extend the Fortran interface of MultiField to return its FieldSet; ex…

…tend FieldSet to concatenate two FieldSets

src/atlas/field/FieldSet.cc

@@ -170,6 +170,14 @@ void atlas__FieldSet__add_field(FieldSetImpl* This, FieldImpl* field) {
     This->add(field);
 }
 
+void atlas__FieldSet__add_fieldset(FieldSetImpl* This, FieldSetImpl* fieldset) {
+    ATLAS_ASSERT(This != nullptr, "Reason: Use of uninitialised atlas_FieldSet");
+    ATLAS_ASSERT(fieldset != nullptr, "Reason: Use of uninitialised atlas_FieldSet");
+    for(int i = 0; i < fieldset->size(); i++) {
+        This->add(fieldset->operator[](i));
+    }
+}
+
 int atlas__FieldSet__has_field(const FieldSetImpl* This, char* name) {
     ATLAS_ASSERT(This != nullptr, "Reason: Use of uninitialised atlas_FieldSet");
     return This->has(std::string(name));

src/atlas/field/FieldSet.h

@@ -151,6 +151,7 @@ extern "C" {
 FieldSetImpl* atlas__FieldSet__new(char* name);
 void atlas__FieldSet__delete(FieldSetImpl* This);
 void atlas__FieldSet__add_field(FieldSetImpl* This, FieldImpl* field);
+void atlas__FieldSet__add_fieldset(FieldSetImpl* This, FieldSetImpl* fieldset);
 int atlas__FieldSet__has_field(const FieldSetImpl* This, char* name);
 const char* atlas__FieldSet__name(FieldSetImpl* This);
 idx_t atlas__FieldSet__size(const FieldSetImpl* This);

src/atlas/field/detail/MultiFieldInterface.cc

@@ -19,7 +19,7 @@ namespace atlas {
 namespace field {
 
 extern "C" {
-::atlas::field::MultiFieldImpl* atlas__MultiField__create(eckit::Configuration* config) {
+MultiFieldImpl* atlas__MultiField__create(eckit::Configuration* config) {
     ATLAS_ASSERT(config != nullptr);
     long nproma = config->getLong("nproma");
     long nlev = config->getLong("nlev");
@@ -59,7 +59,7 @@ ::atlas::field::MultiFieldImpl* atlas__MultiField__create(eckit::Configuration*
     }
     auto multiarray_shape = array::make_shape(nblk, nfld, nlev, nproma);
 
-::atlas::field::MultiFieldImpl* multifield = new ::atlas::field::MultiFieldImpl{array::ArraySpec{datatype, multiarray_shape}};
+MultiFieldImpl* multifield = new MultiFieldImpl{array::ArraySpec{datatype, multiarray_shape}};
     auto& multiarray = multifield->array();
 
     size_t multiarray_field_idx = 0;
@@ -119,9 +119,13 @@ ::atlas::field::MultiFieldImpl* multifield = new ::atlas::field::MultiFieldImpl{
     return multifield;
 }
 
-void atlas__MultiField__delete(::atlas::field::MultiFieldImpl* This) {
+void atlas__MultiField__delete(MultiFieldImpl* This) {
     delete This;
 }
+
+FieldSet* atlas__MultiField__fieldset(MultiFieldImpl* This) {
+    return &This->fieldset();
+}
 }
 
 // ------------------------------------------------------------------

src/atlas/field/detail/MultiFieldInterface.h

@@ -14,6 +14,7 @@
 
 #pragma once
 
+#include "atlas/field/FieldSet.h"
 #include "atlas/field/MultiField.h"
 
 namespace atlas {
@@ -30,6 +31,7 @@ namespace field {
 extern "C" {
 MultiFieldImpl* atlas__MultiField__create(eckit::Configuration* config);
 void atlas__MultiField__delete(MultiFieldImpl* This);
+FieldSet* atlas__MultiField__fieldset(MultiFieldImpl* This);
 }
 
 //----------------------------------------------------------------------------------------------------------------------

src/atlas_f/field/atlas_FieldSet_module.fypp

@@ -51,7 +51,9 @@ contains
   procedure, private :: field_by_name
   procedure, private :: field_by_idx_int
   procedure, private :: field_by_idx_long
-  procedure, public  :: add
+  procedure, public  :: add_field
+  procedure, public  :: add_fset
+  generic :: add => add_field, add_fset
   generic :: field => field_by_name, field_by_idx_int, field_by_idx_long
 
   procedure, public :: set_dirty
@@ -213,14 +215,21 @@ function FieldSet__name(this) result(fieldset_name)
   fieldset_name = c_ptr_to_string(fieldset_name_c_str)
 end function FieldSet__name
 
-subroutine add(this,field)
+subroutine add_field(this,field)
   use atlas_fieldset_c_binding
   use atlas_Field_module, only: atlas_Field
   class(atlas_FieldSet), intent(in) :: this
   type(atlas_Field), intent(in) :: field
   call atlas__FieldSet__add_field(this%CPTR_PGIBUG_A, field%CPTR_PGIBUG_A)
 end subroutine
 
+subroutine add_fset(this,fset)
+  use atlas_fieldset_c_binding
+  class(atlas_FieldSet), intent(inout) :: this
+  class(atlas_FieldSet), intent(in) :: fset
+  call atlas__FieldSet__add_fieldset(this%CPTR_PGIBUG_A, fset%CPTR_PGIBUG_A)
+end subroutine
+
 function has(this,name) result(flag)
   use, intrinsic :: iso_c_binding, only: c_int
   use fckit_c_interop_module, only: c_str

src/atlas_f/field/atlas_MultiField_module.fypp

@@ -15,6 +15,7 @@ module atlas_multifield_module
 
 use fckit_owned_object_module, only : fckit_owned_object
 use atlas_Config_module, only: atlas_Config
+use atlas_fieldset_module, only: atlas_fieldset
 
 implicit none
 
@@ -42,6 +43,8 @@ TYPE, extends(fckit_owned_object) :: atlas_MultiField
 
 !------------------------------------------------------------------------------
 contains
+  procedure, public  :: MultiField__fieldset
+  generic :: fieldset => MultiField__fieldset
 
 #if FCKIT_FINAL_NOT_INHERITING
   final :: atlas_MultiField__final_auto
@@ -83,6 +86,19 @@ end function
 
 !-------------------------------------------------------------------------------
 
+function MultiField__fieldset(this) result(fset)
+  use, intrinsic :: iso_c_binding, only : c_ptr
+  use atlas_multifield_c_binding
+  class(atlas_MultiField), intent(in) :: this
+  type(c_ptr) :: fset_cptr
+  type(atlas_FieldSet) :: fset
+  fset_cptr = atlas__MultiField__fieldset(this%CPTR_PGIBUG_B)
+  fset = atlas_FieldSet( fset_cptr )
+  call fset%return()
+end function
+
+!-------------------------------------------------------------------------------
+
 #if FCKIT_FINAL_NOT_INHERITING
 ATLAS_FINAL subroutine atlas_MultiField__final_auto(this)
   type(atlas_MultiField), intent(inout) :: this