// $Id$

/*

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*/

// Implementation of generic single-linked list.

// NOTE: This list class only works correctly because we use single public
//       inheritance, as opposed to multiple inheritance or public virtual.
//       It relies on a type-unsafe cast from UTL_List to subclasses, which
//       will cease to operate correctly if you use either multiple or
//       public virtual inheritance.

#include "utl_list.h"
#include "ace/OS_Memory.h"

UTL_List::UTL_List (UTL_List *c)
  : pd_cdr_data (c)
{
}

UTL_List::~UTL_List (void)
{
}

// Compute list length.
ACE_CDR::Long
UTL_List::list_length (ACE_CDR::Long n)
{
  if (this->pd_cdr_data == 0)
    {
      return n;
    }
  else
    {
      return this->pd_cdr_data->list_length (n + 1);
    }
}

// Smash last cdr with l.
void
UTL_List::nconc (UTL_List *l)
{
  if (this->pd_cdr_data == 0)
    {
      this->pd_cdr_data = l;
    }
  else
    {
      this->pd_cdr_data->nconc (l);
    }
}

// Override this operation to copy lists of other types.
UTL_List *
UTL_List::copy (void)
{
  UTL_List *retval = 0;

  if (this->pd_cdr_data == 0)
    {
      ACE_NEW_RETURN (retval,
                      UTL_List (0),
                      0);
    }
  else
    {
      ACE_NEW_RETURN (retval,
                      UTL_List (this->pd_cdr_data->copy ()),
                      0);
    }

  return retval;
}

// Get next list.
UTL_List *
UTL_List::tail (void)
{
  return pd_cdr_data;
}

// Set next list.
void
UTL_List::set_tail (UTL_List *l)
{
  this->pd_cdr_data->destroy ();
  delete this->pd_cdr_data;
  this->pd_cdr_data = l;
}

// Compute list length.
ACE_CDR::Long
UTL_List::length (void)
{
  return list_length (1);
}

void
UTL_List::destroy (void)
{
  if (this->pd_cdr_data != 0)
    {
      this->pd_cdr_data->destroy ();
      delete this->pd_cdr_data;
      this->pd_cdr_data = 0;
    }
}

// UTL_List active iterator.

UTL_ListActiveIterator::UTL_ListActiveIterator (UTL_List *s)
  : source (s)
{
}

// Is iterator done?
bool
UTL_ListActiveIterator::is_done (void)
{
  return (this->source == 0) ? true : false;
}

// Advance to next item.
void
UTL_ListActiveIterator::next (void)
{
  if (this->source != 0)
    {
      this->source = this->source->tail ();
    }
}