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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.  
*/

#include <stream.h>
#include <assert.h>
#include "<T>.AVLSet.h"


/*
 constants & inlines for maintaining balance & thread status in tree nodes
*/

#define AVLBALANCEMASK    3
#define AVLBALANCED       0
#define AVLLEFTHEAVY      1
#define AVLRIGHTHEAVY     2

#define LTHREADBIT        4
#define RTHREADBIT        8


static inline int bf(<T>AVLNode* t)
{
  return t->stat & AVLBALANCEMASK;
}

static inline void set_bf(<T>AVLNode* t, int b)
{
  t->stat = (t->stat & ~AVLBALANCEMASK) | (b & AVLBALANCEMASK);
}


static inline int rthread(<T>AVLNode* t)
{
  return t->stat & RTHREADBIT;
}

static inline void set_rthread(<T>AVLNode* t, int b)
{
  if (b)
    t->stat |= RTHREADBIT;
  else
    t->stat &= ~RTHREADBIT;
}

static inline int lthread(<T>AVLNode* t)
{
  return t->stat & LTHREADBIT;
}

static inline void set_lthread(<T>AVLNode* t, int b)
{
  if (b)
    t->stat |= LTHREADBIT;
  else
    t->stat &= ~LTHREADBIT;
}

/*
 traversal primitives
*/


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

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

<T>AVLNode* <T>AVLSet::succ(<T>AVLNode* t)
{
  <T>AVLNode* r = t->rt;
  if (!rthread(t)) while (!lthread(r)) r = r->lt;
  return r;
}

<T>AVLNode* <T>AVLSet::pred(<T>AVLNode* t)
{
  <T>AVLNode* l = t->lt;
  if (!lthread(t)) while (!rthread(l)) l = l->rt;
  return l;
}


Pix <T>AVLSet::seek(<T&> key)
{
  <T>AVLNode* t = root;
  if (t == 0)
    return 0;
  for (;;)
  {
    int cmp = <T>CMP(key, t->item);
    if (cmp == 0)
      return Pix(t);
    else if (cmp < 0)
    {
      if (lthread(t))
        return 0;
      else
        t = t->lt;
    }
    else if (rthread(t))
      return 0;
    else
      t = t->rt;
  }
}


/*
 The combination of threads and AVL bits make adding & deleting
 interesting, but very awkward.

 We use the following statics to avoid passing them around recursively
*/

static int _need_rebalancing;   // to send back balance info from rec. calls
static <T>*   _target_item;     // add/del_item target
static <T>AVLNode* _found_node; // returned added/deleted node
static int    _already_found;   // for deletion subcases

static <T>AVLNode** _hold_nodes;       // used for rebuilding trees
static int  _max_hold_index;              // # elements-1 in _hold_nodes


void <T>AVLSet:: _add(<T>AVLNode*& t)
{
  int cmp = <T>CMP(*_target_item, t->item);
  if (cmp == 0)
  {
    _found_node = t;
    return;
  }
  else if (cmp < 0)
  {
    if (lthread(t))
    {
      ++count;
      _found_node = new <T>AVLNode(*_target_item);
      set_lthread(_found_node, 1);
      set_rthread(_found_node, 1);
      _found_node->lt = t->lt;
      _found_node->rt = t;
      t->lt = _found_node;
      set_lthread(t, 0);
      _need_rebalancing = 1;
    }
    else
      _add(t->lt);
    if (_need_rebalancing)
    {
      switch(bf(t))
      {
      case AVLRIGHTHEAVY:
        set_bf(t, AVLBALANCED);
        _need_rebalancing = 0;
        return;
      case AVLBALANCED:
        set_bf(t, AVLLEFTHEAVY);
        return;
      case AVLLEFTHEAVY:
        <T>AVLNode* l = t->lt;
        if (bf(l) == AVLLEFTHEAVY)
        {
          if (rthread(l))
            t->lt = l;
          else
            t->lt = l->rt;
          set_lthread(t, rthread(l));
          l->rt = t;
          set_rthread(l, 0);
          set_bf(t, AVLBALANCED);
          set_bf(l, AVLBALANCED);
          t = l;
          _need_rebalancing = 0;
        }
        else
        {
          <T>AVLNode* r = l->rt;
          set_rthread(l, lthread(r));
          if (lthread(r))
            l->rt = r;
          else
            l->rt = r->lt;
          r->lt = l;
          set_lthread(r, 0);
          set_lthread(t, rthread(r));
          if (rthread(r))
            t->lt = r;
          else
            t->lt = r->rt;
          r->rt = t;
          set_rthread(r, 0);
          if (bf(r) == AVLLEFTHEAVY)
            set_bf(t, AVLRIGHTHEAVY);
          else
            set_bf(t, AVLBALANCED);
          if (bf(r) == AVLRIGHTHEAVY)
            set_bf(l, AVLLEFTHEAVY);
          else
            set_bf(l, AVLBALANCED);
          set_bf(r, AVLBALANCED);
          t = r;
          _need_rebalancing = 0;
          return;
        }
      }
    }
  }
  else
  {
    if (rthread(t))
    {
      ++count;
      _found_node = new <T>AVLNode(*_target_item);
      set_rthread(t, 0);
      set_lthread(_found_node, 1);
      set_rthread(_found_node, 1);
      _found_node->lt = t;
      _found_node->rt = t->rt;
      t->rt = _found_node;
      _need_rebalancing = 1;
    }
    else
      _add(t->rt);
    if (_need_rebalancing)
    {
      switch(bf(t))
      {
      case AVLLEFTHEAVY:
        set_bf(t, AVLBALANCED);
        _need_rebalancing = 0;
        return;
      case AVLBALANCED:
        set_bf(t, AVLRIGHTHEAVY);
        return;
      case AVLRIGHTHEAVY:
        <T>AVLNode* r = t->rt;
        if (bf(r) == AVLRIGHTHEAVY)
        {
          if (lthread(r))
            t->rt = r;
          else
            t->rt = r->lt;
          set_rthread(t, lthread(r));
          r->lt = t;
          set_lthread(r, 0);
          set_bf(t, AVLBALANCED);
          set_bf(r, AVLBALANCED);
          t = r;
          _need_rebalancing = 0;
        }
        else
        {
          <T>AVLNode* l = r->lt;
          set_lthread(r, rthread(l));
          if (rthread(l))
            r->lt = l;
          else
            r->lt = l->rt;
          l->rt = r;
          set_rthread(l, 0);
          set_rthread(t, lthread(l));
          if (lthread(l))
            t->rt = l;
          else
            t->rt = l->lt;
          l->lt = t;
          set_lthread(l, 0);
          if (bf(l) == AVLRIGHTHEAVY)
            set_bf(t, AVLLEFTHEAVY);
          else
            set_bf(t, AVLBALANCED);
          if (bf(l) == AVLLEFTHEAVY)
            set_bf(r, AVLRIGHTHEAVY);
          else
            set_bf(r, AVLBALANCED);
          set_bf(l, AVLBALANCED);
          t = l;
          _need_rebalancing = 0;
          return;
        }
      }
    }
  }
}

    
Pix <T>AVLSet::add(<T&> item)
{
  if (root == 0)
  {
    ++count;
    root = new <T>AVLNode(item);
    set_rthread(root, 1);
    set_lthread(root, 1);
    return Pix(root);
  }
  else
  {
    _target_item = &item;
    _need_rebalancing = 0;
    _add(root);
    return Pix(_found_node);
  }
}


void <T>AVLSet::_del(<T>AVLNode* par, <T>AVLNode*& t)
{
  int comp;
  if (_already_found)
  {
    if (rthread(t))
      comp = 0;
    else
      comp = 1;
  }
  else 
    comp = <T>CMP(*_target_item, t->item);
  if (comp == 0)
  {
    if (lthread(t) && rthread(t))
    {
      _found_node = t;
      if (t == par->lt)
      {
        set_lthread(par, 1);
        par->lt = t->lt;
      }
      else
      {
        set_rthread(par, 1);
        par->rt = t->rt;
      }
      _need_rebalancing = 1;
      return;
    }
    else if (lthread(t))
    {
      _found_node = t;
      <T>AVLNode* s = succ(t);
      if (s != 0 && lthread(s))
        s->lt = t->lt;
      t = t->rt;
      _need_rebalancing = 1;
      return;
    }
    else if (rthread(t))
    {
      _found_node = t;
      <T>AVLNode* p = pred(t);
      if (p != 0 && rthread(p))
        p->rt = t->rt;
      t = t->lt;
      _need_rebalancing = 1;
      return;
    }
    else                        // replace item & find someone deletable
    {
      <T>AVLNode* p = pred(t);
      t->item = p->item;
      _already_found = 1;
      comp = -1;                // fall through below to left
    }
  }

  if (comp < 0)
  {
    if (lthread(t))
      return;
    _del(t, t->lt);
    if (!_need_rebalancing)
      return;
    switch (bf(t))
    {
    case AVLLEFTHEAVY:
      set_bf(t, AVLBALANCED);
      return;
    case AVLBALANCED:
      set_bf(t, AVLRIGHTHEAVY);
      _need_rebalancing = 0;
      return;
    case AVLRIGHTHEAVY:
      <T>AVLNode* r = t->rt;
      switch (bf(r))
      {
      case AVLBALANCED:
        if (lthread(r))
          t->rt = r;
        else
          t->rt = r->lt;
        set_rthread(t, lthread(r));
        r->lt = t;
        set_lthread(r, 0);
        set_bf(t, AVLRIGHTHEAVY);
        set_bf(r, AVLLEFTHEAVY);
        _need_rebalancing = 0;
        t = r;
        return;
      case AVLRIGHTHEAVY:
        if (lthread(r))
          t->rt = r;
        else
          t->rt = r->lt;
        set_rthread(t, lthread(r));
        r->lt = t;
        set_lthread(r, 0);
        set_bf(t, AVLBALANCED);
        set_bf(r, AVLBALANCED);
        t = r;
        return;
      case AVLLEFTHEAVY:
        <T>AVLNode* l = r->lt;
        set_lthread(r, rthread(l));
        if (rthread(l))
          r->lt = l;
        else
          r->lt = l->rt;
        l->rt = r;
        set_rthread(l, 0);
        set_rthread(t, lthread(l));
        if (lthread(l))
          t->rt = l;
        else
          t->rt = l->lt;
        l->lt = t;
        set_lthread(l, 0);
        if (bf(l) == AVLRIGHTHEAVY)
          set_bf(t, AVLLEFTHEAVY);
        else
          set_bf(t, AVLBALANCED);
        if (bf(l) == AVLLEFTHEAVY)
          set_bf(r, AVLRIGHTHEAVY);
        else
          set_bf(r, AVLBALANCED);
        set_bf(l, AVLBALANCED);
        t = l;
        return;
      }
    }
  }
  else
  {
    if (rthread(t))
      return;
    _del(t, t->rt);
    if (!_need_rebalancing)
      return;
    switch (bf(t))
    {
    case AVLRIGHTHEAVY:
      set_bf(t, AVLBALANCED);
      return;
    case AVLBALANCED:
      set_bf(t, AVLLEFTHEAVY);
      _need_rebalancing = 0;
      return;
    case AVLLEFTHEAVY:
      <T>AVLNode* l = t->lt;
      switch (bf(l))
      {
      case AVLBALANCED:
        if (rthread(l))
          t->lt = l;
        else
          t->lt = l->rt;
        set_lthread(t, rthread(l));
        l->rt = t;
        set_rthread(l, 0);
        set_bf(t, AVLLEFTHEAVY);
        set_bf(l, AVLRIGHTHEAVY);
        _need_rebalancing = 0;
        t = l;
        return;
      case AVLLEFTHEAVY:
        if (rthread(l))
          t->lt = l;
        else
          t->lt = l->rt;
        set_lthread(t, rthread(l));
        l->rt = t;
        set_rthread(l, 0);
        set_bf(t, AVLBALANCED);
        set_bf(l, AVLBALANCED);
        t = l;
        return;
      case AVLRIGHTHEAVY:
        <T>AVLNode* r = l->rt;
        set_rthread(l, lthread(r));
        if (lthread(r))
          l->rt = r;
        else
          l->rt = r->lt;
        r->lt = l;
        set_lthread(r, 0);
        set_lthread(t, rthread(r));
        if (rthread(r))
          t->lt = r;
        else
          t->lt = r->rt;
        r->rt = t;
        set_rthread(r, 0);
        if (bf(r) == AVLLEFTHEAVY)
          set_bf(t, AVLRIGHTHEAVY);
        else
          set_bf(t, AVLBALANCED);
        if (bf(r) == AVLRIGHTHEAVY)
          set_bf(l, AVLLEFTHEAVY);
        else
          set_bf(l, AVLBALANCED);
        set_bf(r, AVLBALANCED);
        t = r;
        return;
      }
    }
  }
}

        

void <T>AVLSet::del(<T&> item)
{
  if (root == 0) return;
  _need_rebalancing = 0;
  _already_found = 0;
  _found_node = 0;
  _target_item = &item;
  _del(root, root);
  if (_found_node)
  {
    delete(_found_node);
    if (--count == 0)
      root = 0;
  }
}

// build an ordered array of pointers to tree nodes back into a tree
// we know that at least one element exists

static <T>AVLNode* _do_treeify(int lo, int hi, int& h)
{
  int lh, rh;
  int mid = (lo + hi) / 2;
  <T>AVLNode* t = _hold_nodes[mid];
  if (lo > mid - 1)
  {
    set_lthread(t, 1);
    if (mid == 0)
      t->lt = 0;
    else
      t->lt = _hold_nodes[mid-1];
    lh = 0;
  }
  else
  {
    set_lthread(t, 0);
    t->lt = _do_treeify(lo, mid-1, lh);
  }
  if (hi < mid + 1)
  {
    set_rthread(t, 1);
    if (mid == _max_hold_index)
      t->rt = 0;
    else
      t->rt = _hold_nodes[mid+1];
    rh = 0;
  }
  else 
  {
    set_rthread(t, 0);
    t->rt = _do_treeify(mid+1, hi, rh);
  }
  if (lh == rh)
  {
    set_bf(t, AVLBALANCED);
    h = lh + 1;
  }
  else if (lh == rh - 1)
  {
    set_bf(t, AVLRIGHTHEAVY);
    h = rh + 1;
  }
  else if (rh == lh - 1)
  {
    set_bf(t, AVLLEFTHEAVY);
    h = lh + 1;
  }
  else                          // can't happen
    abort();

  return t;
}

static <T>AVLNode* _treeify(int n)
{
  <T>AVLNode* t;
  if (n == 0)
    t = 0;
  else
  {
    int b;
    _max_hold_index = n-1;
    t = _do_treeify(0, _max_hold_index, b);
  }
  delete _hold_nodes;
  return t;
}


void <T>AVLSet::_kill(<T>AVLNode* t)
{
  if (t != 0)
  {
    if (!lthread(t)) _kill(t->lt);
    if (!rthread(t)) _kill(t->rt);
    delete t;
  }
}


<T>AVLSet::<T>AVLSet(<T>AVLSet& b)
{
  if ((count = b.count) == 0)
  {
    root = 0;
  }
  else
  {
    _hold_nodes = new <T>AVLNodePtr [count];
    <T>AVLNode* t = b.leftmost();
    int i = 0;
    while (t != 0)
    {
      _hold_nodes[i++] = new <T>AVLNode(t->item);
      t = b.succ(t);
    }
    root = _treeify(count);
  }
}


int <T>AVLSet::operator == (<T>AVLSet& y)
{
  if (count != y.count)
    return 0;
  else
  {
    <T>AVLNode* t = leftmost();
    <T>AVLNode* u = y.leftmost();
    for (;;)
    {
      if (t == 0)
        return 1;
      else if (!(<T>EQ(t->item, u->item)))
        return 0;
      else
      {
        t = succ(t);
        u = y.succ(u);
      }
    }
  }
}

int <T>AVLSet::operator <= (<T>AVLSet& y)
{
  if (count > y.count)
    return 0;
  else
  {
    <T>AVLNode* t = leftmost();
    <T>AVLNode* u = y.leftmost();
    for (;;)
    {
      if (t == 0)
        return 1;
      else if (u == 0)
        return 0;
      int cmp = <T>CMP(t->item, u->item);
      if (cmp == 0)
      {
        t = succ(t);
        u = y.succ(u);
      }
      else if (cmp < 0)
        return 0;
      else
        u = y.succ(u);
    }
  }
}

void <T>AVLSet::operator |=(<T>AVLSet& y)
{
  <T>AVLNode* t = leftmost();
  <T>AVLNode* u = y.leftmost();
  int rsize = count + y.count;
  _hold_nodes = new <T>AVLNodePtr [rsize];
  int k = 0;
  for (;;)
  {
    if (t == 0)
    {
      while (u != 0)
      {
        _hold_nodes[k++] = new <T>AVLNode(u->item);
        u = y.succ(u);
      }
      break;
    }
    else if (u == 0)
    {
      while (t != 0)
      {
        _hold_nodes[k++] = t;
        t = succ(t);
      }
      break;
    }
    int cmp = <T>CMP(t->item, u->item);
    if (cmp == 0)
    {
      _hold_nodes[k++] = t;
      t = succ(t);
      u = y.succ(u);
    }
    else if (cmp < 0)
    {
      _hold_nodes[k++] = t;
      t = succ(t);
    }
    else
    {
      _hold_nodes[k++] = new <T>AVLNode(u->item);
      u = y.succ(u);
    }
  }
  root = _treeify(k);
  count = k;
}

void <T>AVLSet::operator &= (<T>AVLSet& y)
{
  <T>AVLNode* t = leftmost();
  <T>AVLNode* u = y.leftmost();
  int rsize = count <? y.count;
  _hold_nodes = new <T>AVLNodePtr [rsize];
  int k = 0;
  for (;;)
  {
    if (t == 0 || u == 0)
      break;
    int cmp = <T>CMP(t->item, u->item);
    if (cmp == 0)
    {
      _hold_nodes[k++] = t;
      t = succ(t);
      u = y.succ(u);
    }
    else if (cmp < 0)
    {
      <T>AVLNode* tmp = succ(t);
      delete t;
      t = tmp;
    }
    else
      u = y.succ(u);
  }
  root = _treeify(k);
  count = k;
}


void <T>AVLSet::operator -=(<T>AVLSet& y)
{
  <T>AVLNode* t = leftmost();
  <T>AVLNode* u = y.leftmost();
  int rsize = count;
  _hold_nodes = new <T>AVLNodePtr [rsize];
  int k = 0;
  for (;;)
  {
    if (t == 0)
      break;
    else if (u == 0)
    {
      while (t != 0)
      {
        _hold_nodes[k++] = t;
        t = succ(t);
      }
      break;
    }
    int cmp = <T>CMP(t->item, u->item);
    if (cmp == 0)
    {
      <T>AVLNode* tmp = succ(t);
      delete t;
      t = tmp;
      u = y.succ(u);
    }
    else if (cmp < 0)
    {
      _hold_nodes[k++] = t;
      t = succ(t);
    }
    else
      u = y.succ(u);
  }
  root = _treeify(k);
  count = k;
}

int <T>AVLSet::owns(Pix i)
{
  if (i == 0) return 0;
  for (<T>AVLNode* t = leftmost(); t != 0; t = succ(t)) 
    if (Pix(t) == i) return 1;
  return 0;
}

int <T>AVLSet::OK()
{
  int v = 1;
  if (root == 0) 
    v = count == 0;
  else
  {
    int n = 1;
    <T>AVLNode* trail = leftmost();
    <T>AVLNode* 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;
}
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