src/lstring.c

   1 /*
   2 ** $Id: lstring.c,v 1.78 2002/12/04 17:38:31 roberto Exp $
   3 ** String table (keeps all strings handled by Lua)
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <string.h>
   9
  10 #define lstring_c
  11
  12 #include "lua.h"
  13
  14 #include "lmem.h"
  15 #include "lobject.h"
  16 #include "lstate.h"
  17 #include "lstring.h"
  18
  19
  20
  21 void luaS_freeall (lua_State *L) {
  22   lua_assert(G(L)->strt.nuse==0);
  23   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
  24 }
  25
  26
  27 void luaS_resize (lua_State *L, int newsize) {
  28   GCObject **newhash = luaM_newvector(L, newsize, GCObject *);
  29   stringtable *tb = &G(L)->strt;
  30   int i;
  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       lu_hash h = gcotots(p)->tsv.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, lu_hash h) {
  52   TString *ts = cast(TString *, luaM_malloc(L, sizestring(l)));
  53   stringtable *tb;
  54   ts->tsv.len = l;
  55   ts->tsv.hash = h;
  56   ts->tsv.marked = 0;
  57   ts->tsv.tt = LUA_TSTRING;
  58   ts->tsv.reserved = 0;
  59   memcpy(ts+1, str, l*sizeof(char));
  60   ((char *)(ts+1))[l] = '\0';  /* ending 0 */
  61   tb = &G(L)->strt;
  62   h = lmod(h, tb->size);
  63   ts->tsv.next = tb->hash[h];  /* chain new entry */
  64   tb->hash[h] = valtogco(ts);
  65   tb->nuse++;
  66   if (tb->nuse > cast(ls_nstr, tb->size) && tb->size <= MAX_INT/2)
  67     luaS_resize(L, tb->size*2);  /* too crowded */
  68   return ts;
  69 }
  70
  71
  72 TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
  73   GCObject *o;
  74   lu_hash h = (lu_hash)l;  /* seed */
  75   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
  76   size_t l1;
  77   for (l1=l; l1>=step; l1-=step)  /* compute hash */
  78     h = h ^ ((h<<5)+(h>>2)+(unsigned char)(str[l1-1]));
  79   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
  80        o != NULL;
  81        o = o->gch.next) {
  82     TString *ts = gcotots(o);
  83     if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0))
  84       return ts;
  85   }
  86   return newlstr(L, str, l, h);  /* not found */
  87 }
  88
  89
  90 Udata *luaS_newudata (lua_State *L, size_t s) {
  91   Udata *u;
  92   u = cast(Udata *, luaM_malloc(L, sizeudata(s)));
  93   u->uv.marked = (1<<1);  /* is not finalized */
  94   u->uv.tt = LUA_TUSERDATA;
  95   u->uv.len = s;
  96   u->uv.metatable = hvalue(defaultmeta(L));
  97   /* chain it on udata list */
  98   u->uv.next = G(L)->rootudata;
  99   G(L)->rootudata = valtogco(u);
 100   return u;
 101 }
 102