Module: DiffCalc

Included in:
Actions
Defined in:
lib/differencing.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#cnt ⇒ Object (readonly)

Returns the value of attribute cnt.



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

def cnt
  @cnt
end

#mem ⇒ Object (readonly)

Returns the value of attribute mem.



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

def mem
  @mem
end

#new_s ⇒ Object (readonly)

Returns the value of attribute new_s.



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

def new_s
  @new_s
end

#old_s ⇒ Object (readonly)

Returns the value of attribute old_s.



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

def old_s
  @old_s
end

Instance Method Details

#build_sequences ⇒ Object 



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# File 'lib/differencing.rb', line 65

def build_sequences
  i1 = 0
  i2 = 0
  insertion_seq = {}
  deletion_seq = {}

  while i1 < @old_s.length || i2 < @new_s.length
    action = @mem[[i1, i2]][:action]

    case action
    when :done
      break
    when :keep
      i1 += 1
      i2 += 1
    when :delete
      deletion_seq[i2] ||= []
      deletion_seq[i2].push({ old_index: i1, ma_type: 'bs' })
      i1 += 1
    when :insert
      insertion_seq[i2] = { value: @new_s[i2], old_index: i1 }
      i2 += 1
    end
  end

  result = @mem[[0, 0]]
  {
    insertion_seq: insertion_seq,
    deletion_seq: deletion_seq,
    insertions: result[:insertions],
    deletions: result[:deletions],
    diff_cnt: result[:diff_cnt]
  }
end

#compute_diff(old_arr, new_arr) ⇒ Object 



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# File 'lib/differencing.rb', line 10

def compute_diff(old_arr, new_arr)
  @mem = {}
  @old_s = old_arr.is_a?(String) ? old_arr.split("\n").to_a : old_arr
  @new_s = new_arr.is_a?(String) ? new_arr.split("\n").to_a : new_arr
  differencing(0, 0)
end

#differencing(i1 = 0, i2 = 0) ⇒ Object 



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# File 'lib/differencing.rb', line 17

def differencing(i1 = 0, i2 = 0)
  cached = @mem[[i1, i2]]
  return cached if cached

  if i1 >= @old_s.length && i2 >= @new_s.length
    result = { diff_cnt: 0, insertions: 0, deletions: 0, action: :done }
    @mem[[i1, i2]] = result
    return result
  end

  if i1 >= @old_s.length
    result = { diff_cnt: @new_s.length - i2, insertions: @new_s.length - i2, deletions: 0, action: :insert }
    @mem[[i1, i2]] = result
    differencing(i1, i2 + 1) if i2 < @new_s.length
    return result
  end

  if i2 >= @new_s.length
    result = { diff_cnt: @old_s.length - i1, insertions: 0, deletions: @old_s.length - i1, action: :delete }
    @mem[[i1, i2]] = result
    differencing(i1 + 1, i2) if i1 < @old_s.length
    return result
  end

  if @old_s[i1] == @new_s[i2]
    result = differencing(i1 + 1, i2 + 1)
    result = { diff_cnt: result[:diff_cnt], insertions: result[:insertions], deletions: result[:deletions],
               action: :keep }
    @mem[[i1, i2]] = result
    return result
  end

  del = differencing(i1 + 1, i2)
  add = differencing(i1, i2 + 1)

  del_cost = del[:diff_cnt] + 1
  add_cost = add[:diff_cnt] + 1

  result = if del_cost <= add_cost
             { diff_cnt: del_cost, insertions: del[:insertions], deletions: del[:deletions] + 1, action: :delete }
           else
             { diff_cnt: add_cost, insertions: add[:insertions] + 1, deletions: add[:deletions], action: :insert }
           end

  @mem[[i1, i2]] = result
  result
end

#initialize ⇒ Object 



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# File 'lib/differencing.rb', line 5

def initialize
  @mem = {}
  @cnt = 0
end

#print_diff(file_a, file_b) ⇒ Object 



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# File 'lib/differencing.rb', line 100

def print_diff(file_a, file_b)
  compute_diff(file_a, file_b)
  diff = build_sequences
  insertions, deletions, insertion_seq, deletion_seq = diff.values_at(:insertions, :deletions, :insertion_seq,
                                                                      :deletion_seq)
  # printing diff
  print "   (+): #{insertions}".green
  print "   (-): #{deletions}\n".red

  # sorting by keys
  insertion_seq = insertion_seq.sort.to_h
  insertion_seq_keys = insertion_seq.keys

  deletion_seq = deletion_seq.sort.to_h
  deletion_seq_keys = deletion_seq.keys

  # index (old or new)
  # value (styled text to be printed)
  # type (-1 => deletion, 0 => insertion, 1 => not changed)
  edit_list = []

  # Getting a list of all the changes
  insertion_poniter = 0
  deletion_pointer = 0
  while insertion_poniter < insertions || deletion_pointer < deletion_seq_keys.length
    is_insertion = if insertion_poniter >= insertions
                     false
                   elsif deletion_pointer >= deletion_seq_keys.length
                     true
                   else
                     insertion_seq_keys[insertion_poniter] < deletion_seq_keys[deletion_pointer]
                   end
    index = is_insertion ? insertion_seq_keys[insertion_poniter] : deletion_seq_keys[deletion_pointer]
    if is_insertion
      edit_list.push({ index: index, value: "#{insertion_seq[index][:value]}", type: 0,
                       old_index: insertion_seq[index][:old_index] })
      insertion_poniter += 1
    else
      deletion_seq[index] = deletion_seq[index].sort_by { |del| del[:old_index] }
      deletion_seq[index].each do |del|
        old_index = del[:old_index]
        edit_list.push({ index: index, value: "#{@old_s[old_index]}", type: -1,
                         old_index: old_index })
      end
      deletion_pointer += 1
    end

  end

  max_space_diff = 3
  print_queue = {}
  # Getting all the lines to print (including context ones)
  edit_list.each_with_index do |order, _i|
    (order[:index] - max_space_diff..order[:index] + max_space_diff).each do |j|
      next unless j >= 0 && j < @new_s.length

      line = order[:index] == j ? order : { index: j, value: @new_s[j], type: 1, old_index: j }
      print_queue[j] ||= []
      print_queue[j].push(line) unless line[:type] == 1 && print_queue[j].length.positive?
    end
  end

  print_queue = print_queue.sort.to_h
  print_queue_keys = print_queue.keys
  printed = {}

  # Stylizing & printing lines
  def print_line(line)
    sign = if line[:type] == -1
             '-'
           else
             line[:type] == 0 ? '+' : ''
           end

    index = if line[:type] == -1
              line[:old_index]
            else
              line[:index]
            end
    print_text = "(#{index}) #{sign}#{line[:value]}"
    if line[:type] == -1
      print_text = print_text.red
    elsif line[:type] == 0
      print_text = print_text.green
    end
    puts print_text
  end

  # Printing all the lines
  print_queue.each_with_index do |(index, lines), queue_i|
    lines = lines.sort_by { |line| line[:type] }
    is_changed = false
    lines.each do |line, _i|
      next if printed[[index, line[:type]]] == 1

      print_line(line) unless is_changed == true && line[:type] == 1
      is_changed = true

      next unless line[:type] == -1

      j = queue_i + 1

      define_singleton_method :is_deletion? do
        return false if j >= print_queue_keys.length

        print_queue[print_queue_keys[j]]&.any? { |x| x[:type] == -1 }
      end

      while is_deletion?
        q_i = print_queue_keys[j]
        cur_line = print_queue[q_i].find { |x| x[:type] == -1 }
        cur_line ||= print_queue[q_i].find { |x| x[:type] == 1 }
        print_line(cur_line)
        printed[[q_i, cur_line[:type]]] = 1
        j += 1
      end
    end
  end
end

#print_line(line) ⇒ Object

Stylizing & printing lines



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# File 'lib/differencing.rb', line 167

def print_line(line)
  sign = if line[:type] == -1
           '-'
         else
           line[:type] == 0 ? '+' : ''
         end

  index = if line[:type] == -1
            line[:old_index]
          else
            line[:index]
          end
  print_text = "(#{index}) #{sign}#{line[:value]}"
  if line[:type] == -1
    print_text = print_text.red
  elsif line[:type] == 0
    print_text = print_text.green
  end
  puts print_text
end