Lua 5.1.4: lstring.c

L0001    /*
L0002    ** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
L0003    ** String table (keeps all strings handled by Lua)
L0004    ** See Copyright Notice in lua.h
L0005    */
L0006    
L0007    
L0008    #include <string.h>
L0009    
L0010    #define lstring_c
L0011    #define LUA_CORE
L0012    
L0013    #include "lua.h"
L0014    
L0015    #include "lmem.h"
L0016    #include "lobject.h"
L0017    #include "lstate.h"
L0018    #include "lstring.h"
L0019    
L0020    
L0021    
L0022    void luaS_resize (lua_State *L, int newsize) {
L0023      GCObject **newhash;
L0024      stringtable *tb;
L0025      int i;
L0026      if (G(L)->gcstate == GCSsweepstring)
L0027        return;  /* cannot resize during GC traverse */
L0028      newhash = luaM_newvector(L, newsize, GCObject *);
L0029      tb = &G(L)->strt;
L0030      for (i=0; i<newsize; i++) newhash[i] = NULL;
L0031      /* rehash */
L0032      for (i=0; i<tb->size; i++) {
L0033        GCObject *p = tb->hash[i];
L0034        while (p) {  /* for each node in the list */
L0035          GCObject *next = p->gch.next;  /* save next */
L0036          unsigned int h = gco2ts(p)->hash;
L0037          int h1 = lmod(h, newsize);  /* new position */
L0038          lua_assert(cast_int(h%newsize) == lmod(h, newsize));
L0039          p->gch.next = newhash[h1];  /* chain it */
L0040          newhash[h1] = p;
L0041          p = next;
L0042        }
L0043      }
L0044      luaM_freearray(L, tb->hash, tb->size, TString *);
L0045      tb->size = newsize;
L0046      tb->hash = newhash;
L0047    }
L0048    
L0049    
L0050    static TString *newlstr (lua_State *L, const char *str, size_t l,
L0051                                           unsigned int h) {
L0052      TString *ts;
L0053      stringtable *tb;
L0054      if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
L0055        luaM_toobig(L);
L0056      ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
L0057      ts->tsv.len = l;
L0058      ts->tsv.hash = h;
L0059      ts->tsv.marked = luaC_white(G(L));
L0060      ts->tsv.tt = LUA_TSTRING;
L0061      ts->tsv.reserved = 0;
L0062      memcpy(ts+1, str, l*sizeof(char));
L0063      ((char *)(ts+1))[l] = '\0';  /* ending 0 */
L0064      tb = &G(L)->strt;
L0065      h = lmod(h, tb->size);
L0066      ts->tsv.next = tb->hash[h];  /* chain new entry */
L0067      tb->hash[h] = obj2gco(ts);
L0068      tb->nuse++;
L0069      if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
L0070        luaS_resize(L, tb->size*2);  /* too crowded */
L0071      return ts;
L0072    }
L0073    
L0074    
L0075    TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
L0076      GCObject *o;
L0077      unsigned int h = cast(unsigned int, l);  /* seed */
L0078      size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
L0079      size_t l1;
L0080      for (l1=l; l1>=step; l1-=step)  /* compute hash */
L0081        h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
L0082      for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
L0083           o != NULL;
L0084           o = o->gch.next) {
L0085        TString *ts = rawgco2ts(o);
L0086        if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
L0087          /* string may be dead */
L0088          if (isdead(G(L), o)) changewhite(o);
L0089          return ts;
L0090        }
L0091      }
L0092      return newlstr(L, str, l, h);  /* not found */
L0093    }
L0094    
L0095    
L0096    Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
L0097      Udata *u;
L0098      if (s > MAX_SIZET - sizeof(Udata))
L0099        luaM_toobig(L);
L0100      u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
L0101      u->uv.marked = luaC_white(G(L));  /* is not finalized */
L0102      u->uv.tt = LUA_TUSERDATA;
L0103      u->uv.len = s;
L0104      u->uv.metatable = NULL;
L0105      u->uv.env = e;
L0106      /* chain it on udata list (after main thread) */
L0107      u->uv.next = G(L)->mainthread->next;
L0108      G(L)->mainthread->next = obj2gco(u);
L0109      return u;
L0110    }
L0111