Class: Cheat::Diffr

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

Class Method Summary collapse

Class Method Details

.diff(sheet_old, sheet_new) ⇒ Object 



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# File 'lib/cheat/diffr.rb', line 6

def self.diff(sheet_old, sheet_new)
  format, lines, output = :unified, 10000, ''
  file_length_difference = 0

  data_old = sheet_old.body.wrap.split(/\n/).map! { |e| e.chomp }
  data_new = sheet_new.body.wrap.split(/\n/).map! { |e| e.chomp }

  diffs = Diff::LCS.diff(data_old, data_new)
  return if diffs.empty?

  header = ''
  ft = sheet_old.updated_at
  header << "#{'-' * 3} #{sheet_new.title} version #{sheet_old.version}\t#{ft}\n"
  ft = sheet_new.updated_at
  header <<  "#{'+' * 3} #{sheet_new.title} version #{sheet_new.version}\t#{ft}\n"

  oldhunk = hunk = nil

  diffs.each do |piece|
    begin
      hunk = Diff::LCS::Hunk.new(data_old, data_new, piece, lines, file_length_difference)
      file_length_difference = hunk.file_length_difference

      next unless oldhunk

      if lines > 0 && hunk.overlaps?(oldhunk)
        hunk.unshift(oldhunk)
      else
        output << oldhunk.diff(format)
      end
    ensure
      oldhunk = hunk
      output << "\n"
    end
  end

  output << oldhunk.diff(format)
  output << "\n"

  return header + output.lstrip
end