mirror of https://github.com/lua/lua
138 lines
3.6 KiB
C
138 lines
3.6 KiB
C
/*
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** $Id: lstring.c,v 1.47 2000/12/22 16:57:46 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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#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_init (lua_State *L) {
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luaS_resize(L, &L->strt, MINPOWER2);
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luaS_resize(L, &L->udt, MINPOWER2);
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}
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void luaS_freeall (lua_State *L) {
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LUA_ASSERT(L->strt.nuse==0, "non-empty string table");
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luaM_freearray(L, L->strt.hash, L->strt.size, TString *);
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LUA_ASSERT(L->udt.nuse==0, "non-empty udata table");
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luaM_freearray(L, L->udt.hash, L->udt.size, TString *);
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}
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static luint32 hash_s (const char *s, size_t l) {
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luint32 h = 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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for (; l>=step; l-=step)
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h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++));
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return h;
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}
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void luaS_resize (lua_State *L, stringtable *tb, int newsize) {
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TString **newhash = luaM_newvector(L, newsize, TString *);
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int i;
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for (i=0; i<newsize; i++) newhash[i] = NULL;
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/* rehash */
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for (i=0; i<tb->size; i++) {
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TString *p = tb->hash[i];
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while (p) { /* for each node in the list */
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TString *next = p->nexthash; /* save next */
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luint32 h = (tb == &L->strt) ? p->u.s.hash : IntPoint(p->u.d.value);
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int h1 = h&(newsize-1); /* new position */
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LUA_ASSERT(h%newsize == (h&(newsize-1)),
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"a&(x-1) == a%x, for x power of 2");
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p->nexthash = newhash[h1]; /* chain it in new position */
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newhash[h1] = p;
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p = next;
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}
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}
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luaM_freearray(L, tb->hash, tb->size, TString *);
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tb->size = newsize;
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tb->hash = newhash;
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}
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static void newentry (lua_State *L, stringtable *tb, TString *ts, int h) {
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ts->nexthash = tb->hash[h]; /* chain new entry */
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tb->hash[h] = ts;
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tb->nuse++;
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if (tb->nuse > (luint32)tb->size && tb->size < MAX_INT/2) /* too crowded? */
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luaS_resize(L, tb, tb->size*2);
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}
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TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
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luint32 h = hash_s(str, l);
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int h1 = h & (L->strt.size-1);
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TString *ts;
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for (ts = L->strt.hash[h1]; ts; ts = ts->nexthash) {
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if (ts->len == l && (memcmp(str, ts->str, l) == 0))
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return ts;
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}
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/* not found */
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ts = (TString *)luaM_malloc(L, sizestring(l));
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ts->marked = 0;
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ts->nexthash = NULL;
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ts->len = l;
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ts->u.s.hash = h;
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ts->u.s.constindex = 0;
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memcpy(ts->str, str, l);
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ts->str[l] = 0; /* ending 0 */
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newentry(L, &L->strt, ts, h1); /* insert it on table */
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return ts;
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}
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TString *luaS_newudata (lua_State *L, size_t s, void *udata) {
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union L_UTString *uts = (union L_UTString *)luaM_malloc(L, sizeudata(s));
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TString *ts = &uts->ts;
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ts->marked = 0;
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ts->nexthash = NULL;
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ts->len = s;
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ts->u.d.tag = 0;
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ts->u.d.value = (udata == NULL) ? uts+1 : udata;
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/* insert it on table */
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newentry(L, &L->udt, ts, IntPoint(ts->u.d.value) & (L->udt.size-1));
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return ts;
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}
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TString *luaS_createudata (lua_State *L, void *udata, int tag) {
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int h1 = IntPoint(udata) & (L->udt.size-1);
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TString *ts;
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for (ts = L->udt.hash[h1]; ts; ts = ts->nexthash) {
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if (udata == ts->u.d.value && (tag == ts->u.d.tag || tag == LUA_ANYTAG))
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return ts;
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}
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/* not found */
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ts = luaS_newudata(L, 0, udata);
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if (tag != LUA_ANYTAG)
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ts->u.d.tag = tag;
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return ts;
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}
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TString *luaS_new (lua_State *L, const char *str) {
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return luaS_newlstr(L, str, strlen(str));
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}
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TString *luaS_newfixed (lua_State *L, const char *str) {
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TString *ts = luaS_new(L, str);
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if (ts->marked == 0) ts->marked = FIXMARK; /* avoid GC */
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return ts;
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}
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