From 41259bff31dbb904edfb8070006ccb15577f8f04 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 12 Feb 1996 15:32:40 -0300
Subject: [PATCH] BIG CHANGE: new data structure for constants, strings and
 globals, using an array of hash tables for all them.

---
 func.c   |   4 +-
 func.h   |   4 +-
 hash.c   |  26 +++-------
 hash.h   |   4 +-
 inout.c  |   6 +--
 lex.c    |   4 +-
 lua.stx  |  14 ++---
 opcode.c |  15 +-----
 table.c  |  26 ++++++----
 table.h  |   9 ++--
 tree.c   | 152 +++++++++++++++++++++++++++++++++----------------------
 tree.h   |  17 ++-----
 12 files changed, 146 insertions(+), 135 deletions(-)

diff --git a/func.c b/func.c
index 616317d6..6a02c78d 100644
--- a/func.c
+++ b/func.c
@@ -97,7 +97,7 @@ void lua_funcinfo (lua_Object func, char **filename, int *linedefined)
 /*
 ** Stores information to know that variable has been declared in given line
 */
-void luaI_registerlocalvar (TreeNode *varname, int line)
+void luaI_registerlocalvar (TaggedString *varname, int line)
 {
   if (numcurrvars >= maxcurrvars)
     if (currvars == NULL)
@@ -152,7 +152,7 @@ char *luaI_getlocalname (TFunc *func, int local_number, int line)
     if (lv->varname)               /* register */
     {
       if (++count == local_number)
-        varname = lv->varname->ts.str;
+        varname = lv->varname->str;
     }
     else                           /* unregister */
       if (--count < local_number)
diff --git a/func.h b/func.h
index b4c275ad..8208f114 100644
--- a/func.h
+++ b/func.h
@@ -6,7 +6,7 @@
 
 typedef struct LocVar
 {
-  TreeNode  *varname;           /* NULL signals end of scope */
+  TaggedString *varname;           /* NULL signals end of scope */
   int       line;
 } LocVar;
 
@@ -30,7 +30,7 @@ void luaI_insertfunction (TFunc *f);
 
 void luaI_initTFunc (TFunc *f);
 
-void luaI_registerlocalvar (TreeNode *varname, int line);
+void luaI_registerlocalvar (TaggedString *varname, int line);
 void luaI_unregisterlocalvar (int line);
 void luaI_closelocalvars (TFunc *func);
 char *luaI_getlocalname (TFunc *func, int local_number, int line);
diff --git a/hash.c b/hash.c
index 82047f59..c3db2588 100644
--- a/hash.c
+++ b/hash.c
@@ -3,7 +3,7 @@
 ** hash manager for lua
 */
 
-char *rcs_hash="$Id: hash.c,v 2.26 1995/10/04 14:20:26 roberto Exp roberto $";
+char *rcs_hash="$Id: hash.c,v 2.26 1995/10/04 14:20:26 roberto Exp $";
 
 #include <string.h>
 
@@ -13,7 +13,6 @@ char *rcs_hash="$Id: hash.c,v 2.26 1995/10/04 14:20:26 roberto Exp roberto $";
 #include "table.h"
 #include "lua.h"
 
-#define streq(s1,s2)	(s1 == s2 || (*(s1) == *(s2) && strcmp(s1,s2)==0))
 
 #define nhash(t)	((t)->nhash)
 #define nuse(t)		((t)->nuse)
@@ -24,19 +23,18 @@ char *rcs_hash="$Id: hash.c,v 2.26 1995/10/04 14:20:26 roberto Exp roberto $";
 #define val(n)		(&(n)->val)
 
 
-#define REHASH_LIMIT	0.70	/* avoid more than this % full */
+#define REHASH_LIMIT    0.70    /* avoid more than this % full */
 
 
 static Hash *listhead = NULL;
 
 
-
 /* hash dimensions values */
 static Word dimensions[] = 
  {3, 5, 7, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421,
   12853, 25717, 51437, 65521, 0};  /* 65521 == last prime < MAX_WORD */
 
-static Word redimension (Word nhash)
+Word luaI_redimension (Word nhash)
 {
  Word i;
  for (i=0; dimensions[i]!=0; i++)
@@ -58,17 +56,7 @@ static Word hashindex (Hash *t, Object *ref)		/* hash function */
   case LUA_T_NUMBER:
    return (((Word)nvalue(ref))%nhash(t));
   case LUA_T_STRING:
-  {
-   unsigned long h = tsvalue(ref)->hash;
-   if (h == 0)
-   {
-     char *name = svalue(ref);
-     while (*name)
-       h = ((h<<5)-h)^(unsigned char)*(name++);
-     tsvalue(ref)->hash = h;
-   }
-   return (Word)h%nhash(t);  /* make it a valid index */
-  }
+   return (Word)((tsvalue(ref)->hash)%nhash(t));  /* make it a valid index */
   case LUA_T_FUNCTION:
    return (((IntPoint)ref->value.tf)%nhash(t));
   case LUA_T_CFUNCTION:
@@ -87,7 +75,7 @@ int lua_equalObj (Object *t1, Object *t2)
   {
     case LUA_T_NIL: return 1;
     case LUA_T_NUMBER: return nvalue(t1) == nvalue(t2);
-    case LUA_T_STRING: return streq(svalue(t1), svalue(t2));
+    case LUA_T_STRING: return svalue(t1) == svalue(t2);
     case LUA_T_ARRAY: return avalue(t1) == avalue(t2);
     case LUA_T_FUNCTION: return t1->value.tf == t2->value.tf;
     case LUA_T_CFUNCTION: return fvalue(t1) == fvalue(t2);
@@ -126,7 +114,7 @@ static Node *hashnodecreate (Word nhash)
 static Hash *hashcreate (Word nhash)
 {
  Hash *t = new(Hash);
- nhash = redimension((Word)((float)nhash/REHASH_LIMIT));
+ nhash = luaI_redimension((Word)((float)nhash/REHASH_LIMIT));
  nodevector(t) = hashnodecreate(nhash);
  nhash(t) = nhash;
  nuse(t) = 0;
@@ -237,7 +225,7 @@ static void rehash (Hash *t)
  Word i;
  Word   nold = nhash(t);
  Node *vold = nodevector(t);
- nhash(t) = redimension(nhash(t));
+ nhash(t) = luaI_redimension(nhash(t));
  nodevector(t) = hashnodecreate(nhash(t));
  for (i=0; i<nold; i++)
  {
diff --git a/hash.h b/hash.h
index 8ef6ddf1..86660721 100644
--- a/hash.h
+++ b/hash.h
@@ -2,13 +2,14 @@
 ** hash.h
 ** hash manager for lua
 ** Luiz Henrique de Figueiredo - 17 Aug 90
-** $Id: hash.h,v 2.8 1995/01/12 14:19:04 roberto Exp roberto $
+** $Id: hash.h,v 2.9 1996/02/07 14:13:17 roberto Exp roberto $
 */
 
 #ifndef hash_h
 #define hash_h
 
 #include "types.h"
+#include "opcode.h"
 
 typedef struct node
 {
@@ -27,6 +28,7 @@ typedef struct Hash
 
 
 int      lua_equalObj (Object *t1, Object *t2);
+Word     luaI_redimension (Word nhash);
 Hash    *lua_createarray (Word nhash);
 void     lua_hashmark (Hash *h);
 Long     lua_hashcollector (void);
diff --git a/inout.c b/inout.c
index a3100a4f..8ba4b6bb 100644
--- a/inout.c
+++ b/inout.c
@@ -5,7 +5,7 @@
 ** Also provides some predefined lua functions.
 */
 
-char *rcs_inout="$Id: inout.c,v 2.28 1996/01/26 16:52:47 roberto Exp roberto $";
+char *rcs_inout="$Id: inout.c,v 2.29 1996/02/07 14:13:47 roberto Exp roberto $";
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -68,7 +68,7 @@ int lua_openfile (char *fn)
  if (fp == NULL)
    return 1;
  lua_linenumber = 1;
- lua_parsedfile = lua_constcreate(fn)->ts.str;
+ lua_parsedfile = lua_constcreate(fn)->str;
  return 0;
 }
 
@@ -92,7 +92,7 @@ void lua_openstring (char *s)
  lua_setinput (stringinput);
  st = s;
  lua_linenumber = 1;
- lua_parsedfile = lua_constcreate("(string)")->ts.str;
+ lua_parsedfile = lua_constcreate("(string)")->str;
 }
 
 /*
diff --git a/lex.c b/lex.c
index f499d7a6..0940359c 100644
--- a/lex.c
+++ b/lex.c
@@ -1,4 +1,4 @@
-char *rcs_lex = "$Id: lex.c,v 2.23 1996/02/07 14:14:40 roberto Exp roberto $";
+char *rcs_lex = "$Id: lex.c,v 2.24 1996/02/09 19:35:23 roberto Exp roberto $";
  
 
 #include <ctype.h>
@@ -287,7 +287,7 @@ int luaY_lex (void)
         *yytextLast = 0;
         res = findReserved(yytext);
         if (res) return res;
-        luaY_lval.pNode = lua_constcreate(yytext);
+        luaY_lval.pTStr = luaI_createfixedstring(yytext);
         return NAME;
       }
 
diff --git a/lua.stx b/lua.stx
index b48b7e76..f16630d3 100644
--- a/lua.stx
+++ b/lua.stx
@@ -1,6 +1,6 @@
 %{
 
-char *rcs_luastx = "$Id: lua.stx,v 3.28 1996/02/05 13:26:01 roberto Exp roberto $";
+char *rcs_luastx = "$Id: lua.stx,v 3.29 1996/02/07 18:10:27 roberto Exp roberto $";
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -45,7 +45,7 @@ static Long    varbuffer[MAXVAR];    /* variables in an assignment list;
 static int     nvarbuffer=0;	     /* number of variables at a list */
 
 #define MAXLOCALS 32
-static TreeNode *localvar[MAXLOCALS];  /* store local variable names */
+static TaggedString *localvar[MAXLOCALS];  /* store local variable names */
 static int     nlocalvar=0;	     /* number of local variables */
 
 #define MAXFIELDS FIELDS_PER_FLUSH*2
@@ -151,7 +151,7 @@ static void flush_list (int m, int n)
   code_byte(n);
 }
 
-static void store_localvar (TreeNode *name, int n)
+static void store_localvar (TaggedString *name, int n)
 {
  if (nlocalvar+n < MAXLOCALS)
   localvar[nlocalvar+n] = name;
@@ -161,7 +161,7 @@ static void store_localvar (TreeNode *name, int n)
    luaI_registerlocalvar(name, lua_linenumber);
 }
 
-static void add_localvar (TreeNode *name)
+static void add_localvar (TaggedString *name)
 {
   store_localvar(name, 0);
   nlocalvar++;
@@ -202,7 +202,7 @@ static void code_number (float f)
 /*
 ** Search a local name and if find return its index. If do not find return -1
 */
-static int lua_localname (TreeNode *n)
+static int lua_localname (TaggedString *n)
 {
  int i;
  for (i=nlocalvar-1; i >= 0; i--)
@@ -420,7 +420,7 @@ void lua_parse (TFunc *tf)
  Word  vWord;
  Long  vLong;
  TFunc *pFunc;
- TreeNode *pNode;
+ TaggedString *pTStr;
 }
 
 %start functionlist
@@ -433,7 +433,7 @@ void lua_parse (TFunc *tf)
 %token FUNCTION
 %token <vFloat> NUMBER
 %token <vWord>  STRING
-%token <pNode>  NAME 
+%token <pTStr>  NAME 
 %token <vInt>   DEBUG
 
 %type <vLong> PrepJump
diff --git a/opcode.c b/opcode.c
index 5999d7a6..2f77cad4 100644
--- a/opcode.c
+++ b/opcode.c
@@ -3,7 +3,7 @@
 ** TecCGraf - PUC-Rio
 */
 
-char *rcs_opcode="$Id: opcode.c,v 3.55 1996/02/07 18:10:27 roberto Exp roberto $";
+char *rcs_opcode="$Id: opcode.c,v 3.56 1996/02/08 17:03:20 roberto Exp roberto $";
 
 #include <setjmp.h>
 #include <stdlib.h>
@@ -381,7 +381,7 @@ static void getglobal (Word n)
   if (tag(top-1) == LUA_T_NIL)
   { /* must call getglobal fallback */
     tag(top-1) = LUA_T_STRING;
-    tsvalue(top-1) = &lua_table[n].varname->ts;
+    tsvalue(top-1) = lua_table[n].varname;
     callFB(FB_GETGLOBAL);
   }
 }
@@ -791,17 +791,6 @@ void lua_pushstring (char *s)
  incr_top;
 }
 
-/*
-** Push an object (tag=string) on stack and register it on the constant table.
-*/
-void lua_pushliteral (char *s)
-{
- Word ct = luaI_findconstantbyname(s);  /* this call may change lua_constant */
- tsvalue(top) = lua_constant[ct];
- tag(top) = LUA_T_STRING;
- incr_top;
-}
-
 /*
 ** Push an object (tag=cfunction) to stack.
 */
diff --git a/table.c b/table.c
index 587d582d..29d877c2 100644
--- a/table.c
+++ b/table.c
@@ -3,7 +3,7 @@
 ** Module to control static tables
 */
 
-char *rcs_table="$Id: table.c,v 2.43 1996/01/26 14:04:32 roberto Exp roberto $";
+char *rcs_table="$Id: table.c,v 2.44 1996/01/26 18:03:19 roberto Exp $";
 
 /*#include <string.h>*/
 
@@ -85,7 +85,7 @@ void lua_initconstant (void)
 ** Given a name, search it at symbol table and return its index. If not
 ** found, allocate it.
 */
-Word luaI_findsymbol (TreeNode *t)
+Word luaI_findsymbol (TaggedString *t)
 {
  if (lua_table == NULL)
   lua_initsymbol(); 
@@ -111,7 +111,7 @@ Word luaI_findsymbol (TreeNode *t)
 
 Word luaI_findsymbolbyname (char *name)
 {
-  return luaI_findsymbol(lua_constcreate(name));
+  return luaI_findsymbol(luaI_createfixedstring(name));
 }
 
 
@@ -119,7 +119,7 @@ Word luaI_findsymbolbyname (char *name)
 ** Given a tree node, check it is has a correspondent constant index. If not,
 ** allocate it.
 */
-Word luaI_findconstant (TreeNode *t)
+Word luaI_findconstant (TaggedString *t)
 {
  if (lua_constant == NULL)
   lua_initconstant();
@@ -135,7 +135,7 @@ Word luaI_findconstant (TreeNode *t)
    lua_constant = growvector(lua_constant, lua_maxconstant, TaggedString *);
   }
   t->constindex = lua_nconstant;
-  lua_constant[lua_nconstant] = &(t->ts);
+  lua_constant[lua_nconstant] = t;
   lua_nconstant++;
  }
  return t->constindex;
@@ -144,7 +144,13 @@ Word luaI_findconstant (TreeNode *t)
 
 Word  luaI_findconstantbyname (char *name)
 {
-  return luaI_findconstant(lua_constcreate(name));
+  return luaI_findconstant(luaI_createfixedstring(name));
+}
+
+TaggedString *lua_constcreate(char *name)
+{
+  int i = luaI_findconstantbyname(name);
+  return lua_constant[i];
 }
 
 
@@ -156,7 +162,7 @@ static char *lua_travsymbol (int (*fn)(Object *))
  Word i;
  for (i=0; i<lua_ntable; i++)
   if (fn(&s_object(i)))
-    return lua_table[i].varname->ts.str;
+    return lua_table[i].varname->str;
  return NULL;
 }
 
@@ -165,7 +171,7 @@ static char *lua_travsymbol (int (*fn)(Object *))
 ** Mark an object if it is a string or a unmarked array.
 */
 int lua_markobject (Object *o)
-{
+{/* if already marked, does not change mark value */
  if (tag(o) == LUA_T_STRING && !tsvalue(o)->marked)
    tsvalue(o)->marked = 1;
  else if (tag(o) == LUA_T_ARRAY)
@@ -235,10 +241,10 @@ static void lua_nextvar (void)
  }
  else
  {
-  TreeNode *t = lua_table[next].varname;
+  TaggedString *t = lua_table[next].varname;
   Object name;
   tag(&name) = LUA_T_STRING;
-  tsvalue(&name) = &(t->ts);
+  tsvalue(&name) = t;
   luaI_pushobject(&name);
   luaI_pushobject(&s_object(next));
  }
diff --git a/table.h b/table.h
index 10c89a92..37085fec 100644
--- a/table.h
+++ b/table.h
@@ -1,7 +1,7 @@
 /*
 ** Module to control static tables
 ** TeCGraf - PUC-Rio
-** $Id: table.h,v 2.15 1996/01/26 18:03:19 roberto Exp roberto $
+** $Id: table.h,v 2.16 1996/02/06 16:18:21 roberto Exp roberto $
 */
 
 #ifndef table_h
@@ -13,7 +13,7 @@
 typedef struct
 {
  Object  object;
- TreeNode *varname;
+ TaggedString *varname;
 } Symbol;
 
 
@@ -22,9 +22,10 @@ extern TaggedString **lua_constant;
 
 void  lua_initconstant (void);
 Word  luaI_findsymbolbyname (char *name);
-Word  luaI_findsymbol      (TreeNode *t);
-Word  luaI_findconstant    (TreeNode *t);
+Word  luaI_findsymbol      (TaggedString *t);
+Word  luaI_findconstant    (TaggedString *t);
 Word  luaI_findconstantbyname (char *name);
+TaggedString *lua_constcreate  (char *str);
 int   lua_markobject      (Object *o);
 Long luaI_collectgarbage (void);
 void  lua_pack            (void);
diff --git a/tree.c b/tree.c
index f511436a..3b82dc9a 100644
--- a/tree.c
+++ b/tree.c
@@ -3,7 +3,7 @@
 ** TecCGraf - PUC-Rio
 */
  
-char *rcs_tree="$Id: tree.c,v 1.14 1995/10/17 11:53:53 roberto Exp roberto $";
+char *rcs_tree="$Id: tree.c,v 1.15 1996/01/26 18:03:19 roberto Exp $";
 
 
 #include <string.h>
@@ -11,95 +11,127 @@ char *rcs_tree="$Id: tree.c,v 1.14 1995/10/17 11:53:53 roberto Exp roberto $";
 #include "mem.h"
 #include "lua.h"
 #include "tree.h"
+#include "hash.h"
 #include "table.h"
 
 
-#define lua_strcmp(a,b)	(a[0]<b[0]?(-1):(a[0]>b[0]?(1):strcmp(a,b))) 
+#define lua_streq(a,b)	(a[0] == b[0] && strcmp(a,b) == 0)
 
+#define NUM_HASHS  64
 
-typedef struct StringNode {
-  struct StringNode *next;
-  TaggedString ts;
-} StringNode;
+typedef struct {
+  int size;
+  int nuse;  /* number of elements (including EMPTYs) */
+  TaggedString **hash;
+} stringtable;
 
-static StringNode *string_root = NULL;
+static stringtable string_root[NUM_HASHS];
 
-static TreeNode *constant_root = NULL;
+static TaggedString EMPTY = {NOT_USED, NOT_USED, 0, 0, {0}};
 
-/*
-** Insert a new constant/variable at the tree. 
-*/
-static TreeNode *tree_create (TreeNode **node, char *str)
+static unsigned long hash (char *str)
 {
- if (*node == NULL)
- {
-  *node = (TreeNode *) luaI_malloc(sizeof(TreeNode)+strlen(str));
-  (*node)->left = (*node)->right = NULL;
-  strcpy((*node)->ts.str, str);
-  (*node)->ts.marked = 0;
-  (*node)->ts.hash = 0;
-  (*node)->varindex = (*node)->constindex = NOT_USED;
-  return *node;
- }
- else
- {
-  int c = lua_strcmp(str, (*node)->ts.str);
-  if (c < 0) 
-   return tree_create(&(*node)->left, str);
-  else if (c > 0)
-   return tree_create(&(*node)->right, str);
+  unsigned long h = 0;
+  while (*str)
+    h = ((h<<5)-h)^(unsigned char)*(str++);
+  return h;
+}
+
+static void grow (stringtable *tb)
+{
+  int newsize = luaI_redimension(tb->size);
+  TaggedString **newhash = newvector(newsize, TaggedString *);
+  int i;
+  for (i=0; i<newsize; i++)
+    newhash[i] = NULL;
+  if (tb->size > 0)
+  { /* rehash */
+    tb->nuse = 0;
+    for (i=0; i<tb->size; i++)
+      if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY)
+      {
+        int h = tb->hash[i]->hash%newsize;
+        while (newhash[h])
+          h = (h+1)%newsize;
+        newhash[h] = tb->hash[i];
+        tb->nuse++;
+      }
+    luaI_free(tb->hash); 
+  }
+  tb->size = newsize;
+  tb->hash = newhash;
+}
+
+static TaggedString *insert (char *str, stringtable *tb)
+{
+  TaggedString *ts;
+  unsigned long h = hash(str);
+  int i;
+  int j = -1;
+  if ((Long)tb->nuse*3 >= (Long)tb->size*2)
+    grow(tb);
+  i = h%tb->size;
+  while (tb->hash[i])
+  {
+    if (tb->hash[i] == &EMPTY)
+      j = i;
+    else if (lua_streq(str, tb->hash[i]->str))
+      return tb->hash[i];
+    i = (i+1)%tb->size;
+  }
+  /* not found */
+  if (j != -1)  /* is there an EMPTY space? */
+    i = j;
   else
-   return *node;
- }
+    tb->nuse++;
+  ts = tb->hash[i] = (TaggedString *)luaI_malloc(sizeof(TaggedString)+strlen(str));
+  strcpy(ts->str, str);
+  ts->marked = 0;
+  ts->hash = h;
+  ts->varindex = ts->constindex = NOT_USED;
+  return ts;
 }
 
 TaggedString *lua_createstring (char *str) 
 {
-  StringNode *newString;
-  if (str == NULL) return NULL;
-  lua_pack();
-  newString = (StringNode *)luaI_malloc(sizeof(StringNode)+strlen(str));
-  newString->ts.marked = 0;
-  newString->ts.hash = 0;
-  strcpy(newString->ts.str, str);
-  newString->next = string_root;
-  string_root = newString;
-  return &(newString->ts);
+  return insert(str, &string_root[(unsigned)str[0]%NUM_HASHS]);
 }
 
-
-TreeNode *lua_constcreate (char *str) 
+TaggedString *luaI_createfixedstring (char *str) 
 {
- return tree_create(&constant_root, str);
+  TaggedString *ts = lua_createstring(str);
+  ts->marked = 2;  /* to avoid GC */
+  return ts;
 }
 
-
 /*
 ** Garbage collection function.
 ** This function traverse the string list freeing unindexed strings
 */
 Long lua_strcollector (void)
 {
-  StringNode *curr = string_root, *prev = NULL;
   Long counter = 0;
-  while (curr)
+  int i;
+  for (i=0; i<NUM_HASHS; i++)
   {
-    StringNode *next = curr->next;
-    if (!curr->ts.marked)
+    stringtable *tb = &string_root[i];
+    int j;
+    for (j=0; j<tb->size; j++)
     {
-      if (prev == NULL) string_root = next;
-      else prev->next = next;
-      luaI_free(curr);
-      ++counter;
+      TaggedString *t = tb->hash[j];
+      if (t != NULL && t != &EMPTY && t->marked != 2)
+      {
+        if (t->marked)
+          t->marked = 0;
+        else
+        {
+          luaI_free(t);
+          tb->hash[j] = &EMPTY;
+          counter++;
+        }
+      }
     }
-    else
-    {
-      curr->ts.marked = 0;
-      prev = curr;
-    }
-    curr = next;
   }
   return counter;
 }
 
-
diff --git a/tree.h b/tree.h
index bf6eb27d..eb347ed4 100644
--- a/tree.h
+++ b/tree.h
@@ -1,7 +1,7 @@
 /*
 ** tree.h
 ** TecCGraf - PUC-Rio
-** $Id: tree.h,v 1.10 1995/10/17 11:53:53 roberto Exp roberto $
+** $Id: tree.h,v 1.11 1996/01/26 18:03:19 roberto Exp roberto $
 */
 
 #ifndef tree_h
@@ -14,23 +14,16 @@
 
 typedef struct TaggedString
 {
+  unsigned short varindex;  /* != NOT_USED  if this is a symbol */
+  unsigned short constindex;  /* != NOT_USED  if this is a constant */
   unsigned long hash;  /* 0 if not initialized */
-  char marked;   /* for garbage collection */
+  char marked;   /* for garbage collection; 2 means "never collect" */
   char str[1];   /* \0 byte already reserved */
 } TaggedString;
  
-typedef struct TreeNode
-{
- struct TreeNode *right;
- struct TreeNode *left;
- unsigned short varindex;  /* != NOT_USED  if this is a symbol */
- unsigned short constindex;  /* != NOT_USED  if this is a constant */
- TaggedString ts;
-} TreeNode;
-
 
 TaggedString *lua_createstring (char *str);
-TreeNode *lua_constcreate  (char *str);
+TaggedString *luaI_createfixedstring (char *str);
 Long lua_strcollector (void);
 
 #endif