backed-string-view.hh

#pragma once
#include <variant>
#include <string>
#include <string_view>
 
class BackedStringView {
private:
    std::variant<std::string, std::string_view> data;
 
    class Ptr {
    private:
        std::string_view view;
    public:
        Ptr(std::string_view view): view(view) {}
        const std::string_view * operator->() const { return &view; }
    };
 
public:
    BackedStringView(std::string && s): data(std::move(s)) {}
    BackedStringView(std::string_view sv): data(sv) {}
    template<size_t N>
    BackedStringView(const char (& lit)[N]): data(std::string_view(lit)) {}
 
    BackedStringView(const BackedStringView &) = delete;
    BackedStringView & operator=(const BackedStringView &) = delete;
 
    BackedStringView(BackedStringView && other) = default;
    BackedStringView & operator=(BackedStringView && other) = default;
 
    bool isOwned() const
    {
        return std::holds_alternative<std::string>(data);
    }
 
    std::string toOwned() &&
    {
        return isOwned()
            ? std::move(std::get<std::string>(data))
            : std::string(std::get<std::string_view>(data));
    }
 
    std::string_view operator*() const
    {
        return isOwned()
            ? std::get<std::string>(data)
            : std::get<std::string_view>(data);
    }
    Ptr operator->() const { return Ptr(**this); }
};