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// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1988 Free Software Foundation
   written by Doug Lea (dl@rocky.oswego.edu)

This file is part of GNU CC.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.  No author or distributor
accepts responsibility to anyone for the consequences of using it
or for whether it serves any particular purpose or works at all,
unless he says so in writing.  Refer to the GNU CC General Public
License for full details.

Everyone is granted permission to copy, modify and redistribute
GNU CC, but only under the conditions described in the
GNU CC General Public License.   A copy of this license is
supposed to have been given to you along with GNU CC so you
can know your rights and responsibilities.  It should be in a
file named COPYING.  Among other things, the copyright notice
and this notice must be preserved on all copies.  
*/

#ifdef __GNUG__
#pragma implementation
#endif
#include <stream.h>
#include <assert.h>
#include "<T>.SplayBag.h"


/* 

struct to simulate the special `null' node in the Sleater & Tarjan JACM 1985
splay tree algorithms

All routines use a version of their `simple top-down' splay alg. (p 669)

*/

struct _dummySplayNode
{
 <T>SplayNode*    lt;
 <T>SplayNode*    rt;
 <T>SplayNode*    par;
} _dummy_null;


/*
traversal primitives
*/


<T>SplayNode* <T>SplayBag::leftmost()
{
 <T>SplayNode* t = root;
 if (t != 0) while (t->lt != 0) t = t->lt;
 return t;
}

<T>SplayNode* <T>SplayBag::rightmost()
{
 <T>SplayNode* t = root;
 if (t != 0) while (t->rt != 0) t = t->rt;
 return t;
}

<T>SplayNode* <T>SplayBag::succ(<T>SplayNode* t)
{
 if (t == 0)
   return 0;
 if (t->rt != 0)
 {
   t = t->rt;
   while (t->lt != 0) t = t->lt;
   return t;
 }
 else
 {
   for (;;)
   {
     if (t->par == 0 || t == t->par->lt)
       return t->par;
     else
       t = t->par;
   }
 }
}

<T>SplayNode* <T>SplayBag::pred(<T>SplayNode* t)
{
 if (t == 0)
   return 0;
 else if (t->lt != 0)
 {
   t = t->lt;
   while (t->rt != 0) t = t->rt;
   return t;
 }
 else
 {
   for (;;)
   {
     if (t->par == 0 || t == t->par->rt)
       return t->par;
     else
       t = t->par;
   }
 }
}



Pix <T>SplayBag::seek(<T&> key, Pix i)
{
 if (root == 0) return 0;

 <T>SplayNode* t = (<T>SplayNode*) i;
 if (t != 0)
 {
   int cmp = <T>CMP(key, t->item);
   if (cmp == 0)
   {
     t = succ(t);
     if (t != 0 && <T>EQ(key, t->item))
       return Pix(t);
     else
       return 0;
   }
   else if (cmp < 0)
     return 0;
 }

 t = root;
 int comp = <T>CMP(key, t->item);
 if (comp == 0)
   return Pix(t);

 <T>SplayNode* dummy = (<T>SplayNode*)(&_dummy_null);
 <T>SplayNode* l = dummy;
 <T>SplayNode* r = dummy;
 dummy->rt = dummy->lt = dummy->par = 0;

 while (comp != 0)
 {
   if (comp > 0)
   {
     <T>SplayNode* tr = t->rt;
     if (tr == 0)
       break;
     else
     {
       comp = <T>CMP(key, tr->item);
       if (comp <= 0 || tr->rt == 0)
       {
         l->rt = t; t->par = l;
         l = t;
         t = tr;
         if (comp >= 0)
           break;
       }
       else
       {
         if ((t->rt = tr->lt) != 0) t->rt->par = t;
         tr->lt = t; t->par = tr;
         l->rt = tr; tr->par = l;
         l = tr;
         t = tr->rt;
         comp = <T>CMP(key, t->item);
       }
     }
   }
   else
   {
     <T>SplayNode* tl = t->lt;
     if (tl == 0)
       break;
     else
     {
       comp = <T>CMP(key, tl->item);
       if (comp >= 0 || tl->lt == 0)
       {
         r->lt = t; t->par = r;
         r = t;
         t = tl;
         if (comp <= 0)
           break;
       }
       else
       {
         if ((t->lt = tl->rt) != 0) t->lt->par = t;
         tl->rt = t; t->par = tl;
         r->lt = tl; tl->par = r;
         r = tl;
         t = tl->lt;
         comp = <T>CMP(key, t->item);
       }
     }
   }
 }
 if ((r->lt = t->rt) != 0) r->lt->par = r;
 if ((l->rt = t->lt) != 0) l->rt->par = l;
 if ((t->lt = dummy->rt) != 0) t->lt->par = t;
 if ((t->rt = dummy->lt) != 0) t->rt->par = t;
 t->par = 0;
 root = t;
 if (comp != 0)
   return 0;
 else
 {
   l = pred(t);
   while (l != 0 && <T>EQ(l->item, key)) { t = l; l = pred(l); }
   return Pix(t);
 }
}

int <T>SplayBag::nof(<T&> item)
{
 int n = 0;
 <T>SplayNode* t = (<T>SplayNode*)(seek(item));
 if (t != 0)
 {
   do
   {
     ++n;
     t = succ(t);
   } while (t != 0 && <T>EQ(item, t->item));
 }
 return n;
}

Pix <T>SplayBag::add(<T&> item)
{
 ++count;
 <T>SplayNode* newnode = new <T>SplayNode(item);
 <T>SplayNode* t = root;
 if (t == 0)
 {
   root = newnode;
   return Pix(root);
 }

 int comp = <T>CMP(item, t->item);

 <T>SplayNode* dummy = (<T>SplayNode*)(&_dummy_null);
 <T>SplayNode* l = dummy;
 <T>SplayNode* r = dummy;
 dummy->rt = dummy->lt = dummy->par = 0;
 
 int done = 0;
 while (!done)
 {
   if (comp >= 0)
   {
     <T>SplayNode* tr = t->rt;
     if (tr == 0)
     {
       tr = newnode;
       comp = 0; done = 1;
     }
     else
       comp = <T>CMP(item, tr->item);
       
     if (comp <= 0)
     {
       l->rt = t; t->par = l;
       l = t;
       t = tr;
     }
     else 
     {
       <T>SplayNode* trr = tr->rt;
       if (trr == 0)
       {
         trr =  newnode;
         comp = 0; done = 1;
       }
       else
         comp = <T>CMP(item, trr->item);

       if ((t->rt = tr->lt) != 0) t->rt->par = t;
       tr->lt = t; t->par = tr;
       l->rt = tr; tr->par = l;
       l = tr;
       t = trr;
     }
   }
   else
   {
     <T>SplayNode* tl = t->lt;
     if (tl == 0)
     {
       tl = newnode;
       comp = 0; done = 1;
     }
     else
       comp = <T>CMP(item, tl->item);

     if (comp >= 0)
     {
       r->lt = t; t->par = r;
       r = t;
       t = tl;
     }
     else
     {
       <T>SplayNode* tll = tl->lt;
       if (tll == 0)
       {
         tll = newnode;
         comp = 0; done = 1;
       }
       else
         comp = <T>CMP(item, tll->item);

       if ((t->lt = tl->rt) != 0) t->lt->par = t;
       tl->rt = t; t->par = tl;
       r->lt = tl; tl->par = r;
       r = tl;
       t = tll;
     }
   }
 }
 if ((r->lt = t->rt) != 0) r->lt->par = r;
 if ((l->rt = t->lt) != 0) l->rt->par = l;
 if ((t->lt = dummy->rt) != 0) t->lt->par = t;
 if ((t->rt = dummy->lt) != 0) t->rt->par = t;
 t->par = 0;
 root = t;
 return Pix(root);
}

void <T>SplayBag::_del(<T>SplayNode* t)
{
 if (t == 0) return;

 <T>SplayNode* p = t->par;

 --count;
 if (t->rt == 0)
 {
   if (t == root)
   {
     if ((root = t->lt) != 0) root->par = 0;
   }
   else if (t == p->lt)
   {
     if ((p->lt = t->lt) != 0) p->lt->par = p;
   }
   else
     if ((p->rt = t->lt) != 0) p->rt->par = p;
 }
 else
 {
   <T>SplayNode* r = t->rt;
   <T>SplayNode* l = r->lt;
   for(;;)
   {
     if (l == 0)
     {
       if (t == root)
       {
         root = r;
         r->par = 0;
       }
       else if (t == p->lt) 
       {
         p->lt = r;
         r->par = p;
       }
       else
       {
         p->rt = r;
         r->par = p;
       }
       if ((r->lt = t->lt) != 0) r->lt->par = r;
       break;
     }
     else
     {
       if ((r->lt = l->rt) != 0) r->lt->par = r;
       l->rt = r; r->par = l;
       r = l;
       l = l->lt;
     }
   }
 }
 delete t;
}


void <T>SplayBag::remove(<T&> key)
{
 <T>SplayNode* t = (<T>SplayNode*)(seek(key));
 while (t != 0)
 {
   _del(t);
   t = (<T>SplayNode*)(seek(key));
 }
}


void <T>SplayBag::_kill(<T>SplayNode* t)
{
 if (t != 0)
 {
   _kill(t->lt);
   _kill(t->rt);
   delete t;
 }
}


<T>SplayNode* <T>SplayBag::_copy(<T>SplayNode* t)
{
 if (t != 0)
 {
   <T>SplayNode* l = _copy(t->lt);
   <T>SplayNode* r = _copy(t->rt);
   <T>SplayNode* x = new <T>SplayNode(t->item, l, r);
   if (l != 0) l->par = x;
   if (r != 0) r->par = x;
   return x;
 }
 else 
   return 0;
}

int <T>SplayBag::OK()
{
 int v = 1;
 if (root == 0) 
   v = count == 0;
 else
 {
   int n = 1;
   <T>SplayNode* trail = leftmost();
   <T>SplayNode* t = succ(trail);
   while (t != 0)
   {
     ++n;
     v &= <T>CMP(trail->item, t->item) <= 0;
     trail = t;
     t = succ(t);
   }
   v &= n == count;
 }
 if (!v) error("invariant failure");
 return v;
}