From ecdbbfd2b08ccac7fbae9233ce3d9ee457d6e6cf Mon Sep 17 00:00:00 2001
From: Joseph Wynn <joseph@wildlyinaccurate.com>
Date: Tue, 2 Feb 2016 20:33:24 +0000
Subject: [PATCH] [Experimental] enable internal caching of responsive_image
 tag results

---
 lib/jekyll/responsive_image.rb              |  1 +
 lib/jekyll/responsive_image/render_cache.rb | 21 ++++++++++++++++
 lib/jekyll/responsive_image/tag.rb          | 27 ++++++++++++++-------
 3 files changed, 40 insertions(+), 9 deletions(-)
 create mode 100644 lib/jekyll/responsive_image/render_cache.rb

diff --git a/lib/jekyll/responsive_image.rb b/lib/jekyll/responsive_image.rb
index 6d0dcf5..06fd05c 100644
--- a/lib/jekyll/responsive_image.rb
+++ b/lib/jekyll/responsive_image.rb
@@ -7,6 +7,7 @@ require 'rmagick'
 require 'jekyll/responsive_image/version'
 require 'jekyll/responsive_image/defaults'
 require 'jekyll/responsive_image/utils'
+require 'jekyll/responsive_image/render_cache'
 require 'jekyll/responsive_image/image_processor'
 require 'jekyll/responsive_image/resize_handler'
 require 'jekyll/responsive_image/common'
diff --git a/lib/jekyll/responsive_image/render_cache.rb b/lib/jekyll/responsive_image/render_cache.rb
new file mode 100644
index 0000000..6de1768
--- /dev/null
+++ b/lib/jekyll/responsive_image/render_cache.rb
@@ -0,0 +1,21 @@
+module Jekyll
+  class ResponsiveImage
+    class RenderCache
+      attr_accessor :store
+
+      class << self
+        def store
+          @store ||= {}
+        end
+
+        def get(key)
+          store[key]
+        end
+
+        def set(key, val)
+          store[key] = val
+        end
+      end
+    end
+  end
+end
diff --git a/lib/jekyll/responsive_image/tag.rb b/lib/jekyll/responsive_image/tag.rb
index 714dc60..f601aca 100644
--- a/lib/jekyll/responsive_image/tag.rb
+++ b/lib/jekyll/responsive_image/tag.rb
@@ -15,19 +15,28 @@ module Jekyll
       end
 
       def render(context)
-        site = context.registers[:site]
-        config = make_config(site)
+        cache_key = @attributes.to_s
+        result = @attributes['cache'] ? RenderCache.get(cache_key) : nil
 
-        image = ImageProcessor.process(@attributes['path'], config)
-        @attributes['original'] = image[:original]
-        @attributes['resized'] = image[:resized]
+        if result.nil?
+          site = context.registers[:site]
+          config = make_config(site)
 
-        image_template = @attributes['template'] || config['template']
+          image = ImageProcessor.process(@attributes['path'], config)
+          @attributes['original'] = image[:original]
+          @attributes['resized'] = image[:resized]
 
-        partial = File.read(image_template)
-        template = Liquid::Template.parse(partial)
+          image_template = @attributes['template'] || config['template']
 
-        template.render!(@attributes.merge(site.site_payload))
+          partial = File.read(image_template)
+          template = Liquid::Template.parse(partial)
+
+          result = template.render!(@attributes.merge(site.site_payload))
+
+          RenderCache.set(cache_key, result)
+        end
+
+        result
       end
     end
   end