quicksp.h

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#ifndef QUICKSP_H_
#define QUICKSP_H_
 
#include "mythmetaexp.h"
 
struct NoLock
{
    void lock() {}
    void unlock() {}
};
 
// TODO: implement for threads
// If implemented for threads move the instance pointer to simple_ref_ptr
// so simple access isn't synchronized.
struct ThreadLock
{
    void lock() {}
 
    void unlock() {}
};
 
// TODO: Get a real reference counted smart pointer in libmyth
template <typename T, class Locker = NoLock>
class simple_ref_ptr
{
  public:
    simple_ref_ptr() : m_ref(nullptr)
    {
    }
 
    simple_ref_ptr(T *ptr)
    {
        m_ref = new ref(ptr);
    }
 
    simple_ref_ptr(const simple_ref_ptr &rhs) : m_ref(nullptr)
    {
        *this = rhs;
    }
 
    ~simple_ref_ptr()
    {
        unref();
    }
 
    // The first two lines of this function are the clang-tidy
    // recommended solution to make a function properly handle
    // self-assignment.  No idea why clang-tidy doesn't recognize
    // this, unless it has something to do with templates?
    //
    // NOLINTNEXTLINE(bugprone-unhandled-self-assignment,cert-oop54-cpp)
    simple_ref_ptr &operator=(const simple_ref_ptr &rhs)
    {
        if (this == &rhs)
            return *this;
        rhs.m_ref->inc();
        unref();
        m_ref = rhs.m_ref;
 
        return *this;
    }
 
    T *operator->() const
    {
        return get();
    }
 
    T &operator*() const
    {
        return *get();
    }
 
    T *get() const
    {
        if (m_ref) return m_ref->get();
 
        return nullptr;
    }
 
    void reset(T *ptr)
    {
        unref();
        m_ref = new ref(ptr);
    }
 
    using fake_bool = T *(simple_ref_ptr<T>::*)() const;
 
    operator fake_bool() const
    {
        return m_ref == nullptr ? nullptr : &simple_ref_ptr<T>::get;
    }
 
    bool operator!() const
    {
        return m_ref == nullptr;
    }
 
  private:
    class ref : public Locker
    {
      public:
        explicit ref(T *ptr) : m_type(ptr) {}
 
        ~ref()
        {
            delete m_type;
        }
 
        unsigned int inc()
        {
            this->lock();
            ++m_count;
            this->unlock();
            return m_count;
        }
 
        unsigned int dec()
        {
            this->lock();
            --m_count;
            this->unlock();
            return m_count;
        }
 
        T *get()
        {
            return m_type;
        }
 
        T *get() const
        {
            return m_type;
        }
 
      private:
        unsigned int m_count {1};
        T *m_type;
    };
 
    void unref()
    {
        if (m_ref && m_ref->dec() <= 0)
        {
            delete m_ref;
            m_ref = nullptr;
        }
    }
 
  private:
    ref *m_ref;
};
 
template <typename T>
bool operator==(const simple_ref_ptr<T> &lhs, const simple_ref_ptr<T> &rhs)
{
    return lhs.get() == rhs.get();
}
 
template <typename T>
bool operator!=(const simple_ref_ptr<T> &lhs, const simple_ref_ptr<T> &rhs)
{
    return lhs.get() != rhs.get();
}
 
#endif // QUICKSP_H_