149 lines
4.4 KiB
C
149 lines
4.4 KiB
C
/*
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** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
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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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#define lstring_c
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#define LUA_CORE
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#define LUAC_CROSS_FILE
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#include "lua.h"
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#include C_HEADER_STRING
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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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#define LUAS_READONLY_STRING 1
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#define LUAS_REGULAR_STRING 0
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void luaS_resize (lua_State *L, int newsize) {
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stringtable *tb;
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int i;
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tb = &G(L)->strt;
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if (luaC_sweepstrgc(L) || newsize == tb->size || is_resizing_strings_gc(L))
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return; /* cannot resize during GC traverse or doesn't need to be resized */
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set_resizing_strings_gc(L);
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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 = p->gch.next; /* save next */
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unsigned int h = gco2ts(p)->hash;
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int h1 = lmod(h, newsize); /* new position */
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lua_assert(cast_int(h%newsize) == lmod(h, newsize));
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p->gch.next = tb->hash[h1]; /* chain it */
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tb->hash[h1] = 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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luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
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tb->size = newsize;
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unset_resizing_strings_gc(L);
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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, int readonly) {
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TString *ts;
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stringtable *tb;
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if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
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luaM_toobig(L);
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tb = &G(L)->strt;
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if ((tb->nuse + 1) > 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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ts = cast(TString *, luaM_malloc(L, readonly ? sizeof(char**)+sizeof(TString) : (l+1)*sizeof(char)+sizeof(TString)));
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ts->tsv.len = l;
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ts->tsv.hash = h;
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ts->tsv.marked = luaC_white(G(L));
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ts->tsv.tt = LUA_TSTRING;
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if (!readonly) {
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c_memcpy(ts+1, str, l*sizeof(char));
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((char *)(ts+1))[l] = '\0'; /* ending 0 */
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} else {
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*(char **)(ts+1) = (char *)str;
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luaS_readonly(ts);
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}
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h = lmod(h, tb->size);
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ts->tsv.next = tb->hash[h]; /* chain new entry */
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tb->hash[h] = obj2gco(ts);
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tb->nuse++;
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return ts;
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}
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static TString *luaS_newlstr_helper (lua_State *L, const char *str, size_t l, int readonly) {
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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 = o->gch.next) {
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TString *ts = rawgco2ts(o);
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if (ts->tsv.len == l && (c_memcmp(str, getstr(ts), l) == 0)) {
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/* string may be dead */
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if (isdead(G(L), o)) changewhite(o);
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return ts;
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}
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}
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return newlstr(L, str, l, h, readonly); /* not found */
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}
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static int lua_is_ptr_in_ro_area(const char *p) {
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#ifdef LUA_CROSS_COMPILER
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return 0;
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#else
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#include "compiler.h"
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return p >= RODATA_START_ADDRESS && p <= RODATA_END_ADDRESS;
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#endif
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}
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TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
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// If the pointer is in a read-only memory and the string is at least 4 chars in length,
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// create it as a read-only string instead
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if(lua_is_ptr_in_ro_area(str) && l+1 > sizeof(char**) && l == c_strlen(str))
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return luaS_newlstr_helper(L, str, l, LUAS_READONLY_STRING);
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else
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return luaS_newlstr_helper(L, str, l, LUAS_REGULAR_STRING);
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}
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LUAI_FUNC TString *luaS_newrolstr (lua_State *L, const char *str, size_t l) {
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if(l+1 > sizeof(char**) && l == c_strlen(str))
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return luaS_newlstr_helper(L, str, l, LUAS_READONLY_STRING);
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else // no point in creating a RO string, as it would actually be larger
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return luaS_newlstr_helper(L, str, l, LUAS_REGULAR_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 = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
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u->uv.marked = luaC_white(G(L)); /* is not finalized */
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u->uv.tt = LUA_TUSERDATA;
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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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/* chain it on udata list (after main thread) */
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u->uv.next = G(L)->mainthread->next;
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G(L)->mainthread->next = obj2gco(u);
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return u;
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}
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