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Filename : seq_index_ops.hpp
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/* Copyright 2003-2020 Joaquin M Lopez Munoz.
 * 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_SEQ_INDEX_OPS_HPP
#define BOOST_MULTI_INDEX_DETAIL_SEQ_INDEX_OPS_HPP

#if defined(_MSC_VER)
#pragma once
#endif

#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
#include <boost/core/no_exceptions_support.hpp>
#include <boost/multi_index/detail/seq_index_node.hpp>
#include <boost/limits.hpp>
#include <boost/type_traits/aligned_storage.hpp>
#include <boost/type_traits/alignment_of.hpp> 
#include <cstddef>

namespace boost{

namespace multi_index{

namespace detail{

/* Common code for sequenced_index memfuns having templatized and
 * non-templatized versions.
 */

template <typename SequencedIndex,typename Predicate>
void sequenced_index_remove(SequencedIndex& x,Predicate pred)
{
  typedef typename SequencedIndex::iterator iterator;
  iterator first=x.begin(),last=x.end();
  while(first!=last){
    if(pred(*first))x.erase(first++);
    else ++first;
  }
}

template <typename SequencedIndex,class BinaryPredicate>
void sequenced_index_unique(SequencedIndex& x,BinaryPredicate binary_pred)
{
  typedef typename SequencedIndex::iterator iterator;
  iterator first=x.begin();
  iterator last=x.end();
  if(first!=last){
    for(iterator middle=first;++middle!=last;middle=first){
      if(binary_pred(*middle,*first))x.erase(middle);
      else first=middle;
    }
  }
}

template <typename SequencedIndex,typename Compare>
void sequenced_index_merge(SequencedIndex& x,SequencedIndex& y,Compare comp)
{
  typedef typename SequencedIndex::iterator iterator;
  if(&x!=&y){
    iterator first0=x.begin(),last0=x.end();
    iterator first1=y.begin(),last1=y.end();
    while(first0!=last0&&first1!=last1){
      if(comp(*first1,*first0))x.splice(first0,y,first1++);
      else ++first0;
    }
    x.splice(last0,y,first1,last1);
  }
}

/* sorting  */

/* auxiliary stuff */

template<typename Node,typename Compare>
void sequenced_index_collate(
  BOOST_DEDUCED_TYPENAME Node::impl_type* x,
  BOOST_DEDUCED_TYPENAME Node::impl_type* y,
  Compare comp)
{
  typedef typename Node::impl_type    impl_type;
  typedef typename Node::impl_pointer impl_pointer;

  impl_pointer first0=x->next();
  impl_pointer last0=x;
  impl_pointer first1=y->next();
  impl_pointer last1=y;
  while(first0!=last0&&first1!=last1){
    if(comp(
        Node::from_impl(first1)->value(),Node::from_impl(first0)->value())){
      impl_pointer tmp=first1->next();
      impl_type::relink(first0,first1);
      first1=tmp;
    }
    else first0=first0->next();
  }
  impl_type::relink(last0,first1,last1);
}

/* Some versions of CGG require a bogus typename in counter_spc
 * inside sequenced_index_sort if the following is defined
 * also inside sequenced_index_sort.
 */

BOOST_STATIC_CONSTANT(
  std::size_t,
  sequenced_index_sort_max_fill=
    (std::size_t)std::numeric_limits<std::size_t>::digits+1);

#include <boost/multi_index/detail/ignore_wstrict_aliasing.hpp>

template<typename Node,typename Compare>
void sequenced_index_sort(Node* header,Compare comp)
{
  /* Musser's mergesort, see http://www.cs.rpi.edu/~musser/gp/List/lists1.html.
   * The implementation is a little convoluted: in the original code
   * counter elements and carry are std::lists: here we do not want
   * to use multi_index instead, so we do things at a lower level, managing
   * directly the internal node representation.
   * Incidentally, the implementations I've seen of this algorithm (SGI,
   * Dinkumware, STLPort) are not exception-safe: this is. Moreover, we do not
   * use any dynamic storage.
   */

  if(header->next()==header->impl()||
     header->next()->next()==header->impl())return;

  typedef typename Node::impl_type      impl_type;
  typedef typename Node::impl_pointer   impl_pointer;

  typedef typename aligned_storage<
    sizeof(impl_type),
    alignment_of<impl_type>::value
  >::type                               carry_spc_type;
  carry_spc_type                        carry_spc;
  impl_type&                            carry=
    *reinterpret_cast<impl_type*>(&carry_spc);
  typedef typename aligned_storage<
    sizeof(
      impl_type
        [sequenced_index_sort_max_fill]),
    alignment_of<
      impl_type
        [sequenced_index_sort_max_fill]
    >::value
  >::type                               counter_spc_type;
  counter_spc_type                      counter_spc;
  impl_type*                            counter=
    reinterpret_cast<impl_type*>(&counter_spc);
  std::size_t                           fill=0;

  carry.prior()=carry.next()=static_cast<impl_pointer>(&carry);
  counter[0].prior()=counter[0].next()=static_cast<impl_pointer>(&counter[0]);

  BOOST_TRY{
    while(header->next()!=header->impl()){
      impl_type::relink(carry.next(),header->next());
      std::size_t i=0;
      while(i<fill&&counter[i].next()!=static_cast<impl_pointer>(&counter[i])){
        sequenced_index_collate<Node>(&carry,&counter[i++],comp);
      }
      impl_type::swap(
        static_cast<impl_pointer>(&carry),
        static_cast<impl_pointer>(&counter[i]));
      if(i==fill){
        ++fill;
        counter[fill].prior()=counter[fill].next()=
          static_cast<impl_pointer>(&counter[fill]);
      }
    }

    for(std::size_t i=1;i<fill;++i){
      sequenced_index_collate<Node>(&counter[i],&counter[i-1],comp);
    }
    impl_type::swap(
      header->impl(),static_cast<impl_pointer>(&counter[fill-1]));
  }
  BOOST_CATCH(...)
  {
    impl_type::relink(
      header->impl(),carry.next(),static_cast<impl_pointer>(&carry));
    for(std::size_t i=0;i<=fill;++i){
      impl_type::relink(
        header->impl(),counter[i].next(),
        static_cast<impl_pointer>(&counter[i]));
    }
    BOOST_RETHROW;
  }
  BOOST_CATCH_END
}

#include <boost/multi_index/detail/restore_wstrict_aliasing.hpp>

} /* namespace multi_index::detail */

} /* namespace multi_index */

} /* namespace boost */

#endif