From 954f30767307d6e29f51b66b3c6b2848cafc81d5 Mon Sep 17 00:00:00 2001
From: Stan Hu <stanhu@gmail.com>
Date: Mon, 23 Jul 2018 03:05:22 -0700
Subject: Enable frozen strings in remaining lib/banzai/filter/*.rb files

This also fixes a bug with the ImageLazyLoadFilter not doing the right
thing when an existing class attribute is present.

Part of #47424
---
 lib/banzai/filter/image_lazy_load_filter.rb   | 4 +++-
 lib/banzai/filter/syntax_highlight_filter.rb  | 4 +++-
 lib/banzai/filter/table_of_contents_filter.rb | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

(limited to 'lib/banzai')

diff --git a/lib/banzai/filter/image_lazy_load_filter.rb b/lib/banzai/filter/image_lazy_load_filter.rb
index 4cd9b02b76c..afaee70f351 100644
--- a/lib/banzai/filter/image_lazy_load_filter.rb
+++ b/lib/banzai/filter/image_lazy_load_filter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Banzai
   module Filter
     # HTML filter that moves the value of image `src` attributes to `data-src`
@@ -5,7 +7,7 @@ module Banzai
     class ImageLazyLoadFilter < HTML::Pipeline::Filter
       def call
         doc.xpath('descendant-or-self::img').each do |img|
-          img['class'] ||= '' << 'lazy'
+          img.add_class('lazy')
           img['data-src'] = img['src']
           img['src'] = LazyImageTagHelper.placeholder_image
         end
diff --git a/lib/banzai/filter/syntax_highlight_filter.rb b/lib/banzai/filter/syntax_highlight_filter.rb
index 6dbf0d68fe8..8a7f9045c24 100644
--- a/lib/banzai/filter/syntax_highlight_filter.rb
+++ b/lib/banzai/filter/syntax_highlight_filter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rouge/plugins/common_mark'
 require 'rouge/plugins/redcarpet'
 
@@ -15,7 +17,7 @@ module Banzai
       end
 
       def highlight_node(node)
-        css_classes = 'code highlight js-syntax-highlight'
+        css_classes = +'code highlight js-syntax-highlight'
         lang = node.attr('lang')
         retried = false
 
diff --git a/lib/banzai/filter/table_of_contents_filter.rb b/lib/banzai/filter/table_of_contents_filter.rb
index b32660a8341..c6d1e028eaa 100644
--- a/lib/banzai/filter/table_of_contents_filter.rb
+++ b/lib/banzai/filter/table_of_contents_filter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Banzai
   module Filter
     # HTML filter that adds an anchor child element to all Headers in a
@@ -19,7 +21,7 @@ module Banzai
       def call
         return doc if context[:no_header_anchors]
 
-        result[:toc] = ""
+        result[:toc] = +""
 
         headers = Hash.new(0)
         header_root = current_header = HeaderNode.new
-- 
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