MAPL_StateEval Subroutine

  subroutine MAPL_StateEval(state,expression,field,rc)
    type(ESMF_State),        intent(in   ) :: state
    character(len=*),        intent(in   ) :: expression
    type(ESMF_Field),        intent(inout) :: field
    integer, optional,       intent(out  ) :: rc

    character(len=ESMF_MAXSTR), allocatable :: fieldNames(:)
    integer                              :: varCount

    type(ESMF_Field)                     :: state_field

    integer                              :: i
    type(tComp)                          :: pcode
    logical, allocatable                 :: needed(:)
    logical                              :: isConformal
    integer :: status

    call ESMF_StateGet(state,ITEMCOUNT=varCount,_RC)
    allocate(fieldnames(varCount),needed(varCount))
    call ESMF_StateGet(state,itemnamelist=fieldNames,_RC)

    ! confirm that each needed field is conformal
    call CheckSyntax(expression,fieldNames,needed,_RC)
    do i=1,varCount
       if (needed(i)) then
          call ESMF_StateGet(state,fieldNames(i),field=state_field,_RC)

          isConformal = FieldsAreBroadcastConformable(state_field,field,_RC)
          if (.not.isConformal) then
             _FAIL('needs informative message')
          end if
       end if
    end do

    call parsef (pcode, expression, fieldNames, field, _RC)
    call evalf(pcode,state,fieldNames,field,_RC)
    call bytecode_dealloc(pcode,_RC)

    deallocate(fieldNames,needed)


    end subroutine MAPL_StateEval