class RDoc::Parser

def self.alias_extension(old_ext, new_ext)
  old_ext = old_ext.sub(/^\.(.*)/, '\1')
  new_ext = new_ext.sub(/^\.(.*)/, '\1')
  parser = can_parse "xxx.#{old_ext}"
  return false unless parser
  RDoc::Parser.parsers.unshift [/\.#{new_ext}$/, parser]
  true
end

def self.binary?(file)
  s = File.read(file, 1024) or return false
  if s[0, 2] == Marshal.dump('')[0, 2] then
    true
  elsif file =~ /erb\.rb$/ then
    false
  elsif s.scan(/<%|%>/).length >= 4 || s.index("\x00") then
    true
  elsif 0.respond_to? :fdiv then
    s.count("^ -~\t\r\n").fdiv(s.size) > 0.3
  else # HACK 1.8.6
    (s.count("^ -~\t\r\n").to_f / s.size) > 0.3
  end
end

def self.can_parse(file_name)
  parser = RDoc::Parser.parsers.find { |regexp,| regexp =~ file_name }.last
  # HACK Selenium hides a jar file using a .txt extension
  return if parser == RDoc::Parser::Simple and zip? file_name
  # The default parser must not parse binary files
  ext_name = File.extname file_name
  return parser if ext_name.empty?
  return if parser == RDoc::Parser::Simple and ext_name !~ /txt|rdoc/
  parser
end

def self.for(top_level, file_name, body, options, stats)
  return if binary? file_name
  # If no extension, look for shebang
  if file_name !~ /\.\w+$/ && body =~ %r{\A#!(.+)} then
    shebang = $1
    case shebang
    when %r{env\s+ruby}, %r{/ruby}
      file_name = "dummy.rb"
    end
  end
  parser = can_parse file_name
  return unless parser
  parser.new top_level, file_name, body, options, stats
end

def self.parse_files_matching(regexp)
  RDoc::Parser.parsers.unshift [regexp, self]
end

def self.zip? file
  zip_signature = File.read file, 4
  zip_signature == "PK\x03\x04" or
    zip_signature == "PK\x05\x06" or
    zip_signature == "PK\x07\x08"
end

def initialize(top_level, file_name, content, options, stats)
  @top_level = top_level
  @file_name = file_name
  @content = content
  @options = options
  @stats = stats
end