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 

     8 #include <string.h>

     9 

    10 #define lstring_c

    11 #define LUA_CORE

    12 

    13 #include "lua.h"

    14 

    15 #include "lmem.h"

    16 #include "lobject.h"

    17 #include "lstate.h"

    18 #include "lstring.h"

    19 

    20 

    21 

    22 void luaS_resize (lua_State *L, int newsize) {

    23   GCObject **newhash;

    24   stringtable *tb;

    25   int i;

    26   if (G(L)->gcstate == GCSsweepstring)

    27     return;  /* cannot resize during GC traverse */

    28   newhash = luaM_newvector(L, newsize, GCObject *);

    29   tb = &G(L)->strt;

    30   for (i=0; i<newsize; i++) newhash[i] = NULL;

    31   /* rehash */

    32   for (i=0; i<tb->size; i++) {

    33     GCObject *p = tb->hash[i];

    34     while (p) {  /* for each node in the list */

    35       GCObject *next = p->gch.next;  /* save next */

    36       unsigned int h = gco2ts(p)->hash;

    37       int h1 = lmod(h, newsize);  /* new position */

    38       lua_assert(cast_int(h%newsize) == lmod(h, newsize));

    39       p->gch.next = newhash[h1];  /* chain it */

    40       newhash[h1] = p;

    41       p = next;

    42     }

    43   }

    44   luaM_freearray(L, tb->hash, tb->size, TString *);

    45   tb->size = newsize;

    46   tb->hash = newhash;

    47 }

    48 

    49 

    50 static TString *newlstr (lua_State *L, const char *str, size_t l,

    51                                        unsigned int h) {

    52   TString *ts;

    53   stringtable *tb;

    54   if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))

    55     luaM_toobig(L);

    56   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));

    57   ts->tsv.len = l;

    58   ts->tsv.hash = h;

    59   ts->tsv.marked = luaC_white(G(L));

    60   ts->tsv.tt = LUA_TSTRING;

    61   ts->tsv.reserved = 0;

    62   memcpy(ts+1, str, l*sizeof(char));

    63   ((char *)(ts+1))[l] = '\0';  /* ending 0 */

    64   tb = &G(L)->strt;

    65   h = lmod(h, tb->size);

    66   ts->tsv.next = tb->hash[h];  /* chain new entry */

    67   tb->hash[h] = obj2gco(ts);

    68   tb->nuse++;

    69   if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)

    70     luaS_resize(L, tb->size*2);  /* too crowded */

    71   return ts;

    72 }

    73 

    74 

    75 TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {

    76   GCObject *o;

    77   unsigned int h = cast(unsigned int, l);  /* seed */

    78   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */

    79   size_t l1;

    80   for (l1=l; l1>=step; l1-=step)  /* compute hash */

    81     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));

    82   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];

    83        o != NULL;

    84        o = o->gch.next) {

    85     TString *ts = rawgco2ts(o);

    86     if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {

    87       /* string may be dead */

    88       if (isdead(G(L), o)) changewhite(o);

    89       return ts;

    90     }

    91   }

    92   return newlstr(L, str, l, h);  /* not found */

    93 }

    94 

    95 

    96 Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {

    97   Udata *u;

    98   if (s > MAX_SIZET - sizeof(Udata))

    99     luaM_toobig(L);

   100   u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));

   101   u->uv.marked = luaC_white(G(L));  /* is not finalized */

   102   u->uv.tt = LUA_TUSERDATA;

   103   u->uv.len = s;

   104   u->uv.metatable = NULL;

   105   u->uv.env = e;

   106   /* chain it on udata list (after main thread) */

   107   u->uv.next = G(L)->mainthread->next;

   108   G(L)->mainthread->next = obj2gco(u);

   109   return u;

   110 }

   111