mirror of
https://github.com/lua/lua.git
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108 lines
3.1 KiB
C
108 lines
3.1 KiB
C
/*
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** $Id: lstring.c,v 2.15 2009/12/11 21:31:14 roberto Exp roberto $
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** String table (keeps all strings handled by Lua)
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** See Copyright Notice in lua.h
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*/
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#include <string.h>
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#define lstring_c
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#define LUA_CORE
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#include "lua.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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void luaS_resize (lua_State *L, int newsize) {
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int i;
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stringtable *tb = &G(L)->strt;
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/* cannot resize while GC is traversing strings */
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luaC_runtilstate(L, ~bitmask(GCSsweepstring));
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if (newsize > tb->size) {
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luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
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for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL;
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}
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/* rehash */
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for (i=0; i<tb->size; i++) {
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GCObject *p = tb->hash[i];
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tb->hash[i] = NULL;
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while (p) { /* for each node in the list */
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GCObject *next = gch(p)->next; /* save next */
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unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
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gch(p)->next = tb->hash[h]; /* chain it */
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tb->hash[h] = p;
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p = next;
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}
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}
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if (newsize < tb->size) {
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/* shrinking slice must be empty */
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lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
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luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
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}
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tb->size = newsize;
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}
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static TString *newlstr (lua_State *L, const char *str, size_t l,
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unsigned int h) {
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size_t totalsize; /* total size of TString object */
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GCObject **list; /* (pointer to) list where it will be inserted */
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TString *ts;
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stringtable *tb = &G(L)->strt;
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if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
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luaM_toobig(L);
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if (tb->nuse >= cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
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luaS_resize(L, tb->size*2); /* too crowded */
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totalsize = sizeof(TString) + ((l + 1) * sizeof(char));
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list = &tb->hash[lmod(h, tb->size)];
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ts = &luaC_newobj(L, LUA_TSTRING, totalsize, list, 0)->ts;
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ts->tsv.len = l;
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ts->tsv.hash = h;
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ts->tsv.reserved = 0;
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memcpy(ts+1, str, l*sizeof(char));
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((char *)(ts+1))[l] = '\0'; /* ending 0 */
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tb->nuse++;
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return ts;
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}
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TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
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GCObject *o;
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unsigned int h = cast(unsigned int, l); /* seed */
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size_t step = (l>>5)+1; /* if string is too long, don't hash all its chars */
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size_t l1;
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for (l1=l; l1>=step; l1-=step) /* compute hash */
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h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
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for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
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o != NULL;
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o = gch(o)->next) {
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TString *ts = rawgco2ts(o);
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if (h == ts->tsv.hash && ts->tsv.len == l &&
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(memcmp(str, getstr(ts), l) == 0)) {
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if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
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changewhite(o); /* resurrect it */
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return ts;
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}
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}
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return newlstr(L, str, l, h); /* not found; create a new string */
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}
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Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
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Udata *u;
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if (s > MAX_SIZET - sizeof(Udata))
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luaM_toobig(L);
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u = &luaC_newobj(L, LUA_TUSERDATA, sizeof(Udata) + s, NULL, 0)->u;
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u->uv.len = s;
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u->uv.metatable = NULL;
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u->uv.env = e;
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return u;
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}
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