/* Copyright 2016-2017 Joaquin M Lopez Munoz.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org/libs/poly_collection for library home page.
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*/
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#ifndef BOOST_POLY_COLLECTION_DETAIL_SEGMENT_SPLIT_HPP
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#define BOOST_POLY_COLLECTION_DETAIL_SEGMENT_SPLIT_HPP
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/poly_collection/detail/iterator_traits.hpp>
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#include <typeinfo>
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#include <utility>
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namespace boost{
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namespace poly_collection{
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namespace detail{
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/* breakdown of an iterator range into local_base_iterator segments */
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template<typename PolyCollectionIterator>
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class segment_splitter
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{
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using traits=iterator_traits<PolyCollectionIterator>;
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using local_base_iterator=typename traits::local_base_iterator;
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using base_segment_info_iterator=typename traits::base_segment_info_iterator;
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public:
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struct info
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{
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const std::type_info& type_info()const noexcept{return *pinfo_;}
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local_base_iterator begin()const noexcept{return begin_;}
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local_base_iterator end()const noexcept{return end_;}
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const std::type_info* pinfo_;
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local_base_iterator begin_,end_;
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};
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struct iterator:iterator_facade<iterator,info,std::input_iterator_tag,info>
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{
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iterator()=default;
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private:
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friend class segment_splitter;
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friend class boost::iterator_core_access;
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iterator(
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base_segment_info_iterator it,
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const PolyCollectionIterator& first,const PolyCollectionIterator& last):
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it{it},pfirst{&first},plast{&last}{}
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iterator(
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const PolyCollectionIterator& first,const PolyCollectionIterator& last):
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it{traits::base_segment_info_iterator_from(first)},
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pfirst{&first},plast{&last}
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{}
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info dereference()const noexcept
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{
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return {
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&it->type_info(),
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it==traits::base_segment_info_iterator_from(*pfirst)?
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traits::local_base_iterator_from(*pfirst):it->begin(),
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it==traits::base_segment_info_iterator_from(*plast)?
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traits::local_base_iterator_from(*plast):it->end()
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};
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}
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bool equal(const iterator& x)const noexcept{return it==x.it;}
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void increment()noexcept{++it;}
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base_segment_info_iterator it;
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const PolyCollectionIterator* pfirst;
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const PolyCollectionIterator* plast;
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};
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segment_splitter(
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const PolyCollectionIterator& first,const PolyCollectionIterator& last):
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pfirst{&first},plast{&last}{}
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iterator begin()const noexcept{return {*pfirst,*plast};}
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iterator end()const noexcept
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{
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auto slast=traits::base_segment_info_iterator_from(*plast);
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if(slast!=traits::end_base_segment_info_iterator_from(*plast))++slast;
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return {slast,*plast,*plast};
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}
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private:
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const PolyCollectionIterator* pfirst;
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const PolyCollectionIterator* plast;
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};
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template<typename PolyCollectionIterator>
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segment_splitter<PolyCollectionIterator>
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segment_split(
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const PolyCollectionIterator& first,const PolyCollectionIterator& last)
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{
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return {first,last};
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}
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#if 1
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/* equivalent to for(auto i:segment_split(first,last))f(i) */
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template<typename PolyCollectionIterator,typename F>
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void for_each_segment(
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const PolyCollectionIterator& first,const PolyCollectionIterator& last,F&& f)
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{
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using traits=iterator_traits<PolyCollectionIterator>;
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using info=typename segment_splitter<PolyCollectionIterator>::info;
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auto sfirst=traits::base_segment_info_iterator_from(first),
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slast=traits::base_segment_info_iterator_from(last),
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send=traits::end_base_segment_info_iterator_from(last);
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auto lbfirst=traits::local_base_iterator_from(first),
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lblast=traits::local_base_iterator_from(last);
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if(sfirst!=slast){
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for(;;){
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f(info{&sfirst->type_info(),lbfirst,sfirst->end()});
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++sfirst;
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if(sfirst==slast)break;
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lbfirst=sfirst->begin();
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}
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if(sfirst!=send)f(info{&sfirst->type_info(),sfirst->begin(),lblast});
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}
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else if(sfirst!=send){
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f(info{&sfirst->type_info(),lbfirst,lblast});
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}
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}
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#else
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template<typename PolyCollectionIterator,typename F>
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void for_each_segment(
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const PolyCollectionIterator& first,const PolyCollectionIterator& last,F&& f)
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{
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for(auto i:segment_split(first,last))f(i);
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}
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#endif
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} /* namespace poly_collection::detail */
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} /* namespace poly_collection */
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} /* namespace boost */
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#endif
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