Class: CronParser

Inherits:
Object
  • Object
show all
Defined in:
lib/cron_parser.rb

Overview

Parses cron expressions and computes the next occurence of the “job”

Defined Under Namespace

Classes: InternalTime

Constant Summary collapse

SYMBOLS = 
{
   "jan" => "1",
   "feb" => "2",
   "mar" => "3",
   "apr" => "4",
   "may" => "5",
   "jun" => "6",
   "jul" => "7",
   "aug" => "8",
   "sep" => "9",
   "oct" => "10",
   "nov" => "11",
   "dec" => "12",

   "sun" => "0",
   "mon" => "1",
   "tue" => "2",
   "wed" => "3",
   "thu" => "4",
   "fri" => "5",
   "sat" => "6"
}
SUBELEMENT_REGEX = 
%r{^(\d+)(-(\d+)(/(\d+))?)?$}

Instance Method Summary collapse

Constructor Details

#initialize(source, time_source = Time) ⇒ CronParser

Returns a new instance of CronParser.



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# File 'lib/cron_parser.rb', line 54

def initialize(source,time_source = Time)
  @source = interpret_vixieisms(source)
  @time_source = time_source
  validate_source
end

Instance Method Details

#interpret_vixieisms(spec) ⇒ Object 



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# File 'lib/cron_parser.rb', line 60

def interpret_vixieisms(spec)
  case spec
  when '@reboot'
    raise ArgumentError, "Can't predict last/next run of @reboot"
  when '@yearly', '@annually'
    '0 0 1 1 *'
  when '@monthly'
    '0 0 1 * *'
  when '@weekly'
    '0 0 * * 0'
  when '@daily', '@midnight'
    '0 0 * * *'
  when '@hourly'
    '0 * * * *'
  else
    spec
  end
end

#last(now = @time_source.now) ⇒ Object

returns the last occurence before the given date



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# File 'lib/cron_parser.rb', line 105

def last(now = @time_source.now)
  t = InternalTime.new(now,@time_source)

  unless time_specs[:month][0].include?(t.month)
    nudge_month(t, :last)
    t.day = 32
  end

  if t.day == 32 || !interpolate_weekdays(t.year, t.month)[0].include?(t.day)
    nudge_date(t, :last)
    t.hour = 24
  end

  unless time_specs[:hour][0].include?(t.hour)
    nudge_hour(t, :last)
    t.min = 60
  end

  # always nudge the minute
  nudge_minute(t, :last)
  t.to_time
end

#next(now = @time_source.now) ⇒ Object

returns the next occurence after the given date



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# File 'lib/cron_parser.rb', line 81

def next(now = @time_source.now)
  t = InternalTime.new(now, @time_source)

  unless time_specs[:month][0].include?(t.month)
    nudge_month(t)
    t.day = 0
  end

  unless interpolate_weekdays(t.year, t.month)[0].include?(t.day)
    nudge_date(t)
    t.hour = -1
  end

  unless time_specs[:hour][0].include?(t.hour)
    nudge_hour(t)
    t.min = -1
  end

  # always nudge the minute
  nudge_minute(t)
  t.to_time
end

#parse_element(elem, allowed_range) ⇒ Object 



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# File 'lib/cron_parser.rb', line 130

def parse_element(elem, allowed_range)
  values = elem.split(',').map do |subel|
    if subel =~ /^\*/
      step = subel.length > 1 ? subel[2..-1].to_i : 1
      stepped_range(allowed_range, step)
    else
      if SUBELEMENT_REGEX === subel
        if $5 # with range
          stepped_range($1.to_i..$3.to_i, $5.to_i)
        elsif $3 # range without step
          stepped_range($1.to_i..$3.to_i, 1)
        else # just a numeric
          [$1.to_i]
        end
      else
        raise ArgumentError, "Bad Vixie-style specification #{subel}"
      end
    end
  end.flatten.sort

  [Set.new(values), values, elem]
end