Class: Vpim::Rrule

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/vpim/rrule.rb

Overview

Implements the iCalendar recurrence rule syntax. See etc/rrule.txt for the syntax description and examples from RFC 2445. The description is pretty hard to understand, but the examples are more helpful.

The implementation is reasonably complete, but still lacks support for:

Recurrence by date (RDATE) and exclusions (EXDATE, EXRULE).

TODO - BYWEEKNO: rules that are limited to particular weeks in a year.

TODO - BYHOUR, BYMINUTE, BYSECOND: trivial to do, but I don’t have an immediate need for them.

TODO - new API? -> Rrule#infinite?

Examples

  • rrule.txt: utility for printing recurrence rules

Defined Under Namespace

Classes: DaySet, Maker

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dtstart, rrule = nil) ⇒ Rrule

The recurrence rule, rrule, specifies how to generate a set of times from a start time, dtstart (which must the first of the set of recurring times). If rrule is nil, the set contains only dtstart.



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# File 'lib/vpim/rrule.rb', line 59

def initialize(dtstart, rrule = nil)
   @dtstart = dtstart.getlocal
   # The getlocal is a hack so that UTC times get converted to local,
   # because yielded times are always local, because we don't support
   # timezones.
   @rrule = rrule

   # Freq is mandatory, but must occur only once.
   @freq = nil
   
   # Both Until and Count must not occur, neither is OK.
   @until = nil
   @count = nil
   
   # Interval is optional, but defaults to 1.
   @interval = 1

   # WKST defines what day a week begins on, the default is monday.
   @wkst = 'MO'
   
   # Recurrence can modified by these.
   @by = {}
  
   if @rrule
     @rrule.scan(/([^;=]+)=([^;=]+)/) do |key,value|
       key.upcase!
       value.upcase!

       case key
       when 'FREQ'
         @freq = value

       when 'UNTIL'
         if @count
           raise "found UNTIL, but COUNT already specified"
         end
         @until = Rrule.time_from_rfc2425(value)

       when 'COUNT'
         if @until
           raise "found COUNT, but UNTIL already specified"
         end
         @count = value.to_i

       when 'INTERVAL'
         @interval = value.to_i
         if @interval < 1
           raise "interval must be a positive integer"
         end

       when 'WKST'
         # TODO - check value is MO-SU
         @wkst = value

       else
         @by[key] = value
       end
     end

     if !@freq
       # TODO - this shouldn't be an arg error, but a FormatError, its not the
       # caller's fault!
       raise ArgumentError, "recurrence rule lacks a frequency"
     end
   end
end

Class Method Details

.time_from_rfc2425(str) ⇒ Object

:nodoc:



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# File 'lib/vpim/rrule.rb', line 447

def self.time_from_rfc2425(str) #:nodoc:
  # With ruby1.8 we can use DateTime to do this quick-n-easy:
  #  dt = DateTime.parse(str)
  #  Time.local(dt.year, dt.month, dt.day, dt.hour, dt.min, dt.sec, 0)

  # The time can be a DATE or a DATE-TIME, the latter always has a 'T' in it.

  if str =~ /T/
    d = Vpim.decode_date_time(str)
    # We get [ year, month, day, hour, min, sec, usec, tz ]
    if(d.pop == "Z")
      t = Time.gm(*d)
    else
      t = Time.local(*d)
    end
  else
    d = Vpim.decode_date(str)
    # We get [ year, month, day ]
    # FIXME - I have to choose gm or local, though neither makes much
    # sense. This is a bit of a hack - what we should really do is return
    # an instance of Date, and Time should allow itself to be compared to
    # Date... This hack will give odd results when comparing times, because
    # it will create a Time on the right date but whos time is 00:00:00.
    t = Time.local(*d)
  end
  if t.month != d[1] || t.day != d[2] || (d[3] && t.hour != d[3])
    raise Vpim::InvalidEncodingError, "Error - datetime does not exist"
  end
  t
end

Instance Method Details

#byday_in_monthly(year, mon, byday) ⇒ Object

:nodoc:



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# File 'lib/vpim/rrule.rb', line 498

def byday_in_monthly(year, mon, byday) #:nodoc:
  dates = []

  byday.each do |rule|
    if rule[0].empty?
      n = nil
    else
      n = rule[0].to_i
    end
    dates |= DateGen.bywday(year, mon, Date.str2wday(rule[1]), n)
  end
  dates.sort!
  dates
end

#byday_in_weekly(year, mon, day, wkst, byday) ⇒ Object

:nodoc:



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# File 'lib/vpim/rrule.rb', line 513

def byday_in_weekly(year, mon, day, wkst, byday) #:nodoc:
  #    debug ["day", year,mon,day,wkst,byday]
  days = byday.map{ |_, byday| Date.str2wday(byday) }
  week = DateGen.weekofdate(year, mon, day, wkst)
  #    debug [ "week", dates ]
  week.delete_if do |d|
    !days.include?(d.wday)
  end
  week
end

#bymonthday(year, bymday) ⇒ Object

:nodoc:



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# File 'lib/vpim/rrule.rb', line 478

def bymonthday(year, bymday) #:nodoc:
  dates = []

  bymday.each do |mday|
    dates |= DateGen.bymonthday(year, nil, mday[0].to_i)
  end
  dates.sort!
  dates
end

#byyearday(year, byyday) ⇒ Object

:nodoc:



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# File 'lib/vpim/rrule.rb', line 488

def byyearday(year, byyday) #:nodoc:
  dates = []

  byyday.each do |yday|
    dates << Date.ordinal(year, yday[0].to_i)
  end
  dates.sort!
  dates
end

#each(dountil = nil) ⇒ Object

Yields for each ytime in the recurring set of events.

Warning: the set may be infinite! If you need an upper bound on the number of occurrences, you need to implement a count, or pass a time, dountil, which will not be iterated past (i.e. all times yielded will be less than dountil).

Also, iteration will not currently continue past the limit of a Time object, which is some time in 2037 with the 32-bit time_t common on most systems.



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# File 'lib/vpim/rrule.rb', line 142

def each(dountil = nil) #:yield: ytime
  t = @dtstart.clone

  # Time.to_a => [ sec, min, hour, day, month, year, wday, yday, isdst, zone ]

  # Every event occurs at its start time, but only if the start time is
  # earlier than DOUNTIL...
  if !dountil || t < dountil
    yield t
  end
  count = 1

  # With no recurrence, DTSTART is the only occurrence.
  if !@rrule
    return self
  end

  loop do
    # Build the set of times to yield within this interval (and after
    # DTSTART)

    days  = DaySet.new(t)
    hour  = nil
    min   = nil
    sec   = nil

    # Need to make a Dates class, and make month an instance of it, and add
    # the "intersect" operator.

    case @freq
      #when 'YEARLY' then
      # Don't need to keep track of year, all occurrences are within t's
      # year.
    when 'MONTHLY'  then  days.month = t.month
    when 'WEEKLY'   then  #days.month = t.month
      # TODO - WEEKLY
    when 'DAILY'    then  days.mday = t.month, t.mday
    when 'HOURLY'   then  hour  = [t.hour]
    when 'MINUTELY' then  min   = [t.min]
    when 'SECONDLY' then  sec   = [t.sec]
    end

  #      debug [t, days]
    # Process the BY* modifiers in RFC defined order:
    #  BYMONTH,
    #  BYWEEKNO,
    #  BYYEARDAY,
    #  BYMONTHDAY,
    #  BYDAY,
    #  BYHOUR,
    #  BYMINUTE,
    #  BYSECOND,
    #  BYSETPOS

    bymon = [nil]

    if @by['BYMONTH']
      bymon = @by['BYMONTH'].split(',')
      bymon = bymon.map { |m| m.to_i }
  #        debug bymon

      # In yearly, at  this point, month will always be nil. At other
      # frequencies, it will not.
      days.intersect_bymon(bymon)

  #        debug days
    end

    # TODO - BYWEEKNO

    if @by['BYYEARDAY']
      byyday = @by['BYYEARDAY'].scan(/,?([+-]?[1-9]\d*)/)
  #        debug byyday
      dates = byyearday(t.year, byyday)
      days.intersect_dates(dates)
    end

    if @by['BYMONTHDAY']
      bymday = @by['BYMONTHDAY'].scan(/,?([+-]?[1-9]\d*)/)
  #        debug bymday
      # Generate all days matching this for all months. For yearly, this
      # is what we want, for anything of monthly or higher frequency, it
      # is too many days, but that's OK, since  the month will already
      # be specified and intersection will eliminate the out-of-range
      # dates.
      dates = bymonthday(t.year, bymday)
  #        debug dates
      days.intersect_dates(dates)
  #        debug days
    end

    if @by['BYDAY']
      byday = @by['BYDAY'].scan(/,?([+-]?[1-9]?\d*)?(SU|MO|TU|WE|TH|FR|SA)/i)

      # BYDAY means different things in different frequencies. The +n+
      # is only meaningful when freq is yearly or monthly.

      case @freq
        when 'YEARLY'
          dates = bymon.map { |m| byday_in_monthly(t.year, m, byday) }.flatten
        when 'MONTHLY'
          dates = byday_in_monthly(t.year, t.month, byday)
        when 'WEEKLY'
          dates = byday_in_weekly(t.year, t.month, t.mday, @wkst, byday)
        when 'DAILY', 'HOURLY', 'MINUTELY', 'SECONDLY'
          # Reuse the byday_in_monthly. Current day is already specified,
          # so this will just eliminate the current day if its not allowed
          # in BYDAY.
          dates = byday_in_monthly(t.year, t.month, byday)
      end

  #        debug dates
      days.intersect_dates(dates)
  #        debug days
    end

    # TODO - BYHOUR, BYMINUTE, BYSECOND
    
    hour   = [@dtstart.hour]   if !hour 
    min    = [@dtstart.min]    if !min  
    sec    = [@dtstart.sec]    if !sec 

  #      debug days

    # Generate the yield set so BYSETPOS can be evaluated.
    yset = []

    days.each do |m,d|
      hour.each do |h|
        min.each do |n|
          sec.each do |s|
            y = Time.local(t.year, m, d, h, n, s, 0)

            next if y.hour != h

            yset << y
          end
        end
      end
    end

    if @by['BYSETPOS']
      bysetpos = @by['BYSETPOS'].split(',')
      yset = bysetpos.map do |i|
        i = i.to_i
        case
        when i < 0
          # yset[-1] is last
          yset[i]
        when i > 0
          # yset[1] is first
          yset[i-1]
        else
          # ignore invalid syntax
        end
      end.compact # set positions out of scope will be nil, RFC says ignore them
    end

    # Yield the occurrence, if we haven't gone over COUNT, or past UNTIL, or
    # past the end of representable time.

    yset.each do |y|
      # The generated set can sometimes generate results earlier
      # than the DTSTART, skip them. Also, we already yielded
      # DTSTART, skip it.
      next if y <= @dtstart

      count += 1

      # We are done if current count is past @count.
      if(@count && (count > @count))
        return self
      end

      # We are done if current time is past @until.
      if @until && (y > @until)
        return self
      end
      # We are also done if current time is past the
      # caller-requested until.
      if dountil && (y >= dountil)
        return self
      end
      yield y
    end

    # Add @interval to @freq component

    # Note - when we got past representable time, the error is:
    #   time out of range (ArgumentError)
    # Finish when we see this.
    begin
      case @freq
        when 'YEARLY' then
          t = t.plus_year(@interval)

        when 'MONTHLY' then
          t = t.plus_month(@interval)

        when 'WEEKLY' then
          t = t.plus_day(@interval * 7)

        when 'DAILY' then
          t = t.plus_day(@interval)

        when 'HOURLY' then
          t += @interval * 60 * 60

        when 'MINUTELY' then
          t += @interval * 60

        when 'SECONDLY' then
          t += @interval

        when nil
          return self
      end
    rescue ArgumentError
      return self if $!.message =~ /^time out of range$/

      raise ArgumentError, "#{$!.message} while adding interval to #{t.inspect}"
    end

    return self if dountil && (t > dountil)
  end
end

#each_until(dountil) ⇒ Object

Return an Enumerable, it’s #each() will yield over all occurrences up to (and not including) time dountil.



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# File 'lib/vpim/rrule.rb', line 128

def each_until(dountil)
  Vpim::Enumerator.new(self, dountil)
end