cell.h

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/** @file storage/temptable/include/temptable/cell.h
TempTable Cell declaration. */
 
#ifndef TEMPTABLE_CELL_H
#define TEMPTABLE_CELL_H
 
#include <cstdint>
 
namespace temptable {
 
/** A cell is the intersection of a row and a column. In the handler interface
row format (what is provided to the write_row() handler method) a cell may
occupy too much space - in the case of a VARCHAR(N) column it will occupy N
bytes, even if a shorter string is stored in this particular cell. So, our
cell is derived from the above, but does not occupy unnecessary space.
 
This class is just an interpreter - it does not store the actual data, which
is stored in the `Row` class, allocated at once for all the cells of a row. */
class Cell {
 public:
  /** Constructor. */
  Cell(
      /** [in] Designate whether this cell is NULL. */
      bool is_null,
      /** [in] Length of the user data in bytes (no metadata or any leading
       * bytes to designate the length. Just the user data. */
      uint32_t data_length,
      /** [in] Pointer to the user data. It is not copied inside this newly
       * created Cell object, so it must remain valid for the lifetime of this
       * object. */
      const unsigned char *data);
 
  /** Check if this cell is NULL.
   * @return true if NULL */
  bool is_null() const;
 
  /** Get the length of the user data.
   * @return length in bytes */
  uint32_t data_length() const;
 
  /** Get a pointer to the user data inside the row.
   * @return a pointer */
  const unsigned char *data() const;
 
 private:
  /** Designate whether the cell is NULL. */
  const bool m_is_null;
 
  /** Length of the user data pointed by `m_data` in bytes. */
  const uint32_t m_data_length;
 
  /** User data. */
  const unsigned char *const m_data;
};
 
/* Implementation of inlined methods. */
 
inline Cell::Cell(bool is_null, uint32_t data_length, const unsigned char *data)
    : m_is_null(is_null), m_data_length(data_length), m_data(data) {}
 
inline bool Cell::is_null() const { return m_is_null; }
 
inline uint32_t Cell::data_length() const { return m_data_length; }
 
inline const unsigned char *Cell::data() const { return m_data; }
 
} /* namespace temptable */
 
#endif /* TEMPTABLE_CELL_H */