Class: Banzai::Filter::SyntaxHighlightFilter

Inherits:
HTML::Pipeline::Filter
  • Object
show all
Includes:
OutputSafety
Defined in:
lib/banzai/filter/syntax_highlight_filter.rb

Overview

HTML Filter to highlight fenced code blocks

Constant Summary collapse

PARAMS_DELIMITER = 
':'
LANG_PARAMS_ATTR = 
'data-lang-params'

Instance Method Summary collapse

Methods included from OutputSafety

#escape_once

Instance Method Details

#call ⇒ Object 


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# File 'lib/banzai/filter/syntax_highlight_filter.rb', line 16

def call
  doc.search('pre:not([data-math-style]):not([data-mermaid-style]) > code').each do |node|
    highlight_node(node)
  end

  doc
end

#highlight_node(node) ⇒ Object 


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# File 'lib/banzai/filter/syntax_highlight_filter.rb', line 24

def highlight_node(node)
  css_classes = +'code highlight js-syntax-highlight'
  lang, lang_params = parse_lang_params(node.attr('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, node.text), tag: language)
    css_classes << " #{language}" if language
  rescue
    # 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

  highlighted = %(<pre class="#{css_classes}"
                       lang="#{language}"
                       #{lang_params}
                       v-pre="true"><code>#{code}</code></pre>)

  # Extracted to a method to measure it
  replace_parent_pre_element(node, highlighted)
end