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Root/lua/lstring.cc

1/*
2** $Id: lstring.c,v 2.8 2005/12/22 16:19:56 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
22void 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
50static 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
75TString *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
96Udata *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

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