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#pragma once
#include "coding/reader.hpp"
#include "base/base.hpp"
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
// FileReader, cheap to copy, not thread safe.
// It is assumed that file is not modified during FireReader lifetime,
// because of caching and assumption that Size() is constant.
class FileReader : public ModelReader
{
public:
static uint32_t const kDefaultLogPageSize;
static uint32_t const kDefaultLogPageCount;
explicit FileReader(std::string const & fileName);
FileReader(std::string const & fileName, uint32_t logPageSize, uint32_t logPageCount);
// Reader overrides:
uint64_t Size() const override { return m_size; }
void Read(uint64_t pos, void * p, size_t size) const override;
std::unique_ptr<Reader> CreateSubReader(uint64_t pos, uint64_t size) const override;
FileReader SubReader(uint64_t pos, uint64_t size) const;
uint64_t GetOffset() const { return m_offset; }
protected:
// Used in special derived readers.
void SetOffsetAndSize(uint64_t offset, uint64_t size);
private:
class FileReaderData;
FileReader(FileReader const & reader, uint64_t offset, uint64_t size, uint32_t logPageSize,
uint32_t logPageCount);
// Throws an exception if a (pos, size) read would result in an out-of-bounds access.
void CheckPosAndSize(uint64_t pos, uint64_t size) const;
uint32_t m_logPageSize;
uint32_t m_logPageCount;
std::shared_ptr<FileReaderData> m_fileData;
uint64_t m_offset;
uint64_t m_size;
};
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