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
}