248 lines
6.5 KiB
C++
248 lines
6.5 KiB
C++
/*
|
|
** $Id: lstring.c,v 2.56 2015/11/23 11:32:51 roberto Exp $
|
|
** String table (keeps all strings handled by Lua)
|
|
** See Copyright Notice in lua.h
|
|
*/
|
|
|
|
#define lstring_c
|
|
#define LUA_CORE
|
|
|
|
#include "lstring.h"
|
|
#include "lprefix.h"
|
|
|
|
#include <string.h>
|
|
|
|
#include "lua.h"
|
|
#include "ldebug.h"
|
|
#include "ldo.h"
|
|
#include "lmem.h"
|
|
#include "lobject.h"
|
|
#include "lstate.h"
|
|
|
|
namespace NS_SLUA {
|
|
|
|
#define MEMERRMSG "not enough memory"
|
|
|
|
|
|
/*
|
|
** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
|
|
** compute its hash
|
|
*/
|
|
#if !defined(LUAI_HASHLIMIT)
|
|
#define LUAI_HASHLIMIT 5
|
|
#endif
|
|
|
|
|
|
/*
|
|
** equality for long strings
|
|
*/
|
|
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;
|
|
}
|
|
|
|
|
|
/*
|
|
** resizes the string table
|
|
*/
|
|
void luaS_resize (lua_State *L, int newsize) {
|
|
int i;
|
|
stringtable *tb = &G(L)->strt;
|
|
if (newsize > tb->size) { /* grow table if needed */
|
|
luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
|
|
for (i = tb->size; i < newsize; i++)
|
|
tb->hash[i] = NULL;
|
|
}
|
|
for (i = 0; i < tb->size; i++) { /* rehash */
|
|
TString *p = tb->hash[i];
|
|
tb->hash[i] = NULL;
|
|
while (p) { /* for each node in the list */
|
|
TString *hnext = p->u.hnext; /* save next */
|
|
unsigned int h = lmod(p->hash, newsize); /* new position */
|
|
p->u.hnext = tb->hash[h]; /* chain it */
|
|
tb->hash[h] = p;
|
|
p = hnext;
|
|
}
|
|
}
|
|
if (newsize < tb->size) { /* shrink table if needed */
|
|
/* vanishing slice should be empty */
|
|
lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
|
|
luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
|
|
}
|
|
tb->size = newsize;
|
|
}
|
|
|
|
|
|
/*
|
|
** Clear API string cache. (Entries cannot be empty, so fill them with
|
|
** a non-collectable string.)
|
|
*/
|
|
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->memerrmsg; /* replace it with something fixed */
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Initialize the string table and the string cache
|
|
*/
|
|
void luaS_init (lua_State *L) {
|
|
global_State *g = G(L);
|
|
int i, j;
|
|
luaS_resize(L, MINSTRTABSIZE); /* initial size of string table */
|
|
/* pre-create memory-error message */
|
|
g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
|
|
luaC_fix(L, obj2gco(g->memerrmsg)); /* it 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->memerrmsg;
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
** creates a new string object
|
|
*/
|
|
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--;
|
|
}
|
|
|
|
|
|
/*
|
|
** checks whether short string exists and reuses it or creates a new one
|
|
*/
|
|
static TString *internshrstr (lua_State *L, const char *str, size_t l) {
|
|
TString *ts;
|
|
global_State *g = G(L);
|
|
unsigned int h = luaS_hash(str, l, g->seed);
|
|
TString **list = &g->strt.hash[lmod(h, g->strt.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;
|
|
}
|
|
}
|
|
if (g->strt.nuse >= g->strt.size && g->strt.size <= MAX_INT/2) {
|
|
luaS_resize(L, g->strt.size * 2);
|
|
list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute 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;
|
|
g->strt.nuse++;
|
|
return ts;
|
|
}
|
|
|
|
|
|
/*
|
|
** new string (with explicit length)
|
|
*/
|
|
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;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Create or reuse a zero-terminated string, first checking in the
|
|
** cache (using the string address as a key). The cache can contain
|
|
** only zero-terminated strings, so it is safe to use 'strcmp' to
|
|
** check hits.
|
|
*/
|
|
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;
|
|
}
|
|
|
|
} // end NS_SLUA
|