ruby--ruby/doc/rdoc/markup_reference.rb

require 'rdoc'

# \Class \RDoc::MarkupReference exists only to provide a suitable home
# for a reference document for \RDoc markup.
#
# All objects defined in this class -- classes, modules, methods, aliases,
# attributes, and constants -- are solely for illustrating \RDoc markup,
# and have no other legitimate use.
#
# = \RDoc Markup Reference
#
# Notes:
#
# - Examples in this reference are Ruby code and comments;
#   certain differences from other sources
#   (such as C code and comments) are noted.
# - An example that shows rendered HTML output
#   displays that output in a blockquote:
#
#   Rendered HTML:
#   >>>
#     Some stuff
#
# \RDoc-generated documentation is derived from and controlled by:
#
# - Single-line or multi-line comments that precede certain definitions;
#   see {Markup in Comments}[rdoc-ref:RDoc::MarkupReference@Markup+in+Comments].
# - \RDoc directives in trailing comments (on the same line as code);
#   see <tt>:nodoc:</tt>, <tt>:doc:</tt>, and <tt>:notnew</tt>.
# - \RDoc directives in single-line comments;
#   see other {Directives}[rdoc-ref:RDoc::MarkupReference@Directives].
# - The Ruby code itself;
#   see {Documentation Derived from Ruby Code}[rdoc-ref:RDoc::MarkupReference@Documentation+Derived+from+Ruby+Code]
#
# == Markup in Comments
#
# A single-line or multi-line comment that immediately precedes
# the definition of a class, module, method, alias, constant, or attribute
# becomes the documentation for that defined object.
#
# (\RDoc ignores other such comments that do not precede definitions.)
#
# === Margins
#
# In a multi-line comment,
# \RDoc looks for the comment's natural left margin,
# which becomes the <em>base margin</em> for the comment
# and is the initial <em>current margin</em> for for the comment.
#
# The current margin can change, and does so, for example in a list.
#
# === Blocks
#
# It's convenient to think of markup input as a sequence of _blocks_,
# such as:
#
# - {Paragraphs}[rdoc-ref:RDoc::MarkupReference@Paragraphs].
# - {Verbatim text blocks}[rdoc-ref:RDoc::MarkupReference@Verbatim+Text+Blocks].
# - {Code blocks}[rdoc-ref:RDoc::MarkupReference@Code+Blocks].
# - {Block quotes}[rdoc-ref:RDoc::MarkupReference@Block+Quotes].
# - {Bullet lists}[rdoc-ref:RDoc::MarkupReference@Bullet+Lists].
# - {Numbered lists}[rdoc-ref:RDoc::MarkupReference@Numbered+Lists].
# - {Lettered lists}[rdoc-ref:RDoc::MarkupReference@Lettered+Lists].
# - {Labeled lists}[rdoc-ref:RDoc::MarkupReference@Labeled+Lists].
# - {Headings}[rdoc-ref:RDoc::MarkupReference@Headings].
# - {Horizontal rules}[rdoc-ref:RDoc::MarkupReference@Horizontal+Rules].
# - {Directives}[rdoc-ref:RDoc::MarkupReference@Directives].
#
# All of these except paragraph blocks are distinguished by indentation,
# or by unusual initial or embedded characters.
#
# ==== Paragraphs
#
# A paragraph consists of one or more non-empty lines of ordinary text,
# each beginning at the current margin.
#
# Note: Here, <em>ordinary text</em> means text that is <em>not identified</em>
# by indentation, or by unusual initial or embedded characters.
# See below.
#
# Paragraphs are separated by one or more empty lines.
#
# Example input:
#
#   # \RDoc produces HTML and command-line documentation for Ruby projects.
#   # \RDoc includes the rdoc and ri tools for generating and displaying
#   # documentation from the command-line.
#   #
#   # You'll love it.
#
# Rendered HTML:
# >>>
#   \RDoc produces HTML and command-line documentation for Ruby projects.
#   \RDoc includes the rdoc and ri tools for generating and displaying
#   documentation from the command-line.
#
#   You'll love it.
#
# A paragraph may contain nested blocks, including:
#
# - Verbatim text blocks.
# - Code blocks.
# - Block quotes.
# - Lists of any type.
# - Headings.
# - Horizontal rules.
#
# ==== Verbatim Text Blocks
#
# Text indented farther than the current margin becomes a <em>verbatim text block</em>
# (or a code block, described next).
# In the rendered HTML, such text:
#
# - Is indented.
# - Has a contrasting background color.
#
# The verbatim text block ends at the first line beginning at the current margin.
#
# Example input:
#
#   # This is not verbatim text.
#   #
#   #   This is verbatim text.
#   #     Whitespace is honored.     # See?
#   #       Whitespace is honored.     # See?
#   #
#   #   This is still the same verbatim text block.
#   #
#   # This is not verbatim text.
#
# Rendered HTML:
# >>>
#   This is not verbatim text.
#
#     This is verbatim text.
#       Whitespace is honored.     # See?
#         Whitespace is honored.     # See?
#
#     This is still the same verbatim text block.
#
#   This is not verbatim text.
#
# ==== Code Blocks
#
# A special case of verbatim text is the <em>code block</em>,
# which is merely verbatim text that \RDoc recognizes as Ruby code:
#
# In the rendered HTML, the code block:
#
# - Is indented.
# - Has a contrasting background color.
# - Has syntax highlighting.
#
# Example input:
#
#   Consider this method:
#
#     def foo(name = '', value = 0)
#       @name = name      # Whitespace is still honored.
#       @value = value
#     end
#
#
# Rendered HTML:
# >>>
#   Consider this method:
#
#     def foo(name = '', value = 0)
#       @name = name      # Whitespace is still honored.
#       @value = value
#     end
#
# Pro tip:  If your indented Ruby code does not get highlighted,
# it may contain a syntax error.
#
# ==== Block Quotes
#
# You can use the characters <tt>>>></tt> (unindented),
# followed by indented text, to treat the text
# as a {block quote}[https://en.wikipedia.org/wiki/Block_quotation]:
#
# Example input:
#
#   >>>
#     Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer
#     commodo quam iaculis massa posuere, dictum fringilla justo pulvinar.
#     Quisque turpis erat, pharetra eu dui at, sollicitudin accumsan nulla.
#
#     Aenean congue ligula eu ligula molestie, eu pellentesque purus
#     faucibus. In id leo non ligula condimentum lobortis. Duis vestibulum,
#     diam in pellentesque aliquet, mi tellus placerat sapien, id euismod
#     purus magna ut tortor.
#
# Rendered HTML:
#
# >>>
#   Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer
#   commodo quam iaculis massa posuere, dictum fringilla justo pulvinar.
#   Quisque turpis erat, pharetra eu dui at, sollicitudin accumsan nulla.
#
#   Aenean congue ligula eu ligula molestie, eu pellentesque purus
#   faucibus. In id leo non ligula condimentum lobortis. Duis vestibulum,
#   diam in pellentesque aliquet, mi tellus placerat sapien, id euismod
#   purus magna ut tortor.
#
# A block quote may contain nested blocks, including:
#
# - Other block quotes.
# - Paragraphs.
# - Verbatim text blocks.
# - Code blocks.
# - Lists of any type.
# - Headings.
# - Horizontal rules.
#
# Note that, unlike verbatim text, single newlines are not honored,
# but that a double newline begins a new paragraph in the block quote.
#
# ==== Lists
#
# Each type of list item is marked by a special beginning:
#
# - Bullet list item: Begins with a hyphen or asterisk.
# - Numbered list item: Begins with digits and a period.
# - Lettered list item: Begins with an alphabetic character and a period.
# - Labeled list item: Begins with one of:
#   - Square-bracketed text.
#   - A word followed by two colons.
#
# A list begins with a list item and continues, even across blank lines,
# as long as list items of the same type are found at the same indentation level.
#
# A new list resets the current margin inward.
# Additional lines of text aligned at that margin
# are part of the continuing list item.
#
# A list item may be continued on additional lines that are aligned
# with the first line.  See examples below.
#
# A list item may contain nested blocks, including:
#
# - Other lists of any type.
# - Paragraphs.
# - Verbatim text blocks.
# - Code blocks.
# - Block quotes.
# - Headings.
# - Horizontal rules.
#
# ===== Bullet Lists
#
# A bullet list item begins with a hyphen or asterisk.
#
# Example input:
#
#   # - An item.
#   # - Another.
#   # - An item spanning
#   #   multiple lines.
#   #
#   # * Yet another.
#   # - Last one.
#
# Rendered HTML:
# >>>
#   - An item.
#   - Another.
#   - An item spanning
#     multiple lines.
#
#   * Yet another.
#   - Last one.
#
# ===== Numbered Lists
#
# A numbered list item begins with digits and a period.
#
# The items are automatically re-numbered.
#
# Example input:
#
#   # 100. An item.
#   # 10. Another.
#   # 1. An item spanning
#   #    multiple lines.
#   #
#   # 1. Yet another.
#   # 1000. Last one.
#
# Rendered HTML:
# >>>
#   100. An item.
#   10. Another.
#   1. An item spanning
#      multiple lines.
#
#   1. Yet another.
#   1000. Last one.
#
# ===== Lettered Lists
#
# A numbered list item begins with a letters and a period.
#
# The items are automatically "re-lettered."
#
# Example input:
#
#   # z. An item.
#   # y. Another.
#   # x. An item spanning
#   #    multiple lines.
#   #
#   # x. Yet another.
#   # a. Last one.
#
# Rendered HTML:
# >>>
#   z. An item.
#   y. Another.
#
#   x. Yet another.
#   a. Last one.
#
# ===== Labeled Lists
#
# A labeled list item begins with one of:
#
# - Square-bracketed text: the label and text are on two lines.
# - A word followed by two colons: the label and text are on the same line.
#
# Example input:
#
#   # [foo] An item.
#   # bat:: Another.
#   # [bag] An item spanning
#   #       multiple lines.
#   #
#   # [bar baz] Yet another.
#   # bam:: Last one.
#
# Rendered HTML:
# >>>
#   [foo] An item.
#   bat:: Another.
#   [bag] An item spanning
#         multiple lines.
#
#   [bar baz] Yet another.
#   bam:: Last one.
#
# ==== Headings
#
# A heading begins with up to six equal-signs, followed by heading text.
# Whitespace between those and the heading text is optional.
#
# Examples:
#
#   # = Section 1
#   # == Section 1.1
#   # === Section 1.1.1
#   # === Section 1.1.2
#   # == Section 1.2
#   # = Section 2
#   # = Foo
#   # == Bar
#   # === Baz
#   # ==== Bam
#   # ===== Bat
#   # ====== Bad
#   # ============Still a Heading (Level 6)
#   # \== Not a Heading
#
# ==== Horizontal Rules
#
# A horizontal rule begins with three or more hyphens.
#
# Example input:
#
#   # ------
#   # Stuff between.
#   #
#   # \--- Not a horizontal rule.
#   #
#   # -- Also not a horizontal rule.
#   #
#   # ---
#
# Rendered HTML:
# >>>
#   ------
#   Stuff between.
#
#   \--- Not a horizontal rule.
#
#   -- Also not a horizontal rule.
#
#   ---
#
# ==== Directives
#
# ===== Directives for Allowing or Suppressing Documentation
#
# - <tt># :stopdoc:</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that \RDoc should ignore markup
#     until next <tt>:startdoc:</tt> directive or end-of-file.
#
# - <tt># :startdoc:</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that \RDoc should resume parsing markup.
#
# - <tt># :enddoc:</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that \RDoc should ignore markup to end-of-file
#     regardless of other directives.
#
# - <tt># :nodoc:</tt>:
#
#   - Appended to a line of code
#     that defines a class, module, method, alias, constant, or attribute.
#   - Specifies that the defined object should not be documented.
#
# - <tt># :nodoc: all</tt>:
#
#   - Appended to a line of code
#     that defines a class or module.
#   - Specifies that the class or module should not be documented.
#     By default, however, a nested class or module _will_ be documented.
#
# - <tt># :doc:</tt>:
#
#   - Appended to a line of code
#     that defines a class, module, method, alias, constant, or attribute.
#   - Specifies the defined object should be documented, even if otherwise
#     would not be documented.
#
# - <tt># :notnew:</tt> (aliased as <tt>:not_new:</tt> and <tt>:not-new:</tt>):
#
#   - Appended to a line of code
#     that defines instance method +initialize+.
#   - Specifies that singleton method +new+ should not be documented.
#     By default, Ruby fakes a corresponding singleton method +new+,
#     which \RDoc includes in the documentation.
#     Note that instance method +initialize+ is private, and so by default
#     is not documented.
#
# For Ruby code, but not for other \RDoc sources,
# there is a shorthand for <tt>:stopdoc:</tt> and <tt>:startdoc:</tt>:
#
#   # Documented.
#   #--
#   # Not documented.
#   #++
#   # Documented.
#
# For C code, any of directives <tt>:startdoc:</tt>, <tt>:enddoc:</tt>,
# and <tt>:nodoc:</tt> may appear in a stand-alone comment:
#
#   /* :startdoc: */
#   /* :stopdoc: */
#   /* :enddoc: */
#
# ===== Directive for Specifying \RDoc Source Format
#
# - <tt># :markup: _type_</tt>:
#
#   - Appears on a line by itself.
#   - Specifies the format for the \RDoc input;
#     parameter +type+ is one of +markdown+, +rd+, +rdoc+, +tomdoc+.
#
# ===== Directives for HTML Output
#
# - <tt># :title: _text_</tt>:
#
#   - Appears on a line by itself.
#   - Specifies the title for the HTML output.
#
# - <tt># :main: _filename_</tt>:
#   - Appears on a line by itself.
#   - Specifies the HTML file to be displayed first.
#
# ===== Directives for Method Documentation
#
# - <tt># :call-seq:</tt>:
#
#   - Appears on a line by itself.
#   - Specifies the calling sequence to be reported in the HTML,
#     overriding the actual calling sequence in the code.
#     See method #call_seq_directive.
#
#   Note that \RDoc can build the calling sequence for a Ruby-coded method,
#   but not for other languages.
#   You may want to override that by explicitly giving a <tt>:call-seq:</tt>
#   directive if you want to include:
#
#   - A return type, which is not automatically inferred.
#   - Multiple calling sequences.
#
#   For C code, the directive may appear in a stand-alone comment.
#
# - <tt># :args: _arg_names_</tt> (aliased as <tt>:arg:</tt>):
#
#   - Appears on a line by itself.
#   - Specifies the arguments to be reported in the HTML,
#     overriding the actual arguments in the code.
#     See method #args_directive.
#
# - <tt># :yields: _arg_names_</tt> (aliased as <tt>:yield:</tt>):
#
#   - Appears on a line by itself.
#   - Specifies the yield arguments to be reported in the HTML,
#     overriding the actual yield in the code.
#     See method #yields_directive.
#
# ===== Directives for Organizing Documentation
#
# By default, \RDoc groups:
#
# - Singleton methods together in alphabetical order.
# - Instance methods and their aliases together in alphabetical order.
# - Attributes and their aliases together in alphabetical order.
#
# You can use directives to modify those behaviors.
#
# - <tt># :section: _section_title_</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that following methods are to be grouped into the section
#     with the given <em>section_title</em>,
#     or into the default section if no title is given.
#     The directive remains in effect until another such directive is given,
#     but may be temporarily overridden by directive <tt>:category:</tt>.
#     See below.
#
#   The comment block containing this directive:
#
#   - Must be separated by a blank line from the documentation for the next item.
#   - May have one or more lines preceding the directive.
#     These will be removed, along with any trailing lines that match them.
#     Such lines may be visually helpful.
#   - Lines of text that are not so removed become the descriptive text
#     for 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
#
#   You can use directive <tt>:category:</tt> to temporarily
#   override the current section.
#
# - <tt># :category: _section_title_</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that just one following method is to be included
#     in the given section, or in the default section if no title is given.
#     Subsequent methods are to be grouped into the current section.
#
# ===== Directive for Including a File
#
# - <tt># :include: _filepath_</tt>:
#
#   - Appears on a line by itself.
#   - Specifies that the contents of the given file
#     are to be included at this point.
#     The file content is shifted to have the same indentation as the colon
#     at the start of the directive.
#
#     The file is searched for in the directories
#     given with the <tt>--include</tt> command-line option,
#     or by default in the current directory.
#
#   For C code, the directive may appear in a stand-alone comment
#
# === Text Markup
#
# Text in a paragraph, list item (any type), or heading
# may have markup formatting.
#
# ==== Italic
#
# A single word may be italicized by prefixed and suffixed underscores.
#
# Examples:
#
#   # _Word_ in paragraph.
#   # - _Word_ in bullet list item.
#   # 1. _Word_ in numbered list item.
#   # a. _Word_ in lettered list item.
#   # [_word_] _Word_ in labeled list item.
#   # ====== _Word_ in heading
#
# Any text may be italicized via HTML tag +i+ or +em+.
#
# Examples:
#
#   # <i>Two words</i> in paragraph.
#   # - <i>Two words</i> in bullet list item.
#   # 1. <i>Two words</i> in numbered list item.
#   # a. <i>Two words</i> in lettered list item.
#   # [<i>Two words</i>] <i>Two words</i> in labeled list item.
#   # ====== <i>Two words</i> in heading
#
# ==== Bold
#
# A single word may be made bold by prefixed and suffixed asterisks.
#
# Examples:
#
#   # *Word* in paragraph.
#   # - *Word* in bullet list item.
#   # 1. *Word* in numbered list item.
#   # a. *Word* in lettered list item.
#   # [*word*] *Word* in labeled list item.
#   # ====== *Word* in heading
#
# Any text may be made bold via HTML tag +b+.
#
# Examples:
#
#   # <b>Two words</b> in paragraph.
#   # - <b>Two words</b> in bullet list item.
#   # 1. <b>Two words</b> in numbered list item.
#   # a. <b>Two words</b> in lettered list item.
#   # [<b>Two words</b>] <b>Two words</b> in labeled list item.
#   # ====== <b>Two words</b> in heading
#
# ==== Monofont
#
# A single word may be made monofont -- sometimes called "typewriter font" --
# by prefixed and suffixed plus-signs.
#
# Examples:
#
#   # +Word+ in paragraph.
#   # - +Word+ in bullet list item.
#   # 1. +Word+ in numbered list item.
#   # a. +Word+ in lettered list item.
#   # [+word+] +Word+ in labeled list item.
#   # ====== +Word+ in heading
#
# Any text may be made monofont via HTML tag +tt+ or +code+.
#
# Examples:
#
#   # <tt>Two words</tt> in paragraph.
#   # - <tt>Two words</tt> in bullet list item.
#   # 1. <tt>Two words</tt> in numbered list item.
#   # a. <tt>Two words</tt> in lettered list item.
#   # [<tt>Two words</tt>] <tt>Two words</tt> in labeled list item.
#   # ====== <tt>Two words</tt> in heading
#
# ==== Character Conversions
#
# Certain combinations of characters may be converted to special characters;
# whether the conversion occurs depends on whether the special character
# is available in the current encoding.
#
# - <tt>(c)</tt> converts to (c) (copyright character); must be lowercase.
#
# - <tt>(r)</tt> converts to (r) (registered trademark character); must be lowercase.
#
# - <tt>'foo'</tt> converts to 'foo' (smart single-quotes).
#
# - <tt>"foo"</tt> converts to "foo" (smart double-quotes).
#
# - <tt>foo ... bar</tt> converts to foo ... bar (1-character ellipsis).
#
# - <tt>foo -- bar</tt> converts to foo -- bar (1-character en-dash).
#
# - <tt>foo --- bar</tt> converts to foo --- bar (1-character em-dash).
#
# ==== Links
#
# Certain strings in \RDoc text are converted to links.
# Any such link may be suppressed by prefixing a backslash.
# This section shows how to link to various
# targets.
#
# [Class]
#
#   - On-page: <tt>DummyClass</tt> links to DummyClass.
#   - Off-page: <tt>RDoc::Alias</tt> links to RDoc::Alias.
#
# [Module]
#
#   - On-page: <tt>DummyModule</tt> links to DummyModule.
#   - Off-page: <tt>RDoc</tt> links to RDoc.
#
# [Constant]
#
#   - On-page: <tt>DUMMY_CONSTANT</tt> links to DUMMY_CONSTANT.
#   - Off-page: <tt>RDoc::Text::MARKUP_FORMAT</tt> links to RDoc::Text::MARKUP_FORMAT.
#
# [Singleton Method]
#
#   - On-page: <tt>::dummy_singleton_method</tt> links to ::dummy_singleton_method.
#   - Off-page<tt>RDoc::TokenStream::to_html</tt> links to RDoc::TokenStream::to_html.
#     to \RDoc::TokenStream::to_html.
#
#   Note: Occasionally \RDoc is not linked to a method whose name
#   has only special characters. Check whether the links you were expecting
#   are actually there.  If not, you'll need to put in an explicit link;
#   see below.
#
#   Pro tip: The link to any method is available in the alphabetical table of contents
#   at the top left of the page for the class or module.
#
# [Instance Method]
#
#   - On-page: <tt>#dummy_instance_method</tt> links to #dummy_instance_method.
#   - Off-page: <tt>RDoc::Alias#html_name</tt> links to RDoc::Alias#html_name.
#
#     See the Note and Pro Tip immediately above.
#
# [Attribute]
#
#   - On-page: <tt>#dummy_attribute</tt> links to #dummy_attribute.
#   - Off-page: <tt>RDoc::Alias#name</tt> links to RDoc::Alias#name.
#
# [Alias]
#
#   - On-page: <tt>#dummy_instance_alias</tt> links to #dummy_instance_alias.
#   - Off-page: <tt>RDoc::Alias#new_name</tt> links to RDoc::Alias#new_name.
#
# [Protocol +http+]
#
#   - Linked: <tt>http://yahoo.com</tt> links to http://yahoo.com.
#
# [Protocol +https+]
#
#   - Linked: <tt>https://github.com</tt> links to https://github.com.
#
# [Protocol +www+]
#
#   - Linked: <tt>www.yahoo.com</tt> links to www.yahoo.com.
#
# [Protocol +ftp+]
#
#   - Linked: <tt>ftp://nosuch.site</tt> links to ftp://nosuch.site.
#
# [Protocol +mailto+]
#
#   - Linked:  <tt>mailto:/foo@bar.com</tt> links to mailto://foo@bar.com.
#
# [Protocol +irc+]
#
#   - link: <tt>irc://irc.freenode.net/ruby</tt> links to irc://irc.freenode.net/ruby.
#
# [Image Filename Extensions]
#
#   - Link: <tt>https://www.ruby-lang.org/images/header-ruby-logo@2x.png</tt> is
#     converted to an in-line HTML +img+ tag, which displays the image in the HTML:
#
#     https://www.ruby-lang.org/images/header-ruby-logo@2x.png
#
#     Also works for +bmp+, +gif+, +jpeg+, and +jpg+ files.
#
#     Note: Works only for a fully qualified URL.
#
# [Heading]
#
#   - Link: <tt>RDoc::RD@LICENSE</tt> links to RDoc::RDoc::RD@LICENSE.
#
#   Note that spaces in the actual heading are represented by <tt>+</tt> characters
#   in the linkable text.
#
#   - Link: <tt>RDoc::Options@Saved+Options</tt>
#     links to RDoc::Options@Saved+Options.
#
#   Punctuation and other special characters must be escaped like CGI.escape.
#
#   Pro tip: The link to any heading is available in the alphabetical table of contents
#   at the top left of the page for the class or module.
#
# [Section]
#
#   See {Directives for Organizing Documentation}[#class-RDoc::MarkupReference-label-Directives+for+Organizing+Documentation].
#
#   - Link: <tt>RDoc::Markup::ToHtml@Visitor</tt> links to RDoc::Markup::ToHtml@Visitor.
#
#   If a section and a heading share the same name, the link target is the section.
#
# [Single-Word Text Link]
#
#   Use square brackets to create single-word text link:
#
#   - <tt>GitHub[https://github.com]</tt> links to GitHub[https://github.com].
#
# [Multi-Word Text Link]
#
#   Use square brackets and curly braces to create a multi-word text link.
#
#   - <tt>{GitHub home page}[https://github.com]</tt> links to
#     {GitHub home page}[https://github.com].
#
# [<tt>rdoc-ref</tt> Scheme]
#
#   A link with the <tt>rdoc-ref:</tt> scheme links to the referenced item,
#   if that item exists.
#   The referenced item may be a class, module, method, file, etc.
#
#   - Class: <tt>Alias[rdoc-ref:RDoc::Alias]</tt> links to Alias[rdoc-ref:RDoc::Alias].
#   - Module: <tt>RDoc[rdoc-ref:RDoc]</tt> links to RDoc[rdoc-ref:RDoc].
#   - Method: <tt>foo[rdoc-ref:RDoc::Markup::ToHtml#handle_regexp_RDOCLINK]</tt>
#     links to foo[rdoc-ref:RDoc::Markup::ToHtml#handle_regexp_RDOCLINK].
#   - Constant: <tt>bar[rdoc-ref:RDoc::Markup::ToHtml::LIST_TYPE_TO_HTML]</tt>
#     links to bar[rdoc-ref:RDoc::Markup::ToHtml::LIST_TYPE_TO_HTML].
#   - Attribute: <tt>baz[rdoc-ref:RDoc::Markup::ToHtml#code_object]</tt>
#     links to baz[rdoc-ref:RDoc::Markup::ToHtml#code_object].
#   - Alias: <tt>bad[rdoc-ref:RDoc::MarkupReference#dummy_instance_alias]</tt> links to
#     bad[rdoc-ref:RDoc::MarkupReference#dummy_instance_alias].
#
#   If the referenced item does not exist, no link is generated
#   and entire <tt>rdoc-ref:</tt> square-bracketed clause is removed
#   from the resulting text.
#
#   - <tt>Nosuch[rdoc-ref:RDoc::Nosuch]</tt> is rendered as
#     Nosuch[rdoc-ref:RDoc::Nosuch].
#
#
# [<tt>rdoc-label</tt> Scheme]
#
#   [Simple]
#
#     You can specify a link target using this form,
#     where the second part cites the id of an HTML element.
#
#     This link refers to the constant +DUMMY_CONSTANT+ on this page:
#
#     - <tt>{DUMMY_CONSTANT}[rdoc-label:DUMMY_CONSTANT]</tt>
#
#     Thus:
#
#     {DUMMY_CONSTANT}[rdoc-label:DUMMY_CONSTANT]
#
#   [With Return]
#
#     You can specify both a link target and a local label
#     that can be used as the target for a return link.
#     These two links refer to each other:
#
#     - <tt>{go to addressee}[rdoc-label:addressee:sender]</tt>
#     - <tt>{return to sender}[rdoc-label:sender:addressee]</tt>
#
#     Thus:
#
#     {go to addressee}[rdoc-label:addressee:sender]
#
#     Some text.
#
#     {return to sender}[rdoc-label:sender:addressee]
#
# [<tt>link:</tt> Scheme]
#
#   - <tt>link:README_rdoc.html</tt> links to link:README_rdoc.html.
#
# [<tt>rdoc-image</tt> Scheme]
#
#   Use the <tt>rdoc-image</tt> scheme to display an image that is also a link:
#
#     # {rdoc-image:path/to/image}[link_target]
#
#   - Link: <tt>{rdoc-image:https://www.ruby-lang.org/images/header-ruby-logo@2x.png}[https://www.ruby-lang.org]</tt>
#     displays image <tt>https://www.ruby-lang.org/images/header-ruby-logo@2x.png</tt>
#     as a link to <tt>https://www.ruby-lang.org</tt>.
#
#     {rdoc-image:https://www.ruby-lang.org/images/header-ruby-logo@2x.png}[https://www.ruby-lang.org]
#
#   A relative path as the target also works:
#
#   - Link: <tt>{rdoc-image:https://www.ruby-lang.org/images/header-ruby-logo@2x.png}[./Alias.html]</tt> links to <tt>./Alias.html</tt>
#
#     {rdoc-image:https://www.ruby-lang.org/images/header-ruby-logo@2x.png}[./Alias.html]
#
# == Documentation Derived from Ruby Code
#
# [Class]
#
#   By default, \RDoc documents:
#
#   - \Class name.
#   - Parent class.
#   - Singleton methods.
#   - Instance methods.
#   - Aliases.
#   - Constants.
#   - Attributes.
#
# [Module]
#
#   By default, \RDoc documents:
#
#   - \Module name.
#   - \Singleton methods.
#   - Instance methods.
#   - Aliases.
#   - Constants.
#   - Attributes.
#
# [Method]
#
#   By default, \RDoc documents:
#
#   - \Method name.
#   - Arguments.
#   - Yielded values.
#
#   See #method.
#
# [Alias]
#
#   By default, \RDoc documents:
#
#   - Alias name.
#   - Aliased name.
#
#   See #dummy_instance_alias and #dummy_instance_method.
#
# [Constant]
#
#   By default, \RDoc documents:
#
#   - \Constant name.
#
#   See DUMMY_CONSTANT.
#
# [Attribute]
#
#   By default, \RDoc documents:
#
#   - Attribute name.
#   - Attribute type (<tt>[R]</tt>, <tt>[W]</tt>, or <tt>[RW]</tt>)
#
#   See #dummy_attribute.
#
class RDoc::MarkupReference

  class DummyClass; end
  module DummyModule; end
  def self.dummy_singleton_method(foo, bar); end
  def dummy_instance_method(foo, bar); end;
  alias dummy_instance_alias dummy_instance_method
  attr_accessor :dummy_attribute
  alias dummy_attribute_alias dummy_attribute
  DUMMY_CONSTANT = ''

  # :call-seq:
  #   call_seq_directive(foo, bar)
  #   Can be anything -> bar
  #   Also anything more -> baz or bat
  #
  # The <tt>:call-seq:</tt> directive overrides the actual calling sequence
  # found in the Ruby code.
  #
  # - It can specify anything at all.
  # - It can have multiple calling sequences.
  #
  # This one includes <tt>Can be anything -> foo</tt>, which is nonsense.
  #
  # Note that the "arrow" is two characters, hyphen and right angle-bracket,
  # which is made into a single character in the HTML.
  #
  # Click on the calling sequence to see the code.
  #
  # Here is the <tt>:call-seq:</tt> directive given for the method:
  #
  #   # :call-seq:
  #   #   call_seq_directive(foo, bar)
  #   #   Can be anything -> bar
  #   #   Also anything more -> baz or bat
  #
  def call_seq_directive
    nil
  end

  # The <tt>:args:</tt> directive overrides the actual arguments found in the Ruby code.
  #
  # Click on the calling sequence to see the code.
  #
  def args_directive(foo, bar) # :args: baz
    nil
  end

  # The <tt>:yields:</tt> directive overrides the actual yield found in the Ruby code.
  #
  # Click on the calling sequence to see the code.
  #
  def yields_directive(foo, bar) # :yields: 'bat'
    yield 'baz'
  end

  # This method is documented only by \RDoc, except for these comments.
  #
  # Click on the calling sequence to see the code.
  #
  def method(foo, bar)
    yield 'baz'
  end

end