Merge pull request #80 from billsacks/water_tracers_is_wtracer

Add shr_wtracers_is_wtracer_field

The main motivation of adding this is that it helps me break a dependency of CMEPS on CESM_share, which I'll illustrate in ESCOMP/CMEPS#620. But this also feels like it will lead to more self-documenting code, since `shr_wtracers_is_wtracer_field` is more clear than calling `shr_string_withoutSuffix` directly.

Author: billsacks

src/water_isotopes/shr_wtracers_mod.F90

@@ -20,6 +20,7 @@ module shr_wtracers_mod
    use shr_log_mod       , only : shr_log_error
    use shr_log_mod       , only : s_logunit=>shr_log_Unit
    use shr_string_mod    , only : shr_string_listGetAllNames, shr_string_toUpper
+   use shr_string_mod    , only : shr_string_withoutSuffix
    use shr_sys_mod       , only : shr_sys_abort
    use nuopc_shr_methods , only : chkerr
    use NUOPC             , only : NUOPC_CompAttributeGet
@@ -35,6 +36,7 @@ module shr_wtracers_mod
 
    public :: shr_wtracers_init              ! initialize water tracer information
    public :: shr_wtracers_finalize          ! finalize water tracer information
+   public :: shr_wtracers_is_wtracer_field  ! return true if the given field name is a water tracer field
    public :: shr_wtracers_present           ! return true if there are water tracers in this simulation
    public :: shr_wtracers_get_num_tracers   ! get number of water tracers in this simulation
    public :: shr_wtracers_get_name          ! get the name of a given tracer
@@ -354,6 +356,38 @@ subroutine shr_wtracers_check_tracer_num(tracer_num, subname)
       end if
    end subroutine shr_wtracers_check_tracer_num
 
+   !-----------------------------------------------------------------------
+   function shr_wtracers_is_wtracer_field(fieldname)
+      !
+      ! !DESCRIPTION:
+      ! Return true if the given field name is a water tracer field
+      !
+      ! Note that, unlike most other routines in this module, this function works even if
+      ! the data in this module has not been initialized (i.e., even if shr_wtracers_init
+      ! has not been called): it works simply based on naming conventions.
+      !
+      ! !ARGUMENTS
+      character(len=*), intent(in) :: fieldname
+      logical :: shr_wtracers_is_wtracer_field  ! function result
+      !
+      ! !LOCAL VARIABLES:
+      integer :: localrc
+      logical :: is_tracer
+
+      character(len=*), parameter :: subname='shr_wtracers_is_wtracer_field'
+      !-----------------------------------------------------------------------
+
+      call shr_string_withoutSuffix( &
+           in_str = fieldname, &
+           suffix = WTRACERS_SUFFIX, &
+           has_suffix = is_tracer, &
+           rc = localrc)
+      if (localrc /= 0) then
+         call shr_sys_abort(subname//": ERROR in shr_string_withoutSuffix")
+      end if
+      shr_wtracers_is_wtracer_field = is_tracer
+   end function shr_wtracers_is_wtracer_field
+
    !-----------------------------------------------------------------------
    function shr_wtracers_present()
       !