Abstract type example

Add example of using abstract hashmap_type for procedure interrface.

Author: chuckyvt

example/hashmaps/CMakeLists.txt

@@ -1,3 +1,4 @@
+ADD_EXAMPLE(hashmaps_abstract_type)
 ADD_EXAMPLE(hashmaps_calls)
 ADD_EXAMPLE(hashmaps_copy_key)
 ADD_EXAMPLE(hashmaps_entries)

example/hashmaps/example_hashmaps_abstract_type.f90

@@ -0,0 +1,53 @@
+
+! For procedure interfaces, consider using abstract hashmap_type for interface definition. 
+! This allows the procedure to be used for both chaining and open hashmap types.
+    
+program example_abstract_type
+    use stdlib_kinds, only: int8, int64
+    use stdlib_hashmaps, only: chaining_hashmap_type, open_hashmap_type, hashmap_type
+  
+    implicit none
+  
+    integer                     :: out_value
+    type(chaining_hashmap_type) :: chaining_map
+    type(open_hashmap_type)     :: open_map
+    
+    ! Chaining map call
+    call put_int(chaining_map, '1', 1)
+    call get_int(chaining_map, '1', out_value)
+    print *, "Chaining out value is ", out_value
+    
+    ! Open map call
+    call put_int(open_map, '1', 1)
+    call get_int(open_map, '1', out_value)
+    print *, "Open out value is ", out_value
+  
+    contains
+    
+    subroutine put_int(map, key, value)
+        class(hashmap_type), intent(inout) :: map
+        character(len=*), intent(in) :: key
+        integer, intent(in) :: value
+        
+        call map%map_entry(key, value)
+    end subroutine put_int
+    
+    
+    subroutine get_int(map, key, value)
+        class(hashmap_type), intent(inout) :: map
+        character(len=*), intent(in) :: key
+        integer, intent(out) :: value
+        class(*), allocatable :: data
+        
+        call map%get_other_data( key, data)
+  
+        select type (data)
+        type is (integer)
+            value = data
+        class default
+            print *, 'Invalid data type in other'
+        end select
+    end subroutine get_int
+
+        
+end program example_abstract_type