src/google/protobuf/has_bits.h

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#ifndef GOOGLE_PROTOBUF_HAS_BITS_H__
#define GOOGLE_PROTOBUF_HAS_BITS_H__

#include <google/protobuf/stubs/common.h>
#include <google/protobuf/port.h>

// Must be included last.
#include <google/protobuf/port_def.inc>

#ifdef SWIG
#error "You cannot SWIG proto headers"
#endif

namespace google {
namespace protobuf {
namespace internal {

template <size_t doublewords>
class HasBits {
 public:
  PROTOBUF_NDEBUG_INLINE constexpr HasBits() : has_bits_{} {}

  PROTOBUF_NDEBUG_INLINE void Clear() {
    memset(has_bits_, 0, sizeof(has_bits_));
  }

  PROTOBUF_NDEBUG_INLINE uint32_t& operator[](int index) {
    return has_bits_[index];
  }

  PROTOBUF_NDEBUG_INLINE const uint32_t& operator[](int index) const {
    return has_bits_[index];
  }

  bool operator==(const HasBits<doublewords>& rhs) const {
    return memcmp(has_bits_, rhs.has_bits_, sizeof(has_bits_)) == 0;
  }

  bool operator!=(const HasBits<doublewords>& rhs) const {
    return !(*this == rhs);
  }

  void Or(const HasBits<doublewords>& rhs) {
    for (size_t i = 0; i < doublewords; i++) has_bits_[i] |= rhs[i];
  }

  bool empty() const;

 private:
  uint32_t has_bits_[doublewords];
};

template <>
inline bool HasBits<1>::empty() const {
  return !has_bits_[0];
}

template <>
inline bool HasBits<2>::empty() const {
  return !(has_bits_[0] | has_bits_[1]);
}

template <>
inline bool HasBits<3>::empty() const {
  return !(has_bits_[0] | has_bits_[1] | has_bits_[2]);
}

template <>
inline bool HasBits<4>::empty() const {
  return !(has_bits_[0] | has_bits_[1] | has_bits_[2] | has_bits_[3]);
}

template <size_t doublewords>
inline bool HasBits<doublewords>::empty() const {
  for (size_t i = 0; i < doublewords; ++i) {
    if (has_bits_[i]) return false;
  }
  return true;
}

}  // namespace internal
}  // namespace protobuf
}  // namespace google

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_HAS_BITS_H__