constexpr
pct_string_view() = default;

constexpr
pct_string_view(pct_string_view const& other) = default;

template<
    class String,
    class = void>
pct_string_view(String const& s);

pct_string_view(std::nullptr_t) = delete;

pct_string_view(
    char const* s,
    std::size_t len);

pct_string_view(core::string_view s);