blob: b8de400dfbbcb7e0cc9218228c2cb2115799a6fb [file] [log] [blame]
// <ranges> -*- C++ -*-
// Copyright (C) 2019-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/ranges
* This is a Standard C++ Library header.
* @ingroup concepts
*/
#ifndef _GLIBCXX_RANGES
#define _GLIBCXX_RANGES 1
#if __cplusplus > 201703L
#pragma GCC system_header
#include <concepts>
#if __cpp_lib_concepts
#include <compare>
#include <initializer_list>
#include <iterator>
#include <optional>
#include <tuple>
#include <bits/ranges_util.h>
#include <bits/refwrap.h>
/**
* @defgroup ranges Ranges
*
* Components for dealing with ranges of elements.
*/
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace ranges
{
// [range.access] customization point objects
// [range.req] range and view concepts
// [range.dangling] dangling iterator handling
// Defined in <bits/ranges_base.h>
// [view.interface] View interface
// [range.subrange] Sub-ranges
// Defined in <bits/ranges_util.h>
// C++20 24.6 [range.factories] Range factories
/// A view that contains no elements.
template<typename _Tp> requires is_object_v<_Tp>
class empty_view
: public view_interface<empty_view<_Tp>>
{
public:
static constexpr _Tp* begin() noexcept { return nullptr; }
static constexpr _Tp* end() noexcept { return nullptr; }
static constexpr _Tp* data() noexcept { return nullptr; }
static constexpr size_t size() noexcept { return 0; }
static constexpr bool empty() noexcept { return true; }
};
template<typename _Tp>
inline constexpr bool enable_borrowed_range<empty_view<_Tp>> = true;
namespace __detail
{
template<typename _Tp>
concept __boxable = copy_constructible<_Tp> && is_object_v<_Tp>;
template<__boxable _Tp>
struct __box : std::optional<_Tp>
{
using std::optional<_Tp>::optional;
constexpr
__box()
noexcept(is_nothrow_default_constructible_v<_Tp>)
requires default_initializable<_Tp>
: std::optional<_Tp>{std::in_place}
{ }
__box(const __box&) = default;
__box(__box&&) = default;
using std::optional<_Tp>::operator=;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3477. Simplify constraints for semiregular-box
__box&
operator=(const __box& __that)
noexcept(is_nothrow_copy_constructible_v<_Tp>)
requires (!copyable<_Tp>)
{
if (this != std::__addressof(__that))
{
if ((bool)__that)
this->emplace(*__that);
else
this->reset();
}
return *this;
}
__box&
operator=(__box&& __that)
noexcept(is_nothrow_move_constructible_v<_Tp>)
requires (!movable<_Tp>)
{
if (this != std::__addressof(__that))
{
if ((bool)__that)
this->emplace(std::move(*__that));
else
this->reset();
}
return *this;
}
};
// For types which are already copyable, this specialization of the
// copyable wrapper stores the object directly without going through
// std::optional. It provides just the subset of the primary template's
// API that we currently use.
template<__boxable _Tp>
requires copyable<_Tp> || (is_nothrow_move_constructible_v<_Tp>
&& is_nothrow_copy_constructible_v<_Tp>)
struct __box<_Tp>
{
private:
[[no_unique_address]] _Tp _M_value = _Tp();
public:
__box() requires default_initializable<_Tp> = default;
constexpr explicit
__box(const _Tp& __t)
noexcept(is_nothrow_copy_constructible_v<_Tp>)
: _M_value(__t)
{ }
constexpr explicit
__box(_Tp&& __t)
noexcept(is_nothrow_move_constructible_v<_Tp>)
: _M_value(std::move(__t))
{ }
template<typename... _Args>
requires constructible_from<_Tp, _Args...>
constexpr explicit
__box(in_place_t, _Args&&... __args)
noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
: _M_value(std::forward<_Args>(__args)...)
{ }
__box(const __box&) = default;
__box(__box&&) = default;
__box& operator=(const __box&) requires copyable<_Tp> = default;
__box& operator=(__box&&) requires copyable<_Tp> = default;
// When _Tp is nothrow_copy_constructible but not copy_assignable,
// copy assignment is implemented via destroy-then-copy-construct.
constexpr __box&
operator=(const __box& __that) noexcept
{
static_assert(is_nothrow_copy_constructible_v<_Tp>);
if (this != std::__addressof(__that))
{
_M_value.~_Tp();
std::construct_at(std::__addressof(_M_value), *__that);
}
return *this;
}
// Likewise for move assignment.
constexpr __box&
operator=(__box&& __that) noexcept
{
static_assert(is_nothrow_move_constructible_v<_Tp>);
if (this != std::__addressof(__that))
{
_M_value.~_Tp();
std::construct_at(std::__addressof(_M_value), std::move(*__that));
}
return *this;
}
constexpr bool
has_value() const noexcept
{ return true; };
constexpr _Tp&
operator*() noexcept
{ return _M_value; }
constexpr const _Tp&
operator*() const noexcept
{ return _M_value; }
constexpr _Tp*
operator->() noexcept
{ return std::__addressof(_M_value); }
constexpr const _Tp*
operator->() const noexcept
{ return std::__addressof(_M_value); }
};
} // namespace __detail
/// A view that contains exactly one element.
template<copy_constructible _Tp> requires is_object_v<_Tp>
class single_view : public view_interface<single_view<_Tp>>
{
public:
single_view() requires default_initializable<_Tp> = default;
constexpr explicit
single_view(const _Tp& __t)
noexcept(is_nothrow_copy_constructible_v<_Tp>)
: _M_value(__t)
{ }
constexpr explicit
single_view(_Tp&& __t)
noexcept(is_nothrow_move_constructible_v<_Tp>)
: _M_value(std::move(__t))
{ }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3428. single_view's in place constructor should be explicit
template<typename... _Args>
requires constructible_from<_Tp, _Args...>
constexpr explicit
single_view(in_place_t, _Args&&... __args)
noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
: _M_value{in_place, std::forward<_Args>(__args)...}
{ }
constexpr _Tp*
begin() noexcept
{ return data(); }
constexpr const _Tp*
begin() const noexcept
{ return data(); }
constexpr _Tp*
end() noexcept
{ return data() + 1; }
constexpr const _Tp*
end() const noexcept
{ return data() + 1; }
static constexpr size_t
size() noexcept
{ return 1; }
constexpr _Tp*
data() noexcept
{ return _M_value.operator->(); }
constexpr const _Tp*
data() const noexcept
{ return _M_value.operator->(); }
private:
[[no_unique_address]] __detail::__box<_Tp> _M_value;
};
template<typename _Tp>
single_view(_Tp) -> single_view<_Tp>;
namespace __detail
{
template<typename _Wp>
constexpr auto __to_signed_like(_Wp __w) noexcept
{
if constexpr (!integral<_Wp>)
return iter_difference_t<_Wp>();
else if constexpr (sizeof(iter_difference_t<_Wp>) > sizeof(_Wp))
return iter_difference_t<_Wp>(__w);
else if constexpr (sizeof(ptrdiff_t) > sizeof(_Wp))
return ptrdiff_t(__w);
else if constexpr (sizeof(long long) > sizeof(_Wp))
return (long long)(__w);
#ifdef __SIZEOF_INT128__
else if constexpr (__SIZEOF_INT128__ > sizeof(_Wp))
return __int128(__w);
#endif
else
return __max_diff_type(__w);
}
template<typename _Wp>
using __iota_diff_t = decltype(__to_signed_like(std::declval<_Wp>()));
template<typename _It>
concept __decrementable = incrementable<_It>
&& requires(_It __i)
{
{ --__i } -> same_as<_It&>;
{ __i-- } -> same_as<_It>;
};
template<typename _It>
concept __advanceable = __decrementable<_It> && totally_ordered<_It>
&& requires( _It __i, const _It __j, const __iota_diff_t<_It> __n)
{
{ __i += __n } -> same_as<_It&>;
{ __i -= __n } -> same_as<_It&>;
_It(__j + __n);
_It(__n + __j);
_It(__j - __n);
{ __j - __j } -> convertible_to<__iota_diff_t<_It>>;
};
template<typename _Winc>
struct __iota_view_iter_cat
{ };
template<incrementable _Winc>
struct __iota_view_iter_cat<_Winc>
{ using iterator_category = input_iterator_tag; };
} // namespace __detail
template<weakly_incrementable _Winc,
semiregular _Bound = unreachable_sentinel_t>
requires std::__detail::__weakly_eq_cmp_with<_Winc, _Bound>
&& copyable<_Winc>
class iota_view : public view_interface<iota_view<_Winc, _Bound>>
{
private:
struct _Sentinel;
struct _Iterator : __detail::__iota_view_iter_cat<_Winc>
{
private:
static auto
_S_iter_concept()
{
using namespace __detail;
if constexpr (__advanceable<_Winc>)
return random_access_iterator_tag{};
else if constexpr (__decrementable<_Winc>)
return bidirectional_iterator_tag{};
else if constexpr (incrementable<_Winc>)
return forward_iterator_tag{};
else
return input_iterator_tag{};
}
public:
using iterator_concept = decltype(_S_iter_concept());
// iterator_category defined in __iota_view_iter_cat
using value_type = _Winc;
using difference_type = __detail::__iota_diff_t<_Winc>;
_Iterator() requires default_initializable<_Winc> = default;
constexpr explicit
_Iterator(_Winc __value)
: _M_value(__value) { }
constexpr _Winc
operator*() const noexcept(is_nothrow_copy_constructible_v<_Winc>)
{ return _M_value; }
constexpr _Iterator&
operator++()
{
++_M_value;
return *this;
}
constexpr void
operator++(int)
{ ++*this; }
constexpr _Iterator
operator++(int) requires incrementable<_Winc>
{
auto __tmp = *this;
++*this;
return __tmp;
}
constexpr _Iterator&
operator--() requires __detail::__decrementable<_Winc>
{
--_M_value;
return *this;
}
constexpr _Iterator
operator--(int) requires __detail::__decrementable<_Winc>
{
auto __tmp = *this;
--*this;
return __tmp;
}
constexpr _Iterator&
operator+=(difference_type __n) requires __detail::__advanceable<_Winc>
{
using __detail::__is_integer_like;
using __detail::__is_signed_integer_like;
if constexpr (__is_integer_like<_Winc>
&& !__is_signed_integer_like<_Winc>)
{
if (__n >= difference_type(0))
_M_value += static_cast<_Winc>(__n);
else
_M_value -= static_cast<_Winc>(-__n);
}
else
_M_value += __n;
return *this;
}
constexpr _Iterator&
operator-=(difference_type __n) requires __detail::__advanceable<_Winc>
{
using __detail::__is_integer_like;
using __detail::__is_signed_integer_like;
if constexpr (__is_integer_like<_Winc>
&& !__is_signed_integer_like<_Winc>)
{
if (__n >= difference_type(0))
_M_value -= static_cast<_Winc>(__n);
else
_M_value += static_cast<_Winc>(-__n);
}
else
_M_value -= __n;
return *this;
}
constexpr _Winc
operator[](difference_type __n) const
requires __detail::__advanceable<_Winc>
{ return _Winc(_M_value + __n); }
friend constexpr bool
operator==(const _Iterator& __x, const _Iterator& __y)
requires equality_comparable<_Winc>
{ return __x._M_value == __y._M_value; }
friend constexpr bool
operator<(const _Iterator& __x, const _Iterator& __y)
requires totally_ordered<_Winc>
{ return __x._M_value < __y._M_value; }
friend constexpr bool
operator>(const _Iterator& __x, const _Iterator& __y)
requires totally_ordered<_Winc>
{ return __y < __x; }
friend constexpr bool
operator<=(const _Iterator& __x, const _Iterator& __y)
requires totally_ordered<_Winc>
{ return !(__y < __x); }
friend constexpr bool
operator>=(const _Iterator& __x, const _Iterator& __y)
requires totally_ordered<_Winc>
{ return !(__x < __y); }
#ifdef __cpp_lib_three_way_comparison
friend constexpr auto
operator<=>(const _Iterator& __x, const _Iterator& __y)
requires totally_ordered<_Winc> && three_way_comparable<_Winc>
{ return __x._M_value <=> __y._M_value; }
#endif
friend constexpr _Iterator
operator+(_Iterator __i, difference_type __n)
requires __detail::__advanceable<_Winc>
{ return __i += __n; }
friend constexpr _Iterator
operator+(difference_type __n, _Iterator __i)
requires __detail::__advanceable<_Winc>
{ return __i += __n; }
friend constexpr _Iterator
operator-(_Iterator __i, difference_type __n)
requires __detail::__advanceable<_Winc>
{ return __i -= __n; }
friend constexpr difference_type
operator-(const _Iterator& __x, const _Iterator& __y)
requires __detail::__advanceable<_Winc>
{
using __detail::__is_integer_like;
using __detail::__is_signed_integer_like;
using _Dt = difference_type;
if constexpr (__is_integer_like<_Winc>)
{
if constexpr (__is_signed_integer_like<_Winc>)
return _Dt(_Dt(__x._M_value) - _Dt(__y._M_value));
else
return (__y._M_value > __x._M_value)
? _Dt(-_Dt(__y._M_value - __x._M_value))
: _Dt(__x._M_value - __y._M_value);
}
else
return __x._M_value - __y._M_value;
}
private:
_Winc _M_value = _Winc();
friend _Sentinel;
};
struct _Sentinel
{
private:
constexpr bool
_M_equal(const _Iterator& __x) const
{ return __x._M_value == _M_bound; }
constexpr auto
_M_distance_from(const _Iterator& __x) const
{ return _M_bound - __x._M_value; }
_Bound _M_bound = _Bound();
public:
_Sentinel() = default;
constexpr explicit
_Sentinel(_Bound __bound)
: _M_bound(__bound) { }
friend constexpr bool
operator==(const _Iterator& __x, const _Sentinel& __y)
{ return __y._M_equal(__x); }
friend constexpr iter_difference_t<_Winc>
operator-(const _Iterator& __x, const _Sentinel& __y)
requires sized_sentinel_for<_Bound, _Winc>
{ return -__y._M_distance_from(__x); }
friend constexpr iter_difference_t<_Winc>
operator-(const _Sentinel& __x, const _Iterator& __y)
requires sized_sentinel_for<_Bound, _Winc>
{ return __x._M_distance_from(__y); }
};
_Winc _M_value = _Winc();
[[no_unique_address]] _Bound _M_bound = _Bound();
public:
iota_view() requires default_initializable<_Winc> = default;
constexpr explicit
iota_view(_Winc __value)
: _M_value(__value)
{ }
constexpr
iota_view(type_identity_t<_Winc> __value,
type_identity_t<_Bound> __bound)
: _M_value(__value), _M_bound(__bound)
{
if constexpr (totally_ordered_with<_Winc, _Bound>)
__glibcxx_assert( bool(__value <= __bound) );
}
constexpr _Iterator
begin() const { return _Iterator{_M_value}; }
constexpr auto
end() const
{
if constexpr (same_as<_Bound, unreachable_sentinel_t>)
return unreachable_sentinel;
else
return _Sentinel{_M_bound};
}
constexpr _Iterator
end() const requires same_as<_Winc, _Bound>
{ return _Iterator{_M_bound}; }
constexpr auto
size() const
requires (same_as<_Winc, _Bound> && __detail::__advanceable<_Winc>)
|| (integral<_Winc> && integral<_Bound>)
|| sized_sentinel_for<_Bound, _Winc>
{
using __detail::__is_integer_like;
using __detail::__to_unsigned_like;
if constexpr (integral<_Winc> && integral<_Bound>)
{
using _Up = make_unsigned_t<decltype(_M_bound - _M_value)>;
return _Up(_M_bound) - _Up(_M_value);
}
else if constexpr (__is_integer_like<_Winc>)
return __to_unsigned_like(_M_bound) - __to_unsigned_like(_M_value);
else
return __to_unsigned_like(_M_bound - _M_value);
}
};
template<typename _Winc, typename _Bound>
requires (!__detail::__is_integer_like<_Winc>
|| !__detail::__is_integer_like<_Bound>
|| (__detail::__is_signed_integer_like<_Winc>
== __detail::__is_signed_integer_like<_Bound>))
iota_view(_Winc, _Bound) -> iota_view<_Winc, _Bound>;
template<typename _Winc, typename _Bound>
inline constexpr bool
enable_borrowed_range<iota_view<_Winc, _Bound>> = true;
namespace views
{
template<typename _Tp>
inline constexpr empty_view<_Tp> empty{};
struct _Single
{
template<typename _Tp>
[[nodiscard]]
constexpr auto
operator()(_Tp&& __e) const
noexcept(noexcept(single_view<decay_t<_Tp>>(std::forward<_Tp>(__e))))
{ return single_view<decay_t<_Tp>>(std::forward<_Tp>(__e)); }
};
inline constexpr _Single single{};
struct _Iota
{
template<typename _Tp>
[[nodiscard]]
constexpr auto
operator()(_Tp&& __e) const
{ return iota_view(std::forward<_Tp>(__e)); }
template<typename _Tp, typename _Up>
[[nodiscard]]
constexpr auto
operator()(_Tp&& __e, _Up&& __f) const
{ return iota_view(std::forward<_Tp>(__e), std::forward<_Up>(__f)); }
};
inline constexpr _Iota iota{};
} // namespace views
namespace __detail
{
template<typename _Val, typename _CharT, typename _Traits>
concept __stream_extractable
= requires(basic_istream<_CharT, _Traits>& is, _Val& t) { is >> t; };
} // namespace __detail
template<movable _Val, typename _CharT,
typename _Traits = char_traits<_CharT>>
requires default_initializable<_Val>
&& __detail::__stream_extractable<_Val, _CharT, _Traits>
class basic_istream_view
: public view_interface<basic_istream_view<_Val, _CharT, _Traits>>
{
public:
constexpr explicit
basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
: _M_stream(std::__addressof(__stream))
{ }
constexpr auto
begin()
{
*_M_stream >> _M_object;
return _Iterator{this};
}
constexpr default_sentinel_t
end() const noexcept
{ return default_sentinel; }
private:
basic_istream<_CharT, _Traits>* _M_stream;
_Val _M_object;
struct _Iterator
{
public:
using iterator_concept = input_iterator_tag;
using difference_type = ptrdiff_t;
using value_type = _Val;
constexpr explicit
_Iterator(basic_istream_view* __parent) noexcept
: _M_parent(__parent)
{ }
_Iterator(const _Iterator&) = delete;
_Iterator(_Iterator&&) = default;
_Iterator& operator=(const _Iterator&) = delete;
_Iterator& operator=(_Iterator&&) = default;
_Iterator&
operator++()
{
*_M_parent->_M_stream >> _M_parent->_M_object;
return *this;
}
void
operator++(int)
{ ++*this; }
_Val&
operator*() const
{ return _M_parent->_M_object; }
friend bool
operator==(const _Iterator& __x, default_sentinel_t)
{ return __x._M_at_end(); }
private:
basic_istream_view* _M_parent;
bool
_M_at_end() const
{ return !*_M_parent->_M_stream; }
};
friend _Iterator;
};
template<typename _Val, typename _CharT, typename _Traits>
basic_istream_view<_Val, _CharT, _Traits>
istream_view(basic_istream<_CharT, _Traits>& __s)
{ return basic_istream_view<_Val, _CharT, _Traits>{__s}; }
// C++20 24.7 [range.adaptors] Range adaptors
namespace __detail
{
struct _Empty { };
// Alias for a type that is conditionally present
// (and is an empty type otherwise).
// Data members using this alias should use [[no_unique_address]] so that
// they take no space when not needed.
template<bool _Present, typename _Tp>
using __maybe_present_t = __conditional_t<_Present, _Tp, _Empty>;
// Alias for a type that is conditionally const.
template<bool _Const, typename _Tp>
using __maybe_const_t = __conditional_t<_Const, const _Tp, _Tp>;
} // namespace __detail
namespace views::__adaptor
{
// True if the range adaptor _Adaptor can be applied with _Args.
template<typename _Adaptor, typename... _Args>
concept __adaptor_invocable
= requires { std::declval<_Adaptor>()(declval<_Args>()...); };
// True if the range adaptor non-closure _Adaptor can be partially applied
// with _Args.
template<typename _Adaptor, typename... _Args>
concept __adaptor_partial_app_viable = (_Adaptor::_S_arity > 1)
&& (sizeof...(_Args) == _Adaptor::_S_arity - 1)
&& (constructible_from<decay_t<_Args>, _Args> && ...);
template<typename _Adaptor, typename... _Args>
struct _Partial;
template<typename _Lhs, typename _Rhs>
struct _Pipe;
// The base class of every range adaptor closure.
//
// The derived class should define the optional static data member
// _S_has_simple_call_op to true if the behavior of this adaptor is
// independent of the constness/value category of the adaptor object.
struct _RangeAdaptorClosure
{
// range | adaptor is equivalent to adaptor(range).
template<typename _Self, typename _Range>
requires derived_from<remove_cvref_t<_Self>, _RangeAdaptorClosure>
&& __adaptor_invocable<_Self, _Range>
friend constexpr auto
operator|(_Range&& __r, _Self&& __self)
{ return std::forward<_Self>(__self)(std::forward<_Range>(__r)); }
// Compose the adaptors __lhs and __rhs into a pipeline, returning
// another range adaptor closure object.
template<typename _Lhs, typename _Rhs>
requires derived_from<_Lhs, _RangeAdaptorClosure>
&& derived_from<_Rhs, _RangeAdaptorClosure>
friend constexpr auto
operator|(_Lhs __lhs, _Rhs __rhs)
{ return _Pipe<_Lhs, _Rhs>{std::move(__lhs), std::move(__rhs)}; }
};
// The base class of every range adaptor non-closure.
//
// The static data member _Derived::_S_arity must contain the total number of
// arguments that the adaptor takes, and the class _Derived must introduce
// _RangeAdaptor::operator() into the class scope via a using-declaration.
//
// The optional static data member _Derived::_S_has_simple_extra_args should
// be defined to true if the behavior of this adaptor is independent of the
// constness/value category of the extra arguments. This data member could
// also be defined as a variable template parameterized by the types of the
// extra arguments.
template<typename _Derived>
struct _RangeAdaptor
{
// Partially apply the arguments __args to the range adaptor _Derived,
// returning a range adaptor closure object.
template<typename... _Args>
requires __adaptor_partial_app_viable<_Derived, _Args...>
constexpr auto
operator()(_Args&&... __args) const
{
return _Partial<_Derived, decay_t<_Args>...>{std::forward<_Args>(__args)...};
}
};
// True if the range adaptor closure _Adaptor has a simple operator(), i.e.
// one that's not overloaded according to constness or value category of the
// _Adaptor object.
template<typename _Adaptor>
concept __closure_has_simple_call_op = _Adaptor::_S_has_simple_call_op;
// True if the behavior of the range adaptor non-closure _Adaptor is
// independent of the value category of its extra arguments _Args.
template<typename _Adaptor, typename... _Args>
concept __adaptor_has_simple_extra_args = _Adaptor::_S_has_simple_extra_args
|| _Adaptor::template _S_has_simple_extra_args<_Args...>;
// A range adaptor closure that represents partial application of
// the range adaptor _Adaptor with arguments _Args.
template<typename _Adaptor, typename... _Args>
struct _Partial : _RangeAdaptorClosure
{
tuple<_Args...> _M_args;
constexpr
_Partial(_Args... __args)
: _M_args(std::move(__args)...)
{ }
// Invoke _Adaptor with arguments __r, _M_args... according to the
// value category of this _Partial object.
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
constexpr auto
operator()(_Range&& __r) const &
{
auto __forwarder = [&__r] (const auto&... __args) {
return _Adaptor{}(std::forward<_Range>(__r), __args...);
};
return std::apply(__forwarder, _M_args);
}
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, _Args...>
constexpr auto
operator()(_Range&& __r) &&
{
auto __forwarder = [&__r] (auto&... __args) {
return _Adaptor{}(std::forward<_Range>(__r), std::move(__args)...);
};
return std::apply(__forwarder, _M_args);
}
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
};
// A lightweight specialization of the above primary template for
// the common case where _Adaptor accepts a single extra argument.
template<typename _Adaptor, typename _Arg>
struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
{
_Arg _M_arg;
constexpr
_Partial(_Arg __arg)
: _M_arg(std::move(__arg))
{ }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
constexpr auto
operator()(_Range&& __r) const &
{ return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, _Arg>
constexpr auto
operator()(_Range&& __r) &&
{ return _Adaptor{}(std::forward<_Range>(__r), std::move(_M_arg)); }
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
};
// Partial specialization of the primary template for the case where the extra
// arguments of the adaptor can always be safely and efficiently forwarded by
// const reference. This lets us get away with a single operator() overload,
// which makes overload resolution failure diagnostics more concise.
template<typename _Adaptor, typename... _Args>
requires __adaptor_has_simple_extra_args<_Adaptor, _Args...>
&& (is_trivially_copyable_v<_Args> && ...)
struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure
{
tuple<_Args...> _M_args;
constexpr
_Partial(_Args... __args)
: _M_args(std::move(__args)...)
{ }
// Invoke _Adaptor with arguments __r, const _M_args&... regardless
// of the value category of this _Partial object.
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
constexpr auto
operator()(_Range&& __r) const
{
auto __forwarder = [&__r] (const auto&... __args) {
return _Adaptor{}(std::forward<_Range>(__r), __args...);
};
return std::apply(__forwarder, _M_args);
}
static constexpr bool _S_has_simple_call_op = true;
};
// A lightweight specialization of the above template for the common case
// where _Adaptor accepts a single extra argument.
template<typename _Adaptor, typename _Arg>
requires __adaptor_has_simple_extra_args<_Adaptor, _Arg>
&& is_trivially_copyable_v<_Arg>
struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
{
_Arg _M_arg;
constexpr
_Partial(_Arg __arg)
: _M_arg(std::move(__arg))
{ }
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
constexpr auto
operator()(_Range&& __r) const
{ return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
static constexpr bool _S_has_simple_call_op = true;
};
template<typename _Lhs, typename _Rhs, typename _Range>
concept __pipe_invocable
= requires { std::declval<_Rhs>()(std::declval<_Lhs>()(std::declval<_Range>())); };
// A range adaptor closure that represents composition of the range
// adaptor closures _Lhs and _Rhs.
template<typename _Lhs, typename _Rhs>
struct _Pipe : _RangeAdaptorClosure
{
[[no_unique_address]] _Lhs _M_lhs;
[[no_unique_address]] _Rhs _M_rhs;
constexpr
_Pipe(_Lhs __lhs, _Rhs __rhs)
: _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
{ }
// Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
// range adaptor closure object.
template<typename _Range>
requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
constexpr auto
operator()(_Range&& __r) const &
{ return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
template<typename _Range>
requires __pipe_invocable<_Lhs, _Rhs, _Range>
constexpr auto
operator()(_Range&& __r) &&
{ return std::move(_M_rhs)(std::move(_M_lhs)(std::forward<_Range>(__r))); }
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
};
// A partial specialization of the above primary template for the case where
// both adaptor operands have a simple operator(). This in turn lets us
// implement composition using a single simple operator(), which makes
// overload resolution failure diagnostics more concise.
template<typename _Lhs, typename _Rhs>
requires __closure_has_simple_call_op<_Lhs>
&& __closure_has_simple_call_op<_Rhs>
struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure
{
[[no_unique_address]] _Lhs _M_lhs;
[[no_unique_address]] _Rhs _M_rhs;
constexpr
_Pipe(_Lhs __lhs, _Rhs __rhs)
: _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
{ }
template<typename _Range>
requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
constexpr auto
operator()(_Range&& __r) const
{ return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
static constexpr bool _S_has_simple_call_op = true;
};
} // namespace views::__adaptor
template<range _Range> requires is_object_v<_Range>
class ref_view : public view_interface<ref_view<_Range>>
{
private:
_Range* _M_r;
static void _S_fun(_Range&); // not defined
static void _S_fun(_Range&&) = delete;
public:
template<__detail::__different_from<ref_view> _Tp>
requires convertible_to<_Tp, _Range&>
&& requires { _S_fun(declval<_Tp>()); }
constexpr
ref_view(_Tp&& __t)
noexcept(noexcept(static_cast<_Range&>(std::declval<_Tp>())))
: _M_r(std::__addressof(static_cast<_Range&>(std::forward<_Tp>(__t))))
{ }
constexpr _Range&
base() const
{ return *_M_r; }
constexpr iterator_t<_Range>
begin() const
{ return ranges::begin(*_M_r); }
constexpr sentinel_t<_Range>
end() const
{ return ranges::end(*_M_r); }
constexpr bool
empty() const requires requires { ranges::empty(*_M_r); }
{ return ranges::empty(*_M_r); }
constexpr auto
size() const requires sized_range<_Range>
{ return ranges::size(*_M_r); }
constexpr auto
data() const requires contiguous_range<_Range>
{ return ranges::data(*_M_r); }
};
template<typename _Range>
ref_view(_Range&) -> ref_view<_Range>;
template<typename _Tp>
inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
namespace views
{
namespace __detail
{
template<typename _Range>
concept __can_ref_view = requires { ref_view{std::declval<_Range>()}; };
template<typename _Range>
concept __can_subrange = requires { subrange{std::declval<_Range>()}; };
} // namespace __detail
struct _All : __adaptor::_RangeAdaptorClosure
{
template<typename _Range>
static constexpr bool
_S_noexcept()
{
if constexpr (view<decay_t<_Range>>)
return is_nothrow_constructible_v<decay_t<_Range>, _Range>;
else if constexpr (__detail::__can_ref_view<_Range>)
return true;
else
return noexcept(subrange{std::declval<_Range>()});
}
template<viewable_range _Range>
requires view<decay_t<_Range>>
|| __detail::__can_ref_view<_Range>
|| __detail::__can_subrange<_Range>
constexpr auto
operator() [[nodiscard]] (_Range&& __r) const
noexcept(_S_noexcept<_Range>())
{
if constexpr (view<decay_t<_Range>>)
return std::forward<_Range>(__r);
else if constexpr (__detail::__can_ref_view<_Range>)
return ref_view{std::forward<_Range>(__r)};
else
return subrange{std::forward<_Range>(__r)};
}
static constexpr bool _S_has_simple_call_op = true;
};
inline constexpr _All all;
template<viewable_range _Range>
using all_t = decltype(all(std::declval<_Range>()));
} // namespace views
namespace __detail
{
template<typename _Tp>
struct __non_propagating_cache
{
// When _Tp is not an object type (e.g. is a reference type), we make
// __non_propagating_cache<_Tp> empty rather than ill-formed so that
// users can easily conditionally declare data members with this type
// (such as join_view::_M_inner).
};
template<typename _Tp>
struct __cached
{
struct _Deref_t { };
static constexpr _Deref_t __deref{};
// Initialize _M_t directly from the result of dereferencing __i.
// This avoids any unwanted temporary materialization that would
// occur if *__i was bound to a reference before initializing _M_t.
template<typename _Iter>
constexpr explicit
__cached(_Deref_t, _Iter&& __i)
: _M_t(*__i)
{ }
template<typename... _Args>
constexpr explicit
__cached(_Args&&... __args)
: _M_t(std::forward<_Args>(__args)...)
{ }
_Tp _M_t;
};
template<typename _Tp>
requires is_object_v<_Tp>
struct __non_propagating_cache<_Tp>
: protected _Optional_base<__cached<_Tp>>
{
__non_propagating_cache() = default;
constexpr
__non_propagating_cache(const __non_propagating_cache&) noexcept
{ }
constexpr
__non_propagating_cache(__non_propagating_cache&& __other) noexcept
{ __other._M_reset(); }
constexpr __non_propagating_cache&
operator=(const __non_propagating_cache& __other) noexcept
{
if (std::__addressof(__other) != this)
this->_M_reset();
return *this;
}
constexpr __non_propagating_cache&
operator=(__non_propagating_cache&& __other) noexcept
{
this->_M_reset();
__other._M_reset();
return *this;
}
constexpr __non_propagating_cache&
operator=(_Tp __val)
{
this->_M_reset();
std::construct_at(std::__addressof(this->_M_payload._M_payload),
std::in_place, std::move(__val));
this->_M_payload._M_engaged = true;
return *this;
}
constexpr explicit
operator bool() const noexcept
{ return this->_M_is_engaged(); }
constexpr _Tp&
operator*() noexcept
{ return this->_M_get()._M_t; }
constexpr const _Tp&
operator*() const noexcept
{ return this->_M_get()._M_t; }
template<typename _Iter>
constexpr _Tp&
_M_emplace_deref(const _Iter& __i)
{
this->_M_reset();
// Use the special constructor of __cached<_Tp> that does *__i.
std::construct_at(std::__addressof(this->_M_payload._M_payload),
std::in_place, __cached<_Tp>::__deref, __i);
this->_M_payload._M_engaged = true;
return **this;
}
};
template<range _Range>
struct _CachedPosition
{
constexpr bool
_M_has_value() const
{ return false; }
constexpr iterator_t<_Range>
_M_get(const _Range&) const
{
__glibcxx_assert(false);
__builtin_unreachable();
}
constexpr void
_M_set(const _Range&, const iterator_t<_Range>&) const
{ }
};
template<forward_range _Range>
struct _CachedPosition<_Range>
: protected __non_propagating_cache<iterator_t<_Range>>
{
constexpr bool
_M_has_value() const
{ return this->_M_is_engaged(); }
constexpr iterator_t<_Range>
_M_get(const _Range&) const
{
__glibcxx_assert(_M_has_value());
return **this;
}
constexpr void
_M_set(const _Range&, const iterator_t<_Range>& __it)
{
__glibcxx_assert(!_M_has_value());
std::construct_at(std::__addressof(this->_M_payload._M_payload),
in_place, __it);
this->_M_payload._M_engaged = true;
}
};
template<random_access_range _Range>
requires (sizeof(range_difference_t<_Range>)
<= sizeof(iterator_t<_Range>))
struct _CachedPosition<_Range>
{
private:
range_difference_t<_Range> _M_offset = -1;
public:
_CachedPosition() = default;
constexpr
_CachedPosition(const _CachedPosition&) = default;
constexpr
_CachedPosition(_CachedPosition&& __other) noexcept
{ *this = std::move(__other); }
constexpr _CachedPosition&
operator=(const _CachedPosition&) = default;
constexpr _CachedPosition&
operator=(_CachedPosition&& __other) noexcept
{
// Propagate the cached offset, but invalidate the source.
_M_offset = __other._M_offset;
__other._M_offset = -1;
return *this;
}
constexpr bool
_M_has_value() const
{ return _M_offset >= 0; }
constexpr iterator_t<_Range>
_M_get(_Range& __r) const
{
__glibcxx_assert(_M_has_value());
return ranges::begin(__r) + _M_offset;
}
constexpr void
_M_set(_Range& __r, const iterator_t<_Range>& __it)
{
__glibcxx_assert(!_M_has_value());
_M_offset = __it - ranges::begin(__r);
}
};
} // namespace __detail
namespace __detail
{
template<typename _Base>
struct __filter_view_iter_cat
{ };
template<forward_range _Base>
struct __filter_view_iter_cat<_Base>
{
private:
static auto
_S_iter_cat()
{
using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
if constexpr (derived_from<_Cat, bidirectional_iterator_tag>)
return bidirectional_iterator_tag{};
else if constexpr (derived_from<_Cat, forward_iterator_tag>)
return forward_iterator_tag{};
else
return _Cat{};
}
public:
using iterator_category = decltype(_S_iter_cat());
};
} // namespace __detail
template<input_range _Vp,
indirect_unary_predicate<iterator_t<_Vp>> _Pred>
requires view<_Vp> && is_object_v<_Pred>
class filter_view : public view_interface<filter_view<_Vp, _Pred>>
{
private:
struct _Sentinel;
struct _Iterator : __detail::__filter_view_iter_cat<_Vp>
{
private:
static constexpr auto
_S_iter_concept()
{
if constexpr (bidirectional_range<_Vp>)
return bidirectional_iterator_tag{};
else if constexpr (forward_range<_Vp>)
return forward_iterator_tag{};
else
return input_iterator_tag{};
}
friend filter_view;
using _Vp_iter = iterator_t<_Vp>;
_Vp_iter _M_current = _Vp_iter();
filter_view* _M_parent = nullptr;
public:
using iterator_concept = decltype(_S_iter_concept());
// iterator_category defined in __filter_view_iter_cat
using value_type = range_value_t<_Vp>;
using difference_type = range_difference_t<_Vp>;
_Iterator() requires default_initializable<_Vp_iter> = default;
constexpr
_Iterator(filter_view* __parent, _Vp_iter __current)
: _M_current(std::move(__current)),
_M_parent(__parent)
{ }
constexpr const _Vp_iter&
base() const & noexcept
{ return _M_current; }
constexpr _Vp_iter
base() &&
{ return std::move(_M_current); }
constexpr range_reference_t<_Vp>
operator*() const
{ return *_M_current; }
constexpr _Vp_iter
operator->() const
requires __detail::__has_arrow<_Vp_iter>
&& copyable<_Vp_iter>
{ return _M_current; }
constexpr _Iterator&
operator++()
{
_M_current = ranges::find_if(std::move(++_M_current),
ranges::end(_M_parent->_M_base),
std::ref(*_M_parent->_M_pred));
return *this;
}
constexpr void
operator++(int)
{ ++*this; }
constexpr _Iterator
operator++(int) requires forward_range<_Vp>
{
auto __tmp = *this;
++*this;
return __tmp;
}
constexpr _Iterator&
operator--() requires bidirectional_range<_Vp>
{
do
--_M_current;
while (!std::__invoke(*_M_parent->_M_pred, *_M_current));
return *this;
}
constexpr _Iterator
operator--(int) requires bidirectional_range<_Vp>
{
auto __tmp = *this;
--*this;
return __tmp;
}
friend constexpr bool
operator==(const _Iterator& __x, const _Iterator& __y)
requires equality_comparable<_Vp_iter>
{ return __x._M_current == __y._M_current; }
friend constexpr range_rvalue_reference_t<_Vp>
iter_move(const _Iterator& __i)
noexcept(noexcept(ranges::iter_move(__i._M_current)))
{ return ranges::iter_move(__i._M_current); }
friend constexpr void
iter_swap(const _Iterator& __x, const _Iterator& __y)
noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
requires indirectly_swappable<_Vp_iter>
{ ranges::iter_swap(__x._M_current, __y._M_current); }
};
struct _Sentinel
{
private:
sentinel_t<_Vp> _M_end = sentinel_t<_Vp>();
constexpr bool
__equal(const _Iterator& __i) const
{ return __i._M_current == _M_end; }
public:
_Sentinel() = default;
constexpr explicit
_Sentinel(filter_view* __parent)
: _M_end(ranges::end(__parent->_M_base))
{ }
constexpr sentinel_t<_Vp>
base() const
{ return _M_end; }
friend constexpr bool
operator==(const _Iterator& __x, const _Sentinel& __y)
{ return __y.__equal(__x); }
};
[[no_unique_address]] __detail::__box<_Pred> _M_pred;
[[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
_Vp _M_base = _Vp();
public:
filter_view() requires (default_initializable<_Vp>
&& default_initializable<_Pred>)
= default;
constexpr
filter_view(_Vp __base, _Pred __pred)
: _M_pred(std::move(__pred)), _M_base(std::move(__base))
{ }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
constexpr const _Pred&
pred() const
{ return *_M_pred; }
constexpr _Iterator
begin()
{
if (_M_cached_begin._M_has_value())
return {this, _M_cached_begin._M_get(_M_base)};
__glibcxx_assert(_M_pred.has_value());
auto __it = ranges::find_if(ranges::begin(_M_base),
ranges::end(_M_base),
std::ref(*_M_pred));
_M_cached_begin._M_set(_M_base, __it);
return {this, std::move(__it)};
}
constexpr auto
end()
{
if constexpr (common_range<_Vp>)
return _Iterator{this, ranges::end(_M_base)};
else
return _Sentinel{this};
}
};
template<typename _Range, typename _Pred>
filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Pred>
concept __can_filter_view
= requires { filter_view(std::declval<_Range>(), std::declval<_Pred>()); };
} // namespace __detail
struct _Filter : __adaptor::_RangeAdaptor<_Filter>
{
template<viewable_range _Range, typename _Pred>
requires __detail::__can_filter_view<_Range, _Pred>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return filter_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
}
using _RangeAdaptor<_Filter>::operator();
static constexpr int _S_arity = 2;
static constexpr bool _S_has_simple_extra_args = true;
};
inline constexpr _Filter filter;
} // namespace views
template<input_range _Vp, copy_constructible _Fp>
requires view<_Vp> && is_object_v<_Fp>
&& regular_invocable<_Fp&, range_reference_t<_Vp>>
&& std::__detail::__can_reference<invoke_result_t<_Fp&,
range_reference_t<_Vp>>>
class transform_view : public view_interface<transform_view<_Vp, _Fp>>
{
private:
template<bool _Const>
using _Base = __detail::__maybe_const_t<_Const, _Vp>;
template<bool _Const>
struct __iter_cat
{ };
template<bool _Const>
requires forward_range<_Base<_Const>>
struct __iter_cat<_Const>
{
private:
static auto
_S_iter_cat()
{
using _Base = transform_view::_Base<_Const>;
using _Res = invoke_result_t<_Fp&, range_reference_t<_Base>>;
if constexpr (is_lvalue_reference_v<_Res>)
{
using _Cat
= typename iterator_traits<iterator_t<_Base>>::iterator_category;
if constexpr (derived_from<_Cat, contiguous_iterator_tag>)
return random_access_iterator_tag{};
else
return _Cat{};
}
else
return input_iterator_tag{};
}
public:
using iterator_category = decltype(_S_iter_cat());
};
template<bool _Const>
struct _Sentinel;
template<bool _Const>
struct _Iterator : __iter_cat<_Const>
{
private:
using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
using _Base = transform_view::_Base<_Const>;
static auto
_S_iter_concept()
{
if constexpr (random_access_range<_Base>)
return random_access_iterator_tag{};
else if constexpr (bidirectional_range<_Base>)
return bidirectional_iterator_tag{};
else if constexpr (forward_range<_Base>)
return forward_iterator_tag{};
else
return input_iterator_tag{};
}
using _Base_iter = iterator_t<_Base>;
_Base_iter _M_current = _Base_iter();
_Parent* _M_parent = nullptr;
public:
using iterator_concept = decltype(_S_iter_concept());
// iterator_category defined in __transform_view_iter_cat
using value_type
= remove_cvref_t<invoke_result_t<_Fp&, range_reference_t<_Base>>>;
using difference_type = range_difference_t<_Base>;
_Iterator() requires default_initializable<_Base_iter> = default;
constexpr
_Iterator(_Parent* __parent, _Base_iter __current)
: _M_current(std::move(__current)),
_M_parent(__parent)
{ }
constexpr
_Iterator(_Iterator<!_Const> __i)
requires _Const
&& convertible_to<iterator_t<_Vp>, _Base_iter>
: _M_current(std::move(__i._M_current)), _M_parent(__i._M_parent)
{ }
constexpr const _Base_iter&
base() const & noexcept
{ return _M_current; }
constexpr _Base_iter
base() &&
{ return std::move(_M_current); }
constexpr decltype(auto)
operator*() const
noexcept(noexcept(std::__invoke(*_M_parent->_M_fun, *_M_current)))
{ return std::__invoke(*_M_parent->_M_fun, *_M_current); }
constexpr _Iterator&
operator++()
{
++_M_current;
return *this;
}
constexpr void
operator++(int)
{ ++_M_current; }
constexpr _Iterator
operator++(int) requires forward_range<_Base>
{
auto __tmp = *this;
++*this;
return __tmp;
}
constexpr _Iterator&
operator--() requires bidirectional_range<_Base>
{
--_M_current;
return *this;
}
constexpr _Iterator
operator--(int) requires bidirectional_range<_Base>
{
auto __tmp = *this;
--*this;
return __tmp;
}
constexpr _Iterator&
operator+=(difference_type __n) requires random_access_range<_Base>
{
_M_current += __n;
return *this;
}
constexpr _Iterator&
operator-=(difference_type __n) requires random_access_range<_Base>
{
_M_current -= __n;
return *this;
}
constexpr decltype(auto)
operator[](difference_type __n) const
requires random_access_range<_Base>
{ return std::__invoke(*_M_parent->_M_fun, _M_current[__n]); }
friend constexpr bool
operator==(const _Iterator& __x, const _Iterator& __y)
requires equality_comparable<_Base_iter>
{ return __x._M_current == __y._M_current; }
friend constexpr bool
operator<(const _Iterator& __x, const _Iterator& __y)
requires random_access_range<_Base>
{ return __x._M_current < __y._M_current; }
friend constexpr bool
operator>(const _Iterator& __x, const _Iterator& __y)
requires random_access_range<_Base>
{ return __y < __x; }
friend constexpr bool
operator<=(const _Iterator& __x, const _Iterator& __y)
requires random_access_range<_Base>
{ return !(__y < __x); }
friend constexpr bool
operator>=(const _Iterator& __x, const _Iterator& __y)
requires random_access_range<_Base>
{ return !(__x < __y); }
#ifdef __cpp_lib_three_way_comparison
friend constexpr auto
operator<=>(const _Iterator& __x, const _Iterator& __y)
requires random_access_range<_Base>
&& three_way_comparable<_Base_iter>
{ return __x._M_current <=> __y._M_current; }
#endif
friend constexpr _Iterator
operator+(_Iterator __i, difference_type __n)
requires random_access_range<_Base>
{ return {__i._M_parent, __i._M_current + __n}; }
friend constexpr _Iterator
operator+(difference_type __n, _Iterator __i)
requires random_access_range<_Base>
{ return {__i._M_parent, __i._M_current + __n}; }
friend constexpr _Iterator
operator-(_Iterator __i, difference_type __n)
requires random_access_range<_Base>
{ return {__i._M_parent, __i._M_current - __n}; }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3483. transform_view::iterator's difference is overconstrained
friend constexpr difference_type
operator-(const _Iterator& __x, const _Iterator& __y)
requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
{ return __x._M_current - __y._M_current; }
friend constexpr decltype(auto)
iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
{
if constexpr (is_lvalue_reference_v<decltype(*__i)>)
return std::move(*__i);
else
return *__i;
}
friend _Iterator<!_Const>;
template<bool> friend struct _Sentinel;
};
template<bool _Const>
struct _Sentinel
{
private:
using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
using _Base = transform_view::_Base<_Const>;
template<bool _Const2>
constexpr auto
__distance_from(const _Iterator<_Const2>& __i) const
{ return _M_end - __i._M_current; }
template<bool _Const2>
constexpr bool
__equal(const _Iterator<_Const2>& __i) const
{ return __i._M_current == _M_end; }
sentinel_t<_Base> _M_end = sentinel_t<_Base>();
public:
_Sentinel() = default;
constexpr explicit
_Sentinel(sentinel_t<_Base> __end)
: _M_end(__end)
{ }
constexpr
_Sentinel(_Sentinel<!_Const> __i)
requires _Const
&& convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
: _M_end(std::move(__i._M_end))
{ }
constexpr sentinel_t<_Base>
base() const
{ return _M_end; }
template<bool _Const2>
requires sentinel_for<sentinel_t<_Base>,
iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
friend constexpr bool
operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
{ return __y.__equal(__x); }
template<bool _Const2,
typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
friend constexpr range_difference_t<_Base2>
operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
{ return -__y.__distance_from(__x); }
template<bool _Const2,
typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
friend constexpr range_difference_t<_Base2>
operator-(const _Sentinel& __y, const _Iterator<_Const2>& __x)
{ return __y.__distance_from(__x); }
friend _Sentinel<!_Const>;
};
[[no_unique_address]] __detail::__box<_Fp> _M_fun;
_Vp _M_base = _Vp();
public:
transform_view() requires (default_initializable<_Vp>
&& default_initializable<_Fp>)
= default;
constexpr
transform_view(_Vp __base, _Fp __fun)
: _M_fun(std::move(__fun)), _M_base(std::move(__base))
{ }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base ; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
constexpr _Iterator<false>
begin()
{ return _Iterator<false>{this, ranges::begin(_M_base)}; }
constexpr _Iterator<true>
begin() const
requires range<const _Vp>
&& regular_invocable<const _Fp&, range_reference_t<const _Vp>>
{ return _Iterator<true>{this, ranges::begin(_M_base)}; }
constexpr _Sentinel<false>
end()
{ return _Sentinel<false>{ranges::end(_M_base)}; }
constexpr _Iterator<false>
end() requires common_range<_Vp>
{ return _Iterator<false>{this, ranges::end(_M_base)}; }
constexpr _Sentinel<true>
end() const
requires range<const _Vp>
&& regular_invocable<const _Fp&, range_reference_t<const _Vp>>
{ return _Sentinel<true>{ranges::end(_M_base)}; }
constexpr _Iterator<true>
end() const
requires common_range<const _Vp>
&& regular_invocable<const _Fp&, range_reference_t<const _Vp>>
{ return _Iterator<true>{this, ranges::end(_M_base)}; }
constexpr auto
size() requires sized_range<_Vp>
{ return ranges::size(_M_base); }
constexpr auto
size() const requires sized_range<const _Vp>
{ return ranges::size(_M_base); }
};
template<typename _Range, typename _Fp>
transform_view(_Range&&, _Fp) -> transform_view<views::all_t<_Range>, _Fp>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Fp>
concept __can_transform_view
= requires { transform_view(std::declval<_Range>(), std::declval<_Fp>()); };
} // namespace __detail
struct _Transform : __adaptor::_RangeAdaptor<_Transform>
{
template<viewable_range _Range, typename _Fp>
requires __detail::__can_transform_view<_Range, _Fp>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Fp&& __f) const
{
return transform_view(std::forward<_Range>(__r), std::forward<_Fp>(__f));
}
using _RangeAdaptor<_Transform>::operator();
static constexpr int _S_arity = 2;
static constexpr bool _S_has_simple_extra_args = true;
};
inline constexpr _Transform transform;
} // namespace views
template<view _Vp>
class take_view : public view_interface<take_view<_Vp>>
{
private:
template<bool _Const>
using _CI = counted_iterator<
iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>;
template<bool _Const>
struct _Sentinel
{
private:
using _Base = __detail::__maybe_const_t<_Const, _Vp>;
sentinel_t<_Base> _M_end = sentinel_t<_Base>();
public:
_Sentinel() = default;
constexpr explicit
_Sentinel(sentinel_t<_Base> __end)
: _M_end(__end)
{ }
constexpr
_Sentinel(_Sentinel<!_Const> __s)
requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
: _M_end(std::move(__s._M_end))
{ }
constexpr sentinel_t<_Base>
base() const
{ return _M_end; }
friend constexpr bool
operator==(const _CI<_Const>& __y, const _Sentinel& __x)
{ return __y.count() == 0 || __y.base() == __x._M_end; }
template<bool _OtherConst = !_Const,
typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
friend constexpr bool
operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x)
{ return __y.count() == 0 || __y.base() == __x._M_end; }
friend _Sentinel<!_Const>;
};
range_difference_t<_Vp> _M_count = 0;
_Vp _M_base = _Vp();
public:
take_view() requires default_initializable<_Vp> = default;
constexpr
take_view(_Vp base, range_difference_t<_Vp> __count)
: _M_count(std::move(__count)), _M_base(std::move(base))
{ }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
constexpr auto
begin() requires (!__detail::__simple_view<_Vp>)
{
if constexpr (sized_range<_Vp>)
{
if constexpr (random_access_range<_Vp>)
return ranges::begin(_M_base);
else
{
auto __sz = size();
return counted_iterator(ranges::begin(_M_base), __sz);
}
}
else
return counted_iterator(ranges::begin(_M_base), _M_count);
}
constexpr auto
begin() const requires range<const _Vp>
{
if constexpr (sized_range<const _Vp>)
{
if constexpr (random_access_range<const _Vp>)
return ranges::begin(_M_base);
else
{
auto __sz = size();
return counted_iterator(ranges::begin(_M_base), __sz);
}
}
else
return counted_iterator(ranges::begin(_M_base), _M_count);
}
constexpr auto
end() requires (!__detail::__simple_view<_Vp>)
{
if constexpr (sized_range<_Vp>)
{
if constexpr (random_access_range<_Vp>)
return ranges::begin(_M_base) + size();
else
return default_sentinel;
}
else
return _Sentinel<false>{ranges::end(_M_base)};
}
constexpr auto
end() const requires range<const _Vp>
{
if constexpr (sized_range<const _Vp>)
{
if constexpr (random_access_range<const _Vp>)
return ranges::begin(_M_base) + size();
else
return default_sentinel;
}
else
return _Sentinel<true>{ranges::end(_M_base)};
}
constexpr auto
size() requires sized_range<_Vp>
{
auto __n = ranges::size(_M_base);
return std::min(__n, static_cast<decltype(__n)>(_M_count));
}
constexpr auto
size() const requires sized_range<const _Vp>
{
auto __n = ranges::size(_M_base);
return std::min(__n, static_cast<decltype(__n)>(_M_count));
}
};
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3447. Deduction guides for take_view and drop_view have different
// constraints
template<typename _Range>
take_view(_Range&&, range_difference_t<_Range>)
-> take_view<views::all_t<_Range>>;
template<typename _Tp>
inline constexpr bool enable_borrowed_range<take_view<_Tp>>
= enable_borrowed_range<_Tp>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Tp>
concept __can_take_view
= requires { take_view(std::declval<_Range>(), std::declval<_Tp>()); };
} // namespace __detail
struct _Take : __adaptor::_RangeAdaptor<_Take>
{
template<viewable_range _Range, typename _Tp>
requires __detail::__can_take_view<_Range, _Tp>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
{
return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
}
using _RangeAdaptor<_Take>::operator();
static constexpr int _S_arity = 2;
// The count argument of views::take is not always simple -- it can be
// e.g. a move-only class that's implicitly convertible to the difference
// type. But an integer-like count argument is surely simple.
template<typename _Tp>
static constexpr bool _S_has_simple_extra_args
= ranges::__detail::__is_integer_like<_Tp>;
};
inline constexpr _Take take;
} // namespace views
template<view _Vp, typename _Pred>
requires input_range<_Vp> && is_object_v<_Pred>
&& indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
class take_while_view : public view_interface<take_while_view<_Vp, _Pred>>
{
template<bool _Const>
struct _Sentinel
{
private:
using _Base = __detail::__maybe_const_t<_Const, _Vp>;
sentinel_t<_Base> _M_end = sentinel_t<_Base>();
const _Pred* _M_pred = nullptr;
public:
_Sentinel() = default;
constexpr explicit
_Sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
: _M_end(__end), _M_pred(__pred)
{ }
constexpr
_Sentinel(_Sentinel<!_Const> __s)
requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
: _M_end(__s._M_end), _M_pred(__s._M_pred)
{ }
constexpr sentinel_t<_Base>
base() const { return _M_end; }
friend constexpr bool
operator==(const iterator_t<_Base>& __x, const _Sentinel& __y)
{ return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
template<bool _OtherConst = !_Const,
typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
friend constexpr bool
operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y)
{ return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
friend _Sentinel<!_Const>;
};
[[no_unique_address]] __detail::__box<_Pred> _M_pred;
_Vp _M_base = _Vp();
public:
take_while_view() requires (default_initializable<_Vp>
&& default_initializable<_Pred>)
= default;
constexpr
take_while_view(_Vp base, _Pred __pred)
: _M_pred(std::move(__pred)), _M_base(std::move(base))
{ }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
constexpr const _Pred&
pred() const
{ return *_M_pred; }
constexpr auto
begin() requires (!__detail::__simple_view<_Vp>)
{ return ranges::begin(_M_base); }
constexpr auto
begin() const requires range<const _Vp>
&& indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
{ return ranges::begin(_M_base); }
constexpr auto
end() requires (!__detail::__simple_view<_Vp>)
{ return _Sentinel<false>(ranges::end(_M_base),
std::__addressof(*_M_pred)); }
constexpr auto
end() const requires range<const _Vp>
&& indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
{ return _Sentinel<true>(ranges::end(_M_base),
std::__addressof(*_M_pred)); }
};
template<typename _Range, typename _Pred>
take_while_view(_Range&&, _Pred)
-> take_while_view<views::all_t<_Range>, _Pred>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Pred>
concept __can_take_while_view
= requires { take_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
} // namespace __detail
struct _TakeWhile : __adaptor::_RangeAdaptor<_TakeWhile>
{
template<viewable_range _Range, typename _Pred>
requires __detail::__can_take_while_view<_Range, _Pred>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return take_while_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
}
using _RangeAdaptor<_TakeWhile>::operator();
static constexpr int _S_arity = 2;
static constexpr bool _S_has_simple_extra_args = true;
};
inline constexpr _TakeWhile take_while;
} // namespace views
template<view _Vp>
class drop_view : public view_interface<drop_view<_Vp>>
{
private:
range_difference_t<_Vp> _M_count = 0;
_Vp _M_base = _Vp();
// ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
// both random_access_range and sized_range. Otherwise, cache its result.
static constexpr bool _S_needs_cached_begin
= !(random_access_range<const _Vp> && sized_range<const _Vp>);
[[no_unique_address]]
__detail::__maybe_present_t<_S_needs_cached_begin,
__detail::_CachedPosition<_Vp>>
_M_cached_begin;
public:
drop_view() requires default_initializable<_Vp> = default;
constexpr
drop_view(_Vp __base, range_difference_t<_Vp> __count)
: _M_count(__count), _M_base(std::move(__base))
{ __glibcxx_assert(__count >= 0); }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
// This overload is disabled for simple views with constant-time begin().
constexpr auto
begin()
requires (!(__detail::__simple_view<_Vp>
&& random_access_range<const _Vp>
&& sized_range<const _Vp>))
{
if constexpr (_S_needs_cached_begin)
if (_M_cached_begin._M_has_value())
return _M_cached_begin._M_get(_M_base);
auto __it = ranges::next(ranges::begin(_M_base),
_M_count, ranges::end(_M_base));
if constexpr (_S_needs_cached_begin)
_M_cached_begin._M_set(_M_base, __it);
return __it;
}
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3482. drop_view's const begin should additionally require sized_range
constexpr auto
begin() const
requires random_access_range<const _Vp> && sized_range<const _Vp>
{
return ranges::next(ranges::begin(_M_base), _M_count,
ranges::end(_M_base));
}
constexpr auto
end() requires (!__detail::__simple_view<_Vp>)
{ return ranges::end(_M_base); }
constexpr auto
end() const requires range<const _Vp>
{ return ranges::end(_M_base); }
constexpr auto
size() requires sized_range<_Vp>
{
const auto __s = ranges::size(_M_base);
const auto __c = static_cast<decltype(__s)>(_M_count);
return __s < __c ? 0 : __s - __c;
}
constexpr auto
size() const requires sized_range<const _Vp>
{
const auto __s = ranges::size(_M_base);
const auto __c = static_cast<decltype(__s)>(_M_count);
return __s < __c ? 0 : __s - __c;
}
};
template<typename _Range>
drop_view(_Range&&, range_difference_t<_Range>)
-> drop_view<views::all_t<_Range>>;
template<typename _Tp>
inline constexpr bool enable_borrowed_range<drop_view<_Tp>>
= enable_borrowed_range<_Tp>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Tp>
concept __can_drop_view
= requires { drop_view(std::declval<_Range>(), std::declval<_Tp>()); };
} // namespace __detail
struct _Drop : __adaptor::_RangeAdaptor<_Drop>
{
template<viewable_range _Range, typename _Tp>
requires __detail::__can_drop_view<_Range, _Tp>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
{
return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
}
using _RangeAdaptor<_Drop>::operator();
static constexpr int _S_arity = 2;
template<typename _Tp>
static constexpr bool _S_has_simple_extra_args
= _Take::_S_has_simple_extra_args<_Tp>;
};
inline constexpr _Drop drop;
} // namespace views
template<view _Vp, typename _Pred>
requires input_range<_Vp> && is_object_v<_Pred>
&& indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
{
private:
[[no_unique_address]] __detail::__box<_Pred> _M_pred;
[[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
_Vp _M_base = _Vp();
public:
drop_while_view() requires (default_initializable<_Vp>
&& default_initializable<_Pred>)
= default;
constexpr
drop_while_view(_Vp __base, _Pred __pred)
: _M_pred(std::move(__pred)), _M_base(std::move(__base))
{ }
constexpr _Vp
base() const& requires copy_constructible<_Vp>
{ return _M_base; }
constexpr _Vp
base() &&
{ return std::move(_M_base); }
constexpr const _Pred&
pred() const
{ return *_M_pred; }
constexpr auto
begin()
{
if (_M_cached_begin._M_has_value())
return _M_cached_begin._M_get(_M_base);
__glibcxx_assert(_M_pred.has_value());
auto __it = ranges::find_if_not(ranges::begin(_M_base),
ranges::end(_M_base),
std::cref(*_M_pred));
_M_cached_begin._M_set(_M_base, __it);
return __it;
}
constexpr auto
end()
{ return ranges::end(_M_base); }
};
template<typename _Range, typename _Pred>
drop_while_view(_Range&&, _Pred)
-> drop_while_view<views::all_t<_Range>, _Pred>;
template<typename _Tp, typename _Pred>
inline constexpr bool enable_borrowed_range<drop_while_view<_Tp, _Pred>>
= enable_borrowed_range<_Tp>;
namespace views
{
namespace __detail
{
template<typename _Range, typename _Pred>
concept __can_drop_while_view
= requires { drop_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
} // namespace __detail
struct _DropWhile : __adaptor::_RangeAdaptor<_DropWhile>
{
template<viewable_range _Range, typename _Pred>
requires __detail::__can_drop_while_view<_Range, _Pred>
constexpr auto
operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return drop_while_view(std::forward<_Range>(__r),
std::forward<_Pred>(__p));
}
using _RangeAdaptor<_DropWhile>::operator();
static constexpr int _S_arity = 2;
static constexpr bool _S_has_simple_extra_args = true;
};
inline constexpr _DropWhile drop_while;
} // namespace views
template<input_range _Vp>
requires view<_Vp> && input_range<range_reference_t<_Vp>>
class join_view : public view_interface<join_view<_Vp>>
{
private:
using _InnerRange = range_reference_t<_Vp>;
template<bool _Const>
using _Base = __detail::__maybe_const_t<_Const, _Vp>;
template<bool _Const>
using _Outer_iter = iterator_t<_Base<_Const>>;
template<bool _Const>
using _Inner_iter = iterator_t<range_reference_t<_Base<_Const>>>;
template<bool _Const>
static constexpr bool _S_ref_is_glvalue
= is_reference_v<range_reference_t<_Base<_Const>>>;
template<bool _Const>
struct __iter_cat
{ };
template<bool _Const>
requires _S_ref_is_glvalue<_Const>
&& forward_range<_Base<_Const>>
&& forward_range<range_reference_t<_Base<_Const>>>
struct __iter_cat<_Const>
{
private:
static constexpr auto
_S_iter_cat()
{
using _Outer_iter = join_view::_Outer_iter<_Const>;
using _Inner_iter = join_view::_Inner_iter<_Const>;
using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
&& derived_from<_InnerCat, bidirectional_iterator_tag>)
return bidirectional_iterator_tag{};
else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
&& derived_from<_InnerCat, forward_iterator_tag>)
return forward_iterator_tag{};
else
return input_iterator_tag{};
}
public:
using iterator_category = decltype(_S_iter_cat());
};
template<bool _Const>
struct _Sentinel;
template<bool _Const>
struct _Iterator : __iter_cat<_Const>
{
private:
using _Parent = __detail::__maybe_const_t<_Const, join_view>;
using _Base = join_view::_Base<_Const>;
static constexpr bool _S_ref_is_glvalue
= join_view::_S_ref_is_glvalue<_Const>;
constexpr void
_M_satisfy()
{
auto __update_inner = [this] (const iterator_t<_Base>& __x) -> auto&& {
if constexpr (_S_ref_is_glvalue)
return *__x;
else
return _M_parent->_M_inner._M_emplace_deref(__x);
};
for (; _M_outer != ranges::end(_M_parent->_M_base); ++_M_outer)
{
auto&& __inner = __update_inner(_M_outer);
_M_inner = ranges::begin(__inner);
if (_M_inner != ranges::end(__inner))
return;
}
if constexpr (_S_ref_is_glvalue)
_M_inner = _Inner_iter();
}
static constexpr auto
_S_iter_concept()
{
if constexpr (_S_ref_is_glvalue
&& bidirectional_range<_Base>
&& bidirectional_range<range_reference_t<_Base>>)
return bidirectional_iterator_tag{};
else if constexpr (_S_ref_is_glvalue
&& forward_range<_Base>
&& forward_range<range_reference_t<_Base>>)
return forward_iterator_tag{};
else
return input_iterator_tag{};
}
using _Outer_iter = join_view::_Outer_iter<_Const>;
using _Inner_iter = join_view::_Inner_iter<_Const>;
_Outer_iter _M_outer = _Outer_iter();
_Inner_iter _M_inner = _Inner_iter();
_Parent* _M_parent = nullptr;
public:
using iterator_concept = decltype(_S_iter_concept());
// iterator_category defined in __join_view_iter_cat
using value_type = range_value_t<range_reference_t<_Base>>;
using difference_type
= common_type_t<range_difference_t<_Base>,
range_difference_t<range_reference_t<_Base>>>;
_Iterator() requires (default_initializable<_Outer_iter>
&& default_initializable<_Inner_iter>)
= default;
constexpr
_Iterator(_Parent* __parent, _Outer_iter __outer)