boost/multi_index/detail/duplicates_iterator.hpp
/* Copyright 2003-2008 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_DUPLICATES_ITERATOR_HPP
#define BOOST_MULTI_INDEX_DETAIL_DUPLICATES_ITERATOR_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 <cstddef>
#include <iterator>
namespace boost{
namespace multi_index{
namespace detail{
/* duplicates_operator is given a range of ordered elements and
* passes only over those which are duplicated.
*/
template<typename Node,typename Predicate>
class duplicates_iterator
{
public:
typedef typename Node::value_type value_type;
typedef std::ptrdiff_t difference_type;
typedef const typename Node::value_type* pointer;
typedef const typename Node::value_type& reference;
typedef std::forward_iterator_tag iterator_category;
duplicates_iterator(Node* node_,Node* end_,Predicate pred_):
node(node_),begin_chunk(0),end(end_),pred(pred_)
{
advance();
}
duplicates_iterator(Node* end_,Predicate pred_):
node(end_),begin_chunk(end_),end(end_),pred(pred_)
{
}
reference operator*()const
{
return node->value();
}
pointer operator->()const
{
return &node->value();
}
duplicates_iterator& operator++()
{
Node::increment(node);
sync();
return *this;
}
duplicates_iterator operator++(int)
{
duplicates_iterator tmp(*this);
++(*this);
return tmp;
}
Node* get_node()const{return node;}
private:
void sync()
{
if(node!=end&&pred(begin_chunk->value(),node->value()))advance();
}
void advance()
{
for(Node* node2=node;node!=end;node=node2){
Node::increment(node2);
if(node2!=end&&!pred(node->value(),node2->value()))break;
}
begin_chunk=node;
}
Node* node;
Node* begin_chunk;
Node* end;
Predicate pred;
};
template<typename Node,typename Predicate>
bool operator==(
const duplicates_iterator<Node,Predicate>& x,
const duplicates_iterator<Node,Predicate>& y)
{
return x.get_node()==y.get_node();
}
template<typename Node,typename Predicate>
bool operator!=(
const duplicates_iterator<Node,Predicate>& x,
const duplicates_iterator<Node,Predicate>& y)
{
return !(x==y);
}
} /* namespace multi_index::detail */
} /* namespace multi_index */
} /* namespace boost */
#endif