63 lines
1.9 KiB
Ruby
63 lines
1.9 KiB
Ruby
module Banzai
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module Filter
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# HTML filter that adds an anchor child element to all Headers in a
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# document, so that they can be linked to.
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#
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# Generates the Table of Contents with links to each header. See Results.
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#
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# Based on HTML::Pipeline::TableOfContentsFilter.
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#
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# Context options:
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# :no_header_anchors - Skips all processing done by this filter.
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#
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# Results:
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# :toc - String containing Table of Contents data as a `ul` element with
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# `li` child elements.
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class TableOfContentsFilter < HTML::Pipeline::Filter
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PUNCTUATION_REGEXP = /[^\p{Word}\- ]/u
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def call
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return doc if context[:no_header_anchors]
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result[:toc] = ""
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headers = Hash.new(0)
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doc.css('h1, h2, h3, h4, h5, h6').each do |node|
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text = node.text
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id = text.downcase
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id.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
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id.tr!(' ', '-') # replace spaces with dash
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id.squeeze!('-') # replace multiple dashes with one
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uniq = (headers[id] > 0) ? "-#{headers[id]}" : ''
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headers[id] += 1
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if header_content = node.children.first
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# namespace detection will be automatically handled via javascript (see issue #22781)
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namespace = "user-content-"
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href = "#{id}#{uniq}"
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push_toc(href, text)
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header_content.add_previous_sibling(anchor_tag("#{namespace}#{href}", href))
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end
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end
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result[:toc] = %Q{<ul class="section-nav">\n#{result[:toc]}</ul>} unless result[:toc].empty?
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doc
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end
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private
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def anchor_tag(id, href)
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%Q{<a id="#{id}" class="anchor" href="##{href}" aria-hidden="true"></a>}
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end
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def push_toc(href, text)
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result[:toc] << %Q{<li><a href="##{href}">#{text}</a></li>\n}
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end
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end
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end
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end
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