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July 23, 2020 16:57
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Create a function returnable range collection.
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#include <boost/utility/base_from_member.hpp> | |
#include <boost/range/any_range.hpp> | |
#include <boost/iterator/iterator_traits.hpp> | |
#include <any> | |
#include <type_traits> | |
template<typename T, typename Traversal = boost::forward_traversal_tag> | |
struct collection : boost::base_from_member<std::any>, | |
boost::base_from_member<std::function<boost::any_range<T, Traversal>(std::any&)>>, | |
boost::any_range<T, Traversal> { | |
using AnyBase = boost::base_from_member<std::any>; | |
using RangeMakerBase = boost::base_from_member<std::function<boost::any_range<T, Traversal>(std::any&)>>; | |
using RangeBase = boost::any_range<T, Traversal>; | |
collection() = default; | |
template<typename Collection> | |
collection(Collection&& c) : | |
AnyBase{std::forward<Collection>(c)}, | |
RangeMakerBase{[](std::any& any) -> boost::any_range<T, Traversal> { | |
return {*std::any_cast<std::remove_reference_t<Collection>>(std::addressof(any))}; }}, | |
RangeBase{this->RangeMakerBase::member(this->AnyBase::member)} | |
{} | |
template<typename Collection> | |
collection& operator=(Collection&& c) { | |
this->AnyBase::member.emplace<Collection>(std::forward<Collection>(c)); | |
this->RangeMakerBase::member = [] (std::any& any) -> boost::any_range<T, Traversal> { return {*std::any_cast<std::remove_reference_t<Collection>>(std::addressof(any))}; }; | |
this->assign(this->RangeMakerBase::member(this->AnyBase::member)); | |
return *this; | |
} | |
collection(collection&& oth) : | |
AnyBase{std::move(oth.AnyBase::member)}, | |
RangeMakerBase{std::move(oth.RangeMakerBase::member)}, | |
RangeBase{this->RangeMakerBase::member(this->AnyBase::member)} | |
{} | |
collection& operator=(collection&& oth) { | |
this->AnyBase::member = std::move(oth.AnyBase::member); | |
this->RangeMakerBase::member = std::move(oth.RangeMakerBase::member); | |
this->assign(this->RangeMakerBase::member(this->AnyBase::member)); | |
return *this; | |
} | |
collection(const collection& oth) = delete; | |
collection& operator=(const collection& oth) = delete; | |
}; | |
template<typename Collection> | |
collection(Collection&& c) -> collection<typename boost::iterator_value<decltype(boost::begin(std::declval<Collection&>()))>::type>; | |
template<typename Traversal = void, typename Collection> | |
collection<typename boost::iterator_value<decltype(boost::begin(std::declval<Collection&>()))>::type, | |
std::conditional_t<std::is_void_v<Traversal>, | |
typename boost::iterator_traversal<decltype(boost::begin(std::declval<Collection&>()))>::type, Traversal>> | |
make_collection(Collection&& c) { | |
return {std::forward<Collection>(c)}; | |
} |
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