Very Simple Struct Storage System Code

import std.stdio ;
import std.algorithm;
import std.range ;
import std.bitmanip ;


alias NODEp = NODE * ;

version (alpha)
{
  class TAGREF
  {
    struct S
    {
      mixin(taggedClassRef!(
      //      mixin(taggedPointer!(
			   NODE, "p",
			   uint, "flag", 2));
    }
    NODE tag()
    {
      S *sp = new S ;
      sp.p = new NODE ;
      sp.flag = true ;
      return sp.p ;
    }
    //  return null ;
  }
}

enum PtrFlag
{
    A = 1 << 0,
    DeepRoot = 1 << 1,
    C = 1 << 2,
}

class NODE
{
  NODE left, right ;
  long data ;

  this(long v)
  { data = v ;
    writeln(__PRETTY_FUNCTION__, " Value : ", data);
  }
  void setl(NODE n)
  {
    this.left = n ;
  }
  void setr(NODE n)
  {
    this.right = n ;
  }
  
  void setd(long d)
  {
    this.data = d ;
  } 
  
  this()
  {
    writeln(__PRETTY_FUNCTION__, " ", this );
  }

  
  NODE *
  toleft()
  {
    if ( this.left !is null )
      return &this.left ;
    return null ;
  }
  NODE
  toright()
  {
    if ( this.right !is null )
      return this.right ;
    return null ;
  }

  
} ;

class CURSOR : NODE
{
   mixin(taggedClassRef!(
        NODE, "p",
        uint, "flag", 2));
  
  //  NODE p ;
  
  this(NODE set_to)
  {
    p = set_to ;
    flag = PtrFlag.DeepRoot ;
  } 
}

int
main()
{
  
  auto a = new NODE(6);
  auto b = new NODE(9);
  auto c = new NODE(11);
  b.setl(a);
  b.setr(c);
  
  b.setl = a ;
  b.setd = long.max - 1 ;
  writeln(__FUNCTION__, " B: ", b.data);
  
  foreach ( k ; [ a, b, c ] )
    writeln(k.stringof, " : ", k.data);

  auto c0 = new CURSOR(b);
  //  c0.set_to(b);
  writeln(c0.stringof, " : ", c0.p.data);
  
  auto np = &b ;
  writeln(np.stringof, " : ", np.data);

  np = np.toleft() ;

  //  np &= 1 ;
  
  writeln(np.stringof, " : ", np.data);

  writeln(np.stringof, " size : ", np.sizeof );

  np = np.toleft() ; // null
  if ( np !is null )
    writeln(np.stringof, " : ", np.data);

  //  auto tag = TAGREF.tag();

  writeln(a.stringof, " size : ", a.sizeof );

  auto q = b.toright();
  writeln(q.stringof, " : ", q.data);

  b = b.toright();
  writeln(q.stringof, " : ", q.data);

  return 0 ;
}

/* Local Variables: */
/* mode: d */
/* buffer-save-without-query: t */
/* End: */