Should debug_printer be a part of restinio::easy_parser?

[eao197]

RESTinio's easy_parser used in restinio::http_field_parsers doesn't contain debugging facilities (and it's an open question can such facilities be added). So the debugging of PEG parsers is not an easy task.

A simple helper debug_print was very useful in the implementation of parser for Host HTTP-field. Its source code can be found here:

restinio/dev/restinio/helpers/http_field_parsers/host.hpp

Lines 212 to 227 in 3a3e4bf

	struct debug_printer : public ep_impl::clause_tag
	{
	std::string m_tag;
	debug_printer( std::string v ) noexcept : m_tag{ std::move(v) } {}
	template< typename Target_Type >
	RESTINIO_NODISCARD
	optional_t< parse_error_t >
	try_process( ep_impl::source_t & from, Target_Type & /*target*/ )
	{
	std::cout << "*** debug_print: " << m_tag << std::endl;
	return nullopt;
	}
	};

Maybe debug_print should become a part of easy_parser?