Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include <memory>
       4             : 
       5             : namespace elsa
       6             : {
       7             :     /**
       8             :      * @brief Class implementing polymorphic clones with smart pointers and CRTP, as well as
       9             :      * comparison operators.
      10             :      *
      11             :      * @author Tobias Lasser
      12             :      *
      13             :      * This class provides a clone method using CRTP to support covariance with smart pointers.
      14             :      * For details see
      15             :      * https://www.fluentcpp.com/2017/09/12/how-to-return-a-smart-pointer-and-use-covariance/.
      16             :      */
      17             :     template <typename Derived>
      18             :     class Cloneable
      19             :     {
      20             :     public:
      21             :         /// default constructor
      22           0 :         Cloneable() = default;
      23             :         /// virtual default destructor
      24           0 :         virtual ~Cloneable() = default;
      25             : 
      26             :         /// clone object, returning an owning unique_ptr
      27           0 :         std::unique_ptr<Derived> clone() const { return std::unique_ptr<Derived>(cloneImpl()); }
      28             : 
      29             :         /// comparison operators
      30           0 :         bool operator==(const Derived& other) const { return isEqual(other); }
      31             : 
      32           0 :         bool operator!=(const Derived& other) const { return !(*this == other); }
      33             : 
      34             :         /// delete implicitly declared copy assignment to prevent copy assignment of derived classes
      35             :         Cloneable& operator=(const Cloneable&) = delete;
      36             : 
      37             :     protected:
      38             :         /// actual clone implementation method, abstract to force override in derived classes
      39             :         virtual Derived* cloneImpl() const = 0;
      40             : 
      41             :         /// actual comparison method, abstract to force override in derived classes
      42             :         virtual bool isEqual(const Derived& other) const = 0;
      43             : 
      44             :         /// default copy constructor, protected to not be publicly available (but available for
      45             :         /// cloneImpl()
      46           0 :         Cloneable(const Cloneable&) = default;
      47             :     };
      48             : 
      49             : } // namespace elsa