ESMF_FieldHalo Subroutine

  subroutine ESMF_FieldHalo(field, routehandle, keywordEnforcer,  &
                            routesyncflag, finishedflag, checkflag, rc)
!
! !ARGUMENTS:
    type(ESMF_Field),          intent(inout)          :: field
    type(ESMF_RouteHandle),    intent(inout)          :: routehandle
type(ESMF_KeywordEnforcer), optional:: keywordEnforcer ! must use keywords for the below
    type(ESMF_RouteSync_Flag), intent(in),  optional  :: routesyncflag
    logical,                   intent(out), optional  :: finishedflag
    logical,                   intent(in),  optional  :: checkflag
    integer,                   intent(out), optional  :: rc
!
!
! !STATUS:
! \begin{itemize}
! \item\apiStatusCompatibleVersion{5.2.0r}
! \end{itemize}
!
! !DESCRIPTION:
!   Execute a precomputed Field halo operation for {\tt field}. 
!   The {\tt field} argument must match the Field used during 
!   {\tt ESMF\_FieldHaloStore()} in {\em type}, {\em kind}, and 
!   memory layout of the {\em gridded} dimensions. However, the size, number, 
!   and index order of {\em ungridded} dimensions may be different. See section
!   \ref{RH:Reusability} for a more detailed discussion of RouteHandle 
!   reusability.
!
!   See {\tt ESMF\_FieldHaloStore()} on how to precompute {\tt routehandle}.
!
!   This call is {\em collective} across the current VM.
!
!   \begin{description}
!   \item [field]
!     {\tt ESMF\_Field} containing data to be haloed.
!   \item [routehandle]
!     Handle to the precomputed Route.
!   \item [{[routesyncflag]}]
!     Indicate communication option. Default is {\tt ESMF\_ROUTESYNC\_BLOCKING},
!     resulting in a blocking operation.
!     See section \ref{const:routesync} for a complete list of valid settings.
!   \item [{[finishedflag]}]
!     \begin{sloppypar}
!     Used in combination with {\tt routesyncflag = ESMF\_ROUTESYNC\_NBTESTFINISH}.
!     Returned {\tt finishedflag} equal to {\tt .true.} indicates that all
!     operations have finished. A value of {\tt .false.} indicates that there
!     are still unfinished operations that require additional calls with
!     {\tt routesyncflag = ESMF\_ROUTESYNC\_NBTESTFINISH}, or a final call with
!     {\tt routesyncflag = ESMF\_ROUTESYNC\_NBWAITFINISH}. For all other {\tt routesyncflag}
!     settings the returned value in {\tt finishedflag} is always {\tt .true.}.
!     \end{sloppypar}
!   \item [{[checkflag]}]
!     If set to {\tt .TRUE.} the input Field pair will be checked for
!     consistency with the precomputed operation provided by {\tt routehandle}.
!     If set to {\tt .FALSE.} {\em (default)} only a very basic input check
!     will be performed, leaving many inconsistencies undetected. Set
!     {\tt checkflag} to {\tt .FALSE.} to achieve highest performance.
!   \item [{[rc]}]
!     Return code; equals {\tt ESMF\_SUCCESS} if there are no errors.
!   \end{description}
!
!EOP
!------------------------------------------------------------------------------
    integer                 :: localrc      ! local return code

    ! local variables
    type(ESMF_Array)        :: array

    ! initialize return code; assume routine not implemented
    localrc = ESMF_RC_NOT_IMPL
    if (present(rc)) rc = ESMF_RC_NOT_IMPL

    ! Check init status of arguments
    ESMF_INIT_CHECK_DEEP(ESMF_FieldGetInit, field, rc)
    ESMF_INIT_CHECK_DEEP(ESMF_RouteHandleGetInit, routehandle, rc)
    
    call ESMF_FieldGet(field, array=array, rc=localrc)
    if (ESMF_LogFoundError(localrc, ESMF_ERR_PASSTHRU, &
      ESMF_CONTEXT, rcToReturn=rc)) return
    
    ! Call into the Array interface, which will sort out optional arguments
    call ESMF_ArrayHalo(array, routehandle=routehandle, routesyncflag=routesyncflag, &
      finishedflag=finishedflag, checkflag=checkflag, rc=localrc)
    if (ESMF_LogFoundError(localrc, ESMF_ERR_PASSTHRU, &
      ESMF_CONTEXT, rcToReturn=rc)) return
    
    ! return successfully
    if (present(rc)) rc = ESMF_SUCCESS

  end subroutine ESMF_FieldHalo