TOC configuration: configurable heading min_level and max_level (#39)

* Fix duplicated method name

* Add toc_enabled? method

* Add kramdown heading test

* Create `toc` liqud  custom tag

* Check toc is enabled

* unregister_tag toc

* Add TODO

* Make toc headings dynamic

* Add max_level, min_level test

lib/jekyll-toc.rb

@@ -2,31 +2,41 @@
 require 'table_of_contents/parser'
 
 module Jekyll
+  class TocTag < Liquid::Tag
+    def render(context)
+      return unless context.registers[:page]['toc'] == true
+      content_html = context.registers[:page].content
+      ::Jekyll::TableOfContents::Parser.new(content_html).build_toc
+    end
+  end
+
   module TableOfContentsFilter
     def toc_only(html)
-      return html unless page['toc']
-
-      ::Jekyll::TableOfContents::Parser.new(html).build_toc
+      return html unless toc_enabled?
+      ::Jekyll::TableOfContents::Parser.new(html, toc_config).build_toc
     end
 
     def inject_anchors(html)
-      return html unless page['toc']
-
-      ::Jekyll::TableOfContents::Parser.new(html).inject_anchors_into_html
+      return html unless toc_enabled?
+      ::Jekyll::TableOfContents::Parser.new(html, toc_config).inject_anchors_into_html
     end
 
     def toc(html)
-      return html unless page['toc']
-
-      ::Jekyll::TableOfContents::Parser.new(html).toc
+      return html unless toc_enabled?
+      ::Jekyll::TableOfContents::Parser.new(html, toc_config).toc
     end
 
     private
 
-    def page
-      @context.registers[:page]
+    def toc_enabled?
+      @context.registers[:page]['toc'] == true
+    end
+
+    def toc_config
+      @context.registers[:site].config["toc"]
     end
   end
 end
 
 Liquid::Template.register_filter(Jekyll::TableOfContentsFilter)
+# Liquid::Template.register_tag('toc', Jekyll::TocTag) # will be enabled at v1.0

lib/table_of_contents/parser.rb

@@ -4,8 +4,15 @@ module TableOfContents
     class Parser
       PUNCTUATION_REGEXP = /[^\p{Word}\- ]/u
 
-      def initialize(html)
+      DEFAULT_CONFIG = {
+        "min_level" => 1,
+        "max_level" => 6,
+      }
+
+      def initialize(html, options = {})
         @doc = Nokogiri::HTML::DocumentFragment.parse(html)
+        options = DEFAULT_CONFIG.merge(options)
+        @toc_levels = options["min_level"]..options["max_level"]
         @entries = parse_content
       end
 
@@ -33,7 +40,8 @@ def parse_content
         entries = []
         headers = Hash.new(0)
 
-        @doc.css('h1, h2, h3, h4, h5, h6').each do |node|
+        # TODO: Use kramdown auto ids
+        @doc.css(toc_headings).each do |node|
           text = node.text
           id = text.downcase
           id.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
@@ -104,6 +112,10 @@ def get_nest_entries(entries, min_h_num)
           nest_entries << entry
         end
       end
+
+      def toc_headings
+        @toc_levels.map { |level| "h#{level}" }.join(",")
+      end
     end
   end
 end

test/test_kramdown_list.rb

@@ -1,6 +1,23 @@
 require 'test_helper'
 
 class TestKramdownList < Minitest::Test
+  # NOTE: kramdown automatically injects `id` attribute
+  # TODO: test Japanese heading
+  def test_kramdown_heading
+    text = <<-MARKDOWN
+# h1
+
+## h2
+    MARKDOWN
+    expected = <<-HTML
+<h1 id="h1">h1</h1>
+
+<h2 id=\"h2\">h2</h2>
+    HTML
+
+    assert_equal(expected, Kramdown::Document.new(text).to_html)
+  end
+
   def test_kramdown_list_1
     text = <<-MARKDOWN
 * level-1
@@ -72,12 +89,15 @@ def test_kramdown_list_3
 * level-1
     MARKDOWN
     expected = <<-HTML
+<pre><code>  * level-4
+* level-3   * level-2 * level-1
+</code></pre>
     HTML
 
     assert_equal(expected, Kramdown::Document.new(text).to_html)
   end
 
-  def test_kramdown_list_3
+  def test_kramdown_list_4
     text = <<-MARKDOWN
 * level-1
       * level-4
@@ -101,7 +121,7 @@ def test_kramdown_list_3
     assert_equal(expected, Kramdown::Document.new(text).to_html)
   end
 
-    def test_kramdown_list_3
+    def test_kramdown_list_5
       text = <<-MARKDOWN
 * level-1
     * level-3

test/test_various_toc_html.rb

@@ -53,6 +53,18 @@ def test_nested_toc
     assert_equal(expected, doc.css('ul.section-nav').to_s)
   end
 
+  def test_nested_toc_with_min_and_max
+    parser = Jekyll::TableOfContents::Parser.new(TEST_HTML_1, { "min_level" => 2, "max_level" => 5 })
+    doc = Nokogiri::HTML(parser.toc)
+    expected = <<-HTML
+<ul class="section-nav">
+<li class="toc-entry toc-h3"><a href="#h3">h3</a></li>
+</ul>
+    HTML
+
+    assert_equal(expected, doc.css('ul.section-nav').to_s)
+  end
+
   def test_complex_nested_toc
     parser = Jekyll::TableOfContents::Parser.new(TEST_HTML_2)
     doc = Nokogiri::HTML(parser.toc)
@@ -76,7 +88,7 @@ def test_complex_nested_toc
     assert_equal(expected, doc.css('ul.section-nav').to_s)
   end
 
-  def test_decremental_headings
+  def test_decremental_headings1
     parser = Jekyll::TableOfContents::Parser.new(TEST_HTML_3)
     doc = Nokogiri::HTML(parser.toc)
     expected = <<-HTML
@@ -94,7 +106,7 @@ def test_decremental_headings
   end
 
 
-  def test_decremental_headings
+  def test_decremental_headings2
     parser = Jekyll::TableOfContents::Parser.new(TEST_HTML_4)
     doc = Nokogiri::HTML(parser.toc)
     expected = <<-HTML