26 Ranges library [ranges]

26.5 Range utilities [range.utility]

26.5.6 Range conversions [range.utility.conv]

26.5.6.1 General [range.utility.conv.general]

The range conversion functions construct an object (usually a container) from a range, by using a constructor taking a range, a from_­range_­t tagged constructor, or a constructor taking a pair of iterators, or by inserting each element of the range into the default-constructed object.
ranges​::​to is applied recursively, allowing the conversion of a range of ranges.
[Example 1: string_view str = "the quick brown fox"; auto words = views::split(str, ' ') | to<vector<string>>(); // words is vector<string>{"the", "quick", "brown", "fox"} — end example]
Let reservable-container be defined as follows: template<class Container> constexpr bool reservable-container = // exposition only sized_­range<Container> && requires(Container& c, range_size_t<Container> n) { c.reserve(n); { c.capacity() } -> same_­as<decltype(n)>; { c.max_size() } -> same_­as<decltype(n)>; };
Let container-insertable be defined as follows: template<class Container, class Ref> constexpr bool container-insertable = // exposition only requires(Container& c, Ref&& ref) { requires (requires { c.push_back(std::forward<Ref>(ref)); } || requires { c.insert(c.end(), std::forward<Ref>(ref)); }); };
Let container-inserter be defined as follows: template<class Ref, class Container> constexpr auto container-inserter(Container& c) { // exposition only if constexpr (requires { c.push_back(declval<Ref>()); }) return back_inserter(c); else return inserter(c, c.end()); }