Module: DiffFromDelta

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

Constant Summary collapse

VERSION = 
"0.0.2"

Class Method Summary collapse

Class Method Details

.compile_diff_from_delta(text1, delta) ⇒ Object 



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# File 'lib/diff_from_delta.rb', line 3

def self.compile_diff_from_delta(text1, delta)
  diff_from_delta(text1, delta).delete_if{|d| d[0]==-1 }.map{|d| d[1] }.join("")
end

.diff_from_delta(text1, delta) ⇒ Object 



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# File 'lib/diff_from_delta.rb', line 7

def self.diff_from_delta(text1, delta)
  diff_delete = -1
  diff_insert = 1
  diff_equal = 0
  diffs = []
  pointer = 0  # Cursor in text1
  tokens = delta.split("\t")
  for token in tokens
    if token == ""
      # Blank tokens are ok (from a trailing \t).
      next
    end
    # Each token begins with a one character parameter which specifies the
    # operation of this token (delete, insert, equality).
    param = token[1..-1]
    if token[0..0] == "+"
      param = URI.unescape(param)
      diffs << [diff_insert, param]
    elsif token[0..0] == "-" || token[0..0] == "="
      begin
        n = param.to_i
      rescue
        raise("Invalid number in diff_fromDelta: " + param)
      end
      if n < 0
        raise("Negative number in diff_fromDelta: " + param)
      end
      #text = text1[pointer : pointer + n]
      text = text1[pointer..pointer+(n-1)]
      pointer += n
      if token[0..0] == "="
        diffs << [diff_equal, text]
      else
        diffs << [diff_delete, text]
      end
    else
      # Anything else is an error.
      raise("Invalid diff operation in diff_fromDelta: #{token[0..0]}")
    end
  end # end for token in tokens
  if pointer != text1.length
    raise("Delta length (#{pointer}) does not equal source text length (#{text1.length}).")
  end
  return diffs

end