text: // -*- C++ -*-
  
  // Copyright (C) 2005-2013 Free Software Foundation, Inc.
  //
  // This file is part of the GNU ISO C++ Library.  This library is free
  // software; you can redistribute it and/or modify it under the terms
  // of the GNU General Public License as published by the Free Software
  // Foundation; either version 3, or (at your option) any later
  // version.
  
  // This library is distributed in the hope that it will be useful, but
  // WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // General Public License for more details.
  
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  
  // Permission to use, copy, modify, sell, and distribute this software
  // is hereby granted without fee, provided that the above copyright
  // notice appears in all copies, and that both that copyright notice
  // and this permission notice appear in supporting documentation. None
  // of the above authors, nor IBM Haifa Research Laboratories, make any
  // representation about the suitability of this software for any
  // purpose. It is provided "as is" without express or implied
  // warranty.
  
  /**
   * @file trie_policy/order_statistics_imp.hpp
   * Contains forward declarations for order_statistics_key
   */
  
  PB_DS_CLASS_T_DEC
  inline typename PB_DS_CLASS_C_DEC::iterator
  PB_DS_CLASS_C_DEC::
  find_by_order(size_type order)
  {
    if (empty())
      return end();
  
    ++order;
    node_iterator nd_it = node_begin();
  
    while (true)
      {
        if (order > nd_it.get_metadata())
  	return ++base_type::rightmost_it(nd_it);
  
        const size_type num_children = nd_it.num_children();
        if (num_children == 0)
  	return *nd_it;
  
        for (size_type i = 0; i < num_children; ++i)
  	{
  	  node_iterator child_nd_it = nd_it.get_child(i);
  	  if (order <= child_nd_it.get_metadata())
  	    {
  	      i = num_children;
  	      nd_it = child_nd_it;
  	    }
  	  else
  	    order -= child_nd_it.get_metadata();
  	}
      }
  }
  
  PB_DS_CLASS_T_DEC
  inline typename PB_DS_CLASS_C_DEC::const_iterator
  PB_DS_CLASS_C_DEC::
  find_by_order(size_type order) const
  { return const_cast<PB_DS_CLASS_C_DEC*>(this)->find_by_order(order); }
  
  PB_DS_CLASS_T_DEC
  inline typename PB_DS_CLASS_C_DEC::size_type
  PB_DS_CLASS_C_DEC::
  order_of_key(key_const_reference r_key) const
  {
    const _ATraits& r_traits =
      const_cast<PB_DS_CLASS_C_DEC* >(this)->get_access_traits();
  
    return order_of_prefix(r_traits.begin(r_key), r_traits.end(r_key));
  }
  
  PB_DS_CLASS_T_DEC
  inline typename PB_DS_CLASS_C_DEC::size_type
  PB_DS_CLASS_C_DEC::
  order_of_prefix(typename access_traits::const_iterator b,
  		typename access_traits::const_iterator e) const
  {
    if (empty())
      return 0;
  
    const _ATraits& r_traits =
      const_cast<PB_DS_CLASS_C_DEC*>(this)->get_access_traits();
  
    node_const_iterator nd_it = node_begin();
    node_const_iterator end_nd_it = node_end();
    size_type ord = 0;
  
    while (true)
      {
        const size_type num_children = nd_it.num_children();
        if (num_children == 0)
  	{
  	  key_const_reference r_key = base_type::extract_key(*(*nd_it));
  	  typename access_traits::const_iterator key_b =
  	    r_traits.begin(r_key);
  
  	  typename access_traits::const_iterator key_e =
  	    r_traits.end(r_key);
  
  	  return (base_type::less(key_b, key_e,  b, e,  r_traits)) ?
  		  ord + 1 : ord;
  	}
  
        node_const_iterator next_nd_it = end_nd_it;
        size_type i = num_children - 1;
  
        do
  	{
  	  node_const_iterator child_nd_it = nd_it.get_child(i);
  
  	  if (next_nd_it != end_nd_it)
  	    ord += child_nd_it.get_metadata();
  	  else if (!base_type::less(b, e,
  				    child_nd_it.valid_prefix().first,
  				    child_nd_it.valid_prefix().second,
  				    r_traits))
  	    next_nd_it = child_nd_it;
  	}
        while (i-- > 0);
  
        if (next_nd_it == end_nd_it)
  	return ord;
  
        nd_it = next_nd_it;
      }
  }
  
  PB_DS_CLASS_T_DEC
  inline void
  PB_DS_CLASS_C_DEC::
  operator()(node_iterator nd_it, node_const_iterator /*end_nd_it*/) const
  {
    const size_type num_children = nd_it.num_children();
    size_type children_rank = 0;
    for (size_type i = 0; i < num_children; ++i)
      children_rank += nd_it.get_child(i).get_metadata();
  
    const size_type res = (num_children == 0) ? 1 : children_rank;
    const_cast<size_type&>(nd_it.get_metadata()) = res;
  }
  