circularbuf.h

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// This file is part of DynExp.
 
#pragma once
 
#include <streambuf>
 
namespace Util
{
    class circularbuf : public std::streambuf
    {
    public:
        using CharT = char;
 
        circularbuf(size_t size);
 
        bool empty();
        
        size_t gsize();
 
        size_t psize() const noexcept;
 
        pos_type gtellp() const noexcept;
 
        pos_type ptellp() const noexcept;
 
        void clear();
 
        void resize(size_t size);
 
    private:
        std::streamsize avail_get_count() const noexcept;
 
        virtual int_type overflow(int_type c = traits_type::eof()) override;    
        virtual int_type underflow() override;                                  
        virtual std::streamsize showmanyc() override;                           
        virtual int_type pbackfail(int_type c = traits_type::eof()) override;   
 
        virtual int sync() override;
 
        virtual pos_type seekoff(off_type off, std::ios_base::seekdir dir,
            std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override;
 
        virtual pos_type seekpos(pos_type pos,
            std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override;
 
        template <typename T, std::enable_if_t<
            std::is_unsigned_v<T>, int> = 0
        >
        inline pos_type to_pos_type(const T value)
        {
            if (value > static_cast<T>(std::numeric_limits<std::make_signed_t<T>>::max()))
                throw std::overflow_error("Cannot convert a value into pos_type since this would cause an overflow in circularbuf::to_pos_type().");
 
            return static_cast<std::make_signed_t<T>>(value);
        }
 
        std::vector<CharT> buffer;
 
        bool put_overflowed;
    };
}