Inline Macro Processor Extension Example

Purpose: Create an inline macro named man that links to another man page.

sample-with-man-link.adoc

See man:gittutorial[7] to get started.

ManpageInlineMacro

require 'asciidoctor'
require 'asciidoctor/extensions'

class ManInlineMacro < Asciidoctor::Extensions::InlineMacroProcessor
  use_dsl

  named :man
  name_positional_attributes 'volnum'

  def process parent, target, attrs
    text = manname = target
    suffix = ''
    target = %(#{manname}.html)
    suffix = if (volnum = attrs['volnum'])
      "(#{volnum})"
    else
      nil
    end
    parent.document.register :links, target
    %(#{(create_anchor parent, text, type: :link, target: target).convert}#{suffix})
  end
end

Usage

Asciidoctor::Extensions.register do
  inline_macro ManInlineMacro
end

Asciidoctor.convert_file 'sample-with-man-link.adoc', safe: :safe

Tips & Techniques

Apply substitutions

By the time an inline macro is processed, most substitutions have already been applied (since macros is one of the last substitutions). In order to get the processor to apply substitutions to the text of the Inline node returned by the extension, you must specify those extensions on the node instance itself.

You can specify substitutions to apply to the text of the node using the subs attribute. This attribute accepts a symbol, an array of symbols, or a comma-separated string.

Let’s say that we want normal substitutions to be applied to the text. Here’s how that can be done:

create_inline_pass parent, '*https://asciidoctor.org[Asciidoctor]*', attributes: { 'subs' => :normal }

This node will be converted into a link with bold link text.

You can also specify the substitutions as a string, which is parsed just like the value of the subs attribute on a block.

create_inline_pass parent, '*https://asciidoctor.org[Asciidoctor]*', attributes: { 'subs' => 'quotes,macros' }

You can specify whichever substitutions you want applied, and in what order.