class Utils::LinesFile

def self.for_file(file, line_number)
  obj = new(file.readlines, line_number)
  obj.filename = filename
  obj
end

def self.for_filename(filename, line_number = nil)
  obj = new(File.readlines(filename), line_number)
  obj.filename = filename
  obj
end

def self.for_lines(lines, line_number = nil)
  new(lines, line_number)
end

def each(&block)
  @lines.empty? and return
  old_line_number = line_number
  1.upto(last_line_number) do |number|
    self.line_number = number
    block.call(line)
  end
  self
ensure
  self.line_number = old_line_number
end

def empty?
  @lines.empty?
end

def file_linenumber
  "#{filename}:#{line_number}"
end

def initialize(lines, line_number = nil)
  @lines = lines
  @lines.each_with_index do |line, i|
    line.extend LineExtension
    line.instance_variable_set :@line_number, i + 1
    line.instance_variable_set :@lines_file, self
  end
  self.line_number = line_number || (@lines.empty? ? 0 : 1)
end

def inspect
  "#<#{self.class}: #{to_s.inspect}>"
end

def last_line_number
  @lines.size
end

def line
  index = line_number - 1
  @lines[index] if index >= 0
end

def line_number=(number)
  number = number.to_i
  if number > 0 && number <= last_line_number
    @line_number = number
  end
end

def match_backward(regexp, previous_after_match = false)
  empty? and return
  while line_number >= 1
    if line =~ regexp
      previous_after_match and previous!
      return $~.captures
    end
    previous!
  end
end

def match_forward(regexp, next_after_match = false)
  empty? and return
  begin
    if line =~ regexp
      next_after_match and next!
      return $~.captures
    end
    next!
  end while line_number < last_line_number
end

def next!
  self.line_number += 1
  self
end

def previous!
  self.line_number -= 1
  self
end

def rewind
  self.line_number = 1
  self
end

def to_s
  "#{line_number} #{line.chomp}"
end