cs440-assignment3/SharedPtr.hpp

#include <atomic>
#ifndef _POWELLCS440
#include <cassert>
#include <iostream>

#define todo(msg)                                                              \
  std::cerr << msg << std::endl;                                               \
  assert(false);

namespace cs440 {
using counter = std::atomic<std::size_t>;
template <typename T> class SharedPtr;
class Key {
  Key() {}

public:
  template <typename U> friend class SharedPtr;
  template <typename U> void increment(SharedPtr<U> const &ptr) {
    const_cast<std::atomic<size_t> &>(*ptr.count)++;
  }
  template <typename U> counter *get_counter(SharedPtr<U> const &ptr) {
    return const_cast<std::atomic<size_t> *>(ptr.count);
  }
  template <typename U> U *get_ptr(SharedPtr<U> const &ptr) {
    return const_cast<U *>(ptr.ptr);
  }
  template <typename U> void nullify(SharedPtr<U> &&ptr) {
    ptr.ptr = nullptr;
    ptr.count = nullptr;
  }
};
template <typename T> class SharedPtr {
  T *ptr;
  std::atomic<std::size_t> *count;

public:
  friend class Key;
  SharedPtr() : ptr{nullptr}, count{new std::atomic<std::size_t>{1}} {}
  template <typename U>
  explicit SharedPtr(U *ptr)
      : ptr{ptr}, count{new std::atomic<std::size_t>{1}} {}
  SharedPtr(const SharedPtr &p) : ptr{p.ptr} {
    Key().increment(p);
    this->count = Key().get_counter(p);
  }
  template <typename U>
  SharedPtr(const SharedPtr<U> &p) : ptr{Key().get_ptr(p)} {
    Key().increment(p);
    this->count = Key().get_counter(p);
  }
  SharedPtr(SharedPtr &&p)
      : count{Key().get_counter(p)}, ptr{Key().get_ptr(p)} {
    Key().nullify(p);
  }
  template <typename U>
  SharedPtr(SharedPtr<U> &&p)
      : count{Key().get_counter(p)}, ptr{Key().get_ptr(p)} {
    Key().nullify(p);
  }
  SharedPtr &operator=(const SharedPtr &ptr) {
    Key().increment(ptr);
    this->count = Key().get_counter(ptr);
    this->ptr = Key().get_ptr(ptr);
    return *this;
  }
  template <typename U> SharedPtr<T> &operator=(const SharedPtr<U> &ptr) {
    Key().increment(ptr);
    this->count = Key().get_counter(ptr);
    this->ptr = Key().get_ptr(ptr);
    return *this;
  }
  SharedPtr &operator=(SharedPtr &&p) {
    this->count = Key().get_counter(ptr);
    this->ptr = Key().get_ptr(ptr);
    Key().nullify(p);
  }
  template <typename U> SharedPtr &operator=(SharedPtr<U> &&p) {
    this->count = Key().get_counter(ptr);
    this->ptr = Key().get_ptr(ptr);
    Key().nullify(p);
  }
  ~SharedPtr() {
    if (this->count == nullptr) {
      if (this->ptr != nullptr) {
        delete this->ptr;
      }
      return;
    }
    if (--(*this->count) == 0) {
      delete this->count;
      delete this->ptr;
    }
  }
  void reset() {
    if (this->count != nullptr) {
      if (--(*this->count) == 0) {
        delete this->count;
        delete this->ptr;
        return;
      }
    }
    this->ptr = nullptr;
    this->count = nullptr;
  }
  template <typename U> void reset(U *p) {
    this->reset();
    this->count = new counter{1};
    this->ptr = p;
  }
  T *get() const { return this->ptr; }
  T &operator*() const { return *this->ptr; }
  T *operator->() const { return this->ptr; }
  explicit operator bool() const { return this->ptr != nullptr; }
  template <typename T1, typename T2>
  template <typename U>
  friend SharedPtr<T> static_pointer_cast(const SharedPtr<U> &sp) {
    todo("");
  }
  template <typename U>
  friend SharedPtr<T> dynamic_pointer_cast(const SharedPtr<U> &sp) {
    todo("");
  }
};
template <typename T1, typename T2>
bool operator==(const SharedPtr<T1> &lhs, const SharedPtr<T2> &rhs) {
  return lhs.get() == rhs.get();
}
template <typename T>
bool operator==(const SharedPtr<T> &lhs, std::nullptr_t rhs) {

  return lhs.get() == rhs;
}
template <typename T>
bool operator==(std::nullptr_t lhs, const SharedPtr<T> &rhs) {
  return lhs == rhs.get();
}
template <typename T1, typename T2>
bool operator!=(const SharedPtr<T1> &lhs, const SharedPtr<T2> &rhs) {
  return !(lhs == rhs);
}
template <typename T>
bool operator!=(const SharedPtr<T> &lhs, std::nullptr_t rhs) {
  return !(lhs == rhs);
}
template <typename T>
bool operator!=(std::nullptr_t lhs, const SharedPtr<T> &rhs) {
  return !(lhs == rhs);
}
} // namespace cs440
#endif