Allow to append to CSV files

Author: fj-elmer

src/csv_module.F90

@@ -323,22 +323,35 @@ end subroutine read_csv_file
 !
 !  Use `initialize` to set options for the CSV file.
 
-    subroutine open_csv_file(me,filename,n_cols,status_ok)
+    subroutine open_csv_file(me,filename,n_cols,status_ok,append)
 
     implicit none
 
     class(csv_file),intent(inout) :: me
     character(len=*),intent(in) :: filename  !! the CSV file to open
     integer,intent(in) :: n_cols  !! number of columns in the file
     logical,intent(out) :: status_ok  !! status flag
+    logical,intent(in),optional :: append !! Append if file exists
 
     integer :: istat  !! open `iostat` flag
+    logical :: append_flag = .false.
+    logical :: file_exists
 
     call me%destroy()
 
     me%n_cols = n_cols
 
-    open(newunit=me%iunit,file=filename,status='REPLACE',iostat=istat)
+    if (present(append)) append_flag = append
+    if (append_flag) then
+        inquire (file=filename, exist=file_exists)
+        if (file_exists) then
+            open(newunit=me%iunit,file=filename,status='OLD',position='APPEND',iostat=istat)
+        else
+            open(newunit=me%iunit,file=filename,status='REPLACE',iostat=istat)
+        end if
+    else
+       open(newunit=me%iunit,file=filename,status='REPLACE',iostat=istat)
+    end if
     if (istat==0) then
         status_ok = .true.
     else