/* BEGIN CSTYLED */ /* ** $Id: lstring.c,v 2.26.1.1 2013/04/12 18:48:47 roberto Exp $ ** String table (keeps all strings handled by Lua) ** See Copyright Notice in lua.h */ #define lstring_c #define LUA_CORE #include #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->tsv.len; lua_assert(a->tsv.tt == LUA_TLNGSTR && b->tsv.tt == LUA_TLNGSTR); return (a == b) || /* same instance or... */ ((len == b->tsv.len) && /* equal length and ... */ (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */ } /* ** equality for strings */ int luaS_eqstr (TString *a, TString *b) { return (a->tsv.tt == b->tsv.tt) && (a->tsv.tt == LUA_TSHRSTR ? eqshrstr(a, b) : luaS_eqlngstr(a, b)); } 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; /* cannot resize while GC is traversing strings */ luaC_runtilstate(L, ~bitmask(GCSsweepstring)); if (newsize > tb->size) { luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *); for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL; } /* rehash */ for (i=0; isize; i++) { GCObject *p = tb->hash[i]; tb->hash[i] = NULL; while (p) { /* for each node in the list */ GCObject *next = gch(p)->next; /* save next */ unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */ gch(p)->next = tb->hash[h]; /* chain it */ tb->hash[h] = p; resetoldbit(p); /* see MOVE OLD rule */ p = next; } } if (newsize < tb->size) { /* shrinking slice must be empty */ lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL); luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *); } 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, GCObject **list) { TString *ts; char *sbuf; size_t totalsize; /* total size of TString object */ totalsize = sizeof(TString) + ((l + 1) * sizeof(char)); ts = &luaC_newobj(L, tag, totalsize, list, 0)->ts; ts->tsv.len = l; ts->tsv.hash = h; ts->tsv.extra = 0; sbuf = (char *)(TString *)(ts + 1); memcpy(sbuf, str, l*sizeof(char)); sbuf[l] = '\0'; /* ending 0 */ return ts; } /* ** creates a new short string, inserting it into string table */ static TString *newshrstr (lua_State *L, const char *str, size_t l, unsigned int h) { GCObject **list; /* (pointer to) list where it will be inserted */ stringtable *tb = &G(L)->strt; TString *s; if (tb->nuse >= cast(lu_int32, tb->size) && tb->size <= MAX_INT/2) luaS_resize(L, tb->size*2); /* too crowded */ list = &tb->hash[lmod(h, tb->size)]; s = createstrobj(L, str, l, LUA_TSHRSTR, h, list); tb->nuse++; return s; } /* ** 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) { GCObject *o; global_State *g = G(L); unsigned int h = luaS_hash(str, l, g->seed); for (o = g->strt.hash[lmod(h, g->strt.size)]; o != NULL; o = gch(o)->next) { TString *ts = rawgco2ts(o); if (h == ts->tsv.hash && l == ts->tsv.len && (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) { if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */ changewhite(o); /* resurrect it */ return ts; } } return newshrstr(L, str, l, h); /* not found; create a new string */ } /* ** 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_SIZET - sizeof(TString))/sizeof(char)) luaM_toobig(L); return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed, NULL); } } /* ** 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, Table *e) { Udata *u; if (s > MAX_SIZET - sizeof(Udata)) luaM_toobig(L); u = &luaC_newobj(L, LUA_TUSERDATA, sizeof(Udata) + s, NULL, 0)->u; u->uv.len = s; u->uv.metatable = NULL; u->uv.env = e; return u; } /* END CSTYLED */