cppdraft_translate/cppdraft/range/as/rvalue.md

[range.as.rvalue]

25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.7 As rvalue view [range.as.rvalue]

25.7.7.1 Overview [range.as.rvalue.overview]

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as_rvalue_view presents a view of an underlying sequence with the same behavior as the underlying sequence except that its elements are rvalues.

Some generic algorithms can be called with an as_rvalue_view to replace copying with moving.

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The name views​::​as_rvalue denotes a range adaptor object ([range.adaptor.object]).

Let E be an expression and let T be decltype((E)).

The expression views​::​as_rvalue(E) is expression-equivalent to:

• (2.1)

  views​::​all(E) ifT models input_range andsame_as<range_rvalue_reference_t, range_reference_t> is true.

• (2.2)

  Otherwise, as_rvalue_view(E).

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[Example 1: vector words = {"the", "quick", "brown", "fox", "ate", "a", "pterodactyl"}; vector new_words; ranges::copy(words | views::as_rvalue, back_inserter(new_words)); // moves each string from words into new_words — end example]

25.7.7.2 Class template as_rvalue_view [range.as.rvalue.view]

namespace std::ranges {template<view V>requires input_rangeclass as_rvalue_view : public view_interface<as_rvalue_view> { V base_ = V(); // exposition onlypublic: as_rvalue_view() requires default_initializable = default; constexpr explicit as_rvalue_view(V base); constexpr V base() const & requires copy_constructible { return base_; }constexpr V base() && { return std::move(base_); }constexpr auto begin() requires (){ return move_iterator(ranges::begin(base_)); }constexpr auto begin() const requires range{ return move_iterator(ranges::begin(base_)); }constexpr auto end() requires () {if constexpr (common_range) {return move_iterator(ranges::end(base_)); } else {return move_sentinel(ranges::end(base_)); }}constexpr auto end() const requires range {if constexpr (common_range) {return move_iterator(ranges::end(base_)); } else {return move_sentinel(ranges::end(base_)); }}constexpr auto size() requires sized_range { return ranges::size(base_); }constexpr auto size() const requires sized_range { return ranges::size(base_); }constexpr auto reserve_hint() requires approximately_sized_range{ return ranges::reserve_hint(base_); }constexpr auto reserve_hint() const requires approximately_sized_range{ return ranges::reserve_hint(base_); }}; template as_rvalue_view(R&&) -> as_rvalue_view<views::all_t>;}

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constexpr explicit as_rvalue_view(V base);

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Effects: Initializes base_ with std​::​move(base).