#define lstring_c

#define LUA_CORE

#include "lprefix.h"

#include <string.h>

#include "lua.h"

#include "ldebug.h"

#include "ldo.h"

#include "lmem.h"

#include "lobject.h"

#include "lstate.h"

#include "lstring.h"

#if !defined(LUAI_HASHLIMIT)

#define LUAI_HASHLIMIT 5

#define MAXSTRTB cast_int(luaM_limitN(MAX_INT, TString*))

int luaS_eqlngstr (TString *a, TString *b) {

size_t len = a->u.lnglen;

lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);

return (a == b) || /* same instance or... */

((len == b->u.lnglen) && /* equal length and ... */

(memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */

}

unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {

unsigned int h = seed ^ cast(unsigned int, l);

size_t step = (l >> LUAI_HASHLIMIT) + 1;

for (; l >= step; l -= step)

h ^= ((h<<5) + (h>>2) + cast_byte(str[l - 1]));

return h;

}

unsigned int luaS_hashlongstr (TString *ts) {

lua_assert(ts->tt == LUA_TLNGSTR);

if (ts->extra == 0) { /* no hash? */

ts->hash = luaS_hash(getstr(ts), ts->u.lnglen, ts->hash);

ts->extra = 1; /* now it has its hash */

}

return ts->hash;

}

static void tablerehash (TString **vect, int osize, int nsize) {

int i;

for (i = osize; i < nsize; i++) /* clear new elements */

vect[i] = NULL;

for (i = 0; i < osize; i++) { /* rehash old part of the array */

TString *p = vect[i];

vect[i] = NULL;

while (p) { /* for each string in the list */

TString *hnext = p->u.hnext; /* save next */

unsigned int h = lmod(p->hash, nsize); /* new position */

p->u.hnext = vect[h]; /* chain it into array */

vect[h] = p;

p = hnext;

}

}

}

void luaS_resize (lua_State *L, int nsize) {

stringtable *tb = &G(L)->strt;

int osize = tb->size;

TString **newvect;

if (nsize < osize) /* shrinking table? */

tablerehash(tb->hash, osize, nsize); /* depopulate shrinking part */

newvect = luaM_reallocvector(L, tb->hash, osize, nsize, TString*);

if (newvect == NULL) { /* reallocation failed? */

if (nsize < osize) /* was it shrinking table? */

tablerehash(tb->hash, nsize, osize); /* restore to original size */

/* leave table as it was */

}

else { /* allocation succeeded */

tb->hash = newvect;

tb->size = nsize;

if (nsize > osize)

tablerehash(newvect, osize, nsize); /* rehash for new size */

}

}

void luaS_clearcache (global_State *g) {

int i, j;

for (i = 0; i < STRCACHE_N; i++)

for (j = 0; j < STRCACHE_M; j++) {

if (iswhite(g->strcache[i][j])) /* will entry be collected? */

g->strcache[i][j] = g->nfield; /* replace it with something fixed */

}

}

void luaS_init (lua_State *L) {

global_State *g = G(L);

int i, j;

TString *memerrmsg;

stringtable *tb = &G(L)->strt;

tb->hash = luaM_newvector(L, MINSTRTABSIZE, TString*);

tablerehash(tb->hash, 0, MINSTRTABSIZE); /* clear array */

tb->size = MINSTRTABSIZE;

/* pre-create memory-error message */

memerrmsg = luaS_newliteral(L, MEMERRMSG);

luaC_fix(L, obj2gco(memerrmsg)); /* it should never be collected */

g->nfield = luaS_newliteral(L, "n"); /* pre-create "n" field name */

luaC_fix(L, obj2gco(g->nfield)); /* it also should never be collected */

for (i = 0; i < STRCACHE_N; i++) /* fill cache with valid strings */

for (j = 0; j < STRCACHE_M; j++)

g->strcache[i][j] = g->nfield;

}

static TString *createstrobj (lua_State *L, size_t l, int tag, unsigned int h) {

TString *ts;

GCObject *o;

size_t totalsize; /* total size of TString object */

totalsize = sizelstring(l);

o = luaC_newobj(L, tag, totalsize);

ts = gco2ts(o);

ts->hash = h;

ts->extra = 0;

getstr(ts)[l] = '\0'; /* ending 0 */

return ts;

}

TString *luaS_createlngstrobj (lua_State *L, size_t l) {

TString *ts = createstrobj(L, l, LUA_TLNGSTR, G(L)->seed);

ts->u.lnglen = l;

return ts;

}

void luaS_remove (lua_State *L, TString *ts) {

stringtable *tb = &G(L)->strt;

TString **p = &tb->hash[lmod(ts->hash, tb->size)];

while (*p != ts) /* find previous element */

p = &(*p)->u.hnext;

*p = (*p)->u.hnext; /* remove element from its list */

tb->nuse--;

}

static void growstrtab (lua_State *L, stringtable *tb) {

if (tb->nuse == MAX_INT) { /* too many strings? */

luaC_fullgc(L, 1); /* try to free some... */

if (tb->nuse == MAX_INT) /* still too many? */

luaM_error(L); /* cannot even create a message... */

}

if (tb->size <= MAXSTRTB / 2) /* can grow string table? */

luaS_resize(L, tb->size * 2);

}

static TString *internshrstr (lua_State *L, const char *str, size_t l) {

TString *ts;

global_State *g = G(L);

stringtable *tb = &g->strt;

unsigned int h = luaS_hash(str, l, g->seed);

TString **list = &tb->hash[lmod(h, tb->size)];

lua_assert(str != NULL); /* otherwise 'memcmp'/'memcpy' are undefined */

for (ts = *list; ts != NULL; ts = ts->u.hnext) {

if (l == ts->shrlen && (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {

/* found! */

if (isdead(g, ts)) /* dead (but not collected yet)? */

changewhite(ts); /* resurrect it */

return ts;

}

}

/* else must create a new string */

if (tb->nuse >= tb->size) { /* need to grow string table? */

growstrtab(L, tb);

list = &tb->hash[lmod(h, tb->size)]; /* rehash with new size */

}

ts = createstrobj(L, l, LUA_TSHRSTR, h);

memcpy(getstr(ts), str, l * sizeof(char));

ts->shrlen = cast_byte(l);

ts->u.hnext = *list;

*list = ts;

tb->nuse++;

return ts;

}

TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {

if (l <= LUAI_MAXSHORTLEN) /* short string? */

return internshrstr(L, str, l);

else {

TString *ts;

if (l >= (MAX_SIZE - sizeof(TString))/sizeof(char))

luaM_toobig(L);

ts = luaS_createlngstrobj(L, l);

memcpy(getstr(ts), str, l * sizeof(char));

return ts;

}

}

TString *luaS_new (lua_State *L, const char *str) {

unsigned int i = point2uint(str) % STRCACHE_N; /* hash */

int j;

TString **p = G(L)->strcache[i];

for (j = 0; j < STRCACHE_M; j++) {

if (strcmp(str, getstr(p[j])) == 0) /* hit? */

return p[j]; /* that is it */

}

/* normal route */

for (j = STRCACHE_M - 1; j > 0; j--)

p[j] = p[j - 1]; /* move out last element */

/* new element is first in the list */

p[0] = luaS_newlstr(L, str, strlen(str));

return p[0];

}

Udata *luaS_newudata (lua_State *L, size_t s) {

Udata *u;

GCObject *o;

if (s > MAX_SIZE - sizeof(Udata))

luaM_toobig(L);

o = luaC_newobj(L, LUA_TUSERDATA, sizeludata(s));

u = gco2u(o);

u->len = s;

u->metatable = NULL;

setuservalue(L, u, luaO_nilobject);

return u;

}