1*eda14cbcSMatt Macy /*
2*eda14cbcSMatt Macy ** $Id: lstring.c,v 2.26.1.1 2013/04/12 18:48:47 roberto Exp $
3*eda14cbcSMatt Macy ** String table (keeps all strings handled by Lua)
4*eda14cbcSMatt Macy ** See Copyright Notice in lua.h
5*eda14cbcSMatt Macy */
6*eda14cbcSMatt Macy
7*eda14cbcSMatt Macy
8*eda14cbcSMatt Macy #define lstring_c
9*eda14cbcSMatt Macy #define LUA_CORE
10*eda14cbcSMatt Macy
11*eda14cbcSMatt Macy #include <sys/lua/lua.h>
12*eda14cbcSMatt Macy
13*eda14cbcSMatt Macy #include "lmem.h"
14*eda14cbcSMatt Macy #include "lobject.h"
15*eda14cbcSMatt Macy #include "lstate.h"
16*eda14cbcSMatt Macy #include "lstring.h"
17*eda14cbcSMatt Macy
18*eda14cbcSMatt Macy
19*eda14cbcSMatt Macy /*
20*eda14cbcSMatt Macy ** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
21*eda14cbcSMatt Macy ** compute its hash
22*eda14cbcSMatt Macy */
23*eda14cbcSMatt Macy #if !defined(LUAI_HASHLIMIT)
24*eda14cbcSMatt Macy #define LUAI_HASHLIMIT 5
25*eda14cbcSMatt Macy #endif
26*eda14cbcSMatt Macy
27*eda14cbcSMatt Macy
28*eda14cbcSMatt Macy /*
29*eda14cbcSMatt Macy ** equality for long strings
30*eda14cbcSMatt Macy */
luaS_eqlngstr(TString * a,TString * b)31*eda14cbcSMatt Macy int luaS_eqlngstr (TString *a, TString *b) {
32*eda14cbcSMatt Macy size_t len = a->tsv.len;
33*eda14cbcSMatt Macy lua_assert(a->tsv.tt == LUA_TLNGSTR && b->tsv.tt == LUA_TLNGSTR);
34*eda14cbcSMatt Macy return (a == b) || /* same instance or... */
35*eda14cbcSMatt Macy ((len == b->tsv.len) && /* equal length and ... */
36*eda14cbcSMatt Macy (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
37*eda14cbcSMatt Macy }
38*eda14cbcSMatt Macy
39*eda14cbcSMatt Macy
40*eda14cbcSMatt Macy /*
41*eda14cbcSMatt Macy ** equality for strings
42*eda14cbcSMatt Macy */
luaS_eqstr(TString * a,TString * b)43*eda14cbcSMatt Macy int luaS_eqstr (TString *a, TString *b) {
44*eda14cbcSMatt Macy return (a->tsv.tt == b->tsv.tt) &&
45*eda14cbcSMatt Macy (a->tsv.tt == LUA_TSHRSTR ? eqshrstr(a, b) : luaS_eqlngstr(a, b));
46*eda14cbcSMatt Macy }
47*eda14cbcSMatt Macy
48*eda14cbcSMatt Macy
luaS_hash(const char * str,size_t l,unsigned int seed)49*eda14cbcSMatt Macy unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
50*eda14cbcSMatt Macy unsigned int h = seed ^ cast(unsigned int, l);
51*eda14cbcSMatt Macy size_t l1;
52*eda14cbcSMatt Macy size_t step = (l >> LUAI_HASHLIMIT) + 1;
53*eda14cbcSMatt Macy for (l1 = l; l1 >= step; l1 -= step)
54*eda14cbcSMatt Macy h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
55*eda14cbcSMatt Macy return h;
56*eda14cbcSMatt Macy }
57*eda14cbcSMatt Macy
58*eda14cbcSMatt Macy
59*eda14cbcSMatt Macy /*
60*eda14cbcSMatt Macy ** resizes the string table
61*eda14cbcSMatt Macy */
luaS_resize(lua_State * L,int newsize)62*eda14cbcSMatt Macy void luaS_resize (lua_State *L, int newsize) {
63*eda14cbcSMatt Macy int i;
64*eda14cbcSMatt Macy stringtable *tb = &G(L)->strt;
65*eda14cbcSMatt Macy /* cannot resize while GC is traversing strings */
66*eda14cbcSMatt Macy luaC_runtilstate(L, ~bitmask(GCSsweepstring));
67*eda14cbcSMatt Macy if (newsize > tb->size) {
68*eda14cbcSMatt Macy luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
69*eda14cbcSMatt Macy for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL;
70*eda14cbcSMatt Macy }
71*eda14cbcSMatt Macy /* rehash */
72*eda14cbcSMatt Macy for (i=0; i<tb->size; i++) {
73*eda14cbcSMatt Macy GCObject *p = tb->hash[i];
74*eda14cbcSMatt Macy tb->hash[i] = NULL;
75*eda14cbcSMatt Macy while (p) { /* for each node in the list */
76*eda14cbcSMatt Macy GCObject *next = gch(p)->next; /* save next */
77*eda14cbcSMatt Macy unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
78*eda14cbcSMatt Macy gch(p)->next = tb->hash[h]; /* chain it */
79*eda14cbcSMatt Macy tb->hash[h] = p;
80*eda14cbcSMatt Macy resetoldbit(p); /* see MOVE OLD rule */
81*eda14cbcSMatt Macy p = next;
82*eda14cbcSMatt Macy }
83*eda14cbcSMatt Macy }
84*eda14cbcSMatt Macy if (newsize < tb->size) {
85*eda14cbcSMatt Macy /* shrinking slice must be empty */
86*eda14cbcSMatt Macy lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
87*eda14cbcSMatt Macy luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
88*eda14cbcSMatt Macy }
89*eda14cbcSMatt Macy tb->size = newsize;
90*eda14cbcSMatt Macy }
91*eda14cbcSMatt Macy
92*eda14cbcSMatt Macy
93*eda14cbcSMatt Macy /*
94*eda14cbcSMatt Macy ** creates a new string object
95*eda14cbcSMatt Macy */
createstrobj(lua_State * L,const char * str,size_t l,int tag,unsigned int h,GCObject ** list)96*eda14cbcSMatt Macy static TString *createstrobj (lua_State *L, const char *str, size_t l,
97*eda14cbcSMatt Macy int tag, unsigned int h, GCObject **list) {
98*eda14cbcSMatt Macy TString *ts;
99*eda14cbcSMatt Macy char *sbuf;
100*eda14cbcSMatt Macy size_t totalsize; /* total size of TString object */
101*eda14cbcSMatt Macy totalsize = sizeof(TString) + ((l + 1) * sizeof(char));
102*eda14cbcSMatt Macy ts = &luaC_newobj(L, tag, totalsize, list, 0)->ts;
103*eda14cbcSMatt Macy ts->tsv.len = l;
104*eda14cbcSMatt Macy ts->tsv.hash = h;
105*eda14cbcSMatt Macy ts->tsv.extra = 0;
106*eda14cbcSMatt Macy sbuf = (char *)(TString *)(ts + 1);
107*eda14cbcSMatt Macy memcpy(sbuf, str, l*sizeof(char));
108*eda14cbcSMatt Macy sbuf[l] = '\0'; /* ending 0 */
109*eda14cbcSMatt Macy return ts;
110*eda14cbcSMatt Macy }
111*eda14cbcSMatt Macy
112*eda14cbcSMatt Macy
113*eda14cbcSMatt Macy /*
114*eda14cbcSMatt Macy ** creates a new short string, inserting it into string table
115*eda14cbcSMatt Macy */
newshrstr(lua_State * L,const char * str,size_t l,unsigned int h)116*eda14cbcSMatt Macy static TString *newshrstr (lua_State *L, const char *str, size_t l,
117*eda14cbcSMatt Macy unsigned int h) {
118*eda14cbcSMatt Macy GCObject **list; /* (pointer to) list where it will be inserted */
119*eda14cbcSMatt Macy stringtable *tb = &G(L)->strt;
120*eda14cbcSMatt Macy TString *s;
121*eda14cbcSMatt Macy if (tb->nuse >= cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
122*eda14cbcSMatt Macy luaS_resize(L, tb->size*2); /* too crowded */
123*eda14cbcSMatt Macy list = &tb->hash[lmod(h, tb->size)];
124*eda14cbcSMatt Macy s = createstrobj(L, str, l, LUA_TSHRSTR, h, list);
125*eda14cbcSMatt Macy tb->nuse++;
126*eda14cbcSMatt Macy return s;
127*eda14cbcSMatt Macy }
128*eda14cbcSMatt Macy
129*eda14cbcSMatt Macy
130*eda14cbcSMatt Macy /*
131*eda14cbcSMatt Macy ** checks whether short string exists and reuses it or creates a new one
132*eda14cbcSMatt Macy */
internshrstr(lua_State * L,const char * str,size_t l)133*eda14cbcSMatt Macy static TString *internshrstr (lua_State *L, const char *str, size_t l) {
134*eda14cbcSMatt Macy GCObject *o;
135*eda14cbcSMatt Macy global_State *g = G(L);
136*eda14cbcSMatt Macy unsigned int h = luaS_hash(str, l, g->seed);
137*eda14cbcSMatt Macy for (o = g->strt.hash[lmod(h, g->strt.size)];
138*eda14cbcSMatt Macy o != NULL;
139*eda14cbcSMatt Macy o = gch(o)->next) {
140*eda14cbcSMatt Macy TString *ts = rawgco2ts(o);
141*eda14cbcSMatt Macy if (h == ts->tsv.hash &&
142*eda14cbcSMatt Macy l == ts->tsv.len &&
143*eda14cbcSMatt Macy (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
144*eda14cbcSMatt Macy if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
145*eda14cbcSMatt Macy changewhite(o); /* resurrect it */
146*eda14cbcSMatt Macy return ts;
147*eda14cbcSMatt Macy }
148*eda14cbcSMatt Macy }
149*eda14cbcSMatt Macy return newshrstr(L, str, l, h); /* not found; create a new string */
150*eda14cbcSMatt Macy }
151*eda14cbcSMatt Macy
152*eda14cbcSMatt Macy
153*eda14cbcSMatt Macy /*
154*eda14cbcSMatt Macy ** new string (with explicit length)
155*eda14cbcSMatt Macy */
luaS_newlstr(lua_State * L,const char * str,size_t l)156*eda14cbcSMatt Macy TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
157*eda14cbcSMatt Macy if (l <= LUAI_MAXSHORTLEN) /* short string? */
158*eda14cbcSMatt Macy return internshrstr(L, str, l);
159*eda14cbcSMatt Macy else {
160*eda14cbcSMatt Macy if (l + 1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
161*eda14cbcSMatt Macy luaM_toobig(L);
162*eda14cbcSMatt Macy return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed, NULL);
163*eda14cbcSMatt Macy }
164*eda14cbcSMatt Macy }
165*eda14cbcSMatt Macy
166*eda14cbcSMatt Macy
167*eda14cbcSMatt Macy /*
168*eda14cbcSMatt Macy ** new zero-terminated string
169*eda14cbcSMatt Macy */
luaS_new(lua_State * L,const char * str)170*eda14cbcSMatt Macy TString *luaS_new (lua_State *L, const char *str) {
171*eda14cbcSMatt Macy return luaS_newlstr(L, str, strlen(str));
172*eda14cbcSMatt Macy }
173*eda14cbcSMatt Macy
174*eda14cbcSMatt Macy
luaS_newudata(lua_State * L,size_t s,Table * e)175*eda14cbcSMatt Macy Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
176*eda14cbcSMatt Macy Udata *u;
177*eda14cbcSMatt Macy if (s > MAX_SIZET - sizeof(Udata))
178*eda14cbcSMatt Macy luaM_toobig(L);
179*eda14cbcSMatt Macy u = &luaC_newobj(L, LUA_TUSERDATA, sizeof(Udata) + s, NULL, 0)->u;
180*eda14cbcSMatt Macy u->uv.len = s;
181*eda14cbcSMatt Macy u->uv.metatable = NULL;
182*eda14cbcSMatt Macy u->uv.env = e;
183*eda14cbcSMatt Macy return u;
184*eda14cbcSMatt Macy }
185