diff options
Diffstat (limited to 'libs/liblua/src/lstring.c')
-rw-r--r-- | libs/liblua/src/lstring.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/libs/liblua/src/lstring.c b/libs/liblua/src/lstring.c new file mode 100644 index 0000000000..2947113c3c --- /dev/null +++ b/libs/liblua/src/lstring.c @@ -0,0 +1,182 @@ +/* +** $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; +} + |