cpp-descriptive-pointers/const_ptr.hpp

//
//  const_ptr.hpp
//  pointers
//
//  Created by Sam Jaffe on 1/5/17.
//

#pragma once
#include <memory>

#include "pointer_fwd.hpp"
#include "ptr_compare.hpp"

template <typename P>
class const_ptr : private detail::get_ptr<P> {
public:
  using element_type = typename std::pointer_traits<P>::element_type;
  using pointer = element_type const *;
  using reference = element_type const &;

  const_ptr() noexcept : _ptr(nullptr) {}
  const_ptr(P const & p) noexcept(detail::is_nt_cc<P>::value) : _ptr(p) {}
  const_ptr(P && p) noexcept(detail::is_nt_mc<P>::value) : _ptr(std::move(p)) {}
  template <typename Y, typename = typename std::enable_if<std::is_constructible<P, Y>::value>::type>
  const_ptr(Y const & p) : _ptr(p) { }
  template <typename Y, typename = typename std::enable_if<std::is_constructible<P, Y>::value>::type>
  const_ptr(Y && p) : _ptr(std::move(p)) { }

  template <typename Y>
  explicit operator const_ptr<Y>() const noexcept(detail::is_nt_c<P, Y>::value) {
    return _ptr;
  }
  
  operator bool() const noexcept {
    return static_cast<bool>(_ptr);
  }

  reference operator*() const noexcept(noexcept(*_ptr)) { return *_ptr; }
  pointer get() const noexcept(noexcept(detail::get_ptr<P>::get(_ptr))) { return detail::get_ptr<P>::get(_ptr); }
  pointer operator->() const noexcept(noexcept(get())) { return get(); }
private:
  P _ptr;
};

POINTER_TEMPLATE_COMPARE( const_ptr )