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_by_name "xxx.#{old_ext}"
  return false unless parser
  RDoc::Parser.parsers.unshift [/\.#{new_ext}$/, parser]
  true
end

def self.binary?(file)
  return false if file =~ /\.(rdoc|txt)$/
  s = File.read(file, 1024) or return false
  have_encoding = s.respond_to? :encoding
  return true if s[0, 2] == Marshal.dump('')[0, 2] or s.index("\x00")
  if have_encoding then
    mode = "r"
    s.sub!(/\A#!.*\n/, '')     # assume shebang line isn't longer than 1024.
    encoding = s[/^\s*\#\s*(?:-\*-\s*)?(?:en)?coding:\s*([^\s;]+?)(?:-\*-|[\s;])/, 1]
    mode = "rb:#{encoding}" if encoding
    s = File.open(file, mode) {|f| f.gets(nil, 1024)}
    not s.valid_encoding?
  else
    if 0.respond_to? :fdiv then
      s.count("\x00-\x7F", "^ -~\t\r\n").fdiv(s.size) > 0.3
    else # HACK 1.8.6
      (s.count("\x00-\x7F", "^ -~\t\r\n").to_f / s.size) > 0.3
    end
  end
end

def self.can_parse file_name
  parser = can_parse_by_name file_name
  # HACK Selenium hides a jar file using a .txt extension
  return if parser == RDoc::Parser::Simple and zip? file_name
  parser
end

def self.can_parse_by_name file_name
  _, parser = RDoc::Parser.parsers.find { |regexp,| regexp =~ file_name }
  # The default parser must not parse binary files
  ext_name = File.extname file_name
  return parser if ext_name.empty?
  if parser == RDoc::Parser::Simple and ext_name !~ /txt|rdoc/ then
    case check_modeline file_name
    when nil, 'rdoc' then # continue
    else return nil
    end
  end
  parser
rescue Errno::EACCES
end

def self.check_modeline file_name
  line = open file_name do |io|
    io.gets
  end
  /-\*-\s*(.*?\S)\s*-\*-/ =~ line
  return nil unless type = $1
  if /;/ =~ type then
    return nil unless /(?:\s|\A)mode:\s*([^\s;]+)/i =~ type
    type = $1
  end
  return nil if /coding:/i =~ type
  type.downcase
rescue ArgumentError # invalid byte sequence, etc.
end

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

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

def self.process_directive code_object, directive, value
  warn "RDoc::Parser::process_directive is deprecated and wil be removed in RDoc 4.  Use RDoc::Markup::PreProcess#handle_directive instead" if $-w
  case directive
  when 'nodoc' then
    code_object.document_self = nil # notify nodoc
    code_object.document_children = value.downcase != 'all'
  when 'doc' then
    code_object.document_self = true
    code_object.force_documentation = true
  when 'yield', 'yields' then
    # remove parameter &block
    code_object.params.sub!(/,?\s*&\w+/, '') if code_object.params
    code_object.block_params = value
  when 'arg', 'args' then
    code_object.params = value
  end
end

def self.remove_modeline content
  content.sub(/\A.*-\*-\s*(.*?\S)\s*-\*-.*\r?\n/, '')
end

def self.use_markup content
  markup = content.lines.first(3).grep(/markup:\s+(\w+)/) { $1 }.first
  return unless markup
  # TODO Ruby should be returned only when the filename is correct
  return RDoc::Parser::Ruby if %w[tomdoc markdown].include? markup
  markup = Regexp.escape markup
  _, selected = RDoc::Parser.parsers.find do |_, parser|
    /^#{markup}$/i =~ parser.name.sub(/.*:/, '')
  end
  selected
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"
rescue
  false
end

def initialize top_level, file_name, content, options, stats
  @top_level = top_level
  @top_level.parser = self.class
  @store = @top_level.store
  @file_name = file_name
  @content = content
  @options = options
  @stats = stats
  @preprocess = RDoc::Markup::PreProcess.new @file_name, @options.rdoc_include
  @preprocess.options = @options
end