thread_safe_iostream.hpp

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#ifndef THREAD_SAFE_IOSTREAM
#define THREAD_SAFE_IOSTREAM
 
#include <iostream>
#include <limits>
#include <mutex>
#include <sstream>
#include <string>
 
class ThreadSafeIOStream
{
private:
    static std::mutex  _mutex;
    std::ostringstream _buffer;
    std::string        _prefix;
    void               flushBuffer();
 
public:
    template <typename T>
    ThreadSafeIOStream& operator>>(T& value)
    {
        std::lock_guard<std::mutex> lock(_mutex);
        while (1)
        {
            std::cin >> value;
            if (std::cin.fail())
            {
                std::cout << "Invalid input !" << std::endl;
                std::cin.clear();
 
                // Vide completement le buffer (limits.h)
                std::cin.ignore(INT32_MAX, '\n');
                continue;
            }
            break;
        }
        return *this;
    }
 
    ThreadSafeIOStream& operator<<(std::ostream& (*funct)(std::ostream&));
 
    template <typename T>
    ThreadSafeIOStream& operator<<(const T& value)
    {
        _buffer << value;
 
        std::string            line   = _buffer.str();
        std::string::size_type pos    = 0;
        std::string::size_type cursor = 0;
        if (line.find('\n') == std::string::npos)
            return *this;
 
        std::lock_guard<std::mutex> lock(_mutex);
 
        while ((pos = line.find('\n', cursor)) != std::string::npos)
        {
            std::cout << _prefix;
            std::cout << line.substr(cursor, pos - cursor) << '\n';
            cursor = pos + 1;
        }
 
        _buffer.clear();
        _buffer.str("");
        if (cursor < line.length())
            std::cout << line.substr(cursor);
        return *this;
    }
 
    void setPrefix(const std::string& prefix);
 
    template <typename T>
    void prompt(const std::string& question, T& dest)
    {
        {
            std::lock_guard<std::mutex> lock(_mutex);
            std::cout << question;
        }
        *this >> dest;
    }
};
 
extern thread_local ThreadSafeIOStream threadSafeCout;
 
#endif