Improvement: use struct instead of class everywhere

mesh_handle/element.hxx

@@ -42,7 +42,7 @@ namespace t8_mesh_handle
 /** Forward declaration of the \ref mesh class of the handle.
  */
 template <template <typename> class... TCompetences>
-class mesh;
+struct mesh;
 
 /** 
  * Definition of the mesh element class of the \ref mesh handle.
@@ -63,7 +63,8 @@ class mesh;
  * \tparam TCompetences The competences you want to add to the default functionality of the element.
  */
 template <template <typename> class... TCompetences>
-class element: public TCompetences<element<TCompetences...>>... {
+struct element: public TCompetences<element<TCompetences...>>...
+{
  private:
   using SelfType = element<TCompetences...>; /**< Type of the current class with all template parameters specified. */
   using mesh_class = mesh<TCompetences...>;  /**< Type of the mesh class used. */

mesh_handle/mesh.hxx

@@ -42,7 +42,8 @@ namespace t8_mesh_handle
  *         \see element for more details on the choice of the template parameter.   
  */
 template <template <typename> class... TCompetences>
-class mesh {
+struct mesh
+{
  public:
   using element_class = element<TCompetences...>; /**< The element class of the mesh with given competences. */
   friend element_class; /**< Element class as friend such that private members (e.g. the forest) can be accessed. */

src/t8_cad/t8_cad.hxx

@@ -36,7 +36,8 @@
 /**
  * This class manages OpenCASCADE shapes and implements helper functions for working with the shapes.
 */
-class t8_cad {
+struct t8_cad
+{
  public:
   /**
     * Constructor of the cad shape.

src/t8_cmesh/t8_cmesh_vertex_connectivity/t8_cmesh_vertex_conn_tree_to_vertex.hxx

@@ -47,12 +47,13 @@
 #include <span>
 
 /** forward declaration of the class needed since the two class headers include each other. */
-class t8_cmesh_vertex_conn_vertex_to_tree;
+struct t8_cmesh_vertex_conn_vertex_to_tree;
 
 /**
  * A class to hold the tree to vertex connectivity of a cmesh.
  */
-class t8_cmesh_vertex_conn_tree_to_vertex {
+struct t8_cmesh_vertex_conn_tree_to_vertex
+{
  public:
   /** Standard constructor. Does nothing. */
   t8_cmesh_vertex_conn_tree_to_vertex (): current_state (state::EMPTY)
@@ -169,7 +170,7 @@ class t8_cmesh_vertex_conn_tree_to_vertex {
   friend struct t8_cmesh_vertex_connectivity;
 
  private:
-  enum class state {
+  enum struct state {
     EMPTY, /*< Is initialized but empty. */
     FILLED /*< Is filled with at least one entry. */
   };

src/t8_cmesh/t8_cmesh_vertex_connectivity/t8_cmesh_vertex_conn_vertex_to_tree.hxx

@@ -35,7 +35,7 @@
 #include <t8_cmesh/t8_cmesh_vertex_connectivity/t8_cmesh_vertex_connectivity_types.hxx>
 
 /** forward declaration of ttv class needed since the two class headers include each other. */
-class t8_cmesh_vertex_conn_tree_to_vertex;
+struct t8_cmesh_vertex_conn_tree_to_vertex;
 
 /** This class stores the vertex to tree lookup for
  * global vertex indices for a cmesh.
@@ -67,7 +67,8 @@ class t8_cmesh_vertex_conn_tree_to_vertex;
  * Table global_id -> TV_LIST: std::unordered_map<t8_gloidx_t, TV_LIST>
  *
  */
-class t8_cmesh_vertex_conn_vertex_to_tree {
+struct t8_cmesh_vertex_conn_vertex_to_tree
+{
  public:
   /** Standard constructor.
    * Initializes the class and allows setting vertex entries

src/t8_cmesh/t8_cmesh_vertex_connectivity/t8_cmesh_vertex_connectivity.hxx

@@ -53,7 +53,7 @@ struct t8_cmesh_vertex_connectivity
   ~t8_cmesh_vertex_connectivity () {};
 
   /** The state this connectivity can be in. */
-  enum class state {
+  enum struct state {
     INITIALIZED,          /**< Initialized but not filled */
     TREE_TO_VERTEX_VALID, /**< Ready to use, but only tree_to_vertex functionality. */
     VALID                 /**< Ready to use for full vertex connectivity. Cannot be altered anymore. */

src/t8_data/t8_data_handler.hxx

@@ -56,7 +56,8 @@ is_internal_data (const t8_data_handler_type type)
  * \tparam TType The type of data to be handled.
  */
 template <typename TType>
-class t8_data_handler {
+struct t8_data_handler
+{
  public:
   /**
    * Construct a t8_data_handler.

src/t8_data/t8_element_array_iterator.hxx

@@ -44,7 +44,8 @@
  * and let the dereference operator return it as a value_type. Therefore, read-only operations on the
  * \a t8_element_array_t are possible.
  */
-class t8_element_array_iterator {
+struct t8_element_array_iterator
+{
 
  private:
   const t8_scheme* scheme;         /**< The scheme of the elements residing within the array. */

src/t8_data/t8_vector_handler.hxx

@@ -40,7 +40,8 @@
 /**
  * A base class for vector handlers.
  */
-class t8_abstract_vector_handler {
+struct t8_abstract_vector_handler
+{
  public:
   /**
    * Pure virtual function to determine the buffer size.
@@ -140,7 +141,8 @@ class t8_abstract_vector_handler {
  * \tparam TType The type of data to be handled.
  */
 template <typename TType>
-class t8_vector_handler: public t8_abstract_vector_handler {
+struct t8_vector_handler: public t8_abstract_vector_handler
+{
  public:
   /**
    * Construct a t8_vector_handler.

src/t8_forest/t8_forest_pfc_message.hxx

@@ -42,7 +42,8 @@
  * between the processes that will be required to decide on whether and where
  * families are split at process boundaries.
 */
-class t8_forest_pfc_message {
+struct t8_forest_pfc_message
+{
  public:
   /**
    * Pack the data to prepare sending.

src/t8_forest/t8_forest_search/t8_forest_search.hxx

@@ -175,7 +175,8 @@ using t8_partition_search_batched_queries_callback = std::function<void (
 /**
  * A base class that performs a search in a forest.
  */
-class t8_search_base {
+struct t8_search_base
+{
  public:
   /**   Constructor for the t8_search_base class.
    *
@@ -331,7 +332,8 @@ class t8_search_base {
  * \tparam Udata The type of user data to be used in the search.
  */
 template <typename Udata = void>
-class t8_search: public t8_search_base {
+struct t8_search: public t8_search_base
+{
  public:
   /**
   * Constructor for the t8_search class.
@@ -451,7 +453,8 @@ class t8_search: public t8_search_base {
  * \tparam Udata The type of the user data, defaults to void.
 */
 template <typename Query_T, typename Udata = void>
-class t8_search_with_queries: public t8_search<Udata> {
+struct t8_search_with_queries: public t8_search<Udata>
+{
  public:
   /**
    * Constructor for the t8_search_with_queries class.
@@ -564,7 +567,8 @@ class t8_search_with_queries: public t8_search<Udata> {
  * \tparam Udata The type of the user data, defaults to void.
  */
 template <typename Query_T, typename Udata = void>
-class t8_search_with_batched_queries: public t8_search<Udata> {
+struct t8_search_with_batched_queries: public t8_search<Udata>
+{
  public:
   /**
   * Constructor for the t8_search_with_batched_queries class.
@@ -668,7 +672,8 @@ class t8_search_with_batched_queries: public t8_search<Udata> {
 /**
  * A class that performs a search in the partition of a forest.
  */
-class t8_partition_search_base {
+struct t8_partition_search_base
+{
  public:
   /**  Constructor for the t8_partition_search_base class.
    *
@@ -792,7 +797,8 @@ class t8_partition_search_base {
  * \tparam Udata 
  */
 template <typename Udata = void>
-class t8_partition_search: public t8_partition_search_base {
+struct t8_partition_search: public t8_partition_search_base
+{
  public:
   /**
   * Constructor for the t8_partition_search class.
@@ -907,7 +913,8 @@ class t8_partition_search: public t8_partition_search_base {
  * \tparam Udata The type of the user data, defaults to void.
 */
 template <typename Query_T, typename Udata = void>
-class t8_partition_search_with_queries: public t8_partition_search<Udata> {
+struct t8_partition_search_with_queries: public t8_partition_search<Udata>
+{
  public:
   /**
    * Constructor for the t8_partition_search_with_queries class.
@@ -1027,7 +1034,8 @@ class t8_partition_search_with_queries: public t8_partition_search<Udata> {
  * \tparam Udata The type of the user data, defaults to void.
  */
 template <typename Query_T, typename Udata = void>
-class t8_partition_search_with_batched_queries: public t8_partition_search<Udata> {
+struct t8_partition_search_with_batched_queries: public t8_partition_search<Udata>
+{
  public:
   /**
   * Constructor for the t8_partition_search_with_batched_queries class.

src/t8_geometry/t8_geometry_implementations/t8_geometry_lagrange.hxx

@@ -338,7 +338,8 @@ flatten (const std::vector<std::vector<T>> &vec)
  * some specific to the Lagrange geometry, some valid for all the
  * geometries in t8code.
  */
-class t8_lagrange_element {
+struct t8_lagrange_element
+{
  public:
   /**
    * Construct a new t8_lagrange_element object.

src/t8_schemes/t8_default/t8_default_common/t8_default_common.hxx

@@ -89,7 +89,8 @@ count_leaves_from_level (const int element_level, const int refinement_level, co
  * \tparam TUnderlyingEclassScheme The default scheme class of the element shape.
  */
 template <t8_eclass_t TEclass, class TUnderlyingEclassScheme>
-class t8_default_scheme_common: public t8_scheme_helpers<TEclass, TUnderlyingEclassScheme> {
+struct t8_default_scheme_common: public t8_scheme_helpers<TEclass, TUnderlyingEclassScheme>
+{
  private:
   friend TUnderlyingEclassScheme;
   /** Private constructor which can only be used by derived schemes.

src/t8_schemes/t8_default/t8_default_hex/t8_default_hex.hxx

@@ -34,7 +34,7 @@
 #include <t8_schemes/t8_default/t8_default_common/t8_default_common.hxx>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** The class holding a hexahedral element in the default scheme.
  * We make this definition public for interoperability of element classes.
@@ -43,7 +43,8 @@ class t8_scheme;
 typedef p8est_quadrant_t t8_phex_t;
 
 /** Default implementation of the scheme for the hex element class. */
-class t8_default_scheme_hex: public t8_default_scheme_common<T8_ECLASS_HEX, t8_default_scheme_hex> {
+struct t8_default_scheme_hex: public t8_default_scheme_common<T8_ECLASS_HEX, t8_default_scheme_hex>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_hex () noexcept: t8_default_scheme_common (sizeof (t8_phex_t)) {};

src/t8_schemes/t8_default/t8_default_line/t8_default_line.hxx

@@ -34,13 +34,14 @@
 #include <t8_schemes/t8_default/t8_default_line/t8_dline_bits.h>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Provide an implementation for the line element class.
  * It is written as a self-contained library in the t8_dline_* files.
  */
 
-class t8_default_scheme_line: public t8_default_scheme_common<T8_ECLASS_LINE, t8_default_scheme_line> {
+struct t8_default_scheme_line: public t8_default_scheme_common<T8_ECLASS_LINE, t8_default_scheme_line>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_line () noexcept: t8_default_scheme_common (sizeof (t8_dline_t)) {};

src/t8_schemes/t8_default/t8_default_prism/t8_default_prism.hxx

@@ -36,13 +36,14 @@
 #include <t8_schemes/t8_default/t8_default_prism/t8_dprism_bits.h>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Provide an implementation for the prism element class.
  * It is written as a self-contained library in the t8_dprism_* files.
  */
 
-class t8_default_scheme_prism: public t8_default_scheme_common<T8_ECLASS_PRISM, t8_default_scheme_prism> {
+struct t8_default_scheme_prism: public t8_default_scheme_common<T8_ECLASS_PRISM, t8_default_scheme_prism>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_prism () noexcept: t8_default_scheme_common (sizeof (t8_dprism_t)) {};

src/t8_schemes/t8_default/t8_default_pyramid/t8_default_pyramid.hxx

@@ -34,13 +34,14 @@
 #include <t8_schemes/t8_default/t8_default_pyramid/t8_dpyramid_bits.h>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Provide an implementation for the pyramid element class. It is written as a self-contained library in the
  * t8_dpyramid_* files.
  */
 
-class t8_default_scheme_pyramid: public t8_default_scheme_common<T8_ECLASS_PYRAMID, t8_default_scheme_pyramid> {
+struct t8_default_scheme_pyramid: public t8_default_scheme_common<T8_ECLASS_PYRAMID, t8_default_scheme_pyramid>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_pyramid () noexcept: t8_default_scheme_common (sizeof (t8_dpyramid_t)) {};

src/t8_schemes/t8_default/t8_default_quad/t8_default_quad.hxx

@@ -37,7 +37,7 @@
 #include <t8_schemes/t8_default/t8_default_common/t8_default_common.hxx>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** The structure holding a quadrilateral element in the default scheme.
  * We make this definition public for interoperability of element classes.
@@ -79,7 +79,8 @@ typedef p4est_quadrant_t t8_pquad_t;
   } while (0)
 
 /** Default implementation of the scheme for the quad element class. */
-class t8_default_scheme_quad: public t8_default_scheme_common<T8_ECLASS_QUAD, t8_default_scheme_quad> {
+struct t8_default_scheme_quad: public t8_default_scheme_common<T8_ECLASS_QUAD, t8_default_scheme_quad>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_quad () noexcept: t8_default_scheme_common (sizeof (t8_pquad_t)) {};

src/t8_schemes/t8_default/t8_default_tet/t8_default_tet.hxx

@@ -35,10 +35,11 @@
 #include <t8_schemes/t8_default/t8_default_tet/t8_dtet_bits.h>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Default implementation of the scheme for the tet element class. */
-class t8_default_scheme_tet: public t8_default_scheme_common<T8_ECLASS_TET, t8_default_scheme_tet> {
+struct t8_default_scheme_tet: public t8_default_scheme_common<T8_ECLASS_TET, t8_default_scheme_tet>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_tet () noexcept: t8_default_scheme_common (sizeof (t8_dtet_t)) {};

src/t8_schemes/t8_default/t8_default_tri/t8_default_tri.hxx

@@ -35,10 +35,11 @@
 #include <t8_schemes/t8_default/t8_default_tri/t8_dtri_bits.h>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Default implementation of the scheme for the triangular element class. */
-class t8_default_scheme_tri: public t8_default_scheme_common<T8_ECLASS_TRIANGLE, t8_default_scheme_tri> {
+struct t8_default_scheme_tri: public t8_default_scheme_common<T8_ECLASS_TRIANGLE, t8_default_scheme_tri>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_tri () noexcept: t8_default_scheme_common (sizeof (t8_dtri_t)) {};

src/t8_schemes/t8_default/t8_default_vertex/t8_default_vertex.hxx

@@ -32,10 +32,11 @@
 #include <t8_schemes/t8_default/t8_default_common/t8_default_common.hxx>
 
 /* Forward declaration of the scheme so we can use it as an argument in the eclass schemes function. */
-class t8_scheme;
+struct t8_scheme;
 
 /** Default implementation of the scheme for the vertex element class. */
-class t8_default_scheme_vertex: public t8_default_scheme_common<T8_ECLASS_VERTEX, t8_default_scheme_vertex> {
+struct t8_default_scheme_vertex: public t8_default_scheme_common<T8_ECLASS_VERTEX, t8_default_scheme_vertex>
+{
  public:
   /** Constructor which calls the specialized constructor for the base. */
   t8_default_scheme_vertex () noexcept: t8_default_scheme_common (sizeof (t8_dvertex_t)) {};

src/t8_schemes/t8_scheme.hxx

@@ -64,8 +64,9 @@ t8_debug_print_type ()
 
 /** This class holds one or more element schemes.
  * It also relays the function calls to the specific schemes. */
-class t8_scheme {
-  friend class t8_scheme_builder;
+struct t8_scheme
+{
+  friend struct t8_scheme_builder;
 
  public:
   t8_scheme ()

src/t8_schemes/t8_scheme_builder.hxx

@@ -33,7 +33,8 @@
 /** The scheme builder adds eclass schemes to a scheme container and returns it.
  * TODO: Make return value a reference.
  */
-class t8_scheme_builder {
+struct t8_scheme_builder
+{
  public:
   t8_scheme_builder (): scheme (new t8_scheme) {};
   ~t8_scheme_builder () {};