Mercurial > vba-clojure
view src/lua/ltable.c @ 340:dea7e476eba7
preliminary item-writer complete
author | Robert McIntyre <rlm@mit.edu> |
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date | Sun, 08 Apr 2012 04:10:49 -0500 |
parents | 27763b933818 |
children |
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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.h5 */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 array12 ** part. The actual size of the array is the largest `n' such that at13 ** 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 not16 ** in its main position (i.e. the `original' position that its hash gives17 ** 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 */21 #include <math.h>22 #include <string.h>24 #define ltable_c25 #define LUA_CORE27 #include "lua.h"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"38 /*39 ** max size of array part is 2^MAXBITS40 */41 #if LUAI_BITSINT > 2642 #define MAXBITS 2643 #else44 #define MAXBITS (LUAI_BITSINT-2)45 #endif47 #define MAXASIZE (1 << MAXBITS)50 #define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))52 #define hashstr(t,str) hashpow2(t, (str)->tsv.hash)53 #define hashboolean(t,p) hashpow2(t, p)56 /*57 ** for some types, it is better to avoid modulus by power of 2, as58 ** they tend to have many 2 factors.59 */60 #define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))63 #define hashpointer(t,p) hashmod(t, IntPoint(p))66 /*67 ** number of ints inside a lua_Number68 */69 #define numints cast_int(sizeof(lua_Number)/sizeof(int))73 #define dummynode (&dummynode_)75 static const Node dummynode_ = {76 {{NULL}, LUA_TNIL}, /* value */77 {{{NULL}, LUA_TNIL, NULL}} /* key */78 };81 /*82 ** hash for lua_Numbers83 */84 static Node *hashnum (const Table *t, lua_Number n) {85 unsigned int a[numints];86 int i;87 if (luai_numeq(n, 0)) /* avoid problems with -0 */88 return gnode(t, 0);89 memcpy(a, &n, sizeof(a));90 for (i = 1; i < numints; i++) a[0] += a[i];91 return hashmod(t, a[0]);92 }96 /*97 ** returns the `main' position of an element in a table (that is, the index98 ** of its hash value)99 */100 static Node *mainposition (const Table *t, const TValue *key) {101 switch (ttype(key)) {102 case LUA_TNUMBER:103 return hashnum(t, nvalue(key));104 case LUA_TSTRING:105 return hashstr(t, rawtsvalue(key));106 case LUA_TBOOLEAN:107 return hashboolean(t, bvalue(key));108 case LUA_TLIGHTUSERDATA:109 return hashpointer(t, pvalue(key));110 default:111 return hashpointer(t, gcvalue(key));112 }113 }116 /*117 ** returns the index for `key' if `key' is an appropriate key to live in118 ** the array part of the table, -1 otherwise.119 */120 static int arrayindex (const TValue *key) {121 if (ttisnumber(key)) {122 lua_Number n = nvalue(key);123 int k;124 lua_number2int(k, n);125 if (luai_numeq(cast_num(k), n))126 return k;127 }128 return -1; /* `key' did not match some condition */129 }132 /*133 ** returns the index of a `key' for table traversals. First goes all134 ** elements in the array part, then elements in the hash part. The135 ** beginning of a traversal is signalled by -1.136 */137 static int findindex (lua_State *L, Table *t, StkId key) {138 int i;139 if (ttisnil(key)) return -1; /* first iteration */140 i = arrayindex(key);141 if (0 < i && i <= t->sizearray) /* is `key' inside array part? */142 return i-1; /* yes; that's the index (corrected to C) */143 else {144 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 if (luaO_rawequalObj(key2tval(n), key) ||148 (ttype(gkey(n)) == LUA_TDEADKEY && iscollectable(key) &&149 gcvalue(gkey(n)) == gcvalue(key))) {150 i = cast_int(n - gnode(t, 0)); /* key index in hash table */151 /* hash elements are numbered after array ones */152 return i + t->sizearray;153 }154 else n = gnext(n);155 } while (n);156 luaG_runerror(L, "invalid key to " LUA_QL("next")); /* key not found */157 return 0; /* to avoid warnings */158 }159 }162 int luaH_next (lua_State *L, Table *t, StkId key) {163 int i = findindex(L, t, key); /* find original element */164 for (i++; i < t->sizearray; i++) { /* try first array part */165 if (!ttisnil(&t->array[i])) { /* a non-nil value? */166 setnvalue(key, cast_num(i+1));167 setobj2s(L, key+1, &t->array[i]);168 return 1;169 }170 }171 for (i -= t->sizearray; i < sizenode(t); i++) { /* then hash part */172 if (!ttisnil(gval(gnode(t, i)))) { /* a non-nil value? */173 setobj2s(L, key, key2tval(gnode(t, i)));174 setobj2s(L, key+1, gval(gnode(t, i)));175 return 1;176 }177 }178 return 0; /* no more elements */179 }182 /*183 ** {=============================================================184 ** Rehash185 ** ==============================================================186 */189 static int computesizes (int nums[], int *narray) {190 int i;191 int twotoi; /* 2^i */192 int a = 0; /* number of elements smaller than 2^i */193 int na = 0; /* number of elements to go to array part */194 int n = 0; /* optimal size for array part */195 for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {196 if (nums[i] > 0) {197 a += nums[i];198 if (a > twotoi/2) { /* more than half elements present? */199 n = twotoi; /* optimal size (till now) */200 na = a; /* all elements smaller than n will go to array part */201 }202 }203 if (a == *narray) break; /* all elements already counted */204 }205 *narray = n;206 lua_assert(*narray/2 <= na && na <= *narray);207 return na;208 }211 static int countint (const TValue *key, int *nums) {212 int k = arrayindex(key);213 if (0 < k && k <= MAXASIZE) { /* is `key' an appropriate array index? */214 nums[ceillog2(k)]++; /* count as such */215 return 1;216 }217 else218 return 0;219 }222 static int numusearray (const Table *t, int *nums) {223 int lg;224 int ttlg; /* 2^lg */225 int ause = 0; /* summation of `nums' */226 int i = 1; /* count to traverse all array keys */227 for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) { /* for each slice */228 int lc = 0; /* counter */229 int lim = ttlg;230 if (lim > t->sizearray) {231 lim = t->sizearray; /* adjust upper limit */232 if (i > lim)233 break; /* no more elements to count */234 }235 /* count elements in range (2^(lg-1), 2^lg] */236 for (; i <= lim; i++) {237 if (!ttisnil(&t->array[i-1]))238 lc++;239 }240 nums[lg] += lc;241 ause += lc;242 }243 return ause;244 }247 static int numusehash (const Table *t, int *nums, int *pnasize) {248 int totaluse = 0; /* total number of elements */249 int ause = 0; /* summation of `nums' */250 int i = sizenode(t);251 while (i--) {252 Node *n = &t->node[i];253 if (!ttisnil(gval(n))) {254 ause += countint(key2tval(n), nums);255 totaluse++;256 }257 }258 *pnasize += ause;259 return totaluse;260 }263 static void setarrayvector (lua_State *L, Table *t, int size) {264 int i;265 luaM_reallocvector(L, t->array, t->sizearray, size, TValue);266 for (i=t->sizearray; i<size; i++)267 setnilvalue(&t->array[i]);268 t->sizearray = size;269 }272 static void setnodevector (lua_State *L, Table *t, int size) {273 int lsize;274 if (size == 0) { /* no elements to hash part? */275 t->node = cast(Node *, dummynode); /* use common `dummynode' */276 lsize = 0;277 }278 else {279 int i;280 lsize = ceillog2(size);281 if (lsize > MAXBITS)282 luaG_runerror(L, "table overflow");283 size = twoto(lsize);284 t->node = luaM_newvector(L, size, Node);285 for (i=0; i<size; i++) {286 Node *n = gnode(t, i);287 gnext(n) = NULL;288 setnilvalue(gkey(n));289 setnilvalue(gval(n));290 }291 }292 t->lsizenode = cast_byte(lsize);293 t->lastfree = gnode(t, size); /* all positions are free */294 }297 static void resize (lua_State *L, Table *t, int nasize, int nhsize) {298 int i;299 int oldasize = t->sizearray;300 int oldhsize = t->lsizenode;301 Node *nold = t->node; /* save old hash ... */302 if (nasize > oldasize) /* array part must grow? */303 setarrayvector(L, t, nasize);304 /* create new hash part with appropriate size */305 setnodevector(L, t, nhsize);306 if (nasize < oldasize) { /* array part must shrink? */307 t->sizearray = nasize;308 /* re-insert elements from vanishing slice */309 for (i=nasize; i<oldasize; i++) {310 if (!ttisnil(&t->array[i]))311 setobjt2t(L, luaH_setnum(L, t, i+1), &t->array[i]);312 }313 /* shrink array */314 luaM_reallocvector(L, t->array, oldasize, nasize, TValue);315 }316 /* re-insert elements from hash part */317 for (i = twoto(oldhsize) - 1; i >= 0; i--) {318 Node *old = nold+i;319 if (!ttisnil(gval(old)))320 setobjt2t(L, luaH_set(L, t, key2tval(old)), gval(old));321 }322 if (nold != dummynode)323 luaM_freearray(L, nold, twoto(oldhsize), Node); /* free old array */324 }327 void luaH_resizearray (lua_State *L, Table *t, int nasize) {328 int nsize = (t->node == dummynode) ? 0 : sizenode(t);329 resize(L, t, nasize, nsize);330 }333 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 for (i=0; i<=MAXBITS; i++) nums[i] = 0; /* reset counts */339 nasize = numusearray(t, nums); /* count keys in array part */340 totaluse = nasize; /* all those keys are integer keys */341 totaluse += numusehash(t, nums, &nasize); /* count keys in hash part */342 /* count extra key */343 nasize += countint(ek, nums);344 totaluse++;345 /* compute new size for array part */346 na = computesizes(nums, &nasize);347 /* resize the table to new computed sizes */348 resize(L, t, nasize, totaluse - na);349 }353 /*354 ** }=============================================================355 */358 Table *luaH_new (lua_State *L, int narray, int nhash) {359 Table *t = luaM_new(L, Table);360 luaC_link(L, obj2gco(t), LUA_TTABLE);361 t->metatable = NULL;362 t->flags = cast_byte(~0);363 /* temporary values (kept only if some malloc fails) */364 t->array = NULL;365 t->sizearray = 0;366 t->lsizenode = 0;367 t->node = cast(Node *, dummynode);368 setarrayvector(L, t, narray);369 setnodevector(L, t, nhash);370 return t;371 }374 void luaH_free (lua_State *L, Table *t) {375 if (t->node != dummynode)376 luaM_freearray(L, t->node, sizenode(t), Node);377 luaM_freearray(L, t->array, t->sizearray, TValue);378 luaM_free(L, t);379 }382 static Node *getfreepos (Table *t) {383 while (t->lastfree-- > t->node) {384 if (ttisnil(gkey(t->lastfree)))385 return t->lastfree;386 }387 return NULL; /* could not find a free place */388 }392 /*393 ** inserts a new key into a hash table; first, check whether key's main394 ** position is free. If not, check whether colliding node is in its main395 ** position or not: if it is not, move colliding node to an empty place and396 ** put new key in its main position; otherwise (colliding node is in its main397 ** position), new key goes to an empty position.398 */399 static TValue *newkey (lua_State *L, Table *t, const TValue *key) {400 Node *mp = mainposition(t, key);401 if (!ttisnil(gval(mp)) || mp == dummynode) {402 Node *othern;403 Node *n = getfreepos(t); /* get a free place */404 if (n == NULL) { /* cannot find a free place? */405 rehash(L, t, key); /* grow table */406 return luaH_set(L, t, key); /* re-insert key into grown table */407 }408 lua_assert(n != dummynode);409 othern = mainposition(t, key2tval(mp));410 if (othern != mp) { /* is colliding node out of its main position? */411 /* yes; move colliding node into free position */412 while (gnext(othern) != mp) othern = gnext(othern); /* find previous */413 gnext(othern) = n; /* redo the chain with `n' in place of `mp' */414 *n = *mp; /* copy colliding node into free pos. (mp->next also goes) */415 gnext(mp) = NULL; /* now `mp' is free */416 setnilvalue(gval(mp));417 }418 else { /* colliding node is in its own main position */419 /* new node will go into free position */420 gnext(n) = gnext(mp); /* chain new position */421 gnext(mp) = n;422 mp = n;423 }424 }425 gkey(mp)->value = key->value; gkey(mp)->tt = key->tt;426 luaC_barriert(L, t, key);427 lua_assert(ttisnil(gval(mp)));428 return gval(mp);429 }432 /*433 ** search function for integers434 */435 const TValue *luaH_getnum (Table *t, int key) {436 /* (1 <= key && key <= t->sizearray) */437 if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))438 return &t->array[key-1];439 else {440 lua_Number nk = cast_num(key);441 Node *n = hashnum(t, nk);442 do { /* check whether `key' is somewhere in the chain */443 if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))444 return gval(n); /* that's it */445 else n = gnext(n);446 } while (n);447 return luaO_nilobject;448 }449 }452 /*453 ** search function for strings454 */455 const TValue *luaH_getstr (Table *t, TString *key) {456 Node *n = hashstr(t, key);457 do { /* check whether `key' is somewhere in the chain */458 if (ttisstring(gkey(n)) && rawtsvalue(gkey(n)) == key)459 return gval(n); /* that's it */460 else n = gnext(n);461 } while (n);462 return luaO_nilobject;463 }466 /*467 ** main search function468 */469 const TValue *luaH_get (Table *t, const TValue *key) {470 switch (ttype(key)) {471 case LUA_TNIL: return luaO_nilobject;472 case LUA_TSTRING: return luaH_getstr(t, rawtsvalue(key));473 case LUA_TNUMBER: {474 int k;475 lua_Number n = nvalue(key);476 lua_number2int(k, n);477 if (luai_numeq(cast_num(k), nvalue(key))) /* index is int? */478 return luaH_getnum(t, k); /* use specialized version */479 /* else go through */480 }481 default: {482 Node *n = mainposition(t, key);483 do { /* check whether `key' is somewhere in the chain */484 if (luaO_rawequalObj(key2tval(n), key))485 return gval(n); /* that's it */486 else n = gnext(n);487 } while (n);488 return luaO_nilobject;489 }490 }491 }494 TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {495 const TValue *p = luaH_get(t, key);496 t->flags = 0;497 if (p != luaO_nilobject)498 return cast(TValue *, p);499 else {500 if (ttisnil(key)) luaG_runerror(L, "table index is nil");501 else if (ttisnumber(key) && luai_numisnan(nvalue(key)))502 luaG_runerror(L, "table index is NaN");503 return newkey(L, t, key);504 }505 }508 TValue *luaH_setnum (lua_State *L, Table *t, int key) {509 const TValue *p = luaH_getnum(t, key);510 if (p != luaO_nilobject)511 return cast(TValue *, p);512 else {513 TValue k;514 setnvalue(&k, cast_num(key));515 return newkey(L, t, &k);516 }517 }520 TValue *luaH_setstr (lua_State *L, Table *t, TString *key) {521 const TValue *p = luaH_getstr(t, key);522 if (p != luaO_nilobject)523 return cast(TValue *, p);524 else {525 TValue k;526 setsvalue(L, &k, key);527 return newkey(L, t, &k);528 }529 }532 static int unbound_search (Table *t, unsigned int j) {533 unsigned int i = j; /* i is zero or a present index */534 j++;535 /* find `i' and `j' such that i is present and j is not */536 while (!ttisnil(luaH_getnum(t, j))) {537 i = j;538 j *= 2;539 if (j > cast(unsigned int, MAX_INT)) { /* overflow? */540 /* table was built with bad purposes: resort to linear search */541 i = 1;542 while (!ttisnil(luaH_getnum(t, i))) i++;543 return i - 1;544 }545 }546 /* now do a binary search between them */547 while (j - i > 1) {548 unsigned int m = (i+j)/2;549 if (ttisnil(luaH_getnum(t, m))) j = m;550 else i = m;551 }552 return i;553 }556 /*557 ** Try to find a boundary in table `t'. A `boundary' is an integer index558 ** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).559 */560 int luaH_getn (Table *t) {561 unsigned int j = t->sizearray;562 if (j > 0 && ttisnil(&t->array[j - 1])) {563 /* there is a boundary in the array part: (binary) search for it */564 unsigned int i = 0;565 while (j - i > 1) {566 unsigned int m = (i+j)/2;567 if (ttisnil(&t->array[m - 1])) j = m;568 else i = m;569 }570 return i;571 }572 /* else must find a boundary in hash part */573 else if (t->node == dummynode) /* hash part is empty? */574 return j; /* that is easy... */575 else return unbound_search(t, j);576 }580 #if defined(LUA_DEBUG)582 Node *luaH_mainposition (const Table *t, const TValue *key) {583 return mainposition(t, key);584 }586 int luaH_isdummy (Node *n) { return n == dummynode; }588 #endif