From: Bryan Donovan <bdondo@...>
Date: 2006-08-30T00:17:51+09:00
Subject: Fwd: [SOLUTION] [QUIZ] DayRange (#92)

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I thought I should post my original solution that got
me wondering about better solutions and eventually got
me to submit a quiz.

Someone named their class DaySet, and I agree that's a
better name.  I'll probably change mine to match.

My solution isn't complete.. some additional input
formats requirements were added to make it a more
interesting quiz.  Mine only accepts an array of
integers (since that's what I will be using in my
Rails app anyway).  I also changed my argument check
to be similar to James Edward Gray II's.

Also, if anyone is curious about the real-world
application I'm using this for, just send me an email
and I'll send you the url.

Anyway, here's my solution:

#DayRange
#
#DayRange accepts an array of day IDs (Mon = 1, Tue =
2, etc.)
#and returns a formatted string of the days, using day
ranges
#where appropriate, e.g, "Mon-Wed, Fri"
#
#author: Bryan Donovan

class DayRange

  def day_hash
    { '1'=>'Mon',
      '2'=>'Tue',
      '3'=>'Wed',
      '4'=>'Thu',
      '5'=>'Fri',
      '6'=>'Sat',
      '7'=>'Sun' }
  end

  def initialize(day_ids)
    @day_ids = day_ids.uniq.sort
    unless @day_ids.all? { |d| d.between?(1,7) }
      raise ArgumentError "Days must be between 1 and 7"
    end

  end

  #Returns formatted string representing the day array
  def to_s
    day_abbrs = day_hash
    i = 0
    #Array of consec_days arrays
    consec_day_groups = []
    #Array of consecutive days.  This gets
    #reset when we find a day that is not
    #part of a consecutive set of days.
    consec_days = []

    @day_ids.each do |day_id|
      if i == 0
        #add the day abbr for this day if this is the first
        #element of @day_ids.
        consec_days << day_abbrs[day_id.to_s]

      elsif @day_ids[i-1] == (day_id - 1)
        #if this is not the first day in @day_ids, check
        #if the previous day in the array is the real life
        #previous day of the week.  If so, add it to the
        #consec_days array
        consec_days << day_abbrs[day_id.to_s]
      else
        #otherwise start a new consec_days array and
        #add the current consec_days array to the
        #consec_day_groups array.
        consec_day_groups << consec_days

        consec_days = []
        consec_days << day_abbrs[day_id.to_s]
      end
      #Always add the consec_days array when this is the
      #last day of the @day_ids array
      if day_id == @day_ids.last
        consec_day_groups << consec_days
      end
      i += 1
    end

    day_strings = []
    consec_day_groups.each do |c|
      if c.length > 2
        day_strings <<  c.first.to_s + "-" + c.last.to_s
      else
        day_strings << c.join(", ")
      end
    end
    return day_strings.join(", ")
  end

end

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