Repo created

libs/search/cbv.hpp

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+#pragma once
+
+#include "coding/compressed_bit_vector.hpp"
+
+#include "base/ref_counted.hpp"
+
+#include <cstdint>
+#include <memory>
+#include <utility>
+
+namespace search
+{
+// A wrapper around coding::CompressedBitVector that augments the
+// latter with the "full" state and uses reference counting for
+// ownership sharing.
+class CBV
+{
+public:
+  static CBV const & GetFull();
+
+  CBV() = default;
+  explicit CBV(std::unique_ptr<coding::CompressedBitVector> p);
+  CBV(CBV const & cbv) = default;
+  CBV(CBV && cbv);
+
+  inline operator bool() const { return !IsEmpty(); }
+  CBV & operator=(std::unique_ptr<coding::CompressedBitVector> p);
+  CBV & operator=(CBV const & rhs) = default;
+  CBV & operator=(CBV && rhs);
+
+  void SetFull();
+  void Reset();
+
+  inline bool IsEmpty() const { return !m_isFull && coding::CompressedBitVector::IsEmpty(m_p.Get()); }
+  inline bool IsFull() const { return m_isFull; }
+
+  bool HasBit(uint64_t id) const;
+  uint64_t PopCount() const;
+
+  template <typename Fn>
+  void ForEach(Fn && fn) const
+  {
+    ASSERT(!m_isFull, ());
+    if (!IsEmpty())
+      coding::CompressedBitVectorEnumerator::ForEach(*m_p, std::forward<Fn>(fn));
+  }
+
+  CBV Union(CBV const & rhs) const;
+  CBV Intersect(CBV const & rhs) const;
+
+  // Takes first set |n| bits.
+  CBV Take(uint64_t n) const;
+
+  uint64_t Hash() const;
+
+private:
+  explicit CBV(bool full);
+
+  base::RefCountPtr<coding::CompressedBitVector> m_p;
+
+  // True iff all bits are set to one.
+  bool m_isFull = false;
+};
+}  // namespace search