library/cpp/yson_pull/detail/byte_writer.h


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#pragma once

#include "macros.h"

#include <library/cpp/yson_pull/output.h>

#include <util/system/types.h>

#include <cstddef>
#include <cstring>

namespace NYsonPull { 
    namespace NDetail { 
        template <class StreamCounter> 
        class byte_writer { 
            NYsonPull::NOutput::IStream& stream_; 
            StreamCounter stream_counter_; 

        public: 
            byte_writer(NYsonPull::NOutput::IStream& stream) 
                : stream_(stream) 
            { 
            } 

            // const-ness added to prevent direct stream mutation 
            const NYsonPull::NOutput::IStream& stream() { 
                return stream_; 
            } 
            const StreamCounter& counter() { 
                return stream_counter_; 
            } 

            void flush_buffer() { 
                stream_.flush_buffer(); 
            } 

            void advance(size_t bytes) { 
                auto& buf = stream_.buffer(); 
                stream_counter_.update( 
                    buf.pos(), 
                    buf.pos() + bytes); 
                buf.advance(bytes); 
            } 

            void write(ui8 c) { 
                auto& buf = stream_.buffer(); 
                if (Y_LIKELY(!buf.is_full())) {
                    *buf.pos() = c; 
                    advance(1); 
                } else { 
                    auto ptr = reinterpret_cast<char*>(&c); 
                    stream_counter_.update(&c, &c + 1); 
                    stream_.flush_buffer({ptr, 1}); 
                } 
            } 

            void write(const ui8* data, size_t size) { 
                auto& buf = stream_.buffer(); 
                auto free_buf = buf.available(); 
                if (Y_LIKELY(size < free_buf)) {
                    ::memcpy(buf.pos(), data, size); 
                    advance(size); 
                } else { 
                    if (!buf.is_full()) { 
                        ::memcpy(buf.pos(), data, free_buf); 
                        advance(free_buf); 
                        data += free_buf; 
                        size -= free_buf; 
                    } 
                    stream_counter_.update(data, data + size); 
                    stream_.flush_buffer({reinterpret_cast<const char*>(data), 
                                          size}); 
                } 
            }
        }; 
    }
}