/* Copyright 2003-2006 Joaquín M López Muñoz.

 * Distributed under the Boost Software License, Version 1.0.

 * (See accompanying file LICENSE_1_0.txt or copy at

 * http://www.boost.org/LICENSE_1_0.txt)

 *

 * See http://www.boost.org/libs/multi_index for library home page.

 */

#ifndef BOOST_MULTI_INDEX_DETAIL_RND_INDEX_NODE_HPP

#define BOOST_MULTI_INDEX_DETAIL_RND_INDEX_NODE_HPP

#if defined(_MSC_VER)&&(_MSC_VER>=1200)

#pragma once

#endif

#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */

#include <algorithm>

#include <boost/math/common_factor_rt.hpp>

#include <cstddef>

#include <functional>

namespace boost{

namespace multi_index{

namespace detail{

struct random_access_index_node_impl

{

  random_access_index_node_impl**& up(){return up_;}

  random_access_index_node_impl**  up()const{return up_;}

  /* interoperability with rnd_node_iterator */

  static void increment(random_access_index_node_impl*& x)

  {

    x=*(x->up()+1);

  }

  static void decrement(random_access_index_node_impl*& x)

  {

    x=*(x->up()-1);

  }

  static void advance(

    random_access_index_node_impl*& x,std::ptrdiff_t n)

  {

    x=*(x->up()+n);

  }

  static std::ptrdiff_t distance(

    random_access_index_node_impl* x,random_access_index_node_impl* y)

  {

    return y->up()-x->up();

  }

  /* algorithmic stuff */

  static void relocate(

    random_access_index_node_impl** pos,

    random_access_index_node_impl** x)

  {

    random_access_index_node_impl* n=*x;

    if(x<pos){

      extract(x,pos);

      *(pos-1)=n;

      n->up()=pos-1;

    }

    else{

      while(x!=pos){

        *x=*(x-1);

        (*x)->up()=x;

        --x;

      }

      *pos=n;

      n->up()=pos;

    }

  };

  static void relocate(

    random_access_index_node_impl** pos,

    random_access_index_node_impl** first,

    random_access_index_node_impl** last)

  {

    random_access_index_node_impl** begin,**middle,**end;

    if(pos<first){

      begin=pos;

      middle=first;

      end=last;

    }

    else{

      begin=first;

      middle=last;

      end=pos;

    }

    std::ptrdiff_t n=end-begin;

    std::ptrdiff_t m=middle-begin;

    std::ptrdiff_t n_m=n-m;

    std::ptrdiff_t p=math::gcd(n,m);

    for(std::ptrdiff_t i=0;i<p;++i){

      random_access_index_node_impl* tmp=begin[i];

      for(std::ptrdiff_t j=i,k;;){

        if(j<n_m)k=j+m;

        else     k=j-n_m;

        if(k==i){

          begin[j]=tmp;

          begin[j]->up()=&begin[j];

          break;

        }

        else{

          begin[j]=begin[k];

          begin[j]->up()=&begin[j];

        }

        if(k<n_m)j=k+m;

        else     j=k-n_m;

        if(j==i){

          begin[k]=tmp;

          begin[k]->up()=&begin[k];

          break;

        }

        else{

          begin[k]=begin[j];

          begin[k]->up()=&begin[k];

        }

      }

    }

  };

  static void extract(

    random_access_index_node_impl** x,

    random_access_index_node_impl** pend)

  {

    --pend;

    while(x!=pend){

      *x=*(x+1);

      (*x)->up()=x;

      ++x;

    }

  }

  static void transfer(

    random_access_index_node_impl** pbegin0,

    random_access_index_node_impl** pend0,

    random_access_index_node_impl** pbegin1)

  {

    while(pbegin0!=pend0){

      *pbegin1=*pbegin0++;

      (*pbegin1)->up()=pbegin1;

      ++pbegin1;

    }

  }

  static void reverse(

    random_access_index_node_impl** pbegin,

    random_access_index_node_impl** pend)

  {

    std::ptrdiff_t d=(pend-pbegin)/2;

    for(std::ptrdiff_t i=0;i<d;++i){

      std::swap(*pbegin,*--pend);

      (*pbegin)->up()=pbegin;

      (*pend)->up()=pend;

      ++pbegin;

    }

  }

private:

  random_access_index_node_impl** up_;

};

template<typename Super>

struct random_access_index_node_trampoline:random_access_index_node_impl{};

template<typename Super>

struct random_access_index_node:

  Super,random_access_index_node_trampoline<Super>

{

  random_access_index_node_impl**& up(){return impl_type::up();}

  random_access_index_node_impl**  up()const{return impl_type::up();}

  random_access_index_node_impl*       impl()

    {return static_cast<impl_type*>(this);}

  const random_access_index_node_impl* impl()const

    {return static_cast<const impl_type*>(this);}

  static random_access_index_node* from_impl(random_access_index_node_impl *x)

  {

    return static_cast<random_access_index_node*>(

      static_cast<impl_type*>(x));

  }

  static const random_access_index_node* from_impl(

    const random_access_index_node_impl* x)

  {

    return static_cast<const random_access_index_node*>(

      static_cast<const impl_type*>(x));

  }

  /* interoperability with rnd_node_iterator */

  static void increment(random_access_index_node*& x)

  {

    random_access_index_node_impl* xi=x->impl();

    impl_type::increment(xi);

    x=from_impl(xi);

  }

  static void decrement(random_access_index_node*& x)

  {

    random_access_index_node_impl* xi=x->impl();

    impl_type::decrement(xi);

    x=from_impl(xi);

  }

  static void advance(random_access_index_node*& x,std::ptrdiff_t n)

  {

    random_access_index_node_impl* xi=x->impl();

    impl_type::advance(xi,n);

    x=from_impl(xi);

  }

  static std::ptrdiff_t distance(

    random_access_index_node* x,random_access_index_node* y)

  {

    return impl_type::distance(x->impl(),y->impl());

  }

private:

  typedef random_access_index_node_trampoline<Super> impl_type;

};

} /* namespace multi_index::detail */

} /* namespace multi_index */

} /* namespace boost */

#endif