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#ifndef MYGRATE_RAW_DATA_READER_H
#define MYGRATE_RAW_DATA_READER_H
#include "helpers.h"
#include "mariadb_repl.h"
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <span>
#include <stdexcept>
namespace MyGrate {
struct PackedInteger {
};
template<typename T> struct type_map {
using target = T;
};
template<> struct type_map<PackedInteger> {
using target = uint64_t;
};
class RawDataReader {
public:
explicit RawDataReader(const void * const d, std::size_t len);
explicit RawDataReader(const MARIADB_STRING & str);
template<typename T, size_t L = sizeof(T)>
typename type_map<T>::target
readValue()
{
static_assert(L > 0 && L <= sizeof(T), "Read exceeds target size");
return readValue<T>(L);
}
template<typename T>
typename type_map<T>::target
readValue(size_t L)
{
static_assert(std::is_trivial_v<T>, "Do not read non-trivial types");
verify<std::logic_error>(L > 0 && L <= sizeof(T), "Read exceeds target size");
offsetSizeCheck(L);
T v {};
memcpy(&v, rawdata + offset, L);
offset += L;
return v;
}
template<typename T>
T
viewValue(size_t L)
{
static_assert(sizeof(typename T::value_type) == sizeof(std::byte));
offsetSizeCheck(L);
T v {reinterpret_cast<const typename T::value_type *>(rawdata + offset), L};
offset += L;
return v;
}
void discard(size_t);
bool
more() const
{
return offset < len;
}
std::span<const std::byte>
raw() const
{
return {rawdata, len};
}
private:
void offsetSizeCheck(size_t) const;
const std::byte * const rawdata;
const std::size_t len;
std::size_t offset {0};
};
template<> uint64_t RawDataReader::readValue<PackedInteger>();
}
#endif
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