Control jemoji with a front matter variable
| Author: | Admin |
| Title: | Control jemoji plugin with front matter variable |
| Language: | en-US |
| Number of words: | 349 |
| Created: | 04:46 on Friday, 08. October 2021 |
| Modified: | 04:46 on Friday, 08. October 2021 |
| Keywords: | jekyll, ruby, yaml, frontmatter |
| Excerpt: | Use a front matter variable to control the jemoji plugin in Jekyll. This allows to disable emjoi parsing for a single page. |
| Tags: | Jekyll |
| Page layout: | nonav |
This is a very minor modification of the Jekyll jemoji plugin. It allows to set a front matter variable emoji: false to disable emoji parsing for the entire document. The plugin is fairly simple and consists of only a single Ruby source code file with the name jemoji.rb.
The relevant change(s) can be found in the emojiable? method between lines 65 to 68. It checks for the presence of a emoji variable in the document’s data (frontmatter) and returns false when the variable is present with a value of false. This can be useful for pages that contain source code or similar content that might contain emoji character sequences when it is not desirable to parse them.
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# frozen_string_literal: true
require "jekyll"
require "html/pipeline"
module Jekyll
class Emoji
GITHUB_DOT_COM_ASSET_HOST_URL = "https://github.githubassets.com"
ASSET_PATH = "/images/icons/"
BODY_START_TAG = "<body"
OPENING_BODY_TAG_REGEX = %r!<body(.*?)>\s*!m.freeze
class << self
def emojify(doc)
return unless doc.output&.match?(HTML::Pipeline::EmojiFilter.emoji_pattern)
doc.output = if doc.output.include? BODY_START_TAG
replace_document_body(doc)
else
src = emoji_src(doc.site.config)
filter_with_emoji(src).call(doc.output)[:output].to_s
end
end
# Public: Create or fetch the filter for the given asset root.
#
# src - the asset root URL (e.g. https://github.githubassets.com/images/icons/)
#
# Returns an HTML::Pipeline instance for the given asset root.
def filter_with_emoji(src)
filters[src] ||= HTML::Pipeline.new([
HTML::Pipeline::EmojiFilter,
], :asset_root => src, :img_attrs => { :align => nil })
end
# Public: Filters hash where the key is the asset root source.
# Effectively a cache.
def filters
@filters ||= {}
end
# Public: Calculate the asset root source for the given config.
# The custom emoji asset root can be defined in the config as
# emoji.src, and must be a valid URL (i.e. it must include a
# protocol and valid domain)
#
# config - the hash-like configuration of the document's site
#
# Returns a full URL to use as the asset root URL. Defaults to the root
# URL for assets provided by an ASSET_HOST_URL environment variable,
# otherwise the root URL for emoji assets at assets-cdn.github.com.
def emoji_src(config = {})
if config.key?("emoji") && config["emoji"].key?("src")
config["emoji"]["src"]
else
default_asset_root
end
end
# Public: Defines the conditions for a document to be emojiable.
#
# doc - the Jekyll::Document or Jekyll::Page
#
# Returns true if the doc is written & is HTML and does not forbid
# emoji parsing via front matter variable emoji: false.
def emojiable?(doc)
(doc.is_a?(Jekyll::Page) || doc.write?) && doc.data["emoji"] != false &&
doc.output_ext == ".html" || (doc.permalink&.end_with?("/"))
end
private
def default_asset_root
if !ENV["ASSET_HOST_URL"].to_s.empty?
# Ensure that any trailing "/" is trimmed
asset_host_url = ENV["ASSET_HOST_URL"].chomp("/")
"#{asset_host_url}#{ASSET_PATH}"
else
"#{GITHUB_DOT_COM_ASSET_HOST_URL}#{ASSET_PATH}"
end
end
def replace_document_body(doc)
src = emoji_src(doc.site.config)
head, opener, tail = doc.output.partition(OPENING_BODY_TAG_REGEX)
body_content, *rest = tail.partition("</body>")
processed_markup = filter_with_emoji(src).call(body_content)[:output].to_s
String.new(head) << opener << processed_markup << rest.join
end
end
end
end
Jekyll::Hooks.register [:pages, :documents], :post_render do |doc|
Jekyll::Emoji.emojify(doc) if Jekyll::Emoji.emojiable?(doc)
end