How can you pretty-print a `std::tuple` using variadic templates in C 11?

Pretty-Printing std::tuple

In a previous question on embellishing STL containers, we successfully developed a comprehensive and graceful solution. This next step delves into the realm of pretty-printing std::tuple using variadic templates (exclusively C 11).

Background

For std::pair, the syntax is straightforward:

std::ostream & operator &);

Analogous Construction for Tuple

The puzzle lies in defining an analogous construction for printing a tuple. We aim for this behavior:

auto a = std::make_tuple(5, "Hello", -0.1);
std::cout <p><strong>Solution</strong></p><p>The answer lies in exploiting indices:</p><pre class="brush:php;toolbar:false">namespace aux{
template<:size_t... is> struct seq{};

template<:size_t n std::size_t... is>
struct gen_seq : gen_seq<n-1 n-1 is...>{};

template<:size_t... is>
struct gen_seq: seq<is...>{};

template<class ch class tr tuple std::size_t... is>
void print_tuple(std::basic_ostream<ch tr>& os, Tuple const& t, seq<is...>){
  using swallow = int[];
  (void)swallow{0, (void(os (t)), 0)...};
}
} // aux::

template<class ch class tr class... args>
auto operator& os, std::tuple<args...> const& t)
    -> std::basic_ostream<ch tr>&
{
  os ());
  return os <p><strong>Bonus: Delimiters</strong></p>
<p>For added flexibility, we provide partial specializations:</p>
<pre class="brush:php;toolbar:false">// Delimiters for tuple
template<class... args>
struct delimiters<:tuple>, char> {
  static const delimiters_values<char> values;
};

template<class... args>
const delimiters_values<char> delimiters<:tuple>, char>::values = { "(", ", ", ")" };

template<class... args>
struct delimiters<:tuple>, wchar_t> {
  static const delimiters_values<wchar_t> values;
};

template<class... args>
const delimiters_values<wchar_t> delimiters<:tuple>, wchar_t>::values = { L"(", L", ", L")" };</:tuple></wchar_t></class...></wchar_t></:tuple></class...></:tuple></char></class...></char></:tuple></class...>

Conclusion

With the above modifications, pretty-printing std::tuple can be customized to accommodate different character sets and delimiter preferences, offering an elegant and versatile solution.

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