ClientServerProject/osyncstream.h

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2021-02-09 23:02:05 -05:00
/*
* osyncstream - A wrapper around ostream that properly locks while consuming stream operators
* Copyright Riley Strickland 2021
*/
#pragma once
#include <mutex>
#include <ostream>
#include <iostream>
class osyncstream_locked final
{
std::unique_lock<std::recursive_mutex> lock_;
std::ostream& stream_;
public:
osyncstream_locked(std::recursive_mutex& mtx, std::ostream& stream) : lock_(mtx), stream_(stream) {} //construct and lock the mutex from osyncstream.
osyncstream_locked(const osyncstream_locked& o) = delete;
/* A recursive mutex isn't great here (reference forwarding would be better except...only a recursive mutex can assure lock-before-release on ownership transfer */
template<typename T>
friend auto operator<<(osyncstream_locked&& os, const T& d) -> osyncstream_locked&&
{
os.stream_ << d;
return std::move(os); /* move semantics :( ... thanks Clang/GCC */
}
friend auto operator<<(osyncstream_locked&& os, std::ostream& (*func)(std::ostream&)) -> std::ostream&
{
return os.stream_ << func;
}
osyncstream_locked(osyncstream_locked&& o) noexcept : osyncstream_locked(*o.lock_.mutex(), o.stream_) {} //could be better... max depth 2, usual depth 1.
osyncstream_locked& operator=(osyncstream_locked&) = delete; //disallow
osyncstream_locked& operator=(osyncstream_locked&&) = delete; //disallow
~osyncstream_locked() = default;
};
class osyncstream final
{
std::recursive_mutex mutex_{};
std::ostream& stream_;
public:
explicit osyncstream(std::ostream& stream) : stream_(stream) {}
template<typename T>
friend auto operator<<(osyncstream& os, const T& d) -> osyncstream_locked
{
std::unique_lock<std::recursive_mutex> lock(os.mutex_);
os.stream_ << d;
return osyncstream_locked { os.mutex_, os.stream_ };
}
friend auto operator<<(osyncstream& os, std::ostream& (*func)(std::ostream&)) -> osyncstream_locked
{
std::unique_lock<std::recursive_mutex> lock(os.mutex_);
os.stream_ << func;
return osyncstream_locked{ os.mutex_, os.stream_ };
}
};
struct streams
{
static std::ostream& cout;
static std::ostream& cerr;
};
inline std::ostream& streams::cout = std::cout;
inline std::ostream& streams::cerr = std::cerr;
inline osyncstream sscout(streams::cout);
inline osyncstream sscerr(streams::cerr);