Add configuration to enable ordered list

* Created new configuration option to enable ordered list through use_ordered_list input
* Default behaviour is false so users will continue to have ul tags
* Using existing class configuration, user can change styling on top ol tag and sub listing ol tags separately
* No ability to update styling on sub-nested ol tags separately but code is open to this change
* Added tests for new logic
* Update README with example of usage and render

README.md

@@ -19,6 +19,7 @@
   - [Skip TOC Section](#skip-toc-section)
   - [CSS Styling](#css-styling)
   - [Custom CSS Class](#custom-css-class)
+  - [Using Unordered/Ordered lists](#using-unorderedordered-lists)
 
 ## Installation
 
@@ -151,6 +152,7 @@ toc:
   sublist_class: ''
   item_class: toc-entry
   item_prefix: toc-
+  use_ordered_list: false
 ```
 
 ## Customization
@@ -245,3 +247,39 @@ toc:
   # Default is "toc-":
   item_prefix: item-
 ```
+
+### Using Unordered/Ordered lists
+
+By default the table of contents will be generated as an unordered list via `<ul></ul>` tags. This can be configured to use ordered lists instead `<ol></ol>`.
+This can be configured in `_config.yml`:
+
+```yml
+toc:
+  use_ordered_list: true # default is false
+```
+
+In order to change the list type, use the [list-style-type](https://developer.mozilla.org/en-US/docs/Web/CSS/list-style-type) css property.
+Add a class to the `sublist_class` configuration to append it to the `ol` tags so that you can add the `list-style-type` property.
+
+Example
+
+```yml
+toc:
+  use_ordered_list: true
+  list_class: my-list-class
+  sublist_class: my-sublist-class
+```
+
+```css
+.my-list-class {
+  list-style-type: upper-alpha;
+}
+
+.my-sublist-class: {
+  list-style-type: lower-alpha;
+}
+```
+
+This will produce:
+
+![screenshot](https://user-images.githubusercontent.com/7675276/85813980-a0ea5a80-b719-11ea-9458-ccf9b86a778b.png)

lib/table_of_contents/configuration.rb

@@ -5,7 +5,8 @@ module TableOfContents
     # jekyll-toc configuration class
     class Configuration
       attr_reader :toc_levels, :no_toc_class, :no_toc_section_class,
-                  :list_class, :sublist_class, :item_class, :item_prefix
+                  :list_class, :sublist_class, :item_class, :item_prefix,
+                  :use_ordered_list
 
       DEFAULT_CONFIG = {
         'min_level' => 1,
@@ -14,7 +15,8 @@ class Configuration
         'list_class' => 'section-nav',
         'sublist_class' => '',
         'item_class' => 'toc-entry',
-        'item_prefix' => 'toc-'
+        'item_prefix' => 'toc-',
+        'use_ordered_list' => false
       }.freeze
 
       def initialize(options)
@@ -27,6 +29,7 @@ def initialize(options)
         @sublist_class = options['sublist_class']
         @item_class = options['item_class']
         @item_prefix = options['item_prefix']
+        @use_ordered_list = options['use_ordered_list']
       end
 
       private

lib/table_of_contents/parser.rb

@@ -8,6 +8,9 @@ module TableOfContents
     class Parser
       include ::Jekyll::TableOfContents::Helper
 
+      ORDERED_LIST_HTML_TAG = 'ol'
+      UNORDERED_LIST_HTML_TAG = 'ul'
+
       def initialize(html, options = {})
         @doc = Nokogiri::HTML::DocumentFragment.parse(html)
         @configuration = Configuration.new(options)
@@ -19,7 +22,7 @@ def toc
       end
 
       def build_toc
-        %(<ul class="#{@configuration.list_class}">\n#{build_toc_list(@entries)}</ul>)
+        %(<#{list_tag} class="#{@configuration.list_class}">\n#{build_toc_list(@entries)}</#{list_tag}>)
       end
 
       def inject_anchors_into_html
@@ -74,7 +77,7 @@ def build_toc_list(entries)
             next_i = i + 1
             if next_i < entries.count && entries[next_i][:h_num] > min_h_num
               nest_entries = get_nest_entries(entries[next_i, entries.count], min_h_num)
-              toc_list << %(\n<ul#{ul_attributes}>\n#{build_toc_list(nest_entries)}</ul>\n)
+              toc_list << %(\n<#{list_tag}#{ul_attributes}>\n#{build_toc_list(nest_entries)}</#{list_tag}>\n)
               i += nest_entries.count
             end
             # Add the closing tag for the current entry in the list
@@ -121,6 +124,14 @@ def toc_headings_within(class_name)
       def ul_attributes
         @ul_attributes ||= @configuration.sublist_class.empty? ? '' : %( class="#{@configuration.sublist_class}")
       end
+
+      def use_ordered_list?
+        @configuration.use_ordered_list
+      end
+
+      def list_tag
+        use_ordered_list? ? ORDERED_LIST_HTML_TAG : UNORDERED_LIST_HTML_TAG
+      end
     end
   end
 end

test/parser/test_ordered_list.rb

@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class TestOrderedList < Minitest::Test
+  include TestHelpers
+
+  def test_default_configuration
+    configuration = Jekyll::TableOfContents::Configuration.new({})
+
+    assert_equal configuration.use_ordered_list, false
+  end
+
+  def test_disabled_ordered_list
+    configuration = Jekyll::TableOfContents::Configuration.new('use_ordered_list' => false)
+
+    assert_equal configuration.use_ordered_list, false
+  end
+
+  def test_enabled_ordered_list
+    configuration = Jekyll::TableOfContents::Configuration.new('use_ordered_list' => true)
+
+    assert_equal configuration.use_ordered_list, true
+  end
+
+  def test_basic_ordered_list_top_heading
+    parse_with_ordered_list
+    html = @parser.toc
+
+    assert_match(/^<ol class="section-nav">/, html)
+  end
+
+  def test_ordered_list_sub_headings
+    parse_with_ordered_list
+    html = @parser.toc
+
+    assert_match(/<ol>\n<li class="toc-entry/, html)
+  end
+
+  def test_ordered_list_top_heading_with_classes
+    parse_with_ordered_list_and_classes
+    html = @parser.toc
+
+    assert_match(/^<ol class="top-list-class">/, html)
+  end
+
+  def test_ordered_list_sub_headings_with_classes
+    parse_with_ordered_list_and_classes
+    html = @parser.toc
+
+    assert_match(/<ol class="sublist-class">/, html)
+  end
+
+  def test_ordered_list_subheadings_with_classes_nested_structure
+    parse_with_ordered_list_and_classes
+    html = @parser.toc
+
+    occurrences = html.scan(/<ol class="sublist-class">/).count
+
+    assert_equal occurrences, 5
+  end
+
+  private
+
+  def parse_with_ordered_list
+    read_html_and_create_parser('use_ordered_list' => true)
+  end
+
+  def parse_with_ordered_list_and_classes
+    read_html_and_create_parser(
+      'use_ordered_list' => true,
+      'list_class' => 'top-list-class',
+      'sublist_class' => 'sublist-class'
+    )
+  end
+end

test/test_configuration.rb

@@ -12,6 +12,7 @@ def test_default_conf1guration
     assert_equal configuration.sublist_class, ''
     assert_equal configuration.item_class, 'toc-entry'
     assert_equal configuration.item_prefix, 'toc-'
+    assert_equal configuration.use_ordered_list, false
   end
 
   def test_type_error
@@ -23,5 +24,6 @@ def test_type_error
     assert_equal configuration.sublist_class, ''
     assert_equal configuration.item_class, 'toc-entry'
     assert_equal configuration.item_prefix, 'toc-'
+    assert_equal configuration.use_ordered_list, false
   end
 end

test/test_helper.rb

@@ -20,7 +20,7 @@
 HTML
 
 module TestHelpers
-  def read_html_and_create_parser
-    @parser = Jekyll::TableOfContents::Parser.new(SIMPLE_HTML)
+  def read_html_and_create_parser(options = {})
+    @parser = Jekyll::TableOfContents::Parser.new(SIMPLE_HTML, options)
   end
 end