class RDoc::Markup - RDoc Documentation

# class RDoc::Markup

`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` and other markup formats do no output formatting, this is handled by the RDoc::Markup::Formatter subclasses.

# Supported Formats¶ ↑

Besides the `RDoc::Markup` format, the following formats are built in to RDoc:

markdown

  The markdown format as described by daringfireball.net/projects/markdown/. See `RDoc::Markdown` for details on the parser and supported extensions.

rd

  The rdtool format. See `RDoc::RD` for details on the parser and format.

tomdoc

  The TomDoc format as described by tomdoc.org/. See `RDoc::TomDoc` for details on the parser and supported extensions.

You can choose a markup format using the following methods:

per project

  If you build your documentation with rake use `RDoc::Task#markup`.

  If you build your documentation by hand run:

      rdoc --markup your_favorite_format --write-options

  and commit `.rdoc_options` and ship it with your packaged gem.

per file

  At the top of the file use the `:markup:` directive to set the default format for the rest of the file.

per comment

  Use the `:markup:` directive at the top of a comment you want to write in a different format.

# `RDoc::Markup`¶ ↑

`RDoc::Markup` is extensible at runtime: you can add new markup elements to be recognized 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'

    h = RDoc::Markup::ToHtml.new(RDoc::Options.new)

    puts h.convert(input_string)

You can extend the `RDoc::Markup` parser to recognize new markup sequences, and to add regexp handling. 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'

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

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

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

    wh = WikiHtml.new RDoc::Options.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.

For HTML output `RDoc` makes a small effort to determine if a verbatim section contains Ruby source code. If so, the verbatim block will be marked up as HTML. Triggers include “def”, “class”, “module”, “require”, the “hash rocket”# (=>) or a block call with a parameter.

### Headers¶ ↑

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

In HTML output headers have an id matching their name. The above example's HTML is:

    <h3 id="label-Headers">Headers</h3>

If a heading is inside a method body the id will be prefixed with the method's id. If the above header where in the documentation for a method such as:

    ##
    # This method does fun things
    #
    # = Example
    #
    #   Example of fun things goes here ...

    def do_fun_things
    end

The header's id would be:

    <h1 id="method-i-do_fun_things-label-Example">Example</h1>

The label can be linked-to using `SomeClass@Headers`. See Links for further details.

### Rules¶ ↑

A line starting with three or more hyphens (at the current indent) generates a horizontal rule.

    ---

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</b>`

  displays text in a bold font

`<em>text</em>`

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

`<tt>text</tt>`

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

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 is converted into an inline image element.

Classes and methods will be automatically linked to their definition. For example, `RDoc::Markup` will link to this documentation. By default methods will only be automatically linked if they contain an `_` (all methods can be automatically linked through the `--hyperlink-all` command line option).

Single-word methods can be linked by using the `#` character for instance methods or `::` for class methods. For example, `#convert` links to `convert`. A class or method may be combined like `RDoc::Markup#convert`.

A heading inside the documentation can be linked by following the class or method by an `@` then the heading name. `RDoc::Markup@Links` will link to this section like this: Links at `RDoc::Markup`. Spaces in headings with multiple words must be escaped with `+` like `RDoc::Markup@Escaping+Text+Markup`. Punctuation and other special characters must be escaped like `CGI.escape`.

The `@` can also be used to link to sections. If a section and a heading share the same name the section is preferred for the link.

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-image:` scheme will create an image tag for HTML output. Only fully-qualified URLs are supported.

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 `rdoc-label:label_name` will link to the `label_name`. You can create a label for the current link (for bidirectional links) by supplying a name for the current link like `rdoc-label:label-other:label-mine`

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/ruby/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:

- The \ must be doubled if not followed by white space: \.

- But not in <tt> tags: in a `Regexp`, `\S` matches non-space.

- This is a link to ruby-lang

- This is not a link, however: {ruby-lang.org}[www.ruby-lang.org]

- This will not be linked to RDoc::RDoc#document

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.

### `Method` arguments¶ ↑

`:arg:` or `:args:` parameters

  Overrides the default argument handling with exactly these parameters.

      ##
      #  :args: a, b

      def some_method(*a)
      end

`:yield:` or `:yields:` parameters

  Overrides the default yield discovery with these parameters.

      ##
      # :yields: key, value

      def each_thing &block
        @things.each(&block)
      end

`:call-seq:`

  Lines up to the next blank line or lines with a common prefix in the comment are treated as the method's calling sequence, overriding the default parsing of method parameters and yield arguments.

  Multiple lines may be used.

      # :call-seq:
      #   ARGF.readlines(sep=$/)     -> array
      #   ARGF.readlines(limit)      -> array
      #   ARGF.readlines(sep, limit) -> array
      #
      #   ARGF.to_a(sep=$/)     -> array
      #   ARGF.to_a(limit)      -> array
      #   ARGF.to_a(sep, limit) -> array
      #
      # The remaining lines are documentation ...

### Sections¶ ↑

Sections allow you to group methods in a class into sensible containers. If you use the sections 'Public', 'Internal' and 'Deprecated' (the three allowed method statuses from TomDoc) the sections will be displayed in that order placing the most useful methods at the top. Otherwise, sections will be displayed in alphabetical order.

`: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

### Other directives¶ ↑

`:markup:` type

  Overrides the default markup type for this comment with the specified markup type. For Ruby files, if the first comment contains this directive it is applied automatically to all comments in the file.

  Unless you are converting between markup formats you should use a `.rdoc_options` file to specify the default documentation format for your entire project. See Saved Options at `RDoc::Options` for instructions.

  At the top of a file the `:markup:` directive applies to the entire file:

      # coding: UTF-8
      # :markup: TomDoc

      # TomDoc comment here ...

      class MyClass
        # ...

  For just one comment:

        # ...
      end

      # :markup: RDoc
      #
      # This is a comment in RDoc markup format ...

      def some_method
        # ...

  See CONTRIBUTING at `Markup` for instructions on adding a new markup format.

`: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.

### Attributes

attribute_manager[R]

An AttributeManager which handles inline markup.

### Public Class Methods

new(attribute_manager = nil) click to toggle source

Take a block of text and use various heuristics to determine its structure (paragraphs, lists, and so on). Invoke an event handler as we identify significant chunks.

    # File lib/rdoc/markup.rb, line 777
    def initialize attribute_manager = nil
      @attribute_manager = attribute_manager || RDoc::Markup::AttributeManager.new
      @output = nil
    end

parse(str) click to toggle source

Parses `str` into an RDoc::Markup::Document.

    # File lib/rdoc/markup.rb, line 747
      def self.parse str
        RDoc::Markup::Parser.parse str
      rescue RDoc::Markup::Parser::Error => e
        $stderr.puts <<-EOF
    While parsing markup, RDoc encountered a #{e.class}:

    #{e}
    \tfrom #{e.backtrace.join "\n\tfrom "}

    ---8<---
    #{text}
    ---8<---

    RDoc #{RDoc::VERSION}

    Ruby #{RUBY_VERSION}-p#{RUBY_PATCHLEVEL} #{RUBY_RELEASE_DATE}

    Please file a bug report with the above information at:

    https://github.com/ruby/rdoc/issues

        EOF
        raise
      end

### Public Instance Methods

add_html(tag, name) click to toggle source

Add to the sequences recognized as general markup.

    # File lib/rdoc/markup.rb, line 794
    def add_html(tag, name)
      @attribute_manager.add_html(tag, name)
    end

add_regexp_handling(pattern, name) click to toggle source

Add to other inline sequences. For example, we could add WikiWords using something like:

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

Each wiki word will be presented to the output formatter.

    # File lib/rdoc/markup.rb, line 806
    def add_regexp_handling(pattern, name)
      @attribute_manager.add_regexp_handling(pattern, name)
    end

add_word_pair(start, stop, name) click to toggle source

Add to the sequences used to add formatting to an individual word (such as bold). Matching entries will generate attributes that the output formatters can recognize by their `name`.

    # File lib/rdoc/markup.rb, line 787
    def add_word_pair(start, stop, name)
      @attribute_manager.add_word_pair(start, stop, name)
    end

convert(input, formatter) click to toggle source

We take `input`, parse it if necessary, then invoke the output `formatter` using a Visitor to render the result.

    # File lib/rdoc/markup.rb, line 814
    def convert input, formatter
      document = case input
                 when RDoc::Markup::Document then
                   input
                 else
                   RDoc::Markup::Parser.parse input
                 end

      document.accept formatter
    end