include/lldb/Utility/PriorityPointerPair.h

//===-- PriorityPointerPair.h ----------------------------------------*- C++
//-*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_PriorityPointerPair_h_
#define liblldb_PriorityPointerPair_h_

#include "lldb/Utility/SharingPtr.h"
#include "lldb/lldb-public.h"

namespace lldb_utility {

//----------------------------------------------------------------------
// A prioritized pair of SharedPtr<T>. One of the two pointers is high
// priority, the other is low priority.
// The Get() method always returns high, if *high != NULL,
// otherwise, low is returned (even if *low == NULL)
//----------------------------------------------------------------------

template <typename T> class PriorityPointerPair {
public:
  typedef T &reference_type;
  typedef T *pointer_type;

  typedef typename std::shared_ptr<T> T_SP;

  PriorityPointerPair() : m_high(), m_low() {}

  PriorityPointerPair(pointer_type high, pointer_type low)
      : m_high(high), m_low(low) {}

  PriorityPointerPair(pointer_type low) : m_high(), m_low(low) {}

  PriorityPointerPair(T_SP &high, T_SP &low) : m_high(high), m_low(low) {}

  PriorityPointerPair(T_SP &low) : m_high(), m_low(low) {}

  void SwapLow(pointer_type l) { m_low.swap(l); }

  void SwapHigh(pointer_type h) { m_high.swap(h); }

  void SwapLow(T_SP l) { m_low.swap(l); }

  void SwapHigh(T_SP h) { m_high.swap(h); }

  T_SP GetLow() { return m_low; }

  T_SP GetHigh() { return m_high; }

  T_SP Get() {
    if (m_high.get())
      return m_high;
    return m_low;
  }

  void ResetHigh() { m_high.reset(); }

  void ResetLow() { m_low.reset(); }

  void Reset() {
    ResetLow();
    ResetHigh();
  }

  reference_type operator*() const { return Get().operator*(); }

  pointer_type operator->() const { return Get().operator->(); }

  ~PriorityPointerPair();

private:
  T_SP m_high;
  T_SP m_low;

  DISALLOW_COPY_AND_ASSIGN(PriorityPointerPair);
};

} // namespace lldb_utility

#endif // #ifndef liblldb_PriorityPointerPair_h_