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# lua/lstring.c

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    00001 /*
    00002 ** $Id: lstring.c,v 2.8 2005/12/22 16:19:56 roberto Exp $
    00003 ** String table (keeps all strings handled by Lua)
    00004 ** See Copyright Notice in lua.h
    00005 */
    00006
    00007
    00008 #include <string.h>
    00009
    00010 #define lstring_c
    00011 #define LUA_CORE
    00012
    00013 #include "lua.h"
    00014
    00015 #include "lmem.h"
    00016 #include "lobject.h"
    00017 #include "lstate.h"
    00018 #include "lstring.h"
    00019
    00020
    00021
    00022 void luaS_resize (lua_State *L, int newsize) {
    00023   GCObject **newhash;
    00024   stringtable *tb;
    00025   int i;
    00026   if (G(L)->gcstate == GCSsweepstring)
    00027     return;  /* cannot resize during GC traverse */
    00028   newhash = luaM_newvector(L, newsize, GCObject *);
    00029   tb = &G(L)->strt;
    00030   for (i=0; i<newsize; i++) newhash[i] = NULL;
    00031   /* rehash */
    00032   for (i=0; i<tb->size; i++) {
    00033     GCObject *p = tb->hash[i];
    00034     while (p) {  /* for each node in the list */
    00035       GCObject *next = p->gch.next;  /* save next */
    00036       unsigned int h = gco2ts(p)->hash;
    00037       int h1 = lmod(h, newsize);  /* new position */
    00038       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
    00039       p->gch.next = newhash[h1];  /* chain it */
    00040       newhash[h1] = p;
    00041       p = next;
    00042     }
    00043   }
    00044   luaM_freearray(L, tb->hash, tb->size, TString *);
    00045   tb->size = newsize;
    00046   tb->hash = newhash;
    00047 }
    00048
    00049
    00050 static TString *newlstr (lua_State *L, const char *str, size_t l,
    00051                                        unsigned int h) {
    00052   TString *ts;
    00053   stringtable *tb;
    00054   if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
    00055     luaM_toobig(L);
    00056   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
    00057   ts->tsv.len = l;
    00058   ts->tsv.hash = h;
    00059   ts->tsv.marked = luaC_white(G(L));
    00060   ts->tsv.tt = LUA_TSTRING;
    00061   ts->tsv.reserved = 0;
    00062   memcpy(ts+1, str, l*sizeof(char));
    00063   ((char *)(ts+1))[l] = '\0';  /* ending 0 */
    00064   tb = &G(L)->strt;
    00065   h = lmod(h, tb->size);
    00066   ts->tsv.next = tb->hash[h];  /* chain new entry */
    00067   tb->hash[h] = obj2gco(ts);
    00068   tb->nuse++;
    00069   if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
    00070     luaS_resize(L, tb->size*2);  /* too crowded */
    00071   return ts;
    00072 }
    00073
    00074
    00075 TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
    00076   GCObject *o;
    00077   unsigned int h = cast(unsigned int, l);  /* seed */
    00078   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
    00079   size_t l1;
    00080   for (l1=l; l1>=step; l1-=step)  /* compute hash */
    00081     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
    00082   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
    00083        o != NULL;
    00084        o = o->gch.next) {
    00085     TString *ts = rawgco2ts(o);
    00086     if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
    00087       /* string may be dead */
    00088       if (isdead(G(L), o)) changewhite(o);
    00089       return ts;
    00090     }
    00091   }
    00092   return newlstr(L, str, l, h);  /* not found */
    00093 }
    00094
    00095
    00096 Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
    00097   Udata *u;
    00098   if (s > MAX_SIZET - sizeof(Udata))
    00099     luaM_toobig(L);
    00100   u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
    00101   u->uv.marked = luaC_white(G(L));  /* is not finalized */
    00102   u->uv.tt = LUA_TUSERDATA;
    00103   u->uv.len = s;
    00104   u->uv.metatable = NULL;
    00105   u->uv.env = e;
    00106   /* chain it on udata list (after main thread) */
    00107   u->uv.next = G(L)->mainthread->next;
    00108   G(L)->mainthread->next = obj2gco(u);
    00109   return u;
    00110 }
    00111