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# frozen_string_literal: true
# `CommonMark` markdown engine for GitLab's Banzai markdown filter.
# This module is used in Banzai::Filter::MarkdownFilter.
# Used gem is `commonmarker` which is a ruby wrapper for libcmark (CommonMark parser)
# including GitHub's GFM extensions.
# Homepage: https://github.com/gjtorikian/commonmarker
module Banzai
module Filter
module MarkdownEngines
class CommonMark
EXTENSIONS = [
:autolink, # provides support for automatically converting URLs to anchor tags.
:strikethrough, # provides support for strikethroughs.
:table # provides support for tables.
].freeze
PARSE_OPTIONS = [
:FOOTNOTES, # parse footnotes.
:STRIKETHROUGH_DOUBLE_TILDE, # parse strikethroughs by double tildes (as redcarpet does).
:VALIDATE_UTF8 # replace illegal sequences with the replacement character U+FFFD.
].freeze
RENDER_OPTIONS_C = [
:GITHUB_PRE_LANG, # use GitHub-style <pre lang> for fenced code blocks.
:FOOTNOTES, # render footnotes.
:FULL_INFO_STRING, # include full info strings of code blocks in separate attribute.
:UNSAFE # allow raw/custom HTML and unsafe links.
].freeze
# The `:GITHUB_PRE_LANG` option is not used intentionally because
# it renders a fence block with language as `<pre lang="LANG"><code>some code\n</code></pre>`
# while GitLab's syntax is `<pre><code lang="LANG">some code\n</code></pre>`.
# If in the future the syntax is about to be made GitHub-compatible, please, add `:GITHUB_PRE_LANG` render option below
# and remove `code_block` method from `lib/banzai/renderer/common_mark/html.rb`.
RENDER_OPTIONS_RUBY = [
# as of commonmarker 0.18.0, we need to use :UNSAFE to get the same as the original :DEFAULT
# https://github.com/gjtorikian/commonmarker/pull/81
:UNSAFE # allow raw/custom HTML and unsafe links.
].freeze
def initialize(context)
@context = context
@renderer = Banzai::Renderer::CommonMark::HTML.new(options: render_options) if Feature.disabled?(:use_cmark_renderer, default_enabled: :yaml)
end
def render(text)
if Feature.enabled?(:use_cmark_renderer, default_enabled: :yaml)
CommonMarker.render_html(text, render_options, extensions)
else
doc = CommonMarker.render_doc(text, PARSE_OPTIONS, extensions)
@renderer.render(doc)
end
end
private
def extensions
if Feature.enabled?(:use_cmark_renderer, default_enabled: :yaml)
EXTENSIONS
else
EXTENSIONS + [
:tagfilter # strips out several "unsafe" HTML tags from being used: https://github.github.com/gfm/#disallowed-raw-html-extension-
].freeze
end
end
def render_options
@context[:no_sourcepos] ? render_options_no_sourcepos : render_options_sourcepos
end
def render_options_no_sourcepos
Feature.enabled?(:use_cmark_renderer, default_enabled: :yaml) ? RENDER_OPTIONS_C : RENDER_OPTIONS_RUBY
end
def render_options_sourcepos
render_options_no_sourcepos + [
:SOURCEPOS # enable embedding of source position information
].freeze
end
end
end
end
end
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