57 lines
1.5 KiB
Ruby
57 lines
1.5 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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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('lang')
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code = node.text
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css_classes = "code highlight"
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lexer = lexer_for(language)
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lang = lexer.tag
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begin
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code = Rouge::Formatters::HTMLGitlab.format(lex(lexer, code), tag: lang)
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css_classes << " js-syntax-highlight #{lang}"
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rescue
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lang = nil
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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}" lang="#{lang}" v-pre="true"><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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# Separate method so it can be instrumented.
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def lex(lexer, code)
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lexer.lex(code)
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end
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def lexer_for(language)
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(Rouge::Lexer.find(language) || Rouge::Lexers::PlainText).new
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end
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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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end
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end
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end
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