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RDoc::Markup parses plain text documents and attempts to decompose them into their constituent parts. Some of these parts are high-level: paragraphs, chunks of verbatim text, list entries and the like. Other parts happen at the character level: a piece of bold text, a word in code font. This markup is similar in spirit to that used on WikiWiki webs, where folks create web pages using a simple set of formatting rules.

RDoc::Markup itself does no output formatting: this is left to a different set of classes.

RDoc::Markup is extendable at runtime: you can add new markup elements to be recognised in the documents that RDoc::Markup parses.

RDoc::Markup is intended to be the basis for a family of tools which share the common requirement that simple, plain-text should be rendered in a variety of different output formats and media. It is envisaged that RDoc::Markup could be the basis for formatting RDoc style comment blocks, Wiki entries, and online FAQs.

Synopsis

This code converts input_string to HTML. The conversion takes place in the convert method, so you can use the same RDoc::Markup converter to convert multiple input strings.

require 'rdoc/markup/to_html'

h = RDoc::Markup::ToHtml.new

puts h.convert(input_string)

You can extend the RDoc::Markup parser to recognise new markup sequences, and to add special processing for text that matches a regular expression. Here we make WikiWords significant to the parser, and also make the sequences {word} and <no>text…</no> signify strike-through text. We then subclass the HTML output class to deal with these:

require 'rdoc/markup'
require 'rdoc/markup/to_html'

class WikiHtml < RDoc::Markup::ToHtml
  def handle_special_WIKIWORD(special)
    "<font color=red>" + special.text + "</font>"
  end
end

markup = RDoc::Markup.new
markup.add_word_pair("{", "}", :STRIKE)
markup.add_html("no", :STRIKE)

markup.add_special(/\b([A-Z][a-z]+[A-Z]\w+)/, :WIKIWORD)

wh = WikiHtml.new markup
wh.add_tag(:STRIKE, "<strike>", "</strike>")

puts "<body>#{wh.convert ARGF.read}</body>"

Encoding

Where Encoding support is available, RDoc will automatically convert all documents to the same output encoding. The output encoding can be set via RDoc::Options#encoding and defaults to Encoding.default_external.

RDoc Markup Reference

Block Markup

Paragraphs and Verbatim

The markup engine looks for a document’s natural left margin. This is used as the initial margin for the document.

Consecutive lines starting at this margin are considered to be a paragraph. Empty lines separate paragraphs.

Any line that starts to the right of the current margin is treated as verbatim text. This is useful for code listings:

3.times { puts "Ruby" }

In verbatim text, two or more blank lines are collapsed into one, and trailing blank lines are removed:

This is the first line

This is the second non-blank line,
after 2 blank lines in the source markup.

There were two trailing blank lines right above this paragraph, that have been removed. In addition, the verbatim text has been shifted left, so the amount of indentation of verbatim text is unimportant.

Headers and Rules

A line starting with an equal sign (=) is treated as a heading. Level one headings have one equals sign, level two headings have two, and so on until level six, which is the maximum (seven hyphens or more result in a level six heading).

For example, the above header was obtained with:

== Headers and Rules

A line starting with three or more hyphens (at the current indent) generates a horizontal rule. The more hyphens, the thicker the rule (within reason, and if supported by the output device).

In the case of HTML output, three dashes generate a 1-pixel high rule, four dashes result in 2 pixels, and so on. The actual height is limited to 10 pixels:

---
-----
-----------------------------------------------------

produces:




Simple Lists

If a paragraph starts with a “*”, “-”, “<digit>.” or “<letter>.”, then it is taken to be the start of a list. The margin is increased to be the first non-space following the list start flag. Subsequent lines should be indented to this new margin until the list ends. For example:

* this is a list with three paragraphs in
  the first item.  This is the first paragraph.

  And this is the second paragraph.

  1. This is an indented, numbered list.
  2. This is the second item in that list

  This is the third conventional paragraph in the
  first list item.

* This is the second item in the original list

produces:

  • this is a list with three paragraphs in the first item. This is the first paragraph.

    And this is the second paragraph.

    1. This is an indented, numbered list.

    2. This is the second item in that list

    This is the third conventional paragraph in the first list item.

  • This is the second item in the original list

Labeled Lists

You can also construct labeled lists, sometimes called description or definition lists. Do this by putting the label in square brackets and indenting the list body:

[cat]  a small furry mammal
       that seems to sleep a lot

[ant]  a little insect that is known
       to enjoy picnics

produces:

cat

a small furry mammal that seems to sleep a lot

ant

a little insect that is known to enjoy picnics

If you want the list bodies to line up to the left of the labels, use two colons:

cat::  a small furry mammal
       that seems to sleep a lot

ant::  a little insect that is known
       to enjoy picnics

produces:

cat

a small furry mammal that seems to sleep a lot

ant

a little insect that is known to enjoy picnics

Notice that blank lines right after the label are ignored in labeled lists:

[one]

    definition 1

[two]

    definition 2

produces the same output as

[one]  definition 1
[two]  definition 2

Lists and Verbatim

If you want to introduce a verbatim section right after a list, it has to be less indented than the list item bodies, but more indented than the list label, letter, digit or bullet. For instance:

*   point 1

*   point 2, first paragraph

    point 2, second paragraph
      verbatim text inside point 2
    point 2, third paragraph
  verbatim text outside of the list (the list is therefore closed)
regular paragraph after the list

produces:

  • point 1

  • point 2, first paragraph

    point 2, second paragraph

    verbatim text inside point 2
    

    point 2, third paragraph

verbatim text outside of the list (the list is therefore closed)

regular paragraph after the list

Text Markup

Bold, Italic, Typewriter Text

You can use markup within text (except verbatim) to change the appearance of parts of that text. Out of the box, RDoc::Markup supports word-based and general markup.

Word-based markup uses flag characters around individual words:

*word*

displays word in a bold font

_word_

displays word in an emphasized font

+word+

displays word in a code font

General markup affects text between a start delimiter and an end delimiter. Not surprisingly, these delimiters look like HTML markup.

<b>text

displays text in a bold font

<em>text

displays text in an emphasized font (alternate tag: <i>)

<tt>text

displays text in a code font (alternate tag: <tt>)

Unlike conventional Wiki markup, general markup can cross line boundaries. You can turn off the interpretation of markup by preceding the first character with a backslash (see Escaping Text Markup, below).

Links

Links to starting with http:, https:, mailto:, ftp: or www. are recognized. An HTTP url that references an external image file is converted into an inline image element.

Links starting with rdoc-ref: will link to the referenced class, module, method, file, etc. If the referenced item is not documented the text will be and no link will be generated.

Links starting with link: refer to local files whose path is relative to the --op directory.

Links can also be of the form label[url], in which case label is used in the displayed text, and url is used as the target. If label contains multiple words, put it in braces: {multi word label}[url]. The url may be an http:-type link or a cross-reference to a class, module or method with a label.

Links with the rdoc-ref: scheme will link to the referenced class, module, method, file, etc. If the referenced item is does not exist no link will be generated and rdoc-ref: will be removed from the resulting text.

Links starting with link: refer to local files whose path is relative to the --op directory. Use rdoc-ref: instead of link: to link to files generated by RDoc as the link target may be different across RDoc generators.

Example links:

https://github.com/rdoc/rdoc
mailto:user@example.com
{RDoc Documentation}[http://rdoc.rubyforge.org]
{RDoc Markup}[rdoc-ref:RDoc::Markup]

Escaping Text Markup

Text markup can be escaped with a backslash, as in <tt>, which was obtained with \<tt>. Except in verbatim sections and between <tt> tags, to produce a backslash you have to double it unless it is followed by a space, tab or newline. Otherwise, the HTML formatter will discard it, as it is used to escape potential links:

* The \ must be doubled if not followed by white space: \\.
* But not in \<tt> tags: in a Regexp, <tt>\S</tt> matches non-space.
* This is a link to {ruby-lang}[www.ruby-lang.org].
* This is not a link, however: \{ruby-lang.org}[www.ruby-lang.org].
* This will not be linked to \RDoc::RDoc#document

generates:

Inside <tt> tags, more precisely, leading backslashes are removed only if followed by a markup character (<*_+), a backslash, or a known link reference (a known class or method). So in the example above, the backslash of \S would be removed if there was a class or module named S in the current context.

This behavior is inherited from RDoc version 1, and has been kept for compatibility with existing RDoc documentation.

Conversion of characters

HTML will convert two/three dashes to an em-dash. Other common characters are converted as well:

em-dash::  -- or ---
ellipsis:: ...

single quotes:: 'text' or `text'
double quotes:: "text" or ``text''

copyright:: (c)
registered trademark:: (r)

produces:

em-dash

– or —

ellipsis

single quotes

‘text’ or `text’

double quotes

“text” or “text”

copyright

©

registered trademark

®

Documenting Source Code

Comment blocks can be written fairly naturally, either using # on successive lines of the comment, or by including the comment in a =begin/=end block. If you use the latter form, the =begin line must be flagged with an rdoc tag:

=begin rdoc
Documentation to be processed by RDoc.

...
=end

RDoc stops processing comments if it finds a comment line starting with -- right after the # character (otherwise, it will be treated as a rule if it has three dashes or more). This can be used to separate external from internal comments, or to stop a comment being associated with a method, class, or module. Commenting can be turned back on with a line that starts with ++.

##
# Extract the age and calculate the date-of-birth.
#--
# FIXME: fails if the birthday falls on February 29th
#++
# The DOB is returned as a Time object.

def get_dob(person)
  # ...
end

Names of classes, files, and any method names containing an underscore or preceded by a hash character are automatically linked from comment text to their description. This linking works inside the current class or module, and with ancestor methods (in included modules or in the superclass).

Method parameter lists are extracted and displayed with the method description. If a method calls yield, then the parameters passed to yield will also be displayed:

def fred
  ...
  yield line, address

This will get documented as:

fred() { |line, address| ... }

You can override this using a comment containing ‘:yields: …’ immediately after the method definition

def fred # :yields: index, position
  # ...

  yield line, address

which will get documented as

fred() { |index, position| ... }

:yields: is an example of a documentation directive. These appear immediately after the start of the document element they are modifying.

RDoc automatically cross-references words with underscores or camel-case. To suppress cross-references, prefix the word with a \ character. To include special characters like “\n", you’ll need to use two \ characters in normal text, but only one in <tt> text:

"\\n" or "<tt>\n</tt>"

produces:

“\n” or “\n"

Directives

Directives are keywords surrounded by “:” characters.

Controlling what is documented

:nodoc: / :nodoc: all

This directive prevents documentation for the element from being generated. For classes and modules, methods, aliases, constants, and attributes directly within the affected class or module also will be omitted. By default, though, modules and classes within that class or module will be documented. This is turned off by adding the all modifier.

module MyModule # :nodoc:
  class Input
  end
end

module OtherModule # :nodoc: all
  class Output
  end
end

In the above code, only class MyModule::Input will be documented.

The :nodoc: directive, like :enddoc:, :stopdoc: and :startdoc: presented below, is local to the current file: if you do not want to document a module that appears in several files, specify :nodoc: on each appearance, at least once per file.

:stopdoc: / :startdoc:

Stop and start adding new documentation elements to the current container. For example, if a class has a number of constants that you don’t want to document, put a :stopdoc: before the first, and a :startdoc: after the last. If you don’t specify a :startdoc: by the end of the container, disables documentation for the rest of the current file.

:doc:

Forces a method or attribute to be documented even if it wouldn’t be otherwise. Useful if, for example, you want to include documentation of a particular private method.

:enddoc:

Document nothing further at the current level: directives :startdoc: and :doc: that appear after this will not be honored for the current container (file, class or module), in the current file.

:notnew: / :not_new: / :not-new:

Only applicable to the initialize instance method. Normally RDoc assumes that the documentation and parameters for initialize are actually for the new method, and so fakes out a new for the class. The :notnew: directive stops this. Remember that initialize is private, so you won’t see the documentation unless you use the -a command line option.

Other directives

:include: filename

Include the contents of the named file at this point. This directive must appear alone on one line, possibly preceded by spaces. In this position, it can be escaped with a \ in front of the first colon.

The file will be searched for in the directories listed by the --include option, or in the current directory by default. The contents of the file will be shifted to have the same indentation as the ‘:’ at the start of the :include: directive.

:title: text

Sets the title for the document. Equivalent to the --title command line parameter. (The command line parameter overrides any :title: directive in the source).

:main: name

Equivalent to the --main command line parameter.

:category: section

Adds this item to the named section overriding the current section. Use this to group methods by section in RDoc output while maintaining a sensible ordering (like alphabetical).

# :category: Utility Methods
#
# CGI escapes +text+

def convert_string text
  CGI.escapeHTML text
end

An empty category will place the item in the default category:

# :category:
#
# This method is in the default category

def some_method
  # ...
end

Unlike the :section: directive, :category: is not sticky. The category only applies to the item immediately following the comment.

Use the :section: directive to provide introductory text for a section of documentation.

:section: title

Provides section introductory text in RDoc output. The title following :section: is used as the section name and the remainder of the comment containing the section is used as introductory text. A section’s comment block must be separated from following comment blocks. Use an empty title to switch to the default section.

The :section: directive is sticky, so subsequent methods, aliases, attributes, and classes will be contained in this section until the section is changed. The :category: directive will override the :section: directive.

A :section: comment block may have one or more lines before the :section: directive. These will be removed, and any identical lines at the end of the block are also removed. This allows you to add visual cues to the section.

Example:

# ----------------------------------------
# :section: My Section
# This is the section that I wrote.
# See it glisten in the noon-day sun.
# ----------------------------------------

##
# Comment for some_method

def some_method
  # ...
end
:call-seq:

Lines up to the next blank line in the comment are treated as the method’s calling sequence, overriding the default parsing of method parameters and yield arguments.

Further directives can be found in RDoc::Parser::Ruby and RDoc::Parser::C.

Constants

AttrChanger = Struct.new :turn_on, :turn_off

Attributes

[R] attribute_manager

An AttributeManager which handles inline markup.

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