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# frozen_string_literal: true
require 'rouge/plugins/common_mark'
require 'asciidoctor/extensions/asciidoctor_kroki/version'
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
LANG_PARAMS_DELIMITER = ':'
LANG_PARAMS_ATTR = 'data-lang-params'
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
def call
doc.xpath(XPATH).each do |node|
highlight_node(node)
end
doc
end
def highlight_node(node)
return if node.parent&.parent.nil?
lang, lang_params = parse_lang_params(node)
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)
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
# maintain existing attributes already added. e.g math and mermaid nodes
node.children = code
pre_node = node.parent
# ensure there are no extra children, such as a text node that might
# show up from an XSS attack
pre_node.children = node
pre_node[:lang] = language
pre_node.add_class(CSS_CLASSES)
pre_node.add_class("language-#{language}") if language
pre_node.set_attribute('data-canonical-lang', escape_once(lang)) if lang != language
pre_node.set_attribute(LANG_PARAMS_ATTR, escape_once(lang_params)) if lang_params.present?
pre_node.set_attribute('v-pre', 'true')
pre_node.remove_attribute('data-meta')
highlighted = %(<div class="gl-relative markdown-code-block js-markdown-code">#{pre_node.to_html}<copy-code></copy-code></div>)
# Extracted to a method to measure it
replace_pre_element(pre_node, highlighted)
end
private
def parse_lang_params(node)
node = node.parent
# Commonmarker's FULL_INFO_STRING render option works with the space delimiter.
# But the current behavior of GitLab's markdown renderer is different - it grabs everything as the single
# line, including language and its options. To keep backward compatibility, we have to parse the old format and
# merge with the new one.
#
# Behaviors before separating language and its parameters:
# Old ones:
# "```ruby with options```" -> '<pre><code lang="ruby with options">'.
# "```ruby:with:options```" -> '<pre><code lang="ruby:with:options">'.
#
# New ones:
# "```ruby with options```" -> '<pre><code lang="ruby" data-meta="with options">'.
# "```ruby:with:options```" -> '<pre><code lang="ruby:with:options">'.
language = node.attr('lang')
return unless language
language, language_params = language.split(LANG_PARAMS_DELIMITER, 2)
language_params = [node.attr('data-meta'), language_params].compact.join(' ')
[language, language_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
# Replace the `pre` element with the entire highlighted block
def replace_pre_element(pre_node, highlighted)
pre_node.replace(highlighted)
end
def use_rouge?(language)
(%w(math suggestion) + ::AsciidoctorExtensions::Kroki::SUPPORTED_DIAGRAM_NAMES).exclude?(language)
end
end
end
end
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