library/cpp/yson_pull/detail/input/stdio_file.h


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#pragma once

#include "buffered.h"

#include <library/cpp/yson_pull/detail/macros.h>

#include <library/cpp/yson_pull/exceptions.h>
#include <library/cpp/yson_pull/input.h>

#include <cstdio>
#include <memory>

namespace NYsonPull { 
    namespace NDetail { 
        namespace NInput { 
            class TStdioFile: public TBuffered { 
                FILE* file_; 

            public: 
                TStdioFile(FILE* file, size_t buffer_size) 
                    : TBuffered(buffer_size) 
                    , file_{file} { 
                } 

            protected: 
                result do_fill_buffer() override { 
                    auto nread = ::fread(buffer_data(), 1, buffer_size(), file_); 
                    if (Y_UNLIKELY(nread == 0)) {
                        if (ferror(file_)) {
                            throw NException::TSystemError(); 
                        } 
                        if (feof(file_)) {
                            return result::at_end; 
                        } 
                    } 
                    buffer().reset(buffer_data(), buffer_data() + nread); 
                    return result::have_more_data; 
                } 
            }; 
        }
    }     // namespace NDetail 
}