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#pragma once
#include <util/generic/iterator_range.h>
#include <util/generic/store_policy.h>
#include <iterator>
namespace NIteratorPrivate {
template <class TIterator>
constexpr bool HasRandomAccess() {
return std::is_same_v<typename std::iterator_traits<TIterator>::iterator_category,
std::random_access_iterator_tag>;
}
}
template <class TIterator, class TMapper>
class TMappedIterator {
protected:
using TSelf = TMappedIterator<TIterator, TMapper>;
using TSrcPointerType = typename std::iterator_traits<TIterator>::reference;
using TValue = typename std::invoke_result_t<TMapper, TSrcPointerType>;
public:
using difference_type = std::ptrdiff_t;
using value_type = TValue;
using reference = TValue&;
using pointer = std::remove_reference_t<TValue>*;
using iterator_category = std::conditional_t<NIteratorPrivate::HasRandomAccess<TIterator>(),
std::random_access_iterator_tag, std::input_iterator_tag>;
TMappedIterator(TIterator it, TMapper mapper)
: Iter(it)
, Mapper(std::move(mapper))
{
}
TSelf& operator++() {
++Iter;
return *this;
}
TSelf& operator--() {
--Iter;
return *this;
}
TValue operator*() {
return Mapper((*Iter));
}
TValue operator*() const {
return Mapper((*Iter));
}
pointer operator->() const {
return &(Mapper((*Iter)));
}
TValue operator[](difference_type n) const {
return Mapper(*(Iter + n));
}
TSelf& operator+=(difference_type n) {
Iter += n;
return *this;
}
TSelf& operator-=(difference_type n) {
Iter -= n;
return *this;
}
TSelf operator+(difference_type n) const {
return TSelf(Iter + n, Mapper);
}
TSelf operator-(difference_type n) const {
return TSelf(Iter - n, Mapper);
}
difference_type operator-(const TSelf& other) const {
return Iter - other.Iter;
}
bool operator==(const TSelf& other) const {
return Iter == other.Iter;
}
bool operator!=(const TSelf& other) const {
return Iter != other.Iter;
}
bool operator>(const TSelf& other) const {
return Iter > other.Iter;
}
bool operator<(const TSelf& other) const {
return Iter < other.Iter;
}
private:
TIterator Iter;
TMapper Mapper;
};
template <class TContainer, class TMapper>
class TInputMappedRange {
protected:
using TContainerStorage = TAutoEmbedOrPtrPolicy<TContainer>;
using TMapperStorage = TAutoEmbedOrPtrPolicy<TMapper>;
using TMapperWrapper = std::reference_wrapper<std::remove_reference_t<TMapper>>;
using TInternalIterator = decltype(std::begin(std::declval<TContainer&>()));
using TIterator = TMappedIterator<TInternalIterator, TMapperWrapper>;
public:
using iterator = TIterator;
using const_iterator = TIterator;
using value_type = typename TIterator::value_type;
using reference = typename TIterator::reference;
using const_reference = typename TIterator::reference;
TInputMappedRange(TContainer&& container, TMapper&& mapper)
: Container(std::forward<TContainer>(container))
, Mapper(std::forward<TMapper>(mapper))
{
}
TIterator begin() const {
return {std::begin(*Container.Ptr()), {*Mapper.Ptr()}};
}
TIterator end() const {
return {std::end(*Container.Ptr()), {*Mapper.Ptr()}};
}
bool empty() const {
return std::begin(*Container.Ptr()) == std::end(*Container.Ptr());
}
protected:
mutable TContainerStorage Container;
mutable TMapperStorage Mapper;
};
template <class TContainer, class TMapper>
class TRandomAccessMappedRange : public TInputMappedRange<TContainer, TMapper> {
using TBase = TInputMappedRange<TContainer, TMapper>;
using TInternalIterator = typename TBase::TInternalIterator;
using TIterator = typename TBase::TIterator;
public:
using iterator = typename TBase::iterator;
using const_iterator = typename TBase::const_iterator;
using value_type = typename TBase::value_type;
using reference = typename TBase::reference;
using const_reference = typename TBase::const_reference;
using difference_type = typename std::iterator_traits<iterator>::difference_type;
using size_type = std::size_t;
TRandomAccessMappedRange(TContainer&& container, TMapper&& mapper)
: TBase(std::forward<TContainer>(container), std::forward<TMapper>(mapper))
{
}
using TBase::begin;
using TBase::end;
using TBase::empty;
size_type size() const {
return std::end(*this->Container.Ptr()) - std::begin(*this->Container.Ptr());
}
const_reference operator[](size_t at) const {
Y_ASSERT(at < this->size());
return *(this->begin() + at);
}
reference operator[](size_t at) {
Y_ASSERT(at < this->size());
return *(this->begin() + at);
}
};
template <class TIterator, class TMapper>
TMappedIterator<TIterator, TMapper> MakeMappedIterator(TIterator iter, TMapper mapper) {
return {iter, mapper};
}
template <class TIterator, class TMapper>
auto MakeMappedRange(TIterator begin, TIterator end, TMapper mapper) {
return MakeIteratorRange(MakeMappedIterator(begin, mapper), MakeMappedIterator(end, mapper));
}
template <class TContainer, class TMapper>
auto MakeMappedRange(TContainer&& container, TMapper&& mapper) {
if constexpr (NIteratorPrivate::HasRandomAccess<decltype(std::begin(container))>()) {
return TRandomAccessMappedRange<TContainer, TMapper>(std::forward<TContainer>(container), std::forward<TMapper>(mapper));
} else {
return TInputMappedRange<TContainer, TMapper>(std::forward<TContainer>(container), std::forward<TMapper>(mapper));
}
}
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