Module: RangeCompressor

Defined in:
lib/range_compressor.rb,
lib/range_compressor/version.rb

Constant Summary collapse

SORTED_SET_CLASSES = 
%w[
  CharacterSet
  CharacterSet::Pure
  ImmutableSet
  SortedSet
].freeze
VERSION = 
'1.0.0'

Class Method Summary collapse

Class Method Details

.compress(enum) ⇒ Object

Set#divide is very slow unfortunately, else it would be nice for this: divide { |i, j| (i - j).abs == 1 }



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# File 'lib/range_compressor.rb', line 15

def compress(enum)
  if enum.class.ancestors.none? { |anc| SORTED_SET_CLASSES.include? anc.to_s }
    require 'set'
    enum = SortedSet.new(enum)
  end

  ranges = []
  previous = nil
  current_start = nil
  current_end = nil

  enum.each do |object|
    if previous.nil?
      current_start = object
    elsif previous.next != object
      # gap found, finalize previous range
      ranges << (current_start..current_end)
      current_start = object
    end
    current_end = object
    previous = object
  end

  # add final range
  ranges << (current_start..current_end) if current_start

  ranges
end