--- /dev/null
+/*
+** $Id: lstring.c $
+** String table (keeps all strings handled by Lua)
+** See Copyright Notice in lua.h
+*/
+
+#define lstring_c
+#define LUA_CORE
+
+#include "lprefix.h"
+
+
+#include <string.h>
+
+#include "lua.h"
+
+#include "ldebug.h"
+#include "ldo.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lstate.h"
+#include "lstring.h"
+
+
+/*
+** Maximum size for string table.
+*/
+#define MAXSTRTB cast_int(luaM_limitN(MAX_INT, TString*))
+
+
+/*
+** equality for long strings
+*/
+int luaS_eqlngstr (TString *a, TString *b) {
+ size_t len = a->u.lnglen;
+ lua_assert(a->tt == LUA_VLNGSTR && b->tt == LUA_VLNGSTR);
+ return (a == b) || /* same instance or... */
+ ((len == b->u.lnglen) && /* equal length and ... */
+ (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
+}
+
+
+unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
+ unsigned int h = seed ^ cast_uint(l);
+ for (; l > 0; l--)
+ h ^= ((h<<5) + (h>>2) + cast_byte(str[l - 1]));
+ return h;
+}
+
+
+unsigned int luaS_hashlongstr (TString *ts) {
+ lua_assert(ts->tt == LUA_VLNGSTR);
+ if (ts->extra == 0) { /* no hash? */
+ size_t len = ts->u.lnglen;
+ ts->hash = luaS_hash(getstr(ts), len, ts->hash);
+ ts->extra = 1; /* now it has its hash */
+ }
+ return ts->hash;
+}
+
+
+static void tablerehash (TString **vect, int osize, int nsize) {
+ int i;
+ for (i = osize; i < nsize; i++) /* clear new elements */
+ vect[i] = NULL;
+ for (i = 0; i < osize; i++) { /* rehash old part of the array */
+ TString *p = vect[i];
+ vect[i] = NULL;
+ while (p) { /* for each string in the list */
+ TString *hnext = p->u.hnext; /* save next */
+ unsigned int h = lmod(p->hash, nsize); /* new position */
+ p->u.hnext = vect[h]; /* chain it into array */
+ vect[h] = p;
+ p = hnext;
+ }
+ }
+}
+
+
+/*
+** Resize the string table. If allocation fails, keep the current size.
+** (This can degrade performance, but any non-zero size should work
+** correctly.)
+*/
+void luaS_resize (lua_State *L, int nsize) {
+ stringtable *tb = &G(L)->strt;
+ int osize = tb->size;
+ TString **newvect;
+ if (nsize < osize) /* shrinking table? */
+ tablerehash(tb->hash, osize, nsize); /* depopulate shrinking part */
+ newvect = luaM_reallocvector(L, tb->hash, osize, nsize, TString*);
+ if (l_unlikely(newvect == NULL)) { /* reallocation failed? */
+ if (nsize < osize) /* was it shrinking table? */
+ tablerehash(tb->hash, nsize, osize); /* restore to original size */
+ /* leave table as it was */
+ }
+ else { /* allocation succeeded */
+ tb->hash = newvect;
+ tb->size = nsize;
+ if (nsize > osize)
+ tablerehash(newvect, osize, nsize); /* rehash for new size */
+ }
+}
+
+
+/*
+** Clear API string cache. (Entries cannot be empty, so fill them with
+** a non-collectable string.)
+*/
+void luaS_clearcache (global_State *g) {
+ int i, j;
+ for (i = 0; i < STRCACHE_N; i++)
+ for (j = 0; j < STRCACHE_M; j++) {
+ if (iswhite(g->strcache[i][j])) /* will entry be collected? */
+ g->strcache[i][j] = g->memerrmsg; /* replace it with something fixed */
+ }
+}
+
+
+/*
+** Initialize the string table and the string cache
+*/
+void luaS_init (lua_State *L) {
+ global_State *g = G(L);
+ int i, j;
+ stringtable *tb = &G(L)->strt;
+ tb->hash = luaM_newvector(L, MINSTRTABSIZE, TString*);
+ tablerehash(tb->hash, 0, MINSTRTABSIZE); /* clear array */
+ tb->size = MINSTRTABSIZE;
+ /* pre-create memory-error message */
+ g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
+ luaC_fix(L, obj2gco(g->memerrmsg)); /* it should never be collected */
+ for (i = 0; i < STRCACHE_N; i++) /* fill cache with valid strings */
+ for (j = 0; j < STRCACHE_M; j++)
+ g->strcache[i][j] = g->memerrmsg;
+}
+
+
+
+/*
+** creates a new string object
+*/
+static TString *createstrobj (lua_State *L, size_t l, int tag, unsigned int h) {
+ TString *ts;
+ GCObject *o;
+ size_t totalsize; /* total size of TString object */
+ totalsize = sizelstring(l);
+ o = luaC_newobj(L, tag, totalsize);
+ ts = gco2ts(o);
+ ts->hash = h;
+ ts->extra = 0;
+ getstr(ts)[l] = '\0'; /* ending 0 */
+ return ts;
+}
+
+
+TString *luaS_createlngstrobj (lua_State *L, size_t l) {
+ TString *ts = createstrobj(L, l, LUA_VLNGSTR, G(L)->seed);
+ ts->u.lnglen = l;
+ return ts;
+}
+
+
+void luaS_remove (lua_State *L, TString *ts) {
+ stringtable *tb = &G(L)->strt;
+ TString **p = &tb->hash[lmod(ts->hash, tb->size)];
+ while (*p != ts) /* find previous element */
+ p = &(*p)->u.hnext;
+ *p = (*p)->u.hnext; /* remove element from its list */
+ tb->nuse--;
+}
+
+
+static void growstrtab (lua_State *L, stringtable *tb) {
+ if (l_unlikely(tb->nuse == MAX_INT)) { /* too many strings? */
+ luaC_fullgc(L, 1); /* try to free some... */
+ if (tb->nuse == MAX_INT) /* still too many? */
+ luaM_error(L); /* cannot even create a message... */
+ }
+ if (tb->size <= MAXSTRTB / 2) /* can grow string table? */
+ luaS_resize(L, tb->size * 2);
+}
+
+
+/*
+** Checks whether short string exists and reuses it or creates a new one.
+*/
+static TString *internshrstr (lua_State *L, const char *str, size_t l) {
+ TString *ts;
+ global_State *g = G(L);
+ stringtable *tb = &g->strt;
+ unsigned int h = luaS_hash(str, l, g->seed);
+ TString **list = &tb->hash[lmod(h, tb->size)];
+ lua_assert(str != NULL); /* otherwise 'memcmp'/'memcpy' are undefined */
+ for (ts = *list; ts != NULL; ts = ts->u.hnext) {
+ if (l == ts->shrlen && (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
+ /* found! */
+ if (isdead(g, ts)) /* dead (but not collected yet)? */
+ changewhite(ts); /* resurrect it */
+ return ts;
+ }
+ }
+ /* else must create a new string */
+ if (tb->nuse >= tb->size) { /* need to grow string table? */
+ growstrtab(L, tb);
+ list = &tb->hash[lmod(h, tb->size)]; /* rehash with new size */
+ }
+ ts = createstrobj(L, l, LUA_VSHRSTR, h);
+ memcpy(getstr(ts), str, l * sizeof(char));
+ ts->shrlen = cast_byte(l);
+ ts->u.hnext = *list;
+ *list = ts;
+ tb->nuse++;
+ return ts;
+}
+
+
+/*
+** new string (with explicit length)
+*/
+TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
+ if (l <= LUAI_MAXSHORTLEN) /* short string? */
+ return internshrstr(L, str, l);
+ else {
+ TString *ts;
+ if (l_unlikely(l >= (MAX_SIZE - sizeof(TString))/sizeof(char)))
+ luaM_toobig(L);
+ ts = luaS_createlngstrobj(L, l);
+ memcpy(getstr(ts), str, l * sizeof(char));
+ return ts;
+ }
+}
+
+
+/*
+** Create or reuse a zero-terminated string, first checking in the
+** cache (using the string address as a key). The cache can contain
+** only zero-terminated strings, so it is safe to use 'strcmp' to
+** check hits.
+*/
+TString *luaS_new (lua_State *L, const char *str) {
+ unsigned int i = point2uint(str) % STRCACHE_N; /* hash */
+ int j;
+ TString **p = G(L)->strcache[i];
+ for (j = 0; j < STRCACHE_M; j++) {
+ if (strcmp(str, getstr(p[j])) == 0) /* hit? */
+ return p[j]; /* that is it */
+ }
+ /* normal route */
+ for (j = STRCACHE_M - 1; j > 0; j--)
+ p[j] = p[j - 1]; /* move out last element */
+ /* new element is first in the list */
+ p[0] = luaS_newlstr(L, str, strlen(str));
+ return p[0];
+}
+
+
+Udata *luaS_newudata (lua_State *L, size_t s, int nuvalue) {
+ Udata *u;
+ int i;
+ GCObject *o;
+ if (l_unlikely(s > MAX_SIZE - udatamemoffset(nuvalue)))
+ luaM_toobig(L);
+ o = luaC_newobj(L, LUA_VUSERDATA, sizeudata(nuvalue, s));
+ u = gco2u(o);
+ u->len = s;
+ u->nuvalue = nuvalue;
+ u->metatable = NULL;
+ for (i = 0; i < nuvalue; i++)
+ setnilvalue(&u->uv[i].uv);
+ return u;
+}
+
projects / ceph.git / blobdiff