Ease the way to use base interpolation schemes for particle interpolators

include/aspect/particle/interpolator/interface.h

@@ -84,11 +84,15 @@ namespace aspect
 
 
       /**
-       * Return a list of names (separated by '|') of possible interpolator
-       * classes for particles.
+       * Return a string that consists of the names of interpolator classes
+       * for particles that can be selected.
+       * These names are separated by a vertical line '|' so
+       * that the string can be an input to the deal.II classes
+       * Patterns::Selection or Patterns::MultipleSelection.
        */
+      template <int dim>
       std::string
-      interpolator_object_names ();
+      get_valid_interpolator_names_pattern ();
 
 
       /**
@@ -113,10 +117,27 @@ namespace aspect
                                       void (*declare_parameters_function) (ParameterHandler &),
                                       std::unique_ptr<Interface<dim>> (*factory_function) ());
 
+
+      /**
+       * A function that given the name of an interpolation scheme
+       * returns a pointer to an object that describes it.
+       * Ownership of the pointer is transferred to the caller.
+       *
+       * The model object returned is not yet initialized and has not
+       * read its runtime parameters yet.
+       *
+       * @ingroup ParticleInterpolators
+       */
+      template <int dim>
+      std::unique_ptr<Interface<dim>>
+      create_particle_interpolator (const std::string &interpolator_name);
+
+
       /**
-       * A function that given the name of a model returns a pointer to an
-       * object that describes it. Ownership of the pointer is transferred to
-       * the caller.
+       * A function that reads the name of an interpolation scheme
+       * from the parameter object and then returns a pointer
+       * to an object that describes it.
+       * Ownership of the pointer is transferred to the caller.
        *
        * The model object returned is not yet initialized and has not
        * read its runtime parameters yet.

source/particle/interpolator/interface.cc

@@ -58,29 +58,45 @@ namespace aspect
 
       template <int dim>
       std::unique_ptr<Interface<dim>>
-      create_particle_interpolator (ParameterHandler &prm)
+      create_particle_interpolator (const std::string &interpolator_name)
       {
-        std::string name;
-        name = prm.get ("Interpolation scheme");
-
         // 'bilinear least squares' is the deprecated old name of the 'linear least squares'
         // interpolator. The old name will be removed in the future.
-        if (name == "bilinear least squares")
-          name = "linear least squares";
+        if (interpolator_name == "bilinear least squares")
+          return std::get<dim>(registered_plugins).create_plugin ("linear least squares",
+                                                                  "Particle::Interpolator name");
+        else
+          return std::get<dim>(registered_plugins).create_plugin (interpolator_name,
+                                                                  "Particle::Interpolator name");
+      }
+
+
+
+      template <int dim>
+      std::unique_ptr<Interface<dim>>
+      create_particle_interpolator (ParameterHandler &prm)
+      {
+        const std::string name = prm.get ("Interpolation scheme");
 
-        return std::get<dim>(registered_plugins).create_plugin (name,
-                                                                "Particle::Interpolator name");
+        return create_particle_interpolator<dim> (name);
       }
 
 
+      template <int dim>
+      std::string
+      get_valid_interpolator_names_pattern ()
+      {
+        return std::get<dim>(registered_plugins).get_pattern_of_names ();
+      }
+
 
       template <int dim>
       void
       declare_parameters (ParameterHandler &prm)
       {
         // declare the entry in the parameter file
         const std::string pattern_of_names
-          = std::get<dim>(registered_plugins).get_pattern_of_names ();
+          = get_valid_interpolator_names_pattern<dim>();
 
         // 'bilinear least squares' is the deprecated old name of the 'linear least squares'
         // interpolator. The old name will be removed in the future.
@@ -128,6 +144,10 @@ namespace aspect
                                        void ( *) (ParameterHandler &), \
                                        std::unique_ptr<Interface<dim>>( *) ()); \
   \
+  template \
+  std::string \
+  get_valid_interpolator_names_pattern<dim> (); \
+  \
   template  \
   void \
   declare_parameters<dim> (ParameterHandler &); \
@@ -138,6 +158,10 @@ namespace aspect
   \
   template \
   std::unique_ptr<Interface<dim>> \
+  create_particle_interpolator<dim> (const std::string &interpolator_name); \
+  \
+  template \
+  std::unique_ptr<Interface<dim>> \
   create_particle_interpolator<dim> (ParameterHandler &prm);
 
       ASPECT_INSTANTIATE(INSTANTIATE)