UUID
====

A version 4 `UUID <https://www.rfc-editor.org/info/rfc9562/#name-uuid-version-4>`__ generator.

.. admonition:: Info

   To use declarations from this page, include the ``<essence/uuid.hpp>`` header.

.. note:: Performance

   Generates 50,000,000 UUID's over 100 iterations in an average of 1.387 seconds, or roughly 36 million per second.

.. cpp:namespace-push:: essence

.. cpp:class:: uuid

   Container class for a version 4 UUID. Specialization available for
   :cpp:expr:`std::hash` and :cpp:expr:`std::formatter`.

   .. cpp:function:: uuid::uuid()

      Default constructor, generates immediately.

   .. cpp:function:: std::string_view view() const noexcept

      Get a view of the UUID string.

   .. cpp:function:: std::string string() const

      Get a copy of the UUID string.

   .. cpp:function:: const std::string& cref() const

      Get a constant reference to the UUID string.

   .. cpp::function:: constexpr operator std::string_view() const noexcept
      
      Implicit conversion operator to a ``std::string_view``.

   .. cpp:function:: friend std::ostream& operator<<(std::ostream& os, const uuid& self)

      Stream overload for :cpp:expr:`std::cout` and the like.