Do a second xpath search to match elements without parent node

Fixes gjtorikian#133

lib/html/pipeline/emoji_filter.rb

@@ -15,16 +15,28 @@ class Pipeline
     #   :asset_path (optional) - url path to link to emoji sprite. :file_name can be used as a placeholder for the sprite file name. If no asset_path is set "emoji/:file_name" is used.
     class EmojiFilter < Filter
       def call
-        doc.search('text()').each do |node|
-          content = node.to_html
-          next if !content.include?(':')
-          next if has_ancestor?(node, %w(pre code))
-          html = emoji_image_filter(content)
-          next if html == content
-          node.replace(html)
+        doc.xpath('.//text()').each do |node|
+          process_node(node)
+        end
+
+        # Second search to match text nodes which don't have a parent node
+        doc.xpath('text()').each do |node|
+          process_node(node)
         end
         doc
       end
+
+      # Process a given node and replaces all :emoji: with corresponding image.
+      #
+      # node - Text node to be processed
+      def process_node(node)
+        content = node.to_html
+        return unless content.include?(':')
+        return if has_ancestor?(node, %w(pre code))
+        html = emoji_image_filter(content)
+        return if html == content
+        node.replace(html)
+      end
 
       # Implementation of validate hook.
       # Errors should raise exceptions or use an existing validator.

test/html/pipeline/emoji_filter_test.rb

@@ -8,6 +8,12 @@ def test_emojify
     doc = filter.call
     assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
   end
+
+  def test_emojify_on_string
+    filter = EmojiFilter.new(":shipit:", {:asset_root => 'https://foo.com'})
+    doc = filter.call
+    assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
+  end
 
   def test_uri_encoding
     filter = EmojiFilter.new("<p>:+1:</p>", {:asset_root => 'https://foo.com'})