/lib/banzai/filter/table_of_contents_filter.rb
https://gitlab.com/vicvega/gitlab-ce · Ruby · 60 lines · 35 code · 12 blank · 13 comment · 2 complexity · 98dce5d29457e4d0b21b87f04a657c5f MD5 · raw file
- module Banzai
- module Filter
- # HTML filter that adds an anchor child element to all Headers in a
- # document, so that they can be linked to.
- #
- # Generates the Table of Contents with links to each header. See Results.
- #
- # Based on HTML::Pipeline::TableOfContentsFilter.
- #
- # Context options:
- # :no_header_anchors - Skips all processing done by this filter.
- #
- # Results:
- # :toc - String containing Table of Contents data as a `ul` element with
- # `li` child elements.
- class TableOfContentsFilter < HTML::Pipeline::Filter
- PUNCTUATION_REGEXP = /[^\p{Word}\- ]/u
- def call
- return doc if context[:no_header_anchors]
- result[:toc] = ""
- headers = Hash.new(0)
- doc.css('h1, h2, h3, h4, h5, h6').each do |node|
- text = node.text
- id = text.downcase
- id.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
- id.tr!(' ', '-') # replace spaces with dash
- id.squeeze!('-') # replace multiple dashes with one
- uniq = (headers[id] > 0) ? "-#{headers[id]}" : ''
- headers[id] += 1
- if header_content = node.children.first
- href = "#{id}#{uniq}"
- push_toc(href, text)
- header_content.add_previous_sibling(anchor_tag(href))
- end
- end
- result[:toc] = %Q{<ul class="section-nav">\n#{result[:toc]}</ul>} unless result[:toc].empty?
- doc
- end
- private
- def anchor_tag(href)
- %Q{<a id="#{href}" class="anchor" href="##{href}" aria-hidden="true"></a>}
- end
- def push_toc(href, text)
- result[:toc] << %Q{<li><a href="##{href}">#{text}</a></li>\n}
- end
- end
- end
- end