[range.utility.conv.general]

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-appendable be defined as follows: template<class Container, class Ref> constexpr bool container-appendable = / exposition only requires(Container& c, Ref&& ref) { requires (requires { c.emplace_back(std::forward<Ref>(ref)); } || requires { c.push_back(std::forward<Ref>(ref)); } || requires { c.emplace(c.end(), std::forward<Ref>(ref)); } || requires { c.insert(c.end(), std::forward<Ref>(ref)); }); };

Let container-append be defined as follows: template<class Container> constexpr auto container-append(Container& c) { / exposition only return [&c]<class Ref>(Ref&& ref) { if constexpr (requires { c.emplace_back(declval<Ref>(); }) c.emplace_back(std::forward<Ref>(ref)); else if constexpr (requires { c.push_back(declval<Ref>(); }) c.push_back(std::forward<Ref>(ref)); else if constexpr (requires { c.emplace(c.end(), declval<Ref>(); }) c.emplace(c.end(), std::forward<Ref>(ref)); else c.insert(c.end(), std::forward<Ref>(ref)); }; }