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// -*- C++ -*-

// Copyright (C) 2005, 2006, 2009 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_base.hpp

 * Contains an implementation of trie_policy_base.

 */

#ifndef PB_DS_TRIE_POLICY_BASE_HPP

#define PB_DS_TRIE_POLICY_BASE_HPP

#include <ext/pb_ds/detail/basic_tree_policy/basic_tree_policy_base.hpp>

namespace __gnu_pbds

{

  namespace detail

  {

#define PB_DS_CLASS_T_DEC                                               \

    template<                                                           \

                                                class Const_Node_Iterator, \

                                                class Node_Iterator,    \

                                                class E_Access_Traits,  \

                                                typename Allocator>

#define PB_DS_CLASS_C_DEC                                               \

    trie_policy_base<                                                   \

                                                Const_Node_Iterator,    \

                                                Node_Iterator,          \

                                                E_Access_Traits,        \

                                                Allocator>

#define PB_DS_BASE_C_DEC                                                \

    basic_tree_policy_base<                             \

                                                                Const_Node_Iterator, \

                                                                Node_Iterator, \

                                                                Allocator>

    template<typename Const_Node_Iterator,

             class Node_Iterator,

             class E_Access_Traits,

             class Allocator>

    class trie_policy_base : public PB_DS_BASE_C_DEC

    {

    public:

      typedef E_Access_Traits e_access_traits;

      typedef Allocator allocator_type;

      typedef typename allocator_type::size_type size_type;

      typedef null_node_metadata metadata_type;

      typedef Const_Node_Iterator const_node_iterator;

      typedef Node_Iterator node_iterator;

      typedef typename const_node_iterator::value_type const_iterator;

      typedef typename node_iterator::value_type iterator;

    public:

      typedef typename PB_DS_BASE_C_DEC::key_type key_type;

      typedef

      typename PB_DS_BASE_C_DEC::const_key_reference

      const_key_reference;

    protected:

      virtual const_iterator

      end() const = 0;

      virtual iterator

      end() = 0;

      virtual const_node_iterator

      node_begin() const = 0;

      virtual node_iterator

      node_begin() = 0;

      virtual const_node_iterator

      node_end() const = 0;

      virtual node_iterator

      node_end() = 0;

      virtual const e_access_traits&

      get_e_access_traits() const = 0;

    private:

      typedef

      std::pair<

      typename e_access_traits::const_iterator,

      typename e_access_traits::const_iterator>

      prefix_range_t;

      typedef PB_DS_BASE_C_DEC base_type;

    protected:

      static size_type

      common_prefix_len(node_iterator nd_it, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits);

      static iterator

      leftmost_it(node_iterator nd_it);

      static iterator

      rightmost_it(node_iterator nd_it);

      static bool

      less(typename e_access_traits::const_iterator b_l, typename e_access_traits::const_iterator e_l, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits);

    };

    PB_DS_CLASS_T_DEC

    typename PB_DS_CLASS_C_DEC::size_type

    PB_DS_CLASS_C_DEC::

    common_prefix_len(node_iterator nd_it, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits)

    {

      prefix_range_t pref_range = nd_it.valid_prefix();

      typename e_access_traits::const_iterator b_l = pref_range.first;

      typename e_access_traits::const_iterator e_l = pref_range.second;

      const size_type range_length_l =

        std::distance(b_l, e_l);

      const size_type range_length_r =

        std::distance(b_r, e_r);

      if (range_length_r < range_length_l)

        {

          std::swap(b_l, b_r);

          std::swap(e_l, e_r);

        }

      size_type ret = 0;

      while (b_l != e_l)

        {

          if (r_traits.e_pos(*b_l) != r_traits.e_pos(*b_r))

            return (ret);

          ++ret;

          ++b_l;

          ++b_r;

        }

      return (ret);

    }

    PB_DS_CLASS_T_DEC

    typename PB_DS_CLASS_C_DEC::iterator

    PB_DS_CLASS_C_DEC::

    leftmost_it(node_iterator nd_it)

    {

      if (nd_it.num_children() == 0)

        return (*nd_it);

      return (leftmost_it(nd_it.get_child(0)));

    }

    PB_DS_CLASS_T_DEC

    typename PB_DS_CLASS_C_DEC::iterator

    PB_DS_CLASS_C_DEC::

    rightmost_it(node_iterator nd_it)

    {

      const size_type num_children = nd_it.num_children();

      if (num_children == 0)

        return (*nd_it);

      return (rightmost_it(nd_it.get_child(num_children - 1)));

    }

    PB_DS_CLASS_T_DEC

    bool

    PB_DS_CLASS_C_DEC::

    less(typename e_access_traits::const_iterator b_l, typename e_access_traits::const_iterator e_l, typename e_access_traits::const_iterator b_r, typename e_access_traits::const_iterator e_r, const e_access_traits& r_traits)

    {

      while (b_l != e_l)

        {

          if (b_r == e_r)

            return (false);

          size_type l_pos =

            r_traits.e_pos(*b_l);

          size_type r_pos =

            r_traits.e_pos(*b_r);

          if (l_pos != r_pos)

            return (l_pos < r_pos);

          ++b_l;

          ++b_r;

        }

      return (b_r != e_r);

    }

#undef PB_DS_CLASS_T_DEC

#undef PB_DS_CLASS_C_DEC

#undef PB_DS_BASE_C_DEC

  } // namespace detail

} // namespace __gnu_pbds

#endif // #ifndef PB_DS_TRIE_POLICY_BASE_HPP