/*** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp $** String table (keeps all strings handled by Lua)** See Copyright Notice in lua.h*/ #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" /*** 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->len; lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR); return (a == b) || /* same instance or... */ ((len == b->len) && /* 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 l1; size_t step = (l >> LUAI_HASHLIMIT) + 1; for (l1 = l; l1 >= step; l1 -= step) h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1])); return h;} /*** 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->hnext; /* save next */ unsigned int h = lmod(p->hash, newsize); /* new position */ p->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;} /*** creates a new string object*/static TString *createstrobj (lua_State *L, const char *str, 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->len = l; ts->hash = h; ts->extra = 0; memcpy(getaddrstr(ts), str, l * sizeof(char)); getaddrstr(ts)[l] = '\0'; /* ending 0 */ 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)->hnext; *p = (*p)->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)]; for (ts = *list; ts != NULL; ts = ts->hnext) { if (l == ts->len && (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, str, l, LUA_TSHRSTR, h); ts->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 { if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char)) luaM_toobig(L); return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed); }} /*** new zero-terminated string*/TString *luaS_new (lua_State *L, const char *str) { return luaS_newlstr(L, str, strlen(str));} 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;}
/*
** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
#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"
/*
** 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->len;
lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
return (a == b) || /* same instance or... */
((len == b->len) && /* 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 l1;
size_t step = (l >> LUAI_HASHLIMIT) + 1;
for (l1 = l; l1 >= step; l1 -= step)
h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
return h;
}
/*
** 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->hnext; /* save next */
unsigned int h = lmod(p->hash, newsize); /* new position */
p->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;
}
/*
** creates a new string object
*/
static TString *createstrobj (lua_State *L, const char *str, 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->len = l;
ts->hash = h;
ts->extra = 0;
memcpy(getaddrstr(ts), str, l * sizeof(char));
getaddrstr(ts)[l] = '\0'; /* ending 0 */
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)->hnext;
*p = (*p)->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)];
for (ts = *list; ts != NULL; ts = ts->hnext) {
if (l == ts->len &&
(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, str, l, LUA_TSHRSTR, h);
ts->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 {
if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
luaM_toobig(L);
return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
}
}
/*
** new zero-terminated string
*/
TString *luaS_new (lua_State *L, const char *str) {
return luaS_newlstr(L, str, strlen(str));
}
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;
}