update to lua 5.3.1

3rd/lua/lstring.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp $
+** $Id: lstring.c,v 2.49 2015/06/01 16:34:37 roberto Exp $
 ** String table (keeps all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -22,6 +22,8 @@
 #include "lstring.h"
 
 
+#define MEMERRMSG       "not enough memory"
+
 
 /*
 ** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
@@ -36,10 +38,10 @@
 ** equality for long strings
 */
 int luaS_eqlngstr (TString *a, TString *b) {
-  size_t len = a->len;
+  size_t len = a->u.lnglen;
   lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
   return (a == b) ||  /* same instance or... */
-    ((len == b->len) &&  /* equal length and ... */
+    ((len == b->u.lnglen) &&  /* equal length and ... */
      (memcmp(getstr(a), getstr(b), len) == 0));  /* equal contents */
 }
 
@@ -69,9 +71,9 @@ void luaS_resize (lua_State *L, int newsize) {
     TString *p = tb->hash[i];
     tb->hash[i] = NULL;
     while (p) {  /* for each node in the list */
-      TString *hnext = p->hnext;  /* save next */
+      TString *hnext = p->u.hnext;  /* save next */
       unsigned int h = lmod(p->hash, newsize);  /* new position */
-      p->hnext = tb->hash[h];  /* chain it */
+      p->u.hnext = tb->hash[h];  /* chain it */
       tb->hash[h] = p;
       p = hnext;
     }
@@ -85,6 +87,34 @@ void luaS_resize (lua_State *L, int newsize) {
 }
 
 
+/*
+** Clear API string cache. (Entries cannot be empty, so fill them with
+** a non-collectable string.)
+*/
+void luaS_clearcache (global_State *g) {
+  int i;
+  for (i = 0; i < STRCACHE_SIZE; i++) {
+    if (iswhite(g->strcache[i][0]))  /* will entry be collected? */
+      g->strcache[i][0] = 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;
+  luaS_resize(L, MINSTRTABSIZE);  /* initial size of string table */
+  /* 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_SIZE; i++)  /* fill cache with valid strings */
+    g->strcache[i][0] = g->memerrmsg;
+}
+
+
 
 /*
 ** creates a new string object
@@ -97,7 +127,6 @@ static TString *createstrobj (lua_State *L, const char *str, size_t l,
   totalsize = sizelstring(l);
   o = luaC_newobj(L, tag, totalsize);
   ts = gco2ts(o);
-  ts->len = l;
   ts->hash = h;
   ts->extra = 0;
   memcpy(getaddrstr(ts), str, l * sizeof(char));
@@ -110,8 +139,8 @@ 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)->hnext;
-  *p = (*p)->hnext;  /* remove element from its list */
+    p = &(*p)->u.hnext;
+  *p = (*p)->u.hnext;  /* remove element from its list */
   tb->nuse--;
 }
 
@@ -124,8 +153,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
   global_State *g = G(L);
   unsigned int h = luaS_hash(str, l, g->seed);
   TString **list = &g->strt.hash[lmod(h, g->strt.size)];
-  for (ts = *list; ts != NULL; ts = ts->hnext) {
-    if (l == ts->len &&
+  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)? */
@@ -138,7 +167,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
     list = &g->strt.hash[lmod(h, g->strt.size)];  /* recompute with new size */
   }
   ts = createstrobj(L, str, l, LUA_TSHRSTR, h);
-  ts->hnext = *list;
+  ts->shrlen = cast_byte(l);
+  ts->u.hnext = *list;
   *list = ts;
   g->strt.nuse++;
   return ts;
@@ -152,18 +182,32 @@ 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 + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
       luaM_toobig(L);
-    return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
+    ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
+    ts->u.lnglen = l;
+    return ts;
   }
 }
 
 
 /*
-** new zero-terminated string
+** 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) {
-  return luaS_newlstr(L, str, strlen(str));
+  unsigned int i = point2uint(str) % STRCACHE_SIZE;  /* hash */
+  TString **p = G(L)->strcache[i];
+  if (strcmp(str, getstr(p[0])) == 0)  /* hit? */
+    return p[0];  /* that it is */
+  else {  /* normal route */
+    TString *s = luaS_newlstr(L, str, strlen(str));
+    p[0] = s;
+    return s;
+  }
 }