lua/lstring.c

   1 /*
   2 ** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
   3 ** String table (keeps all strings handled by Lua)
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <string.h>
   9 #endif
  10
  11 #define lstring_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lmem.h"
  17 #include "lobject.h"
  18 #include "lstate.h"
  19 #include "lstring.h"
  20
  21
  22
  23 void luaS_resize (lua_State *L, int newsize) {
  24   GCObject **newhash;
  25   stringtable *tb;
  26   int i;
  27   if (G(L)->gcstate == GCSsweepstring)
  28     return;  /* cannot resize during GC traverse */
  29   newhash = luaM_newvector(L, newsize, GCObject *);
  30   tb = &G(L)->strt;
  31   for (i=0; i<newsize; i++) newhash[i] = NULL;
  32   /* rehash */
  33   for (i=0; i<tb->size; i++) {
  34     GCObject *p = tb->hash[i];
  35     while (p) {  /* for each node in the list */
  36       GCObject *next = p->gch.next;  /* save next */
  37       unsigned int h = gco2ts(p)->hash;
  38       int h1 = lmod(h, newsize);  /* new position */
  39       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
  40       p->gch.next = newhash[h1];  /* chain it */
  41       newhash[h1] = p;
  42       p = next;
  43     }
  44   }
  45   luaM_freearray(L, tb->hash, tb->size, TString *);
  46   tb->size = newsize;
  47   tb->hash = newhash;
  48 }
  49
  50
  51 static TString *newlstr (lua_State *L, const char *str, size_t l,
  52                                        unsigned int h) {
  53   TString *ts;
  54   stringtable *tb;
  55   if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
  56     luaM_toobig(L);
  57   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
  58   ts->tsv.len = l;
  59   ts->tsv.hash = h;
  60   ts->tsv.marked = luaC_white(G(L));
  61   ts->tsv.tt = LUA_TSTRING;
  62   ts->tsv.reserved = 0;
  63   memcpy(ts+1, str, l*sizeof(char));
  64   ((char *)(ts+1))[l] = '\0';  /* ending 0 */
  65   tb = &G(L)->strt;
  66   h = lmod(h, tb->size);
  67   ts->tsv.next = tb->hash[h];  /* chain new entry */
  68   tb->hash[h] = obj2gco(ts);
  69   tb->nuse++;
  70   if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
  71     luaS_resize(L, tb->size*2);  /* too crowded */
  72   return ts;
  73 }
  74
  75
  76 TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
  77   GCObject *o;
  78   unsigned int h = cast(unsigned int, l);  /* seed */
  79   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
  80   size_t l1;
  81   for (l1=l; l1>=step; l1-=step)  /* compute hash */
  82     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
  83   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
  84        o != NULL;
  85        o = o->gch.next) {
  86     TString *ts = rawgco2ts(o);
  87     if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
  88       /* string may be dead */
  89       if (isdead(G(L), o)) changewhite(o);
  90       return ts;
  91     }
  92   }
  93   return newlstr(L, str, l, h);  /* not found */
  94 }
  95
  96
  97 Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
  98   Udata *u;
  99   if (s > MAX_SIZET - sizeof(Udata))
 100     luaM_toobig(L);
 101   u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
 102   u->uv.marked = luaC_white(G(L));  /* is not finalized */
 103   u->uv.tt = LUA_TUSERDATA;
 104   u->uv.len = s;
 105   u->uv.metatable = NULL;
 106   u->uv.env = e;
 107   /* chain it on udata list (after main thread) */
 108   u->uv.next = G(L)->mainthread->next;
 109   G(L)->mainthread->next = obj2gco(u);
 110   return u;
 111 }
 112