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#pragma once

#include "buffer.h"

#include <util/generic/ptr.h>
#include <util/generic/strbuf.h>
#include <util/system/types.h>
#include <util/system/yassert.h>

#include <cstddef>
#include <cstdio>
#include <cstring>
#include <memory>

//! \brief Output stream adaptor interface.
//!
//! Represents a model of an optionally-buffered writer.
namespace NYsonPull { 
    namespace NOutput { 
        class IStream { 
            output_buffer buffer_; 

        public: 
            virtual ~IStream() = default; 

            output_buffer& buffer() noexcept { 
                return buffer_; 
            } 
            const output_buffer& buffer() const noexcept { 
                return buffer_; 
            } 

            void flush_buffer(TStringBuf extra = {}) { 
                if (!extra.empty() || !buffer_.is_empty()) { 
                    do_flush_buffer(extra); 
                } 
                while (!buffer_.is_empty()) { 
                    do_flush_buffer({}); 
                } 
            } 

        protected: 
            //! \brief Flush data to underlying stream. 
            //! 
            //! The implementation is to flush the buffer contents AND 
            //! extra argument to underlying stream. 
            //! 
            //! This way, at zero buffer size this interface implements an unbuffered 
            //! stream (with an added cost of a virtual call per each write). 
            //! 
            //! Write is assumed to always succeed unless it throws an exception. 
            virtual void do_flush_buffer(TStringBuf extra) = 0; 
        }; 

        //! \brief Write data to C FILE* object.
        THolder<IStream> FromStdioFile(FILE* file, size_t buffer_size = 0);

        //! \brief Write data to POSIX file descriptor
        THolder<IStream> FromPosixFd(int fd, size_t buffer_size = 65536);

        THolder<IStream> FromOutputStream(IOutputStream* output, size_t buffer_size = 65536);

        THolder<IStream> FromString(TString* output, size_t buffer_size = 1024);
    } 
}