feat: Don’t mark external links based on selector

riboseinc/jekyll-theme-open-project#48

lib/jekyll-theme-open-project-helpers/external_links.rb

@@ -1,27 +1,48 @@
 require 'nokogiri'
 require 'uri'
 
-def process_content(site_hostname, content)
+# Given hostname and content, updates <a> elements as follows:
+#
+# - Adds `rel` attribute
+# - Appends inner markup for FontAwesome external link icon
+#
+# Only processes external links where `href` starts with "http"
+# and target host does not include given site hostname.
+def process_content(site_hostname, content, exclude_selectors=[])
   content = Nokogiri::HTML(content)
   content.css('body.site--project main a, body.site--hub.layout--post main a').each do |a|
     next unless a.get_attribute('href') =~ /\Ahttp/i
     next if a.get_attribute('href').include? site_hostname
+    next if matches_one_of(a, exclude_selectors)
     a.set_attribute('rel', 'external')
     a.inner_html = "#{a.inner_html}<span class='ico-ext'><i class='fas fa-external-link-square'></i></span>"
   end
   return content.to_s
 end
 
+# Returns true if Nokogiri’s Node matches one of selectors,
+# otherwise return false
+def matches_one_of(node, selectors)
+  for selector in selectors
+    if node.matches? selector
+      return true
+    end
+  end
+  return false
+end
+
 Jekyll::Hooks.register :documents, :post_render do |doc|
   site_hostname = URI(doc.site.config['url']).host
+  unmarked_link_selectors = doc.site.config['unmarked_external_link_selectors']
   unless doc.asset_file?
-    doc.output = process_content(site_hostname, doc.output)
+    doc.output = process_content(site_hostname, doc.output, unmarked_link_selectors)
   end
 end
 
 Jekyll::Hooks.register :pages, :post_render do |page|
   site_hostname = URI(page.site.config['url']).host
+  unmarked_link_selectors = page.site.config['unmarked_external_link_selectors']
   unless page.asset_file?
-    page.output = process_content(site_hostname, page.output)
+    page.output = process_content(site_hostname, page.output, unmarked_link_selectors)
   end
 end