| /* |
| ** $Id: lstring.c,v 1.33 2000/03/10 14:38:10 roberto Exp roberto $ |
| ** String table (keeps all strings handled by Lua) |
| ** See Copyright Notice in lua.h |
| */ |
| |
| |
| #include <string.h> |
| |
| #define LUA_REENTRANT |
| |
| #include "lmem.h" |
| #include "lobject.h" |
| #include "lstate.h" |
| #include "lstring.h" |
| #include "lua.h" |
| |
| |
| |
| #define gcsizestring(L, l) numblocks(L, 0, sizeof(TString)+l) |
| #define gcsizeudata gcsizestring(L, 0) |
| |
| |
| |
| void luaS_init (lua_State *L) { |
| int i; |
| L->string_root = luaM_newvector(L, NUM_HASHS, stringtable); |
| for (i=0; i<NUM_HASHS; i++) { |
| L->string_root[i].size = 1; |
| L->string_root[i].nuse = 0; |
| L->string_root[i].hash = luaM_newvector(L, 1, TString *);; |
| L->string_root[i].hash[0] = NULL; |
| } |
| } |
| |
| |
| void luaS_freeall (lua_State *L) { |
| int i; |
| for (i=0; i<NUM_HASHS; i++) { |
| LUA_ASSERT(L, L->string_root[i].nuse==0, "non-empty string table"); |
| luaM_free(L, L->string_root[i].hash); |
| } |
| luaM_free(L, L->string_root); |
| } |
| |
| |
| static unsigned long hash_s (const char *s, long l) { |
| unsigned long h = l; /* seed */ |
| long step = (l>>6)+1; /* if string is too long, don't hash all its chars */ |
| for (; l>0; l-=step) |
| h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++)); |
| return h; |
| } |
| |
| |
| void luaS_resize (lua_State *L, stringtable *tb, int newsize) { |
| TString **newhash = luaM_newvector(L, newsize, TString *); |
| int i; |
| for (i=0; i<newsize; i++) newhash[i] = NULL; |
| /* rehash */ |
| for (i=0; i<tb->size; i++) { |
| TString *p = tb->hash[i]; |
| while (p) { /* for each node in the list */ |
| TString *next = p->nexthash; /* save next */ |
| int h = p->hash&(newsize-1); /* new position */ |
| LUA_ASSERT(L, p->hash%newsize == (p->hash&(newsize-1)), |
| "a&(x-1) == a%x, for x power of 2"); |
| p->nexthash = newhash[h]; /* chain it in new position */ |
| newhash[h] = p; |
| p = next; |
| } |
| } |
| luaM_free(L, tb->hash); |
| tb->size = newsize; |
| tb->hash = newhash; |
| } |
| |
| |
| static TString *newone (lua_State *L, long l, unsigned long h) { |
| TString *ts = (TString *)luaM_malloc(L, |
| sizeof(TString)+l*sizeof(char)); |
| ts->marked = 0; |
| ts->nexthash = NULL; |
| ts->hash = h; |
| return ts; |
| } |
| |
| |
| static TString *newone_s (lua_State *L, const char *str, |
| long l, unsigned long h) { |
| TString *ts = newone(L, l, h); |
| memcpy(ts->str, str, l); |
| ts->str[l] = 0; /* ending 0 */ |
| ts->u.s.gv = NULL; /* no global value */ |
| ts->u.s.len = l; |
| ts->constindex = 0; |
| L->nblocks += gcsizestring(L, l); |
| return ts; |
| } |
| |
| |
| static TString *newone_u (lua_State *L, void *buff, |
| int tag, unsigned long h) { |
| TString *ts = newone(L, 0, h); |
| ts->u.d.value = buff; |
| ts->u.d.tag = (tag == LUA_ANYTAG) ? 0 : tag; |
| ts->constindex = -1; /* tag -> this is a userdata */ |
| L->nblocks += gcsizeudata; |
| return ts; |
| } |
| |
| |
| static void newentry (lua_State *L, stringtable *tb, TString *ts, int h) { |
| ts->nexthash = tb->hash[h]; /* chain new entry */ |
| tb->hash[h] = ts; |
| tb->nuse++; |
| if (tb->nuse > tb->size) /* too crowded? */ |
| luaS_resize(L, tb, tb->size*2); |
| } |
| |
| |
| TString *luaS_newlstr (lua_State *L, const char *str, long l) { |
| unsigned long h = hash_s(str, l); |
| stringtable *tb = &L->string_root[(l==0) ? 0 : |
| ((unsigned int)(str[0]+str[l-1]))&(NUM_HASHSTR-1)]; |
| int h1 = h&(tb->size-1); |
| TString *ts; |
| for (ts = tb->hash[h1]; ts; ts = ts->nexthash) { |
| if (ts->u.s.len == l && (memcmp(str, ts->str, l) == 0)) |
| return ts; |
| } |
| /* not found */ |
| ts = newone_s(L, str, l, h); /* create new entry */ |
| newentry(L, tb, ts, h1); /* insert it on table */ |
| return ts; |
| } |
| |
| |
| /* |
| ** uses '%' for one hashing with userdata because addresses are too regular, |
| ** so two '&' operations would be highly correlated |
| */ |
| TString *luaS_createudata (lua_State *L, void *udata, int tag) { |
| unsigned long h = IntPoint(L, udata); |
| stringtable *tb = &L->string_root[(h%NUM_HASHUDATA)+NUM_HASHSTR]; |
| int h1 = h&(tb->size-1); |
| TString *ts; |
| for (ts = tb->hash[h1]; ts; ts = ts->nexthash) { |
| if (udata == ts->u.d.value && (tag == ts->u.d.tag || tag == LUA_ANYTAG)) |
| return ts; |
| } |
| /* not found */ |
| ts = newone_u(L, udata, tag, h); |
| newentry(L, tb, ts, h1); |
| return ts; |
| } |
| |
| |
| TString *luaS_new (lua_State *L, const char *str) { |
| return luaS_newlstr(L, str, strlen(str)); |
| } |
| |
| TString *luaS_newfixed (lua_State *L, const char *str) { |
| TString *ts = luaS_new(L, str); |
| if (ts->marked == 0) ts->marked = FIXMARK; /* avoid GC */ |
| return ts; |
| } |
| |
| |
| void luaS_free (lua_State *L, TString *t) { |
| if (t->constindex == -1) /* is userdata? */ |
| L->nblocks -= gcsizeudata; |
| else { /* is string */ |
| L->nblocks -= gcsizestring(L, t->u.s.len); |
| luaM_free(L, t->u.s.gv); |
| } |
| luaM_free(L, t); |
| } |
| |
| |
| GlobalVar *luaS_assertglobal (lua_State *L, TString *ts) { |
| GlobalVar *gv = ts->u.s.gv; |
| if (!gv) { /* no global value yet? */ |
| gv = luaM_new(L, GlobalVar); |
| gv->value.ttype = TAG_NIL; /* initial value */ |
| gv->name = ts; |
| gv->next = L->rootglobal; /* chain in global list */ |
| L->rootglobal = gv; |
| ts->u.s.gv = gv; |
| } |
| return gv; |
| } |
| |
| |
| GlobalVar *luaS_assertglobalbyname (lua_State *L, const char *name) { |
| return luaS_assertglobal(L, luaS_new(L, name)); |
| } |
| |
| |
| int luaS_globaldefined (lua_State *L, const char *name) { |
| TString *ts = luaS_new(L, name); |
| return ts->u.s.gv && ts->u.s.gv->value.ttype != TAG_NIL; |
| } |
| |
| |