93 lines
2.6 KiB
Ruby
93 lines
2.6 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
require 'rouge/plugins/common_mark'
|
|
|
|
# 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]) > 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}" 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
|
|
|
|
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 mermaid plantuml suggestion).exclude?(language)
|
|
end
|
|
end
|
|
end
|
|
end
|