 : lua_number2int(k, n);
489 151670 : if (luai_numeq(cast_num(k), n)) /* index is int? */
490 151361 : return luaH_getint(t, k); /* use specialized version */
491 : /* else go through */
492 : }
493 : default: {
494 1797 : Node *n = mainposition(t, key);
495 : do { /* check whether `key' is somewhere in the chain */
496 2188 : if (luaV_rawequalobj(gkey(n), key))
497 745 : return gval(n); /* that's it */
498 1443 : else n = gnext(n);
499 1443 : } while (n);
500 1052 : return luaO_nilobject;
501 : }
502 : }
503 : }
504 :
505 :
506 : /*
507 : ** beware: when using this function you probably need to check a GC
508 : ** barrier and invalidate the TM cache.
509 : */
510 169808 : TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
511 169808 : const TValue *p = luaH_get(t, key);
512 169808 : if (p != luaO_nilobject)
513 72414 : return cast(TValue *, p);
514 97394 : else return luaH_newkey(L, t, key);
515 : }
516 :
517 :
518 87937 : void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {
519 87937 : const TValue *p = luaH_getint(t, key);
520 : TValue *cell;
521 87937 : if (p != luaO_nilobject)
522 87670 : cell = cast(TValue *, p);
523 : else {
524 : TValue k;
525 267 : setnvalue(&k, cast_num(key));
526 267 : cell = luaH_newkey(L, t, &k);
527 : }
528 87937 : setobj2t(L, cell, value);
529 87937 : }
530 :
531 :
532 2 : static int unbound_search (Table *t, unsigned int j) {
533 2 : unsigned int i = j; /* i is zero or a present index */
534 2 : j++;
535 : /* find `i' and `j' such that i is present and j is not */
536 2 : while (!ttisnil(luaH_getint(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_getint(t, i))) i++;
543 0 : return i - 1;
544 : }
545 : }
546 : /* now do a binary search between them */
547 2 : while (j - i > 1) {
548 0 : unsigned int m = (i+j)/2;
549 0 : if (ttisnil(luaH_getint(t, m))) j = m;
550 0 : else i = m;
551 : }
552 2 : 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 18668 : int luaH_getn (Table *t) {
561 18668 : unsigned int j = t->sizearray;
562 18668 : if (j > 0 && ttisnil(&t->array[j - 1])) {
563 : /* there is a boundary in the array part: (binary) search for it */
564 17797 : unsigned int i = 0;
565 70992 : while (j - i > 1) {
566 53195 : unsigned int m = (i+j)/2;
567 53195 : if (ttisnil(&t->array[m - 1])) j = m;
568 50621 : else i = m;
569 : }
570 17797 : return i;
571 : }
572 : /* else must find a boundary in hash part */
573 871 : else if (isdummy(t->node)) /* hash part is empty? */
574 869 : return j; /* that is easy... */
575 2 : 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 isdummy(n); }
587 :
588 : #endif
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