/usr/include/range/v3/view/concat.hpp is in librange-v3-dev 0.3.5-1.
This file is owned by root:root, with mode 0o644.
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// Range v3 library
//
// Copyright Eric Niebler 2013-2014.
//
// Use, modification and distribution is subject to 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)
//
// Project home: https://github.com/ericniebler/range-v3
//
#ifndef RANGES_V3_VIEW_CONCAT_HPP
#define RANGES_V3_VIEW_CONCAT_HPP
#include <tuple>
#include <utility>
#include <type_traits>
#include <meta/meta.hpp>
#include <range/v3/detail/satisfy_boost_range.hpp>
#include <range/v3/range_fwd.hpp>
#include <range/v3/size.hpp>
#include <range/v3/begin_end.hpp>
#include <range/v3/range_traits.hpp>
#include <range/v3/range_concepts.hpp>
#include <range/v3/view_facade.hpp>
#include <range/v3/utility/variant.hpp>
#include <range/v3/utility/iterator.hpp>
#include <range/v3/utility/functional.hpp>
#include <range/v3/utility/tuple_algorithm.hpp>
#include <range/v3/utility/static_const.hpp>
#include <range/v3/view/all.hpp>
namespace ranges
{
inline namespace v3
{
/// \cond
namespace detail
{
template<typename State, typename Value>
using concat_cardinality_ =
std::integral_constant<cardinality,
State::value == infinite || Value::value == infinite ?
infinite :
State::value == unknown || Value::value == unknown ?
unknown :
State::value == finite || Value::value == finite ?
finite :
static_cast<cardinality>(State::value + Value::value)>;
template<typename... Rngs>
using concat_cardinality = meta::fold<
meta::list<range_cardinality<Rngs>...>,
std::integral_constant<cardinality, static_cast<cardinality>(0)>,
meta::quote<concat_cardinality_>>;
}
/// \endcond
/// \addtogroup group-views
/// @{
template<typename...Rngs>
struct concat_view
: view_facade<concat_view<Rngs...>,
detail::concat_cardinality<Rngs...>::value>
{
private:
friend range_access;
using difference_type_ = common_type_t<range_difference_type_t<Rngs>...>;
using size_type_ = meta::_t<std::make_unsigned<difference_type_>>;
static constexpr std::size_t cranges{sizeof...(Rngs)};
std::tuple<Rngs...> rngs_;
template<bool IsConst>
struct cursor;
template<bool IsConst>
struct sentinel
{
private:
friend struct cursor<IsConst>;
template<typename T>
using constify_if = meta::const_if_c<IsConst, T>;
using concat_view_t = constify_if<concat_view>;
sentinel_t<constify_if<meta::back<meta::list<Rngs...>>>> end_;
public:
sentinel() = default;
sentinel(concat_view_t &rng, end_tag)
: end_(end(std::get<cranges - 1>(rng.rngs_)))
{}
};
template<bool IsConst>
struct cursor
{
using difference_type = common_type_t<range_difference_type_t<Rngs>...>;
private:
template<typename T>
using constify_if = meta::const_if_c<IsConst, T>;
using concat_view_t = constify_if<concat_view>;
concat_view_t *rng_;
variant<iterator_t<constify_if<Rngs>>...> its_;
template<std::size_t N>
void satisfy(meta::size_t<N>)
{
RANGES_EXPECT(its_.index() == N);
if(ranges::get<N>(its_) == end(std::get<N>(rng_->rngs_)))
{
ranges::emplace<N + 1>(its_, begin(std::get<N + 1>(rng_->rngs_)));
this->satisfy(meta::size_t<N + 1>{});
}
}
void satisfy(meta::size_t<cranges - 1>)
{
RANGES_EXPECT(its_.index() == cranges - 1);
}
struct next_fun
{
cursor *pos;
template<typename I, std::size_t N,
CONCEPT_REQUIRES_(Iterator<I>())>
void operator()(indexed_element<I, N> it) const
{
RANGES_ASSERT(it.get() != end(std::get<N>(pos->rng_->rngs_)));
++it.get();
pos->satisfy(meta::size_t<N>{});
}
};
struct prev_fun
{
cursor *pos;
template<typename I,
CONCEPT_REQUIRES_(BidirectionalIterator<I>())>
void operator()(indexed_element<I, 0> it) const
{
RANGES_ASSERT(it.get() != begin(std::get<0>(pos->rng_->rngs_)));
--it.get();
}
template<typename I, std::size_t N,
CONCEPT_REQUIRES_(N != 0 && BidirectionalIterator<I>())>
void operator()(indexed_element<I, N> it) const
{
if(it.get() == begin(std::get<N>(pos->rng_->rngs_)))
{
auto &&rng = std::get<N - 1>(pos->rng_->rngs_);
ranges::emplace<N - 1>(pos->its_,
ranges::next(ranges::begin(rng), ranges::end(rng)));
pos->its_.visit_i(*this);
}
else
--it.get();
}
};
struct advance_fwd_fun
{
cursor *pos;
difference_type n;
template<typename I,
CONCEPT_REQUIRES_(RandomAccessIterator<I>())>
void operator()(indexed_element<I, cranges - 1> it) const
{
ranges::advance(it.get(), n);
}
template<typename I, std::size_t N,
CONCEPT_REQUIRES_(RandomAccessIterator<I>())>
void operator()(indexed_element<I, N> it) const
{
auto end = ranges::end(std::get<N>(pos->rng_->rngs_));
// BUGBUG If distance(it, end) > n, then using bounded advance
// is O(n) when it need not be since the end iterator position
// is actually not interesting. Only the "rest" is needed, which
// can sometimes be O(1).
auto rest = ranges::advance(it.get(), n, std::move(end));
pos->satisfy(meta::size_t<N>{});
if(rest != 0)
pos->its_.visit_i(advance_fwd_fun{pos, rest});
}
};
struct advance_rev_fun
{
cursor *pos;
difference_type n;
template<typename I,
CONCEPT_REQUIRES_(RandomAccessIterator<I>())>
void operator()(indexed_element<I, 0> it) const
{
ranges::advance(it.get(), n);
}
template<typename I, std::size_t N,
CONCEPT_REQUIRES_(RandomAccessIterator<I>())>
void operator()(indexed_element<I, N> it) const
{
auto begin = ranges::begin(std::get<N>(pos->rng_->rngs_));
if(it.get() == begin)
{
auto &&rng = std::get<N - 1>(pos->rng_->rngs_);
ranges::emplace<N - 1>(pos->its_,
ranges::next(ranges::begin(rng), ranges::end(rng)));
pos->its_.visit_i(*this);
}
else
{
auto rest = ranges::advance(it.get(), n, std::move(begin));
if(rest != 0)
pos->its_.visit_i(advance_rev_fun{pos, rest});
}
}
};
[[noreturn]] static difference_type distance_to_(meta::size_t<cranges>, cursor const &, cursor const &)
{
RANGES_EXPECT(false);
}
template<std::size_t N>
static difference_type distance_to_(meta::size_t<N>, cursor const &from, cursor const &to)
{
if(from.its_.index() > N)
return cursor::distance_to_(meta::size_t<N + 1>{}, from, to);
if(from.its_.index() == N)
{
if(to.its_.index() == N)
return distance(ranges::get<N>(from.its_), ranges::get<N>(to.its_));
return distance(ranges::get<N>(from.its_), end(std::get<N>(from.rng_->rngs_))) +
cursor::distance_to_(meta::size_t<N + 1>{}, from, to);
}
if(from.its_.index() < N && to.its_.index() > N)
return distance(std::get<N>(from.rng_->rngs_)) +
cursor::distance_to_(meta::size_t<N + 1>{}, from, to);
RANGES_EXPECT(to.its_.index() == N);
return distance(begin(std::get<N>(from.rng_->rngs_)), ranges::get<N>(to.its_));
}
public:
// BUGBUG what about rvalue_reference and common_reference?
using reference = common_reference_t<range_reference_t<constify_if<Rngs>>...>;
using single_pass = meta::strict_or<SinglePass<iterator_t<Rngs>>...>;
cursor() = default;
cursor(concat_view_t &rng, begin_tag)
: rng_(&rng), its_{emplaced_index<0>, begin(std::get<0>(rng.rngs_))}
{
this->satisfy(meta::size_t<0>{});
}
cursor(concat_view_t &rng, end_tag)
: rng_(&rng), its_{emplaced_index<cranges-1>, end(std::get<cranges-1>(rng.rngs_))}
{}
reference read() const
{
// Kind of a dumb implementation. Surely there's a better way.
return ranges::get<0>(unique_variant(its_.visit(
compose(convert_to<reference>{}, dereference_fn{}))));
}
void next()
{
its_.visit_i(next_fun{this});
}
CONCEPT_REQUIRES(EqualityComparable<decltype(its_)>())
bool equal(cursor const &pos) const
{
return its_ == pos.its_;
}
bool equal(sentinel<IsConst> const &pos) const
{
return its_.index() == cranges - 1 &&
ranges::get<cranges - 1>(its_) == pos.end_;
}
CONCEPT_REQUIRES(meta::and_c<(bool)BidirectionalRange<Rngs>()...>::value)
void prev()
{
its_.visit_i(prev_fun{this});
}
CONCEPT_REQUIRES(meta::and_c<(bool)RandomAccessRange<Rngs>()...>::value)
void advance(difference_type n)
{
if(n > 0)
its_.visit_i(advance_fwd_fun{this, n});
else if(n < 0)
its_.visit_i(advance_rev_fun{this, n});
}
CONCEPT_REQUIRES(meta::and_c<(bool)
SizedSentinel<iterator_t<Rngs>, iterator_t<Rngs>>()...>::value)
difference_type distance_to(cursor const &that) const
{
if(its_.index() <= that.its_.index())
return cursor::distance_to_(meta::size_t<0>{}, *this, that);
return -cursor::distance_to_(meta::size_t<0>{}, that, *this);
}
};
cursor<false> begin_cursor()
{
return {*this, begin_tag{}};
}
meta::if_<meta::and_c<(bool)BoundedRange<Rngs>()...>, cursor<false>, sentinel<false>>
end_cursor()
{
return {*this, end_tag{}};
}
CONCEPT_REQUIRES(meta::and_c<(bool)Range<Rngs const>()...>())
cursor<true> begin_cursor() const
{
return {*this, begin_tag{}};
}
CONCEPT_REQUIRES(meta::and_c<(bool)Range<Rngs const>()...>())
meta::if_<meta::and_c<(bool)BoundedRange<Rngs>()...>, cursor<true>, sentinel<true>>
end_cursor() const
{
return {*this, end_tag{}};
}
public:
concat_view() = default;
explicit concat_view(Rngs...rngs)
: rngs_{std::move(rngs)...}
{}
CONCEPT_REQUIRES(detail::concat_cardinality<Rngs...>::value >= 0)
constexpr size_type_ size() const
{
return static_cast<size_type_>(detail::concat_cardinality<Rngs...>::value);
}
CONCEPT_REQUIRES(detail::concat_cardinality<Rngs...>::value < 0 &&
meta::and_c<(bool)SizedRange<Rngs const>()...>::value)
RANGES_CXX14_CONSTEXPR size_type_ size() const
{
return const_cast<concat_view *>(this)->size();
}
CONCEPT_REQUIRES(detail::concat_cardinality<Rngs...>::value < 0 &&
meta::and_c<(bool)SizedRange<Rngs>()...>::value)
RANGES_CXX14_CONSTEXPR size_type_ size()
{
return tuple_foldl(tuple_transform(rngs_, ranges::size), size_type_{0}, plus{});
}
};
namespace view
{
struct concat_fn
{
template<typename...Rngs>
concat_view<all_t<Rngs>...> operator()(Rngs &&... rngs) const
{
static_assert(meta::and_c<(bool)InputRange<Rngs>()...>::value,
"Expecting Input Ranges");
return concat_view<all_t<Rngs>...>{all(static_cast<Rngs&&>(rngs))...};
}
};
/// \relates concat_fn
/// \ingroup group-views
RANGES_INLINE_VARIABLE(concat_fn, concat)
}
/// @}
}
}
RANGES_SATISFY_BOOST_RANGE(::ranges::v3::concat_view)
#endif
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