Class: Banzai::Filter::SyntaxHighlightFilter

Inherits:
TimeoutHtmlPipelineFilter show all
Includes:
OutputSafety
Defined in:
lib/banzai/filter/syntax_highlight_filter.rb

Overview

HTML Filter to highlight fenced code blocks

Constant Summary collapse

CSS_CLASSES = 
'code highlight js-syntax-highlight'
CSS = 
'pre:not([data-kroki-style]) > code:only-child'
XPATH = 
Gitlab::Utils::Nokogiri.css_to_xpath(CSS).freeze

Constants inherited from TimeoutHtmlPipelineFilter

TimeoutHtmlPipelineFilter::RENDER_TIMEOUT

Instance Method Summary collapse

Methods included from OutputSafety

#escape_once

Methods inherited from TimeoutHtmlPipelineFilter

#call

Instance Method Details

#call_with_timeout ⇒ Object 



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# File 'lib/banzai/filter/syntax_highlight_filter.rb', line 20

def call_with_timeout
  doc.xpath(XPATH).each do |node|
    highlight_node(node)
  end

  doc
end

#highlight_node(code_node) ⇒ Object 



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# File 'lib/banzai/filter/syntax_highlight_filter.rb', line 28

def highlight_node(code_node)
  return if code_node.parent&.parent.nil?

  # maintain existing attributes already added. e.g math and mermaid nodes
  pre_node = code_node.parent

  lang = pre_node['data-canonical-lang']
  retried = false

  if use_rouge?(lang)
    lexer = lexer_for(lang)
    language = lexer.tag
  else
    lexer = Rouge::Lexers::PlainText.new
    language = lang
  end

  begin
    code = Rouge::Formatters::HTMLGitlab.format(lex(lexer, code_node.text), tag: language)
  rescue StandardError
    # Gracefully handle syntax highlighter bugs/errors to ensure users can
    # still access an issue/comment/etc. First, retry with the plain text
    # filter. If that fails, then just skip this entirely, but that would
    # be a pretty bad upstream bug.
    return if retried

    language = nil
    lexer = Rouge::Lexers::PlainText.new
    retried = true

    retry
  end

  code_node.children = code

  # ensure there are no extra children, such as a text node that might
  # show up from an XSS attack
  pre_node.children = code_node

  pre_node.add_class(CSS_CLASSES)
  pre_node.add_class("language-#{language}") if language
  pre_node.set_attribute('lang', language)
  pre_node.set_attribute('v-pre', 'true')
  copy_code_btn = "<copy-code></copy-code>" unless language == 'suggestion'

  highlighted = %(<div class="gl-relative markdown-code-block js-markdown-code">#{pre_node.to_html}#{copy_code_btn}</div>)

  # Extracted to a method to measure it
  replace_pre_element(pre_node, highlighted)
end