data_version.h

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#pragma once
 
#include <iostream>
#include <string>
 
namespace point_one {
namespace fusion_engine {
namespace messages {
 
// Enforce 4-byte alignment and packing of all data structures and values.
// Floating point values are aligned on platforms that require it. This is done
// with a combination of setting struct attributes, and manual alignment
// within the definitions. See the "Message Packing" section of the README.
#pragma pack(push, 1)
 
/**
 * @brief A struct representing the version of a data object.
 *
 * The version is considered invalid if @ref major_version is 0xFF and @ref minor_version is
 * 0xFFFF.
 */
struct alignas(4) DataVersion {
  // The reserved bytes must be 0xFF for backward compatibility.
  uint8_t reserved = 0xFF;
  uint8_t major_version = 0xFF;
  uint16_t minor_version = 0xFFFF;
 
  constexpr DataVersion() = default;
  constexpr DataVersion(uint8_t major, uint16_t minor)
      : major_version{major}, minor_version{minor} {}
 
  /**
   * @brief Returns whether the stored version is valid.
   *
   * @return `true` if the version is valid, `false` otherwise.
   */
  bool IsValid() const {
    return major_version != 0xFF || minor_version != 0xFFFF;
  }
};
 
#pragma pack(pop)
 
constexpr DataVersion INVALID_DATA_VERSION;
 
inline constexpr bool operator==(const DataVersion& a, const DataVersion& b) {
  return a.major_version == b.major_version &&
         a.minor_version == b.minor_version;
}
 
inline constexpr bool operator!=(const DataVersion& a, const DataVersion& b) {
  return !(a == b);
}
 
inline constexpr bool operator<(const DataVersion& a, const DataVersion& b) {
  return a.major_version < b.major_version ||
         (a.major_version == b.major_version &&
          a.minor_version < b.minor_version);
}
 
inline constexpr bool operator>(const DataVersion& a, const DataVersion& b) {
  return b < a;
}
 
inline constexpr bool operator<=(const DataVersion& a, const DataVersion& b) {
  return !(a > b);
}
 
inline constexpr bool operator>=(const DataVersion& a, const DataVersion& b) {
  return !(a < b);
}
 
/**
 * @brief Helper class for printing out X.Y form of @ref DataVersion.
 *
 * ```cpp
 * DataVersion ver{3, 2};
 * std::cout << "Ver: " << ver;
 * // Ver: 3.2
 * ```
 */
std::ostream& operator<<(std::ostream& stream, const DataVersion& ver);
 
std::string ToString(const DataVersion& ver);
 
DataVersion FromString(const char* str);
 
inline DataVersion FromString(std::string str) {
  return FromString(str.c_str());
}
 
} // namespace messages
} // namespace fusion_engine
} // namespace point_one