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Aug 17, 2022
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P2494R2 Relaxing range adaptors to allow for move only types #5710

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b5898af
P2494R2 Relaxing range adaptors to allow for move only types
jensmaurer Aug 5, 2022
1df7957
[range.chunk.by.view] Change copyable-box to movable-box.
tkoeppe Aug 17, 2022
d5aea28
[range.repeat.view] Apply modifications from P2494R2
jensmaurer Aug 5, 2022
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81 changes: 45 additions & 36 deletions source/ranges.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -170,7 +170,7 @@
}

// \ref{range.single}, single view
template<@\libconcept{copy_constructible}@ T>
template<@\libconcept{move_constructible}@ T>
requires is_object_v<T>
class single_view; // freestanding

Expand Down Expand Up @@ -256,7 +256,7 @@
namespace views { inline constexpr @\unspecnc@ filter = @\unspecnc@; } // freestanding

// \ref{range.transform}, transform view
template<@\libconcept{input_range}@ V, @\libconcept{copy_constructible}@ F>
template<@\libconcept{input_range}@ V, @\libconcept{move_constructible}@ F>
requires @\libconcept{view}@<V> && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<V>> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<V>>>
Expand Down Expand Up @@ -421,7 +421,7 @@
namespace views { inline constexpr @\unspecnc@ zip = @\unspecnc@; } // freestanding

// \ref{range.zip.transform}, zip transform view
template<@\libconcept{copy_constructible}@ F, @\libconcept{input_range}@... Views>
template<@\libconcept{move_constructible}@ F, @\libconcept{input_range}@... Views>
requires (@\libconcept{view}@<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<Views>...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<Views>...>>
Expand All @@ -445,7 +445,7 @@
}

// \ref{range.adjacent.transform}, adjacent transform view
template<@\libconcept{forward_range}@ V, @\libconcept{copy_constructible}@ F, size_t N>
template<@\libconcept{forward_range}@ V, @\libconcept{move_constructible}@ F, size_t N>
requires @\seebelow@
class adjacent_transform_view; // freestanding

Expand Down Expand Up @@ -2473,15 +2473,15 @@
\indexlibraryglobal{single_view}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{copy_constructible}@ T>
template<@\libconcept{move_constructible}@ T>
requires is_object_v<T>
class single_view : public view_interface<single_view<T>> {
private:
@\exposidnc{copyable-box}@<T> @\exposidnc{value_}@; // \expos{} (see \ref{range.copy.wrap})
@\exposidnc{movable-box}@<T> @\exposidnc{value_}@; // \expos{} (see \ref{range.move.wrap})

public:
single_view() requires @\libconcept{default_initializable}@<T> = default;
constexpr explicit single_view(const T& t);
constexpr explicit single_view(const T& t) requires @\libconcept{copy_constructible}@<T>;
constexpr explicit single_view(T&& t);
template<class... Args>
requires @\libconcept{constructible_from}@<T, Args...>
Expand All @@ -2503,7 +2503,7 @@

\indexlibraryctor{single_view}%
\begin{itemdecl}
constexpr explicit single_view(const T& t);
constexpr explicit single_view(const T& t) requires @\libconcept{copy_constructible}@<T>;;
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -4072,31 +4072,32 @@
the initialization of the bound argument entities of the result,
as specified above, are all well-formed.

\rSec2[range.copy.wrap]{Copyable wrapper}
\rSec2[range.move.wrap]{Movable wrapper}

\pnum
Many types in this subclause are specified in terms of
an exposition-only class template \exposid{copyable-box}.
\tcode{\exposid{copyable-box}<T>} behaves exactly like \tcode{optional<T>}
an exposition-only class template \exposid{movable-box}.
\tcode{\exposid{movable-box}<T>} behaves exactly like \tcode{optional<T>}
with the following differences:
\begin{itemize}
\item \tcode{\exposid{copyable-box}<T>} constrains
\item \tcode{\exposid{movable-box}<T>} constrains
its type parameter \tcode{T} with
\tcode{\libconcept{copy_constructible}<T> \&\& is_object_v<T>}.

\item The default
constructor of \tcode{\exposid{copyable-box}<T>} is equivalent to:
constructor of \tcode{\exposid{movable-box}<T>} is equivalent to:
\begin{codeblock}
constexpr @\exposid{copyable-box}@() noexcept(is_nothrow_default_constructible_v<T>)
constexpr @\exposid{movable-box}@() noexcept(is_nothrow_default_constructible_v<T>)
requires @\libconcept{default_initializable}@<T>
: @\exposid{copyable-box}@{in_place} {}
: @\exposid{movable-box}@{in_place} {}
\end{codeblock}

\item If \tcode{\libconcept{copyable}<T>} is not
modeled, the copy assignment operator is equivalent to:
\begin{codeblock}
constexpr @\exposid{copyable-box}@& operator=(const @\exposid{copyable-box}@& that)
noexcept(is_nothrow_copy_constructible_v<T>) {
constexpr @\exposid{movable-box}@& operator=(const @\exposid{movable-box}@& that)
noexcept(is_nothrow_copy_constructible_v<T>)
requires @\libconcept{copy_constructible}@<T> {
if (this != addressof(that)) {
if (that) emplace(*that);
else reset();
Expand All @@ -4108,7 +4109,7 @@
\item If \tcode{\libconcept{movable}<T>} is not modeled,
the move assignment operator is equivalent to:
\begin{codeblock}
constexpr @\exposid{copyable-box}@& operator=(@\exposid{copyable-box}@&& that)
constexpr @\exposid{movable-box}@& operator=(@\exposid{movable-box}@&& that)
noexcept(is_nothrow_move_constructible_v<T>) {
if (this != addressof(that)) {
if (that) emplace(std::move(*that));
Expand All @@ -4121,10 +4122,18 @@

\pnum
\recommended
\tcode{\exposid{copyable-box}<T>} should store only a \tcode{T}
if either \tcode{T} models \libconcept{copyable} or
\begin{itemize}
\item
If \tcode{\libconcept{copy_constructible}<T>} is \tcode{true},
\tcode{\exposid{movable-box}<T>} should store only a \exposid{T}
if either \tcode{T} models \libconcept{copyable}, or
\tcode{is_nothrow_move_constructible_v<T> \&\& is_nothrow_copy_constructible_v<T>}
is \tcode{true}.
\item
Otherwise, \tcode{\exposid{movable-box}<T>} should store only a \tcode{T}
if either \tcode{T} models \libconcept{movable} or
\tcode{is_nothrow_move_constructible_v<T>} is \tcode{true}.
\end{itemize}

\rSec2[range.nonprop.cache]{Non-propagating cache}

Expand Down Expand Up @@ -4523,7 +4532,7 @@
class filter_view : public view_interface<filter_view<V, Pred>> {
private:
V @\exposid{base_}@ = V(); // \expos
@\exposidnc{copyable-box}@<Pred> @\exposid{pred_}@; // \expos
@\exposidnc{movable-box}@<Pred> @\exposid{pred_}@; // \expos

// \ref{range.filter.iterator}, class \tcode{filter_view::\exposid{iterator}}
class @\exposid{iterator}@; // \expos
Expand Down Expand Up @@ -4943,7 +4952,7 @@
\indexlibrarymember{size}{transform_view}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{input_range}@ V, @\libconcept{copy_constructible}@ F>
template<@\libconcept{input_range}@ V, @\libconcept{move_constructible}@ F>
requires @\libconcept{view}@<V> && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<V>> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<V>>>
Expand All @@ -4956,7 +4965,7 @@
template<bool> struct @\exposid{sentinel}@; // \expos

V @\exposid{base_}@ = V(); // \expos
@\placeholdernc{copyable-box}@<F> @\exposid{fun_}@; // \expos
@\placeholdernc{movable-box}@<F> @\exposid{fun_}@; // \expos

public:
transform_view() requires @\libconcept{default_initializable}@<V> && @\libconcept{default_initializable}@<F> = default;
Expand Down Expand Up @@ -5096,7 +5105,7 @@
\indexlibraryglobal{transform_view::iterator}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{input_range}@ V, @\libconcept{copy_constructible}@ F>
template<@\libconcept{input_range}@ V, @\libconcept{move_constructible}@ F>
requires @\libconcept{view}@<V> && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<V>> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<V>>>
Expand Down Expand Up @@ -5480,7 +5489,7 @@
\indexlibraryglobal{transform_view::sentinel}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{input_range}@ V, @\libconcept{copy_constructible}@ F>
template<@\libconcept{input_range}@ V, @\libconcept{move_constructible}@ F>
requires @\libconcept{view}@<V> && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<V>> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<V>>>
Expand Down Expand Up @@ -5910,7 +5919,7 @@
template<bool> class @\exposidnc{sentinel}@; // \expos

V @\exposid{base_}@ = V(); // \expos
@\exposidnc{copyable-box}@<Pred> @\exposid{pred_}@; // \expos
@\exposidnc{movable-box}@<Pred> @\exposid{pred_}@; // \expos

public:
take_while_view() requires @\libconcept{default_initializable}@<V> && @\libconcept{default_initializable}@<Pred> = default;
Expand Down Expand Up @@ -6277,7 +6286,7 @@

private:
V @\exposid{base_}@ = V(); // \expos
@\placeholder{copyable-box}@<Pred> @\exposid{pred_}@; @\itcorr[-1]@ // \expos
@\placeholder{movable-box}@<Pred> @\exposid{pred_}@; @\itcorr[-1]@ // \expos
};

template<class R, class Pred>
Expand Down Expand Up @@ -10007,12 +10016,12 @@
\indexlibrarymember{size}{zip_transform_view}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{copy_constructible}@ F, @\libconcept{input_range}@... Views>
template<@\libconcept{mmove_constructible}@ F, @\libconcept{input_range}@... Views>
requires (@\libconcept{view}@<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<Views>...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<Views>...>>
class zip_transform_view : public view_interface<zip_transform_view<F, Views...>> {
@\exposidnc{copyable-box}@<F> @\exposid{fun_}@; // \expos
@\exposidnc{movable-box}@<F> @\exposid{fun_}@; // \expos
zip_view<Views...> @\exposid{zip_}@; // \expos

using @\exposidnc{InnerView}@ = zip_view<Views...>; // \expos
Expand Down Expand Up @@ -10088,7 +10097,7 @@
\indexlibraryglobal{zip_transform_view::iterator}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{copy_constructible}@ F, @\libconcept{input_range}@... Views>
template<@\libconcept{move_constructible}@ F, @\libconcept{input_range}@... Views>
requires (@\libconcept{view}@<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<Views>...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<Views>...>>
Expand Down Expand Up @@ -10400,7 +10409,7 @@
\indexlibraryglobal{zip_transform_view::sentinel}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{copy_constructible}@ F, @\libconcept{input_range}@... Views>
template<@\libconcept{move_constructible}@ F, @\libconcept{input_range}@... Views>
requires (@\libconcept{view}@<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, range_reference_t<Views>...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, range_reference_t<Views>...>>
Expand Down Expand Up @@ -11165,12 +11174,12 @@
\indexlibrarymember{size}{adjacent_transform_view}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{forward_range}@ V, @\libconcept{copy_constructible}@ F, size_t N>
template<@\libconcept{forward_range}@ V, @\libconcept{move_constructible}@ F, size_t N>
requires @\libconcept{view}@<V> && (N > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...>>
class adjacent_transform_view : public view_interface<adjacent_transform_view<V, F, N>> {
@\exposidnc{copyable-box}@<F> @\exposid{fun_}@; // \expos
@\exposidnc{movable-box}@<F> @\exposid{fun_}@; // \expos
adjacent_view<V, N> @\exposid{inner_}@; // \expos

using @\exposidnc{InnerView}@ = adjacent_view<V, N>; // \expos
Expand Down Expand Up @@ -11244,7 +11253,7 @@
\indexlibraryglobal{adjacent_transform_view::iterator}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{forward_range}@ V, @\libconcept{copy_constructible}@ F, size_t N>
template<@\libconcept{forward_range}@ V, @\libconcept{move_constructible}@ F, size_t N>
requires @\libconcept{view}@<V> && (N > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...>>
Expand Down Expand Up @@ -11547,7 +11556,7 @@
\indexlibraryglobal{adjacent_transform_view::sentinel}%
\begin{codeblock}
namespace std::ranges {
template<@\libconcept{forward_range}@ V, @\libconcept{copy_constructible}@ F, size_t N>
template<@\libconcept{forward_range}@ V, @\libconcept{move_constructible}@ F, size_t N>
requires @\libconcept{view}@<V> && (N > 0) && is_object_v<F> &&
@\libconcept{regular_invocable}@<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...> &&
@\exposconcept{can-reference}@<invoke_result_t<F&, @\exposid{REPEAT}@(range_reference_t<V>, N)...>>
Expand Down Expand Up @@ -13293,7 +13302,7 @@
requires @\libconcept{view}@<V> && is_object_v<Pred>
class chunk_by_view : public view_interface<chunk_by_view<V, Pred>> {
V @\exposid{base_}@ = V(); // \expos
@\exposid{copyable-box}@<Pred> @\exposid{pred_}@ = Pred(); // \expos
@\exposid{movable-box}@<Pred> @\exposid{pred_}@ = Pred(); // \expos
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A space is needed before the comment to keep them aligned.

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Will fix!


// \ref{range.chunk.by.iter}, class \tcode{chunk_by_view::\exposid{iterator}}
class @\exposid{iterator}@; // \expos
Expand Down
2 changes: 1 addition & 1 deletion source/support.tex
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -681,7 +681,7 @@
#define @\defnlibxname{cpp_lib_polymorphic_allocator}@ 201902L // also in \libheader{memory_resource}
#define @\defnlibxname{cpp_lib_print}@ 202207L // also in \libheader{print}, \libheader{ostream}
#define @\defnlibxname{cpp_lib_quoted_string_io}@ 201304L // also in \libheader{iomanip}
#define @\defnlibxname{cpp_lib_ranges}@ 202202L
#define @\defnlibxname{cpp_lib_ranges}@ 202207L
// also in \libheader{algorithm}, \libheader{functional}, \libheader{iterator}, \libheader{memory}, \libheader{ranges}
#define @\defnlibxname{cpp_lib_ranges_as_const}@ 202207L // also in \libheader{ranges}
#define @\defnlibxname{cpp_lib_ranges_as_rvalue}@ 202207L // also in \libheader{ranges}
Expand Down