emscripten/tests/lua/src/ltable.c at universal-python · JavaScriptIOT/emscripten · GitHub

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** $Id: ltable.c,v 2.72 2012/09/11 19:37:16 roberto Exp $

** Lua tables (hash)

** See Copyright Notice in lua.h

** Implementation of tables (aka arrays, objects, or hash tables).

** Tables keep its elements in two parts: an array part and a hash part.

** Non-negative integer keys are all candidates to be kept in the array

** part. The actual size of the array is the largest `n' such that at

** least half the slots between 0 and n are in use.

** Hash uses a mix of chained scatter table with Brent's variation.

** A main invariant of these tables is that, if an element is not

** in its main position (i.e. the `original' position that its hash gives

** to it), then the colliding element is in its own main position.

** Hence even when the load factor reaches 100%, performance remains good.

#include <string.h>

#define ltable_c

#define LUA_CORE

#include "lua.h"

#include "ldebug.h"

#include "ldo.h"

#include "lgc.h"

#include "lmem.h"

#include "lobject.h"

#include "lstate.h"

#include "lstring.h"

#include "ltable.h"

#include "lvm.h"

** max size of array part is 2^MAXBITS

#if LUAI_BITSINT >= 32

#define MAXBITS 30

#else

#define MAXBITS (LUAI_BITSINT-2)

#endif

#define MAXASIZE (1 << MAXBITS)

#define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))

#define hashstr(t,str) hashpow2(t, (str)->tsv.hash)

#define hashboolean(t,p) hashpow2(t, p)

** for some types, it is better to avoid modulus by power of 2, as

** they tend to have many 2 factors.

#define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))

#define hashpointer(t,p) hashmod(t, IntPoint(p))

#define dummynode (&dummynode_)

#define isdummy(n) ((n) == dummynode)

static const Node dummynode_ = {

{NILCONSTANT}, /* value */

{{NILCONSTANT, NULL}} /* key */

};

** hash for lua_Numbers

static Node *hashnum (const Table *t, lua_Number n) {

int i;

luai_hashnum(i, n);

if (i < 0) {

if (cast(unsigned int, i) == 0u - i) /* use unsigned to avoid overflows */

i = 0; /* handle INT_MIN */

i = -i; /* must be a positive value */

}

return hashmod(t, i);

}

** returns the `main' position of an element in a table (that is, the index

** of its hash value)

static Node *mainposition (const Table *t, const TValue *key) {

switch (ttype(key)) {

case LUA_TNUMBER:

return hashnum(t, nvalue(key));

case LUA_TLNGSTR: {

TString *s = rawtsvalue(key);

if (s->tsv.extra == 0) { /* no hash? */

s->tsv.hash = luaS_hash(getstr(s), s->tsv.len, s->tsv.hash);

s->tsv.extra = 1; /* now it has its hash */

}

return hashstr(t, rawtsvalue(key));

}

case LUA_TSHRSTR:

return hashstr(t, rawtsvalue(key));

case LUA_TBOOLEAN:

return hashboolean(t, bvalue(key));

case LUA_TLIGHTUSERDATA:

return hashpointer(t, pvalue(key));

case LUA_TLCF:

return hashpointer(t, fvalue(key));

default:

return hashpointer(t, gcvalue(key));

}

** returns the index for `key' if `key' is an appropriate key to live in

** the array part of the table, -1 otherwise.

static int arrayindex (const TValue *key) {

if (ttisnumber(key)) {

lua_Number n = nvalue(key);

int k;

lua_number2int(k, n);

if (luai_numeq(cast_num(k), n))

return k;

}

return -1; /* `key' did not match some condition */

}

** returns the index of a `key' for table traversals. First goes all

** elements in the array part, then elements in the hash part. The

** beginning of a traversal is signaled by -1.

static int findindex (lua_State *L, Table *t, StkId key) {

int i;

if (ttisnil(key)) return -1; /* first iteration */

i = arrayindex(key);

if (0 < i && i <= t->sizearray) /* is `key' inside array part? */

return i-1; /* yes; that's the index (corrected to C) */

else {

Node *n = mainposition(t, key);

for (;;) { /* check whether `key' is somewhere in the chain */

/* key may be dead already, but it is ok to use it in `next' */

if (luaV_rawequalobj(gkey(n), key) ||

(ttisdeadkey(gkey(n)) && iscollectable(key) &&

deadvalue(gkey(n)) == gcvalue(key))) {

i = cast_int(n - gnode(t, 0)); /* key index in hash table */

/* hash elements are numbered after array ones */

return i + t->sizearray;

}

else n = gnext(n);

if (n == NULL)

luaG_runerror(L, "invalid key to " LUA_QL("next")); /* key not found */

}

int luaH_next (lua_State *L, Table *t, StkId key) {

int i = findindex(L, t, key); /* find original element */

for (i++; i < t->sizearray; i++) { /* try first array part */

if (!ttisnil(&t->array[i])) { /* a non-nil value? */

setnvalue(key, cast_num(i+1));

setobj2s(L, key+1, &t->array[i]);

return 1;

}

for (i -= t->sizearray; i < sizenode(t); i++) { /* then hash part */

if (!ttisnil(gval(gnode(t, i)))) { /* a non-nil value? */

setobj2s(L, key, gkey(gnode(t, i)));

setobj2s(L, key+1, gval(gnode(t, i)));

return 1;

}

return 0; /* no more elements */

}

** {=============================================================

** Rehash

** ==============================================================

static int computesizes (int nums[], int *narray) {

int i;

int twotoi; /* 2^i */

int a = 0; /* number of elements smaller than 2^i */

int na = 0; /* number of elements to go to array part */

int n = 0; /* optimal size for array part */

for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {

if (nums[i] > 0) {

a += nums[i];

if (a > twotoi/2) { /* more than half elements present? */

n = twotoi; /* optimal size (till now) */

na = a; /* all elements smaller than n will go to array part */

}

if (a == *narray) break; /* all elements already counted */

}

*narray = n;

lua_assert(*narray/2 <= na && na <= *narray);

return na;

}

static int countint (const TValue *key, int *nums) {

int k = arrayindex(key);

if (0 < k && k <= MAXASIZE) { /* is `key' an appropriate array index? */

nums[luaO_ceillog2(k)]++; /* count as such */

return 1;

}

else

return 0;

}

static int numusearray (const Table *t, int *nums) {

int lg;

int ttlg; /* 2^lg */

int ause = 0; /* summation of `nums' */

int i = 1; /* count to traverse all array keys */

for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) { /* for each slice */

int lc = 0; /* counter */

int lim = ttlg;

if (lim > t->sizearray) {

lim = t->sizearray; /* adjust upper limit */

if (i > lim)

break; /* no more elements to count */

}

/* count elements in range (2^(lg-1), 2^lg] */

for (; i <= lim; i++) {

if (!ttisnil(&t->array[i-1]))

lc++;

}

nums[lg] += lc;

ause += lc;

}

return ause;

}

static int numusehash (const Table *t, int *nums, int *pnasize) {

int totaluse = 0; /* total number of elements */

int ause = 0; /* summation of `nums' */

int i = sizenode(t);

while (i--) {

Node *n = &t->node[i];

if (!ttisnil(gval(n))) {

ause += countint(gkey(n), nums);

totaluse++;

}

*pnasize += ause;

return totaluse;

}

static void setarrayvector (lua_State *L, Table *t, int size) {

int i;

luaM_reallocvector(L, t->array, t->sizearray, size, TValue);

for (i=t->sizearray; i<size; i++)

setnilvalue(&t->array[i]);

t->sizearray = size;

}

static void setnodevector (lua_State *L, Table *t, int size) {

int lsize;

if (size == 0) { /* no elements to hash part? */

t->node = cast(Node *, dummynode); /* use common `dummynode' */

lsize = 0;

}

else {

int i;

lsize = luaO_ceillog2(size);

if (lsize > MAXBITS)

luaG_runerror(L, "table overflow");

size = twoto(lsize);

t->node = luaM_newvector(L, size, Node);

for (i=0; i<size; i++) {

Node *n = gnode(t, i);

gnext(n) = NULL;

setnilvalue(gkey(n));

setnilvalue(gval(n));

}

t->lsizenode = cast_byte(lsize);

t->lastfree = gnode(t, size); /* all positions are free */

}

void luaH_resize (lua_State *L, Table *t, int nasize, int nhsize) {

int i;

int oldasize = t->sizearray;

int oldhsize = t->lsizenode;

Node *nold = t->node; /* save old hash ... */

if (nasize > oldasize) /* array part must grow? */

setarrayvector(L, t, nasize);

/* create new hash part with appropriate size */

setnodevector(L, t, nhsize);

if (nasize < oldasize) { /* array part must shrink? */

t->sizearray = nasize;

/* re-insert elements from vanishing slice */

for (i=nasize; i<oldasize; i++) {

if (!ttisnil(&t->array[i]))

luaH_setint(L, t, i + 1, &t->array[i]);

}

/* shrink array */

luaM_reallocvector(L, t->array, oldasize, nasize, TValue);

}

/* re-insert elements from hash part */

for (i = twoto(oldhsize) - 1; i >= 0; i--) {

Node *old = nold+i;

if (!ttisnil(gval(old))) {

/* doesn't need barrier/invalidate cache, as entry was

already present in the table */

setobjt2t(L, luaH_set(L, t, gkey(old)), gval(old));

}

if (!isdummy(nold))

luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old array */

}

void luaH_resizearray (lua_State *L, Table *t, int nasize) {

int nsize = isdummy(t->node) ? 0 : sizenode(t);

luaH_resize(L, t, nasize, nsize);

}

static void rehash (lua_State *L, Table *t, const TValue *ek) {

int nasize, na;

int nums[MAXBITS+1]; /* nums[i] = number of keys with 2^(i-1) < k <= 2^i */

int i;

int totaluse;

for (i=0; i<=MAXBITS; i++) nums[i] = 0; /* reset counts */

nasize = numusearray(t, nums); /* count keys in array part */

totaluse = nasize; /* all those keys are integer keys */

totaluse += numusehash(t, nums, &nasize); /* count keys in hash part */

/* count extra key */

nasize += countint(ek, nums);

totaluse++;

/* compute new size for array part */

na = computesizes(nums, &nasize);

/* resize the table to new computed sizes */

luaH_resize(L, t, nasize, totaluse - na);

}

** }=============================================================

Table *luaH_new (lua_State *L) {

Table *t = &luaC_newobj(L, LUA_TTABLE, sizeof(Table), NULL, 0)->h;

t->metatable = NULL;

t->flags = cast_byte(~0);

t->array = NULL;

t->sizearray = 0;

setnodevector(L, t, 0);

return t;

}

void luaH_free (lua_State *L, Table *t) {

if (!isdummy(t->node))

luaM_freearray(L, t->node, cast(size_t, sizenode(t)));

luaM_freearray(L, t->array, t->sizearray);

luaM_free(L, t);

}

static Node *getfreepos (Table *t) {

while (t->lastfree > t->node) {

t->lastfree--;

if (ttisnil(gkey(t->lastfree)))

return t->lastfree;

}

return NULL; /* could not find a free place */

}

** inserts a new key into a hash table; first, check whether key's main

** position is free. If not, check whether colliding node is in its main

** position or not: if it is not, move colliding node to an empty place and

** put new key in its main position; otherwise (colliding node is in its main

** position), new key goes to an empty position.

TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {

Node *mp;

if (ttisnil(key)) luaG_runerror(L, "table index is nil");

else if (ttisnumber(key) && luai_numisnan(L, nvalue(key)))

luaG_runerror(L, "table index is NaN");

mp = mainposition(t, key);

if (!ttisnil(gval(mp)) || isdummy(mp)) { /* main position is taken? */

Node *othern;

Node *n = getfreepos(t); /* get a free place */

if (n == NULL) { /* cannot find a free place? */

rehash(L, t, key); /* grow table */

/* whatever called 'newkey' take care of TM cache and GC barrier */

return luaH_set(L, t, key); /* insert key into grown table */

}

lua_assert(!isdummy(n));

othern = mainposition(t, gkey(mp));

if (othern != mp) { /* is colliding node out of its main position? */

/* yes; move colliding node into free position */

while (gnext(othern) != mp) othern = gnext(othern); /* find previous */

gnext(othern) = n; /* redo the chain with `n' in place of `mp' */

*n = *mp; /* copy colliding node into free pos. (mp->next also goes) */

gnext(mp) = NULL; /* now `mp' is free */

setnilvalue(gval(mp));

}

else { /* colliding node is in its own main position */

/* new node will go into free position */

gnext(n) = gnext(mp); /* chain new position */

gnext(mp) = n;

mp = n;

}

setobj2t(L, gkey(mp), key);

luaC_barrierback(L, obj2gco(t), key);

lua_assert(ttisnil(gval(mp)));

return gval(mp);

}

** search function for integers

const TValue *luaH_getint (Table *t, int key) {

/* (1 <= key && key <= t->sizearray) */

if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))

return &t->array[key-1];

else {

lua_Number nk = cast_num(key);

Node *n = hashnum(t, nk);

do { /* check whether `key' is somewhere in the chain */

if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))

return gval(n); /* that's it */

else n = gnext(n);

} while (n);

return luaO_nilobject;

}

** search function for short strings

const TValue *luaH_getstr (Table *t, TString *key) {

Node *n = hashstr(t, key);

lua_assert(key->tsv.tt == LUA_TSHRSTR);

do { /* check whether `key' is somewhere in the chain */

if (ttisshrstring(gkey(n)) && eqshrstr(rawtsvalue(gkey(n)), key))

return gval(n); /* that's it */

else n = gnext(n);

} while (n);

return luaO_nilobject;

}

** main search function

const TValue *luaH_get (Table *t, const TValue *key) {

switch (ttype(key)) {

case LUA_TSHRSTR: return luaH_getstr(t, rawtsvalue(key));

case LUA_TNIL: return luaO_nilobject;

case LUA_TNUMBER: {

int k;

lua_Number n = nvalue(key);

lua_number2int(k, n);

if (luai_numeq(cast_num(k), n)) /* index is int? */

return luaH_getint(t, k); /* use specialized version */

/* else go through */

}

default: {

Node *n = mainposition(t, key);

do { /* check whether `key' is somewhere in the chain */

if (luaV_rawequalobj(gkey(n), key))

return gval(n); /* that's it */

else n = gnext(n);

} while (n);

return luaO_nilobject;

}

** beware: when using this function you probably need to check a GC

** barrier and invalidate the TM cache.

TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {

const TValue *p = luaH_get(t, key);

if (p != luaO_nilobject)

return cast(TValue *, p);

else return luaH_newkey(L, t, key);

}

void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {

const TValue *p = luaH_getint(t, key);

TValue *cell;

if (p != luaO_nilobject)

cell = cast(TValue *, p);

else {

TValue k;

setnvalue(&k, cast_num(key));

cell = luaH_newkey(L, t, &k);

}

setobj2t(L, cell, value);

}

static int unbound_search (Table *t, unsigned int j) {

unsigned int i = j; /* i is zero or a present index */

j++;

/* find `i' and `j' such that i is present and j is not */

while (!ttisnil(luaH_getint(t, j))) {

i = j;

j *= 2;

if (j > cast(unsigned int, MAX_INT)) { /* overflow? */

/* table was built with bad purposes: resort to linear search */

i = 1;

while (!ttisnil(luaH_getint(t, i))) i++;

return i - 1;

}

/* now do a binary search between them */

while (j - i > 1) {

unsigned int m = (i+j)/2;

if (ttisnil(luaH_getint(t, m))) j = m;

else i = m;

}

return i;

}

** Try to find a boundary in table `t'. A `boundary' is an integer index

** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).

int luaH_getn (Table *t) {

unsigned int j = t->sizearray;

if (j > 0 && ttisnil(&t->array[j - 1])) {

/* there is a boundary in the array part: (binary) search for it */

unsigned int i = 0;

while (j - i > 1) {

unsigned int m = (i+j)/2;

if (ttisnil(&t->array[m - 1])) j = m;

else i = m;

}

return i;

}

/* else must find a boundary in hash part */

else if (isdummy(t->node)) /* hash part is empty? */

return j; /* that is easy... */

else return unbound_search(t, j);

}

#if defined(LUA_DEBUG)

Node *luaH_mainposition (const Table *t, const TValue *key) {

return mainposition(t, key);

}

int luaH_isdummy (Node *n) { return isdummy(n); }

#endif

emscripten/tests/lua/src/ltable.c at universal-python · JavaScriptIOT/emscripten · GitHub

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