== Code Highlighter Rouge

_Rouge_ is a pure Ruby and themeable syntax highlighter. It can highlight
100+ different languages and output HTML or ANSI 256-color text. Find all
available themes and examples for several languages of how
highlighting works using _Rouge_.

For the default theme `Uno` of J1 Theme, the following _Rouge_ themes
are used:

* light: `igorpro`
* dark: `monokai.sublime`

NOTE: The default themes used for the J1 Theme can be configured with the
global template config file `~/_data/j1_config.yml`.


=== Apply a theme

Make a selection of a theme below to preview.

++++
<div class="btn-group">
  <!-- See: https://stackoverflow.com/questions/47242702/force-bootstrap-dropdown-menu-to-always-display-at-the-bottom-and-allow-it-go-of -->
  <!-- NOTE: control the behaviour of popper.js for positioning -->
  <!-- NOTE: set attribute data-flip="false" to open the SELECT list at the BOTTOM of the BUTTON -->
  <button class="btn btn-primary btn-flex btn-lg dropdown-toggle" data-flip="false" type="button" data-bs-toggle="dropdown" data-bs-target="#navbarDropdown" aria-haspopup="true" aria-expanded="false">
  Select Theme<span class="caret"></span>
  </button>
  <ul class="dropdown-menu scrollable-menu" role="menu">
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.dark')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.dark</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.light')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.light</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.monokai')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.monokai</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.monokai.dark')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.monokai.dark</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.monokai.light')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.monokai.light</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.solarized')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.solarized</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.solarized.dark')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.solarized.dark</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('base16.solarized.light')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>base16.solarized.light</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('colorful')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>colorful</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('github')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>github</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('gruvbox')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>gruvbox</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('gruvbox.light')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>gruvbox.light</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('igorpro')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>igorpro</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('molokai')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>molokai</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('monokai')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>monokai</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('monokai.sublime')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>monokai.sublime</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('pastie')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>pastie</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('thankful_eyes')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>thankful_eyes</a></li>
    <li><a class="dropdown-item" onclick="j1.adapter.rouge.reaplyStyles('tulip')"> <i class="mdi mdi-view-quilt mdi-18px mr-2" style="color: #9E9E9E"></i>tulip</a></li>
  </ul>
</div>
<div id="selected" class="mt-1 mb-3"></div>
++++

=== Highlight Liquid code

{% raw %}
[source, liquid]
----
Hello {{ 'now' | date: "%Y %h" }}

{% comment %} if item.quantity is 4... {% endcomment %}
{% for i in (1..item.quantity) %}
  {{ i }}
{% endfor %}
----
{% endraw %}

=== Highlight Javascript code

[source, javascript]
----
// helper functions
//
function styleSheetLoaded(styleSheet) {
  var sheets     = document.styleSheets,
      stylesheet = sheets[(sheets.length - 1)];

  // find CSS file 'styleSheetName' in document
  for(var i in document.styleSheets) {
    if(sheets[i].href && sheets[i].href.indexOf(styleSheet) > -1) {
      return true;;
    }
  }
}
----

=== Highlight Ruby code

[source, ruby]
----
require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'
include Asciidoctor <1>

Asciidoctor::Extensions.register do
  class J1BlockMacro < Extensions::BlockMacroProcessor
    use_dsl
    named :banner
    name_positional_attributes 'role'

    def process parent, target, attrs
      html = %(<div id="#{target}" class="#{attrs['role']}"></div>)
      create_pass_block parent, html, attrs, subs: nil
    end
  end
  block_macro J1BlockMacro
end
----
<1> don't miss to load the Asciidoctor ruby