56 lines
1.4 KiB
Ruby
56 lines
1.4 KiB
Ruby
require 'rouge/plugins/redcarpet'
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module Banzai
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module Filter
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# HTML Filter to highlight fenced code blocks
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#
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class SyntaxHighlightFilter < HTML::Pipeline::Filter
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include Rouge::Plugins::Redcarpet
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def call
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doc.search('pre > code').each do |node|
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highlight_node(node)
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end
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doc
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end
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def highlight_node(node)
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language = node.attr('class')
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code = node.text
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css_classes = "code highlight"
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lexer = Rouge::Lexer.find_fancy(language) || Rouge::Lexers::PlainText
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formatter = Rouge::Formatters::HTML.new
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begin
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code = formatter.format(lexer.lex(code))
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css_classes << " js-syntax-highlight #{lexer.tag}"
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rescue
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# Gracefully handle syntax highlighter bugs/errors to ensure
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# users can still access an issue/comment/etc.
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end
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highlighted = %(<pre class="#{css_classes}"><code>#{code}</code></pre>)
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# Extracted to a method to measure it
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replace_parent_pre_element(node, highlighted)
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end
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private
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def replace_parent_pre_element(node, highlighted)
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# Replace the parent `pre` element with the entire highlighted block
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node.parent.replace(highlighted)
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end
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# Override Rouge::Plugins::Redcarpet#rouge_formatter
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def rouge_formatter(lexer)
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Rouge::Formatters::HTML.new
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end
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end
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end
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end
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