class RDoc::Parser

A parser is simple a class that subclasses RDoc::Parser and implements scan to fill in an RDoc::TopLevel with parsed data.

The initialize method takes an RDoc::TopLevel to fill with parsed content, the name of the file to be parsed, the content of the file, an RDoc::Options object and an RDoc::Stats object to inform the user of parsed items. The scan method is then called to parse the file and must return the RDoc::TopLevel object. By calling super these items will be set for you.

In order to be used by RDoc the parser needs to register the file extensions it can parse. Use ::parse_files_matching to register extensions.

require 'rdoc'

class RDoc::Parser::Xyz < RDoc::Parser
  parse_files_matching /\.xyz$/

  def initialize top_level, file_name, content, options, stats

    # extra initialization if needed

  def scan
    # parse file and fill in @top_level



An Array of arrays that maps file extension (or name) regular expressions to parser classes that will parse matching filenames.

Use parse_files_matching to register a parser’s file extensions.


The name of the file being parsed

Public Class Methods

alias_extension(old_ext, new_ext) click to toggle source

Alias an extension to another extension. After this call, files ending “new_ext” will be parsed using the same parser as “old_ext”

# File rdoc/parser.rb, line 57
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]

binary?(file) click to toggle source

Determines if the file is a “binary” file which basically means it has content that an RDoc parser shouldn’t try to consume.

# File rdoc/parser.rb, line 73
def self.binary?(file)
  return false if file =~ /\.(rdoc|txt)$/

  s =, 1024) or return false

  return true if s[0, 2] == Marshal.dump('')[0, 2] or s.index("\x00")

  mode = 'r:utf-8' # default source encoding has been changed to utf-8
  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 =, mode) {|f| f.gets(nil, 1024)}

  not s.valid_encoding?
can_parse(file_name) click to toggle source

Return a parser that can handle a particular extension

# File rdoc/parser.rb, line 106
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

can_parse_by_name(file_name) click to toggle source

Returns a parser that can handle the extension for file_name. This does not depend upon the file being readable.

# File rdoc/parser.rb, line 119
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

rescue Errno::EACCES
check_modeline(file_name) click to toggle source

Returns the file type from the modeline in file_name

# File rdoc/parser.rb, line 140
def self.check_modeline file_name
  line = file_name do |io|

  /-\*-\s*(.*?\S)\s*-\*-/ =~ line

  return nil unless type = $1

  if /;/ =~ type then
    return nil unless /(?:\s|\A)mode:\s*([^\s;]+)/i =~ type
    type = $1

  return nil if /coding:/i =~ type

rescue ArgumentError
rescue Encoding::InvalidByteSequenceError # invalid byte sequence

for(top_level, file_name, content, options, stats) click to toggle source

Finds and instantiates the correct parser for the given file_name and content.

# File rdoc/parser.rb, line 166
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'

    parser = can_parse parse_name

  return unless parser

  content = remove_modeline content top_level, file_name, content, options, stats
rescue SystemCallError
new(top_level, file_name, content, options, stats) click to toggle source

Creates a new Parser storing top_level, file_name, content, options and stats in instance variables. In +@preprocess+ an RDoc::Markup::PreProcess object is created which allows processing of directives.

# File rdoc/parser.rb, line 251
def initialize top_level, file_name, content, options, stats
  @top_level = top_level
  @top_level.parser = self.class
  @store =

  @file_name = file_name
  @content = content
  @options = options
  @stats = stats

  @preprocess = @file_name, @options.rdoc_include
  @preprocess.options = @options
parse_files_matching(regexp) click to toggle source

Record which file types this parser can understand.

It is ok to call this multiple times.

# File rdoc/parser.rb, line 200
def self.parse_files_matching(regexp)
  RDoc::Parser.parsers.unshift [regexp, self]
remove_modeline(content) click to toggle source

Removes an emacs-style modeline from the first line of the document

# File rdoc/parser.rb, line 207
def self.remove_modeline content
  content.sub(/\A.*-\*-\s*(.*?\S)\s*-\*-.*\r?\n/, '')
use_markup(content) click to toggle source

If there is a markup: parser_name comment at the front of the file, use it to determine the parser. For example:

# markup: rdoc
# Class comment can go here

class C

The comment should appear as the first line of the content.

If the content contains a shebang or editor modeline the comment may appear on the second or third line.

Any comment style may be used to hide the markup comment.

# File rdoc/parser.rb, line 228
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 =~*:/, '')

zip?(file) click to toggle source

Checks if file is a zip file in disguise. Signatures from

# File rdoc/parser.rb, line 93
def file
  zip_signature = file, 4

  zip_signature == "PK\x03\x04" or
    zip_signature == "PK\x05\x06" or
    zip_signature == "PK\x07\x08"

Public Instance Methods

handle_tab_width(body) click to toggle source

Normalizes tabs in body

# File rdoc/parser.rb, line 271
def handle_tab_width(body)
  if /\t/ =~ body
    tab_width = @options.tab_width
    body.split(/\n/).map do |line|
      1 while line.gsub!(/\t+/) do
        b, e = $~.offset(0)
        ' ' * (tab_width * (e-b) - b % tab_width)
    end.join "\n"