class LCS::Hunk

# File lib/diff/lcs/hunk.rb, line 16
def initialize(data_old, data_new, piece, flag_context, file_length_difference)
  # At first, a hunk will have just one Block in it
  @blocks = [Diff::LCS::Block.new(piece)]

  if @blocks[0].remove.empty? && @blocks[0].insert.empty?
    fail "Cannot build a hunk from #{piece.inspect}; has no add or remove actions"
  end

  if String.method_defined?(:encoding)
    @preferred_data_encoding = data_old.fetch(0) { data_new.fetch(0) { "" } }.encoding
  end

  @data_old = data_old
  @data_new = data_new
  @old_empty = data_old.empty? || (data_old.size == 1 && data_old[0].empty?)
  @new_empty = data_new.empty? || (data_new.size == 1 && data_new[0].empty?)

  before = after = file_length_difference
  after += @blocks[0].diff_size
  @file_length_difference = after # The caller must get this manually
  @max_diff_size = @blocks.map { |e| e.diff_size.abs }.max

  # Save the start & end of each array. If the array doesn't exist (e.g.,
  # we're only adding items in this block), then figure out the line number
  # based on the line number of the other file and the current difference in
  # file lengths.
  if @blocks[0].remove.empty?
    a1 = a2 = nil
  else
    a1 = @blocks[0].remove[0].position
    a2 = @blocks[0].remove[-1].position
  end

  if @blocks[0].insert.empty?
    b1 = b2 = nil
  else
    b1 = @blocks[0].insert[0].position
    b2 = @blocks[0].insert[-1].position
  end

  @start_old = a1 || (b1 - before)
  @start_new = b1 || (a1 + before)
  @end_old = a2 || (b2 - after)
  @end_new = b2 || (a2 + after)

  self.flag_context = flag_context
end

# File lib/diff/lcs/hunk.rb, line 115
def diff(format, last = false)
  case format
  when :old
    old_diff(last)
  when :unified
    unified_diff(last)
  when :context
    context_diff(last)
  when :ed
    self
  when :reverse_ed, :ed_finish
    ed_diff(format, last)
  else
    fail "Unknown diff format #{format}."
  end
end

# File lib/diff/lcs/hunk.rb, line 97
def merge(hunk)
  return unless overlaps?(hunk)

  @start_old = hunk.start_old
  @start_new = hunk.start_new
  blocks.unshift(*hunk.blocks)
end

# File lib/diff/lcs/hunk.rb, line 347
def missing_last_newline?(data)
  newline = encode("\n")

  if data[-2]
    data[-2].end_with?(newline) && !data[-1].end_with?(newline)
  elsif data[-1]
    !data[-1].end_with?(newline)
  else
    true
  end
end

# File lib/diff/lcs/hunk.rb, line 109
def overlaps?(hunk)
  hunk and (((@start_old - hunk.end_old) <= 1) or
            ((@start_new - hunk.end_new) <= 1))
end