# frozen_string_literal: true require 'rouge/plugins/common_mark' require "asciidoctor/extensions/asciidoctor_kroki/extension" # Generated HTML is transformed back to GFM by app/assets/javascripts/behaviors/markdown/nodes/code_block.js module Banzai module Filter # HTML Filter to highlight fenced code blocks # class SyntaxHighlightFilter < HTML::Pipeline::Filter include OutputSafety PARAMS_DELIMITER = ':' LANG_PARAMS_ATTR = 'data-lang-params' def call doc.search('pre:not([data-math-style]):not([data-mermaid-style]):not([data-kroki-style]) > code').each do |node| highlight_node(node) end doc end 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-#{language}" if 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 highlighted = %(
#{code}
)
# Extracted to a method to measure it
replace_parent_pre_element(node, highlighted)
end
private
def parse_lang_params(language)
return unless language
lang, params = language.split(PARAMS_DELIMITER, 2)
formatted_params = %(#{LANG_PARAMS_ATTR}="#{escape_once(params)}") if params
[lang, formatted_params]
end
# Separate method so it can be instrumented.
def lex(lexer, code)
lexer.lex(code)
end
def lexer_for(language)
(Rouge::Lexer.find(language) || Rouge::Lexers::PlainText).new
end
def replace_parent_pre_element(node, highlighted)
# Replace the parent `pre` element with the entire highlighted block
node.parent.replace(highlighted)
end
def use_rouge?(language)
(%w(math suggestion) + ::AsciidoctorExtensions::Kroki::SUPPORTED_DIAGRAM_NAMES).exclude?(language)
end
end
end
end