dcdatetimezone.f90

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! -*- mode: f90; coding: utf-8 -*-
!-----------------------------------------------------------------------
! Copyright (c) 2000-2026 Gtool Development Group. All rights reserved.
!-----------------------------------------------------------------------
 
subroutine dcdatetimesetzone(time, zone, err)
 
  use dc_types,      only: string
  use dc_date_types, only: dc_datetime, dc_difftime
  use dc_date_generic, only: validzone, zonetodiff, tochar, eval, &
    & operator(-), operator(+)
  use dc_error, only: storeerror, dc_ebadtimezone, dc_noerr
  use dc_message, only: messagenotify
  use dc_trace, only: beginsub, endsub
  use dc_string, only: stoi
  implicit none
  type(dc_datetime), intent(inout):: time
  character(*), intent(in):: zone
  logical, intent(out), optional:: err
  type(dc_difftime):: diff, diff_in
  integer :: stat
  character(STRING) :: zone_in, cause_c
  character(*), parameter :: subname = 'DCDateTimeSetZone'
continue
  call beginsub(subname, 'time=%c, zone=%c', &
    & c1=trim(tochar(time)), c2=trim(zone))
  stat = dc_noerr
  cause_c = ''
 
  if (.not. validzone(zone)) then
    stat = dc_ebadtimezone
    cause_c = zone
    if (present(err)) then
      call messagenotify('W', subname, &
        & 'zone=<%c> is invalid.', &
        & c1=trim(zone))
    else
      goto 999
    end if
  end if
 
  call eval(time, zone = zone_in)
  diff_in = zonetodiff(zone_in)
  diff = zonetodiff(zone)
 
  time = time + (diff_in - diff)
  time % zone = zone
 
999 continue
  call storeerror(stat, subname, err, cause_c)
  call endsub(subname, 'time=%c', &
    & c1=trim(tochar(time)))
end subroutine dcdatetimesetzone
 
function dcdatetimezonetodiff(zone) result(diff)
 
  use dc_date_types, only: dc_difftime
  use dc_date_generic, only: validzone, dcdifftimecreate
  use dc_string, only: stoi
  implicit none
  type(dc_difftime):: diff
  character(*), intent(in):: zone
  integer:: hour, min, sgn
continue
  if (.not. validzone(zone)) then
    call dcdifftimecreate(diff)
  else
    if (zone(1:1) == '-') then
      sgn = 1
    else
      sgn = -1
    end if
    hour = stoi(zone(2:3))
    min = stoi(zone(5:6))
    call dcdifftimecreate(diff, hour = hour * sgn, min = min * sgn)
  end if
end function dcdatetimezonetodiff
 
function dcdatetimevalidzone(zone) result(result)
 
  implicit none
  character(*), intent(in):: zone
  logical:: result
continue
  result = .false.
  if (len(zone) < 6) return
  if (verify(zone(1:1), '+-') /= 0) return
  if (verify(zone(2:3), '1234567890') /= 0) return
  if (verify(zone(5:6), '1234567890') /= 0) return
  if (zone(4:4) /= ':') return
  result = .true.
end function dcdatetimevalidzone