dncurrency/nano/lib/object_stream_adapters.hpp
2024-03-13 09:56:35 +01:00

150 lines
No EOL
4 KiB
C++

#pragma once
#include <nano/lib/object_stream.hpp>
#include <nano/lib/utility.hpp>
#include <ostream>
#include <sstream>
#include <fmt/ostream.h>
namespace nano
{
template <class Streamable, class Writer>
struct object_stream_formatter
{
nano::object_stream_config const & config;
Streamable const & value;
Writer writer;
explicit object_stream_formatter (Streamable const & value, Writer writer, nano::object_stream_config const & config) :
config{ config },
value{ value },
writer{ writer }
{
}
friend std::ostream & operator<< (std::ostream & os, object_stream_formatter<Streamable, Writer> const & self)
{
nano::root_object_stream obs{ os, self.config };
self.writer (self.value, obs);
return os;
}
// Needed for fmt formatting, uses the ostream operator under the hood
friend auto format_as (object_stream_formatter<Streamable, Writer> const & self)
{
return fmt::streamed (self);
}
};
enum class streamed_format
{
basic,
json
};
inline nano::object_stream_config const & to_object_stream_config (streamed_format format)
{
switch (format)
{
case streamed_format::basic:
return nano::object_stream_config::default_config ();
case streamed_format::json:
return nano::object_stream_config::json_config ();
default:
debug_assert (false);
return nano::object_stream_config::default_config ();
}
}
template <class Streamable>
auto streamed (Streamable const & value, streamed_format format = streamed_format::basic)
{
return object_stream_formatter{ value, [] (auto const & value, nano::root_object_stream & obs) { obs.write (value); }, to_object_stream_config (format) };
}
template <class StreamableRange>
auto streamed_range (StreamableRange const & value, streamed_format format = streamed_format::basic)
{
return object_stream_formatter{ value, [] (auto const & value, nano::root_object_stream & obs) { obs.write_range (value); }, to_object_stream_config (format) };
}
/**
* Wraps {name,value} args and provides `<<(std::ostream &, ...)` and fmt format operator that writes the arguments to the stream in a lazy manner.
*/
template <class... Args>
struct object_stream_args_formatter
{
nano::object_stream_config const & config;
std::tuple<Args...> args;
explicit object_stream_args_formatter (nano::object_stream_config const & config, Args &&... args) :
config{ config },
args{ std::forward<Args> (args)... }
{
}
friend std::ostream & operator<< (std::ostream & os, object_stream_args_formatter<Args...> const & self)
{
nano::object_stream obs{ os, self.config };
std::apply ([&obs] (auto &&... args) {
((obs.write (args.name, args.value)), ...);
},
self.args);
return os;
}
// Needed for fmt formatting, uses the ostream operator under the hood
friend auto format_as (object_stream_args_formatter<Args...> const & val)
{
return fmt::streamed (val);
}
};
template <class... Args>
auto streamed_args (nano::object_stream_config const & config, Args &&... args)
{
return object_stream_args_formatter<Args...>{ config, std::forward<Args> (args)... };
}
}
/*
* Adapter that allows for printing using '<<' operator for all classes that implement object streaming
*/
namespace nano::object_stream_adapters
{
template <nano::object_or_array_streamable Value>
std::ostream & operator<< (std::ostream & os, Value const & value)
{
return os << nano::streamed (value);
}
template <nano::object_or_array_streamable Value>
std::string to_string (Value const & value)
{
std::stringstream ss;
ss << nano::streamed (value);
return ss.str ();
}
template <nano::object_or_array_streamable Value>
std::string to_json (Value const & value)
{
std::stringstream ss;
ss << nano::streamed (value, nano::streamed_format::json);
return ss.str ();
}
}
/*
* Adapter that allows for printing using fmt library for all classes that implement object streaming
*/
template <nano::object_or_array_streamable Streamable>
struct fmt::formatter<Streamable> : fmt::ostream_formatter
{
auto format (Streamable const & value, format_context & ctx)
{
return fmt::ostream_formatter::format (nano::streamed (value), ctx);
}
};