From 7e872091e104be09deb8b39ec73ab4792a44d4e9 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Mon, 24 Feb 2020 19:17:38 -0800
Subject: [PATCH 01/44] pull template keys up

---
 .../action_view/renderer/partial_renderer.rb  | 25 +++++++++----------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index b008b1fdd2..5150d7df53 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -296,12 +296,21 @@ module ActionView
       setup(context, options, as, block)
 
       if @path
+        @variable           = nil
+        @variable_counter   = nil
+        @variable_iteration = nil
+        @template_keys      = @locals.keys
+
         if @has_object || @collection
           @variable, @variable_counter, @variable_iteration = retrieve_variable(@path, as)
-          @template_keys = retrieve_template_keys(@variable)
-        else
-          @template_keys = @locals.keys
+          @template_keys << @variable
+
+          if @collection
+            @template_keys << @variable_counter
+            @template_keys << @variable_iteration
+          end
         end
+
         template = find_template(@path, @template_keys)
         @variable ||= template.variable
       else
@@ -517,16 +526,6 @@ module ActionView
         end
       end
 
-      def retrieve_template_keys(variable)
-        keys = @locals.keys
-        keys << variable
-        if @collection
-          keys << @variable_counter
-          keys << @variable_iteration
-        end
-        keys
-      end
-
       def retrieve_variable(path, as)
         variable = as || begin
           base = path[-1] == "/" ? "" : File.basename(path)

From dc1633090e6689d53e688c7bc8357ac3b31f4c70 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Mon, 24 Feb 2020 19:43:28 -0800
Subject: [PATCH 02/44] extract template keys to a method

---
 .../action_view/renderer/partial_renderer.rb  | 23 ++++++++++---------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 5150d7df53..e8faef27a3 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -291,27 +291,28 @@ module ActionView
       @context_prefix = @lookup_context.prefixes.first
     end
 
+    def template_keys
+      if @has_object || @collection
+        @locals.keys + retrieve_variable(@path, @as)
+      else
+        @locals.keys
+      end
+    end
+
     def render(context, options, block)
-      as = as_variable(options)
+      as = @as = as_variable(options)
       setup(context, options, as, block)
 
       if @path
         @variable           = nil
         @variable_counter   = nil
         @variable_iteration = nil
-        @template_keys      = @locals.keys
 
         if @has_object || @collection
           @variable, @variable_counter, @variable_iteration = retrieve_variable(@path, as)
-          @template_keys << @variable
-
-          if @collection
-            @template_keys << @variable_counter
-            @template_keys << @variable_iteration
-          end
         end
 
-        template = find_template(@path, @template_keys)
+        template = find_template(@path, template_keys)
         @variable ||= template.variable
       else
         if options[:cached]
@@ -357,7 +358,7 @@ module ActionView
           object, as = @object, @variable
 
           if !block && (layout = @options[:layout])
-            layout = find_template(layout.to_s, @template_keys)
+            layout = find_template(layout.to_s, template_keys)
           end
 
           object = locals[as] if object.nil? # Respect object when object is false
@@ -443,7 +444,7 @@ module ActionView
         as, counter, iteration = @variable, @variable_counter, @variable_iteration
 
         if layout = @options[:layout]
-          layout = find_template(layout, @template_keys)
+          layout = find_template(layout, template_keys)
         end
 
         partial_iteration = PartialIteration.new(@collection.size)

From 96f89fbf5dd345116ead5e88fa99723985c7a4ff Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 10:05:42 -0800
Subject: [PATCH 03/44] collection with/without template are more similar

---
 .../action_view/renderer/partial_renderer.rb  | 30 +++++++++----------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index e8faef27a3..461976fd0b 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -300,20 +300,12 @@ module ActionView
     end
 
     def render(context, options, block)
-      as = @as = as_variable(options)
-      setup(context, options, as, block)
+      @as = as_variable(options)
+      setup(context, options, @as, block)
 
       if @path
-        @variable           = nil
-        @variable_counter   = nil
-        @variable_iteration = nil
-
-        if @has_object || @collection
-          @variable, @variable_counter, @variable_iteration = retrieve_variable(@path, as)
-        end
-
         template = find_template(@path, template_keys)
-        @variable ||= template.variable
+        @variable = template.variable
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -395,6 +387,11 @@ module ActionView
           @object     = options[:object]
           @collection = collection_from_options
           @path       = partial
+
+          if @collection
+            paths = @collection_data = @collection.map { |o| @path }
+            paths.map! { |path| retrieve_variable(path, as).unshift(path) }
+          end
         else
           @has_object = true
           @object = partial
@@ -404,6 +401,7 @@ module ActionView
             paths = @collection_data = @collection.map { |o| partial_path(o, context) }
             if paths.uniq.length == 1
               @path = paths.first
+              paths.map! { |path| retrieve_variable(path, as).unshift(path) }
             else
               paths.map! { |path| retrieve_variable(path, as).unshift(path) }
               @path = nil
@@ -440,19 +438,21 @@ module ActionView
       end
 
       def collection_with_template(view, template)
-        locals = @locals
-        as, counter, iteration = @variable, @variable_counter, @variable_iteration
+        locals, collection_data = @locals, @collection_data
 
         if layout = @options[:layout]
           layout = find_template(layout, template_keys)
         end
 
         partial_iteration = PartialIteration.new(@collection.size)
-        locals[iteration] = partial_iteration
 
         @collection.map do |object|
+          index = partial_iteration.index
+          path, as, counter, iteration = collection_data[index]
+
           locals[as]        = object
-          locals[counter]   = partial_iteration.index
+          locals[counter]   = index
+          locals[iteration] = partial_iteration
 
           content = template.render(view, locals)
           content = layout.render(view, locals) { content } if layout

From 867c4c2e601ea204a59ed020e440df9b58af802f Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 10:19:19 -0800
Subject: [PATCH 04/44] collection with/without template are the same

---
 .../action_view/renderer/partial_renderer.rb  | 30 ++++---------------
 .../collection_cache_association_loading.rb   |  5 ----
 2 files changed, 5 insertions(+), 30 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 461976fd0b..e3f54e0603 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -338,7 +338,7 @@ module ActionView
               collection_with_template(view, template)
             end
           else
-            collection_without_template(view)
+            collection_with_template(view, nil)
           end
           build_rendered_collection(collection_body, spacer)
         end
@@ -439,6 +439,7 @@ module ActionView
 
       def collection_with_template(view, template)
         locals, collection_data = @locals, @collection_data
+        cache = {}
 
         if layout = @options[:layout]
           layout = find_template(layout, template_keys)
@@ -454,32 +455,11 @@ module ActionView
           locals[counter]   = index
           locals[iteration] = partial_iteration
 
-          content = template.render(view, locals)
+          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
+          content = _template.render(view, locals)
           content = layout.render(view, locals) { content } if layout
           partial_iteration.iterate!
-          build_rendered_template(content, template)
-        end
-      end
-
-      def collection_without_template(view)
-        locals, collection_data = @locals, @collection_data
-        cache = {}
-        keys  = @locals.keys
-
-        partial_iteration = PartialIteration.new(@collection.size)
-
-        @collection.map do |object|
-          index = partial_iteration.index
-          path, as, counter, iteration = collection_data[index]
-
-          locals[as]        = object
-          locals[counter]   = index
-          locals[iteration] = partial_iteration
-
-          template = (cache[path] ||= find_template(path, keys + [as, counter, iteration]))
-          content = template.render(view, locals)
-          partial_iteration.iterate!
-          build_rendered_template(content, template)
+          build_rendered_template(content, _template)
         end
       end
 
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index 6d1bc8e3c4..f529f601bc 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -22,11 +22,6 @@ module ActiveRecord
         end
       end
 
-      def collection_without_template(*)
-        @relation.preload_associations(@collection) if @relation
-        super
-      end
-
       def collection_with_template(*)
         @relation.preload_associations(@collection) if @relation
         super

From 64b3bcb0b9dd4f778cf84eb41c9ea321c7be2417 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 10:26:43 -0800
Subject: [PATCH 05/44] block does not need to be an ivar

---
 .../lib/action_view/renderer/partial_renderer.rb      | 11 +++++------
 .../railties/collection_cache_association_loading.rb  |  2 +-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index e3f54e0603..bede112a36 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -301,7 +301,7 @@ module ActionView
 
     def render(context, options, block)
       @as = as_variable(options)
-      setup(context, options, @as, block)
+      setup(context, options, @as)
 
       if @path
         template = find_template(@path, template_keys)
@@ -316,7 +316,7 @@ module ActionView
       if @collection
         render_collection(context, template)
       else
-        render_partial(context, template)
+        render_partial(context, template, block)
       end
     end
 
@@ -344,9 +344,9 @@ module ActionView
         end
       end
 
-      def render_partial(view, template)
+      def render_partial(view, template, block)
         instrument(:partial, identifier: template.identifier) do |payload|
-          locals, block = @locals, @block
+          locals = @locals
           object, as = @object, @variable
 
           if !block && (layout = @options[:layout])
@@ -373,9 +373,8 @@ module ActionView
       # If +options[:partial]+ is a string, then the <tt>@path</tt> instance variable is
       # set to that string. Otherwise, the +options[:partial]+ object must
       # respond to +to_partial_path+ in order to set up the path.
-      def setup(context, options, as, block)
+      def setup(context, options, as)
         @options = options
-        @block   = block
 
         @locals  = options[:locals] || {}
         @details = extract_details(options)
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index f529f601bc..a8cc6fe9ae 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -3,7 +3,7 @@
 module ActiveRecord
   module Railties # :nodoc:
     module CollectionCacheAssociationLoading #:nodoc:
-      def setup(context, options, as, block)
+      def setup(context, options, as)
         @relation = nil
 
         return super unless options[:cached]

From 99d74cac990981357ae902bcffd38869cae05405 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 13:31:49 -0800
Subject: [PATCH 06/44] Don't rely on the collection ivar

We're going to turn this in to a more complex iterator
---
 .../lib/action_view/renderer/partial_renderer.rb   | 12 ++++++------
 .../partial_renderer/collection_caching.rb         | 14 +++++++-------
 .../collection_cache_association_loading.rb        |  4 ++--
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index bede112a36..b3d8e63e42 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -334,11 +334,11 @@ module ActionView
           end
 
           collection_body = if template
-            cache_collection_render(payload, view, template) do
-              collection_with_template(view, template)
+            cache_collection_render(payload, view, template, @collection) do |collection|
+              collection_with_template(view, template, collection)
             end
           else
-            collection_with_template(view, nil)
+            collection_with_template(view, nil, @collection)
           end
           build_rendered_collection(collection_body, spacer)
         end
@@ -436,7 +436,7 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
 
-      def collection_with_template(view, template)
+      def collection_with_template(view, template, collection)
         locals, collection_data = @locals, @collection_data
         cache = {}
 
@@ -444,9 +444,9 @@ module ActionView
           layout = find_template(layout, template_keys)
         end
 
-        partial_iteration = PartialIteration.new(@collection.size)
+        partial_iteration = PartialIteration.new(collection.size)
 
-        @collection.map do |object|
+        collection.map do |object|
           index = partial_iteration.index
           path, as, counter, iteration = collection_data[index]
 
diff --git a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
index c12a25a5ec..c863ede182 100644
--- a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
@@ -11,13 +11,13 @@ module ActionView
     end
 
     private
-      def cache_collection_render(instrumentation_payload, view, template)
-        return yield unless @options[:cached] && view.controller.respond_to?(:perform_caching) && view.controller.perform_caching
+      def cache_collection_render(instrumentation_payload, view, template, collection)
+        return yield(collection) unless @options[:cached] && view.controller.respond_to?(:perform_caching) && view.controller.perform_caching
 
         # Result is a hash with the key represents the
         # key used for cache lookup and the value is the item
         # on which the partial is being rendered
-        keyed_collection, ordered_keys = collection_by_cache_keys(view, template)
+        keyed_collection, ordered_keys = collection_by_cache_keys(view, template, collection)
 
         # Pull all partials from cache
         # Result is a hash, key matches the entry in
@@ -29,7 +29,7 @@ module ActionView
         # Extract the items for the keys that are not found
         # Set the uncached values to instance variable @collection
         # which is used by the caller
-        @collection = keyed_collection.reject { |key, _| cached_partials.key?(key) }.values
+        collection = keyed_collection.reject { |key, _| cached_partials.key?(key) }.values
 
         # If all elements are already in cache then
         # rendered partials will be an empty array
@@ -37,7 +37,7 @@ module ActionView
         # If the cache is missing elements then
         # the block will be called against the remaining items
         # in the @collection.
-        rendered_partials = @collection.empty? ? [] : yield
+        rendered_partials = collection.empty? ? [] : yield(collection)
 
         index = 0
         keyed_partials = fetch_or_cache_partial(cached_partials, template, order_by: keyed_collection.each_key) do
@@ -55,12 +55,12 @@ module ActionView
         @options[:cached].respond_to?(:call)
       end
 
-      def collection_by_cache_keys(view, template)
+      def collection_by_cache_keys(view, template, collection)
         seed = callable_cache_key? ? @options[:cached] : ->(i) { i }
 
         digest_path = view.digest_path_from_template(template)
 
-        @collection.each_with_object([{}, []]) do |item, (hash, ordered_keys)|
+        collection.each_with_object([{}, []]) do |item, (hash, ordered_keys)|
           key = expanded_cache_key(seed.call(item), view, template, digest_path)
           ordered_keys << key
           hash[key] = item
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index a8cc6fe9ae..2fb44713d5 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -22,8 +22,8 @@ module ActiveRecord
         end
       end
 
-      def collection_with_template(*)
-        @relation.preload_associations(@collection) if @relation
+      def collection_with_template(_, _, collection)
+        @relation.preload_associations(collection) if @relation
         super
       end
     end

From 7a9c90184a932f6a2765248f14597bc37568e534 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 13:42:05 -0800
Subject: [PATCH 07/44] variable ivar is not needed anymore

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index b3d8e63e42..1ac2ad12f5 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -305,7 +305,6 @@ module ActionView
 
       if @path
         template = find_template(@path, template_keys)
-        @variable = template.variable
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -347,7 +346,8 @@ module ActionView
       def render_partial(view, template, block)
         instrument(:partial, identifier: template.identifier) do |payload|
           locals = @locals
-          object, as = @object, @variable
+          as     = template.variable
+          object = @object
 
           if !block && (layout = @options[:layout])
             layout = find_template(layout.to_s, template_keys)
@@ -388,6 +388,7 @@ module ActionView
           @path       = partial
 
           if @collection
+            @has_object = true
             paths = @collection_data = @collection.map { |o| @path }
             paths.map! { |path| retrieve_variable(path, as).unshift(path) }
           end

From 67b1a7942e8b0bc2f30af78bbcb81c535a87e5dc Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 13:52:45 -0800
Subject: [PATCH 08/44] remove useless conditional

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 1ac2ad12f5..6c7715de36 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -353,7 +353,6 @@ module ActionView
             layout = find_template(layout.to_s, template_keys)
           end
 
-          object = locals[as] if object.nil? # Respect object when object is false
           locals[as] = object if @has_object
 
           content = template.render(view, locals) do |*name|

From c52fa675b8784c1bcdc996a353a44922443b0b9f Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 14:12:38 -0800
Subject: [PATCH 09/44] Find the layout earlier

Remove duplication in finding a layout.  Remove `@as` ivar.
---
 .../action_view/renderer/partial_renderer.rb  | 50 +++++++++----------
 .../collection_cache_association_loading.rb   |  2 +-
 2 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 6c7715de36..3672169adb 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -291,20 +291,12 @@ module ActionView
       @context_prefix = @lookup_context.prefixes.first
     end
 
-    def template_keys
-      if @has_object || @collection
-        @locals.keys + retrieve_variable(@path, @as)
-      else
-        @locals.keys
-      end
-    end
-
     def render(context, options, block)
-      @as = as_variable(options)
-      setup(context, options, @as)
+      as = as_variable(options)
+      setup(context, options, as)
 
       if @path
-        template = find_template(@path, template_keys)
+        template = find_template(@path, template_keys(@path, as))
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -312,15 +304,27 @@ module ActionView
         template = nil
       end
 
+      if !block && (layout = @options[:layout])
+        layout = find_template(layout.to_s, template_keys(@path, as))
+      end
+
       if @collection
-        render_collection(context, template)
+        render_collection(context, template, layout)
       else
-        render_partial(context, template, block)
+        render_partial(context, template, layout, block)
       end
     end
 
     private
-      def render_collection(view, template)
+      def template_keys(path, as)
+        if @has_object || @collection
+          @locals.keys + retrieve_variable(path, as)
+        else
+          @locals.keys
+        end
+      end
+
+      def render_collection(view, template, layout)
         identifier = (template && template.identifier) || @path
         instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
           return RenderedCollection.empty(@lookup_context.formats.first) if @collection.blank?
@@ -334,25 +338,21 @@ module ActionView
 
           collection_body = if template
             cache_collection_render(payload, view, template, @collection) do |collection|
-              collection_with_template(view, template, collection)
+              collection_with_template(view, template, layout, collection)
             end
           else
-            collection_with_template(view, nil, @collection)
+            collection_with_template(view, nil, layout, @collection)
           end
           build_rendered_collection(collection_body, spacer)
         end
       end
 
-      def render_partial(view, template, block)
+      def render_partial(view, template, layout, block)
         instrument(:partial, identifier: template.identifier) do |payload|
           locals = @locals
           as     = template.variable
           object = @object
 
-          if !block && (layout = @options[:layout])
-            layout = find_template(layout.to_s, template_keys)
-          end
-
           locals[as] = object if @has_object
 
           content = template.render(view, locals) do |*name|
@@ -436,13 +436,9 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
 
-      def collection_with_template(view, template, collection)
+      def collection_with_template(view, template, layout, collection)
         locals, collection_data = @locals, @collection_data
-        cache = {}
-
-        if layout = @options[:layout]
-          layout = find_template(layout, template_keys)
-        end
+        cache = template || {}
 
         partial_iteration = PartialIteration.new(collection.size)
 
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index 2fb44713d5..2c54647c25 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -22,7 +22,7 @@ module ActiveRecord
         end
       end
 
-      def collection_with_template(_, _, collection)
+      def collection_with_template(_, _, _, collection)
         @relation.preload_associations(collection) if @relation
         super
       end

From 5fa2c69e4b33452020cb4de7d202b3fc787868ea Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 14:42:52 -0800
Subject: [PATCH 10/44] Don't to_a things when we don't need to.

If the partial renderer is passed a relation or collection proxy, it
will be good for us to resolve that relation or collection proxy as late
as possible.
---
 .../lib/action_view/renderer/partial_renderer.rb       | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 3672169adb..fec2f49f42 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -423,12 +423,12 @@ module ActionView
       def collection_from_options
         if @options.key?(:collection)
           collection = @options[:collection]
-          collection ? collection.to_a : []
+          collection || []
         end
       end
 
       def collection_from_object
-        @object.to_ary if @object.respond_to?(:to_ary)
+        @object if @object.respond_to?(:to_ary)
       end
 
       def find_template(path, locals)
@@ -475,16 +475,12 @@ module ActionView
         end
 
         if view.prefix_partial_path_with_controller_namespace
-          prefixed_partial_names[path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
+          PREFIXED_PARTIAL_NAMES[@context_prefix][path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
         else
           path
         end
       end
 
-      def prefixed_partial_names
-        @prefixed_partial_names ||= PREFIXED_PARTIAL_NAMES[@context_prefix]
-      end
-
       def merge_prefix_into_object_path(prefix, object_path)
         if prefix.include?(?/) && object_path.include?(?/)
           prefixes = []

From 638cc381b11d421f30670ea3cf9aa780d710b7bf Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 15:17:05 -0800
Subject: [PATCH 11/44] rely less on the collection ivar

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index fec2f49f42..79b21da623 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -327,8 +327,6 @@ module ActionView
       def render_collection(view, template, layout)
         identifier = (template && template.identifier) || @path
         instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
-          return RenderedCollection.empty(@lookup_context.formats.first) if @collection.blank?
-
           spacer = if @options.key?(:spacer_template)
             spacer_template = find_template(@options[:spacer_template], @locals.keys)
             build_rendered_template(spacer_template.render(view, @locals), spacer_template)
@@ -343,6 +341,9 @@ module ActionView
           else
             collection_with_template(view, nil, layout, @collection)
           end
+
+          return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
+
           build_rendered_collection(collection_body, spacer)
         end
       end

From 347094856caa872117721b0f753a0eb8bdd862a8 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 25 Feb 2020 16:07:36 -0800
Subject: [PATCH 12/44] Only iterate over collections once when a path is
 provided

We'll later reuse this object to speed up the case when a relation is
passed in.
---
 .../action_view/renderer/partial_renderer.rb  | 68 +++++++++++++++++--
 .../partial_renderer/collection_caching.rb    | 10 ++-
 .../collection_cache_association_loading.rb   |  2 +-
 3 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 79b21da623..87d9a620f7 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -366,6 +366,61 @@ module ActionView
         end
       end
 
+      class CollectionIterator # :nodoc:
+        include Enumerable
+
+        attr_reader :collection
+
+        def initialize(collection, path, variables)
+          @collection = collection
+          @path       = path
+          @variables  = variables
+        end
+
+        def from_collection(collection)
+          return collection if collection == self
+
+          self.class.new(collection, @path, @variables)
+        end
+
+        def each(&blk)
+          @collection.each(&blk)
+        end
+
+        def each_with_info
+          return enum_for(:each_with_info) unless block_given?
+
+          variables = [@path] + @variables
+          @collection.each { |o| yield(o, variables) }
+        end
+
+        def size
+          @collection.size
+        end
+      end
+
+      class MixedCollectionIterator # :nodoc:
+        include Enumerable
+
+        def initialize(collection, paths)
+          @collection = collection
+          @paths      = paths
+        end
+
+        def each(&blk)
+          @collection.each(&blk)
+        end
+
+        def each_with_info
+          return enum_for(:each_with_info) unless block_given?
+          @collection.each_with_index { |o, i| yield(o, @paths[i]) }
+        end
+
+        def size
+          @collection.size
+        end
+      end
+
       # Sets up instance variables needed for rendering a partial. This method
       # finds the options and details and extracts them. The method also contains
       # logic that handles the type of object passed in as the partial.
@@ -389,8 +444,7 @@ module ActionView
 
           if @collection
             @has_object = true
-            paths = @collection_data = @collection.map { |o| @path }
-            paths.map! { |path| retrieve_variable(path, as).unshift(path) }
+            @collection = CollectionIterator.new(@collection, @path, retrieve_variable(@path, as))
           end
         else
           @has_object = true
@@ -398,13 +452,14 @@ module ActionView
           @collection = collection_from_object || collection_from_options
 
           if @collection
-            paths = @collection_data = @collection.map { |o| partial_path(o, context) }
+            paths = @collection.map { |o| partial_path(o, context) }
             if paths.uniq.length == 1
               @path = paths.first
-              paths.map! { |path| retrieve_variable(path, as).unshift(path) }
+              @collection = CollectionIterator.new(@collection, @path, retrieve_variable(@path, as))
             else
               paths.map! { |path| retrieve_variable(path, as).unshift(path) }
               @path = nil
+              @collection = MixedCollectionIterator.new(@collection, paths)
             end
           else
             @path = partial_path(@object, context)
@@ -438,14 +493,13 @@ module ActionView
       end
 
       def collection_with_template(view, template, layout, collection)
-        locals, collection_data = @locals, @collection_data
+        locals = @locals
         cache = template || {}
 
         partial_iteration = PartialIteration.new(collection.size)
 
-        collection.map do |object|
+        collection.each_with_info.map do |object, (path, as, counter, iteration)|
           index = partial_iteration.index
-          path, as, counter, iteration = collection_data[index]
 
           locals[as]        = object
           locals[counter]   = index
diff --git a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
index c863ede182..4cf94cd6e2 100644
--- a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
@@ -11,8 +11,14 @@ module ActionView
     end
 
     private
+      def will_cache?(options, view)
+        options[:cached] && view.controller.respond_to?(:perform_caching) && view.controller.perform_caching
+      end
+
       def cache_collection_render(instrumentation_payload, view, template, collection)
-        return yield(collection) unless @options[:cached] && view.controller.respond_to?(:perform_caching) && view.controller.perform_caching
+        return yield(collection) unless will_cache?(@options, view)
+
+        collection_iterator = collection
 
         # Result is a hash with the key represents the
         # key used for cache lookup and the value is the item
@@ -37,7 +43,7 @@ module ActionView
         # If the cache is missing elements then
         # the block will be called against the remaining items
         # in the @collection.
-        rendered_partials = collection.empty? ? [] : yield(collection)
+        rendered_partials = collection.empty? ? [] : yield(collection_iterator.from_collection(collection))
 
         index = 0
         keyed_partials = fetch_or_cache_partial(cached_partials, template, order_by: keyed_collection.each_key) do
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index 2c54647c25..a729e474ad 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -23,7 +23,7 @@ module ActiveRecord
       end
 
       def collection_with_template(_, _, _, collection)
-        @relation.preload_associations(collection) if @relation
+        @relation.preload_associations(collection.collection) if @relation
         super
       end
     end

From 6539657a3c7bb205e9c0812d6c73a2326699ec52 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 08:18:47 -0800
Subject: [PATCH 13/44] pull iterator allocation in to a factory method

---
 .../action_view/renderer/partial_renderer.rb  | 80 ++++++++++---------
 1 file changed, 42 insertions(+), 38 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 87d9a620f7..f505c3afcf 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -316,8 +316,25 @@ module ActionView
     end
 
     private
+      def build_collection_iterator(collection, path, as, context)
+        if path
+          SameCollectionIterator.new(collection, path, retrieve_variable(path, as))
+        else
+          paths = collection.map { |o| partial_path(o, context) }
+
+          if paths.uniq.length == 1
+            @path = paths.first
+            build_collection_iterator(collection, @path, as, context)
+          else
+            paths.map! { |path| retrieve_variable(path, as).unshift(path) }
+            @path = nil
+            MixedCollectionIterator.new(collection, paths)
+          end
+        end
+      end
+
       def template_keys(path, as)
-        if @has_object || @collection
+        if @has_object
           @locals.keys + retrieve_variable(path, as)
         else
           @locals.keys
@@ -371,53 +388,47 @@ module ActionView
 
         attr_reader :collection
 
-        def initialize(collection, path, variables)
+        def initialize(collection)
           @collection = collection
-          @path       = path
-          @variables  = variables
-        end
-
-        def from_collection(collection)
-          return collection if collection == self
-
-          self.class.new(collection, @path, @variables)
         end
 
         def each(&blk)
           @collection.each(&blk)
         end
 
-        def each_with_info
-          return enum_for(:each_with_info) unless block_given?
-
-          variables = [@path] + @variables
-          @collection.each { |o| yield(o, variables) }
-        end
-
         def size
           @collection.size
         end
       end
 
-      class MixedCollectionIterator # :nodoc:
-        include Enumerable
-
-        def initialize(collection, paths)
-          @collection = collection
-          @paths      = paths
+      class SameCollectionIterator < CollectionIterator # :nodoc:
+        def initialize(collection, path, variables)
+          super(collection)
+          @path      = path
+          @variables = variables
         end
 
-        def each(&blk)
-          @collection.each(&blk)
+        def from_collection(collection)
+          return collection if collection == self
+          self.class.new(collection, @path, @variables)
         end
 
         def each_with_info
           return enum_for(:each_with_info) unless block_given?
-          @collection.each_with_index { |o, i| yield(o, @paths[i]) }
+          variables = [@path] + @variables
+          @collection.each { |o| yield(o, variables) }
+        end
+      end
+
+      class MixedCollectionIterator < CollectionIterator # :nodoc:
+        def initialize(collection, paths)
+          super(collection)
+          @paths = paths
         end
 
-        def size
-          @collection.size
+        def each_with_info
+          return enum_for(:each_with_info) unless block_given?
+          collection.each_with_index { |o, i| yield(o, @paths[i]) }
         end
       end
 
@@ -444,23 +455,16 @@ module ActionView
 
           if @collection
             @has_object = true
-            @collection = CollectionIterator.new(@collection, @path, retrieve_variable(@path, as))
+            @collection = build_collection_iterator(@collection, @path, as, context)
           end
+
         else
           @has_object = true
           @object = partial
           @collection = collection_from_object || collection_from_options
 
           if @collection
-            paths = @collection.map { |o| partial_path(o, context) }
-            if paths.uniq.length == 1
-              @path = paths.first
-              @collection = CollectionIterator.new(@collection, @path, retrieve_variable(@path, as))
-            else
-              paths.map! { |path| retrieve_variable(path, as).unshift(path) }
-              @path = nil
-              @collection = MixedCollectionIterator.new(@collection, paths)
-            end
+            @collection = build_collection_iterator(@collection, nil, as, context)
           else
             @path = partial_path(@object, context)
           end

From 0c1d14a810dac369c2032e9df6df89cc69209fef Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 08:34:03 -0800
Subject: [PATCH 14/44] a collection is never rendered with an object

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index f505c3afcf..32eb5224c9 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -460,12 +460,12 @@ module ActionView
 
         else
           @has_object = true
-          @object = partial
-          @collection = collection_from_object || collection_from_options
+          @collection = collection_from_object(partial) || collection_from_options
 
           if @collection
             @collection = build_collection_iterator(@collection, nil, as, context)
           else
+            @object = partial
             @path = partial_path(@object, context)
           end
         end
@@ -487,8 +487,8 @@ module ActionView
         end
       end
 
-      def collection_from_object
-        @object if @object.respond_to?(:to_ary)
+      def collection_from_object(partial)
+        partial if partial.respond_to?(:to_ary)
       end
 
       def find_template(path, locals)

From 0c1fbc7e04063e63894a87ad7d90ec225d87e7fd Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 14:51:31 -0800
Subject: [PATCH 15/44] collection rendering has its own class

---
 actionview/lib/action_view.rb                 |   1 +
 .../action_view/renderer/partial_renderer.rb  | 263 ++++++++++--------
 .../lib/action_view/renderer/renderer.rb      |  50 +++-
 .../activerecord/multifetch_cache_test.rb     |   2 +-
 activerecord/lib/active_record/railtie.rb     |   2 +-
 .../collection_cache_association_loading.rb   |  22 +-
 6 files changed, 213 insertions(+), 127 deletions(-)

diff --git a/actionview/lib/action_view.rb b/actionview/lib/action_view.rb
index 497e0d43c9..8d8a1be56d 100644
--- a/actionview/lib/action_view.rb
+++ b/actionview/lib/action_view.rb
@@ -51,6 +51,7 @@ module ActionView
       autoload :Renderer
       autoload :AbstractRenderer
       autoload :PartialRenderer
+      autoload :CollectionRenderer, "action_view/renderer/partial_renderer"
       autoload :TemplateRenderer
       autoload :StreamingTemplateRenderer
     end
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 32eb5224c9..279c1c47cd 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -296,7 +296,7 @@ module ActionView
       setup(context, options, as)
 
       if @path
-        template = find_template(@path, template_keys(@path, as))
+        template = find_template(@path, template_keys(@path, as, @collection))
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -305,66 +305,21 @@ module ActionView
       end
 
       if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(@path, as))
+        layout = find_template(layout.to_s, template_keys(@path, as, @collection))
       end
 
-      if @collection
-        render_collection(context, template, layout)
-      else
-        render_partial(context, template, layout, block)
-      end
+      render_partial(context, template, layout, block)
     end
 
     private
-      def build_collection_iterator(collection, path, as, context)
-        if path
-          SameCollectionIterator.new(collection, path, retrieve_variable(path, as))
-        else
-          paths = collection.map { |o| partial_path(o, context) }
-
-          if paths.uniq.length == 1
-            @path = paths.first
-            build_collection_iterator(collection, @path, as, context)
-          else
-            paths.map! { |path| retrieve_variable(path, as).unshift(path) }
-            @path = nil
-            MixedCollectionIterator.new(collection, paths)
-          end
-        end
-      end
-
-      def template_keys(path, as)
+      def template_keys(path, as, collection)
         if @has_object
-          @locals.keys + retrieve_variable(path, as)
+          @locals.keys + retrieve_variable(path, as, collection)
         else
           @locals.keys
         end
       end
 
-      def render_collection(view, template, layout)
-        identifier = (template && template.identifier) || @path
-        instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
-          spacer = if @options.key?(:spacer_template)
-            spacer_template = find_template(@options[:spacer_template], @locals.keys)
-            build_rendered_template(spacer_template.render(view, @locals), spacer_template)
-          else
-            RenderedTemplate::EMPTY_SPACER
-          end
-
-          collection_body = if template
-            cache_collection_render(payload, view, template, @collection) do |collection|
-              collection_with_template(view, template, layout, collection)
-            end
-          else
-            collection_with_template(view, nil, layout, @collection)
-          end
-
-          return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
-
-          build_rendered_collection(collection_body, spacer)
-        end
-      end
-
       def render_partial(view, template, layout, block)
         instrument(:partial, identifier: template.identifier) do |payload|
           locals = @locals
@@ -383,55 +338,6 @@ module ActionView
         end
       end
 
-      class CollectionIterator # :nodoc:
-        include Enumerable
-
-        attr_reader :collection
-
-        def initialize(collection)
-          @collection = collection
-        end
-
-        def each(&blk)
-          @collection.each(&blk)
-        end
-
-        def size
-          @collection.size
-        end
-      end
-
-      class SameCollectionIterator < CollectionIterator # :nodoc:
-        def initialize(collection, path, variables)
-          super(collection)
-          @path      = path
-          @variables = variables
-        end
-
-        def from_collection(collection)
-          return collection if collection == self
-          self.class.new(collection, @path, @variables)
-        end
-
-        def each_with_info
-          return enum_for(:each_with_info) unless block_given?
-          variables = [@path] + @variables
-          @collection.each { |o| yield(o, variables) }
-        end
-      end
-
-      class MixedCollectionIterator < CollectionIterator # :nodoc:
-        def initialize(collection, paths)
-          super(collection)
-          @paths = paths
-        end
-
-        def each_with_info
-          return enum_for(:each_with_info) unless block_given?
-          collection.each_with_index { |o, i| yield(o, @paths[i]) }
-        end
-      end
-
       # Sets up instance variables needed for rendering a partial. This method
       # finds the options and details and extracts them. The method also contains
       # logic that handles the type of object passed in as the partial.
@@ -450,17 +356,11 @@ module ActionView
         if String === partial
           @has_object = options.key?(:object)
           @object     = options[:object]
-          @collection = collection_from_options
+          @collection = collection_from_options(options)
           @path       = partial
-
-          if @collection
-            @has_object = true
-            @collection = build_collection_iterator(@collection, @path, as, context)
-          end
-
         else
           @has_object = true
-          @collection = collection_from_object(partial) || collection_from_options
+          @collection = collection_from_object(partial) || collection_from_options(options)
 
           if @collection
             @collection = build_collection_iterator(@collection, nil, as, context)
@@ -473,6 +373,17 @@ module ActionView
         self
       end
 
+      def collection_from_options(options)
+        if options.key?(:collection)
+          collection = options[:collection]
+          collection || []
+        end
+      end
+
+      def collection_from_object(object)
+        object if object.respond_to?(:to_ary)
+      end
+
       def as_variable(options)
         if as = options[:as]
           raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
@@ -480,17 +391,6 @@ module ActionView
         end
       end
 
-      def collection_from_options
-        if @options.key?(:collection)
-          collection = @options[:collection]
-          collection || []
-        end
-      end
-
-      def collection_from_object(partial)
-        partial if partial.respond_to?(:to_ary)
-      end
-
       def find_template(path, locals)
         prefixes = path.include?(?/) ? [] : @lookup_context.prefixes
         @lookup_context.find_template(path, prefixes, true, locals, @details)
@@ -557,13 +457,13 @@ module ActionView
         end
       end
 
-      def retrieve_variable(path, as)
+      def retrieve_variable(path, as, collection)
         variable = as || begin
           base = path[-1] == "/" ? "" : File.basename(path)
           raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
           $1.to_sym
         end
-        if @collection
+        if collection
           variable_counter = :"#{variable}_counter"
           variable_iteration = :"#{variable}_iteration"
         end
@@ -585,4 +485,127 @@ module ActionView
         raise ArgumentError.new(OPTION_AS_ERROR_MESSAGE % (as))
       end
   end
+
+  class CollectionRenderer < PartialRenderer
+    class CollectionIterator # :nodoc:
+      include Enumerable
+
+      attr_reader :collection
+
+      def initialize(collection)
+        @collection = collection
+      end
+
+      def each(&blk)
+        @collection.each(&blk)
+      end
+
+      def size
+        @collection.size
+      end
+    end
+
+    class SameCollectionIterator < CollectionIterator # :nodoc:
+      def initialize(collection, path, variables)
+        super(collection)
+        @path      = path
+        @variables = variables
+      end
+
+      def from_collection(collection)
+        return collection if collection == self
+        self.class.new(collection, @path, @variables)
+      end
+
+      def each_with_info
+        return enum_for(:each_with_info) unless block_given?
+        variables = [@path] + @variables
+        @collection.each { |o| yield(o, variables) }
+      end
+    end
+
+    class MixedCollectionIterator < CollectionIterator # :nodoc:
+      def initialize(collection, paths)
+        super(collection)
+        @paths = paths
+      end
+
+      def each_with_info
+        return enum_for(:each_with_info) unless block_given?
+        collection.each_with_index { |o, i| yield(o, @paths[i]) }
+      end
+    end
+
+    def render_collection_with_partial(collection, partial, context, options, block)
+      as = as_variable(options)
+
+      @options = options
+
+      @locals  = options[:locals] || {}
+      @details = extract_details(options)
+      @path    = partial
+
+      @has_object = true
+      @collection = build_collection_iterator(collection, partial, as, context)
+
+      if options[:cached] && !partial
+        raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
+      end
+
+      template = find_template(partial, template_keys(partial, as, collection)) if partial
+
+      if !block && (layout = options[:layout])
+        layout = find_template(layout.to_s, template_keys(partial, as, collection))
+      end
+
+      render_collection(context, template, layout)
+    end
+
+    def render_collection_derive_partial(collection, context, options, block)
+      paths = collection.map { |o| partial_path(o, context) }
+
+      if paths.uniq.length == 1
+        # Homogeneous
+        render_collection_with_partial(collection, paths.first, context, options, block)
+      else
+        render_collection_with_partial(collection, nil, context, options, block)
+      end
+    end
+
+    private
+      def build_collection_iterator(collection, path, as, context)
+        if path
+          SameCollectionIterator.new(collection, path, retrieve_variable(path, as, collection))
+        else
+          paths = collection.map { |o| partial_path(o, context) }
+          paths.map! { |path| retrieve_variable(path, as, collection).unshift(path) }
+          @path = nil
+          MixedCollectionIterator.new(collection, paths)
+        end
+      end
+
+      def render_collection(view, template, layout)
+        identifier = (template && template.identifier) || @path
+        instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
+          spacer = if @options.key?(:spacer_template)
+            spacer_template = find_template(@options[:spacer_template], @locals.keys)
+            build_rendered_template(spacer_template.render(view, @locals), spacer_template)
+          else
+            RenderedTemplate::EMPTY_SPACER
+          end
+
+          collection_body = if template
+            cache_collection_render(payload, view, template, @collection) do |collection|
+              collection_with_template(view, template, layout, collection)
+            end
+          else
+            collection_with_template(view, nil, layout, @collection)
+          end
+
+          return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
+
+          build_rendered_collection(collection_body, spacer)
+        end
+      end
+  end
 end
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index 75f235fe63..7e34f6cbf8 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -65,7 +65,55 @@ module ActionView
     end
 
     def render_partial_to_object(context, options, &block) #:nodoc:
-      PartialRenderer.new(@lookup_context).render(context, options, block)
+      make_renderer(options, context, block)
     end
+
+    private
+
+      def make_renderer(options, context, block)
+        partial = options[:partial]
+        if String === partial
+          collection = collection_from_options(options)
+
+          if collection
+            # Collection + Partial
+            renderer = CollectionRenderer.new(@lookup_context)
+            renderer.render_collection_with_partial(collection, partial, context, options, block)
+          else
+            if options.key?(:object)
+              # Object + Partial
+              renderer = PartialRenderer.new(@lookup_context)
+              renderer.render(context, options, block)
+            else
+              # Partial
+              renderer = PartialRenderer.new(@lookup_context)
+              renderer.render(context, options, block)
+            end
+          end
+        else
+          collection = collection_from_object(partial) || collection_from_options(options)
+
+          if collection
+            # Collection + Derived Partial
+            renderer = CollectionRenderer.new(@lookup_context)
+            renderer.render_collection_derive_partial(collection, context, options, block)
+          else
+            # Object + Derived Partial
+            renderer = PartialRenderer.new(@lookup_context)
+            renderer.render(context, options, block)
+          end
+        end
+      end
+
+      def collection_from_options(options)
+        if options.key?(:collection)
+          collection = options[:collection]
+          collection || []
+        end
+      end
+
+      def collection_from_object(object)
+        object if object.respond_to?(:to_ary)
+      end
   end
 end
diff --git a/actionview/test/activerecord/multifetch_cache_test.rb b/actionview/test/activerecord/multifetch_cache_test.rb
index ab4bb4dc3e..3e4782bc86 100644
--- a/actionview/test/activerecord/multifetch_cache_test.rb
+++ b/actionview/test/activerecord/multifetch_cache_test.rb
@@ -3,7 +3,7 @@
 require "active_record_unit"
 require "active_record/railties/collection_cache_association_loading"
 
-ActionView::PartialRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
+ActionView::CollectionRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
 
 class MultifetchCacheTest < ActiveRecordTestCase
   fixtures :topics, :replies
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 239ce54d87..9bae89a7ae 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -224,7 +224,7 @@ To keep using the current cache store, you can turn off cache versioning entirel
     initializer "active_record.collection_cache_association_loading" do
       require "active_record/railties/collection_cache_association_loading"
       ActiveSupport.on_load(:action_view) do
-        ActionView::PartialRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
+        ActionView::CollectionRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
       end
     end
 
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index a729e474ad..d1301a2c06 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -13,13 +13,27 @@ module ActiveRecord
         super
       end
 
+      def render_collection_with_partial(collection, partial, context, options, block)
+        @relation = nil
+
+        return super unless options[:cached]
+
+        @relation = get_relation(collection)
+
+        super
+      end
+
+      def get_relation(relation)
+        if relation && relation.is_a?(ActiveRecord::Relation) && !relation.loaded?
+          relation.skip_preloading!
+          relation
+        end
+      end
+
       def relation_from_options(partial, collection)
         relation = partial if partial.is_a?(ActiveRecord::Relation)
         relation ||= collection if collection.is_a?(ActiveRecord::Relation)
-
-        if relation && !relation.loaded?
-          relation.skip_preloading!
-        end
+        get_relation(relation)
       end
 
       def collection_with_template(_, _, _, collection)

From 974ddb035c6fdba92883309b25fdd25befd74bd0 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 14:59:33 -0800
Subject: [PATCH 16/44] remove collection references from the superclass

---
 .../action_view/renderer/partial_renderer.rb  | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 279c1c47cd..87aff8742f 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -292,11 +292,11 @@ module ActionView
     end
 
     def render(context, options, block)
-      as = as_variable(options)
-      setup(context, options, as)
+      @as = as_variable(options)
+      setup(context, options, @as)
 
       if @path
-        template = find_template(@path, template_keys(@path, as, @collection))
+        template = find_template(@path, template_keys(@path, @as))
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -305,16 +305,16 @@ module ActionView
       end
 
       if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(@path, as, @collection))
+        layout = find_template(layout.to_s, template_keys(@path, @as))
       end
 
       render_partial(context, template, layout, block)
     end
 
     private
-      def template_keys(path, as, collection)
+      def template_keys(path, as)
         if @has_object
-          @locals.keys + retrieve_variable(path, as, collection)
+          @locals.keys + retrieve_variable(path, as)
         else
           @locals.keys
         end
@@ -457,17 +457,13 @@ module ActionView
         end
       end
 
-      def retrieve_variable(path, as, collection)
+      def retrieve_variable(path, as)
         variable = as || begin
           base = path[-1] == "/" ? "" : File.basename(path)
           raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
           $1.to_sym
         end
-        if collection
-          variable_counter = :"#{variable}_counter"
-          variable_iteration = :"#{variable}_iteration"
-        end
-        [variable, variable_counter, variable_iteration]
+        [variable]
       end
 
       IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
@@ -552,10 +548,10 @@ module ActionView
         raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
       end
 
-      template = find_template(partial, template_keys(partial, as, collection)) if partial
+      template = find_template(partial, template_keys(partial, as)) if partial
 
       if !block && (layout = options[:layout])
-        layout = find_template(layout.to_s, template_keys(partial, as, collection))
+        layout = find_template(layout.to_s, template_keys(partial, as))
       end
 
       render_collection(context, template, layout)
@@ -573,12 +569,20 @@ module ActionView
     end
 
     private
+      def retrieve_variable(path, as)
+        vars = super
+        variable = vars.first
+        vars << :"#{variable}_counter"
+        vars << :"#{variable}_iteration"
+        vars
+      end
+
       def build_collection_iterator(collection, path, as, context)
         if path
-          SameCollectionIterator.new(collection, path, retrieve_variable(path, as, collection))
+          SameCollectionIterator.new(collection, path, retrieve_variable(path, as))
         else
           paths = collection.map { |o| partial_path(o, context) }
-          paths.map! { |path| retrieve_variable(path, as, collection).unshift(path) }
+          paths.map! { |path| retrieve_variable(path, as).unshift(path) }
           @path = nil
           MixedCollectionIterator.new(collection, paths)
         end

From 10f7201fc5a43460c0b4015b056f5ece4709e335 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 15:04:18 -0800
Subject: [PATCH 17/44] remove more collection references from the superclass

---
 .../action_view/renderer/partial_renderer.rb  | 65 +++++++------------
 1 file changed, 24 insertions(+), 41 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 87aff8742f..3843621a6e 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -347,7 +347,6 @@ module ActionView
       # respond to +to_partial_path+ in order to set up the path.
       def setup(context, options, as)
         @options = options
-
         @locals  = options[:locals] || {}
         @details = extract_details(options)
 
@@ -356,34 +355,17 @@ module ActionView
         if String === partial
           @has_object = options.key?(:object)
           @object     = options[:object]
-          @collection = collection_from_options(options)
           @path       = partial
         else
           @has_object = true
-          @collection = collection_from_object(partial) || collection_from_options(options)
 
-          if @collection
-            @collection = build_collection_iterator(@collection, nil, as, context)
-          else
-            @object = partial
-            @path = partial_path(@object, context)
-          end
+          @object = partial
+          @path = partial_path(@object, context)
         end
 
         self
       end
 
-      def collection_from_options(options)
-        if options.key?(:collection)
-          collection = options[:collection]
-          collection || []
-        end
-      end
-
-      def collection_from_object(object)
-        object if object.respond_to?(:to_ary)
-      end
-
       def as_variable(options)
         if as = options[:as]
           raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
@@ -396,27 +378,6 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
 
-      def collection_with_template(view, template, layout, collection)
-        locals = @locals
-        cache = template || {}
-
-        partial_iteration = PartialIteration.new(collection.size)
-
-        collection.each_with_info.map do |object, (path, as, counter, iteration)|
-          index = partial_iteration.index
-
-          locals[as]        = object
-          locals[counter]   = index
-          locals[iteration] = partial_iteration
-
-          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
-          content = _template.render(view, locals)
-          content = layout.render(view, locals) { content } if layout
-          partial_iteration.iterate!
-          build_rendered_template(content, _template)
-        end
-      end
-
       # Obtains the path to where the object's partial is located. If the object
       # responds to +to_partial_path+, then +to_partial_path+ will be called and
       # will provide the path. If the object does not respond to +to_partial_path+,
@@ -611,5 +572,27 @@ module ActionView
           build_rendered_collection(collection_body, spacer)
         end
       end
+
+      def collection_with_template(view, template, layout, collection)
+        locals = @locals
+        cache = template || {}
+
+        partial_iteration = PartialIteration.new(collection.size)
+
+        collection.each_with_info.map do |object, (path, as, counter, iteration)|
+          index = partial_iteration.index
+
+          locals[as]        = object
+          locals[counter]   = index
+          locals[iteration] = partial_iteration
+
+          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
+          content = _template.render(view, locals)
+          content = layout.render(view, locals) { content } if layout
+          partial_iteration.iterate!
+          build_rendered_template(content, _template)
+        end
+      end
+
   end
 end

From 844568c23195a4061400c69129d327ba315bddd3 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 15:06:29 -0800
Subject: [PATCH 18/44] remove at ivar again

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 3843621a6e..e6fbc73570 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -292,11 +292,11 @@ module ActionView
     end
 
     def render(context, options, block)
-      @as = as_variable(options)
-      setup(context, options, @as)
+      as = as_variable(options)
+      setup(context, options, as)
 
       if @path
-        template = find_template(@path, template_keys(@path, @as))
+        template = find_template(@path, template_keys(@path, as))
       else
         if options[:cached]
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -305,7 +305,7 @@ module ActionView
       end
 
       if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(@path, @as))
+        layout = find_template(layout.to_s, template_keys(@path, as))
       end
 
       render_partial(context, template, layout, block)

From 8b6c5850a5fe3b28c9d8c72d089dcabdd17386a0 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 15:37:45 -0800
Subject: [PATCH 19/44] introduce an object renderer

---
 actionview/lib/action_view.rb                 |  1 +
 .../action_view/renderer/partial_renderer.rb  | 36 ++++++++++++-------
 .../lib/action_view/renderer/renderer.rb      |  8 ++---
 3 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/actionview/lib/action_view.rb b/actionview/lib/action_view.rb
index 8d8a1be56d..fd14094792 100644
--- a/actionview/lib/action_view.rb
+++ b/actionview/lib/action_view.rb
@@ -52,6 +52,7 @@ module ActionView
       autoload :AbstractRenderer
       autoload :PartialRenderer
       autoload :CollectionRenderer, "action_view/renderer/partial_renderer"
+      autoload :ObjectRenderer, "action_view/renderer/partial_renderer"
       autoload :TemplateRenderer
       autoload :StreamingTemplateRenderer
     end
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index e6fbc73570..46f9db3442 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -308,7 +308,7 @@ module ActionView
         layout = find_template(layout.to_s, template_keys(@path, as))
       end
 
-      render_partial(context, template, layout, block)
+      render_partial(context, @locals, template, layout, block)
     end
 
     private
@@ -320,14 +320,8 @@ module ActionView
         end
       end
 
-      def render_partial(view, template, layout, block)
+      def render_partial(view, locals, template, layout, block)
         instrument(:partial, identifier: template.identifier) do |payload|
-          locals = @locals
-          as     = template.variable
-          object = @object
-
-          locals[as] = object if @has_object
-
           content = template.render(view, locals) do |*name|
             view._layout_for(*name, &block)
           end
@@ -354,12 +348,8 @@ module ActionView
 
         if String === partial
           @has_object = options.key?(:object)
-          @object     = options[:object]
           @path       = partial
         else
-          @has_object = true
-
-          @object = partial
           @path = partial_path(@object, context)
         end
 
@@ -593,6 +583,28 @@ module ActionView
           build_rendered_template(content, _template)
         end
       end
+  end
 
+  class ObjectRenderer < PartialRenderer
+    def render_object_with_partial(object, partial, context, options, block)
+      @has_object = true
+      @object = object
+
+      render(context, options, block)
+    end
+
+    def render_object_derive_partial(object, context, options, block)
+      path = partial_path(object, context)
+
+      render_object_with_partial(object, path, context, options, block)
+    end
+
+    private
+
+      def render_partial(view, locals, template, layout, block)
+        as     = template.variable
+        locals[as] = @object
+        super(view, locals, template, layout, block)
+      end
   end
 end
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index 7e34f6cbf8..ac22a2bb61 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -82,8 +82,8 @@ module ActionView
           else
             if options.key?(:object)
               # Object + Partial
-              renderer = PartialRenderer.new(@lookup_context)
-              renderer.render(context, options, block)
+              renderer = ObjectRenderer.new(@lookup_context)
+              renderer.render_object_with_partial(options[:object], partial, context, options, block)
             else
               # Partial
               renderer = PartialRenderer.new(@lookup_context)
@@ -99,8 +99,8 @@ module ActionView
             renderer.render_collection_derive_partial(collection, context, options, block)
           else
             # Object + Derived Partial
-            renderer = PartialRenderer.new(@lookup_context)
-            renderer.render(context, options, block)
+            renderer = ObjectRenderer.new(@lookup_context)
+            renderer.render_object_derive_partial(partial, context, options, block)
           end
         end
       end

From feec68436c921eb8b4e8dfba89eaa98eb93a7035 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 15:39:57 -0800
Subject: [PATCH 20/44] remove has_object ivar

---
 .../action_view/renderer/partial_renderer.rb  | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 46f9db3442..b81d8e0368 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -313,11 +313,7 @@ module ActionView
 
     private
       def template_keys(path, as)
-        if @has_object
-          @locals.keys + retrieve_variable(path, as)
-        else
-          @locals.keys
-        end
+        @locals.keys
       end
 
       def render_partial(view, locals, template, layout, block)
@@ -347,7 +343,6 @@ module ActionView
         partial = options[:partial]
 
         if String === partial
-          @has_object = options.key?(:object)
           @path       = partial
         else
           @path = partial_path(@object, context)
@@ -492,7 +487,6 @@ module ActionView
       @details = extract_details(options)
       @path    = partial
 
-      @has_object = true
       @collection = build_collection_iterator(collection, partial, as, context)
 
       if options[:cached] && !partial
@@ -520,6 +514,10 @@ module ActionView
     end
 
     private
+      def template_keys(path, as)
+        super + retrieve_variable(path, as)
+      end
+
       def retrieve_variable(path, as)
         vars = super
         variable = vars.first
@@ -587,20 +585,21 @@ module ActionView
 
   class ObjectRenderer < PartialRenderer
     def render_object_with_partial(object, partial, context, options, block)
-      @has_object = true
       @object = object
-
       render(context, options, block)
     end
 
     def render_object_derive_partial(object, context, options, block)
       path = partial_path(object, context)
-
       render_object_with_partial(object, path, context, options, block)
     end
 
     private
 
+      def template_keys(path, as)
+        super + retrieve_variable(path, as)
+      end
+
       def render_partial(view, locals, template, layout, block)
         as     = template.variable
         locals[as] = @object

From 9187f7482c40bfcb090e2107b274384f12db4f0b Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 15:57:59 -0800
Subject: [PATCH 21/44] partial renderer is specialized for rendering partials
 now

---
 .../action_view/renderer/partial_renderer.rb  | 50 +++++--------------
 .../lib/action_view/renderer/renderer.rb      |  2 +-
 .../collection_cache_association_loading.rb   | 10 ----
 3 files changed, 13 insertions(+), 49 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index b81d8e0368..90d223e9ae 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -291,24 +291,21 @@ module ActionView
       @context_prefix = @lookup_context.prefixes.first
     end
 
-    def render(context, options, block)
-      as = as_variable(options)
-      setup(context, options, as)
+    def render(partial, context, options, block)
+      @options = options
+      @locals  = options[:locals] || {}
+      @details = extract_details(options)
+      @path    = partial
 
-      if @path
-        template = find_template(@path, template_keys(@path, as))
-      else
-        if options[:cached]
-          raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
-        end
-        template = nil
-      end
+      as = as_variable(options)
+
+      template = find_template(@path, template_keys(@path, as))
 
       if !block && (layout = @options[:layout])
         layout = find_template(layout.to_s, template_keys(@path, as))
       end
 
-      render_partial(context, @locals, template, layout, block)
+      render_partial_template(context, @locals, template, layout, block)
     end
 
     private
@@ -316,7 +313,7 @@ module ActionView
         @locals.keys
       end
 
-      def render_partial(view, locals, template, layout, block)
+      def render_partial_template(view, locals, template, layout, block)
         instrument(:partial, identifier: template.identifier) do |payload|
           content = template.render(view, locals) do |*name|
             view._layout_for(*name, &block)
@@ -328,29 +325,6 @@ module ActionView
         end
       end
 
-      # Sets up instance variables needed for rendering a partial. This method
-      # finds the options and details and extracts them. The method also contains
-      # logic that handles the type of object passed in as the partial.
-      #
-      # If +options[:partial]+ is a string, then the <tt>@path</tt> instance variable is
-      # set to that string. Otherwise, the +options[:partial]+ object must
-      # respond to +to_partial_path+ in order to set up the path.
-      def setup(context, options, as)
-        @options = options
-        @locals  = options[:locals] || {}
-        @details = extract_details(options)
-
-        partial = options[:partial]
-
-        if String === partial
-          @path       = partial
-        else
-          @path = partial_path(@object, context)
-        end
-
-        self
-      end
-
       def as_variable(options)
         if as = options[:as]
           raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
@@ -586,7 +560,7 @@ module ActionView
   class ObjectRenderer < PartialRenderer
     def render_object_with_partial(object, partial, context, options, block)
       @object = object
-      render(context, options, block)
+      render(partial, context, options, block)
     end
 
     def render_object_derive_partial(object, context, options, block)
@@ -600,7 +574,7 @@ module ActionView
         super + retrieve_variable(path, as)
       end
 
-      def render_partial(view, locals, template, layout, block)
+      def render_partial_template(view, locals, template, layout, block)
         as     = template.variable
         locals[as] = @object
         super(view, locals, template, layout, block)
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index ac22a2bb61..bf619c03db 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -87,7 +87,7 @@ module ActionView
             else
               # Partial
               renderer = PartialRenderer.new(@lookup_context)
-              renderer.render(context, options, block)
+              renderer.render(partial, context, options, block)
             end
           end
         else
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index d1301a2c06..766f25beed 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -3,16 +3,6 @@
 module ActiveRecord
   module Railties # :nodoc:
     module CollectionCacheAssociationLoading #:nodoc:
-      def setup(context, options, as)
-        @relation = nil
-
-        return super unless options[:cached]
-
-        @relation = relation_from_options(options[:partial], options[:collection])
-
-        super
-      end
-
       def render_collection_with_partial(collection, partial, context, options, block)
         @relation = nil
 

From f0a15484335341f14f36d6d2e98f447f1b4e24fe Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:13:12 -0800
Subject: [PATCH 22/44] as: doesn't make sense without an object parameter

The local variable name in `as:` may not be a valid local variable name,
but if there is no object specified to be assigned to the parameter,
then why supply the `as:`?  This commit adds an object for the as param
---
 actionview/test/template/render_test.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/actionview/test/template/render_test.rb b/actionview/test/template/render_test.rb
index eab73d622c..c22bdd6659 100644
--- a/actionview/test/template/render_test.rb
+++ b/actionview/test/template/render_test.rb
@@ -265,14 +265,14 @@ module RenderTestCases
   end
 
   def test_render_partial_with_invalid_option_as
-    e = assert_raises(ArgumentError) { @view.render(partial: "test/partial_only", as: "a-in") }
+    e = assert_raises(ArgumentError) { @view.render(partial: "test/partial_only", as: "a-in", object: nil) }
     assert_equal "The value (a-in) of the option `as` is not a valid Ruby identifier; " \
       "make sure it starts with lowercase letter, " \
       "and is followed by any combination of letters, numbers and underscores.", e.message
   end
 
   def test_render_partial_with_hyphen_and_invalid_option_as
-    e = assert_raises(ArgumentError) { @view.render(partial: "test/a-in", as: "a-in") }
+    e = assert_raises(ArgumentError) { @view.render(partial: "test/a-in", as: "a-in", object: nil) }
     assert_equal "The value (a-in) of the option `as` is not a valid Ruby identifier; " \
       "make sure it starts with lowercase letter, " \
       "and is followed by any combination of letters, numbers and underscores.", e.message

From f8f2f9ce32965c06a7af588582ed2f0d03b4c543 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:17:49 -0800
Subject: [PATCH 23/44] remove the as_variable method

---
 .../action_view/renderer/partial_renderer.rb  | 54 +++++++++----------
 1 file changed, 24 insertions(+), 30 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 90d223e9ae..d6f206c46f 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -297,19 +297,17 @@ module ActionView
       @details = extract_details(options)
       @path    = partial
 
-      as = as_variable(options)
-
-      template = find_template(@path, template_keys(@path, as))
+      template = find_template(@path, template_keys(@path))
 
       if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(@path, as))
+        layout = find_template(layout.to_s, template_keys(@path))
       end
 
       render_partial_template(context, @locals, template, layout, block)
     end
 
     private
-      def template_keys(path, as)
+      def template_keys(path)
         @locals.keys
       end
 
@@ -325,13 +323,6 @@ module ActionView
         end
       end
 
-      def as_variable(options)
-        if as = options[:as]
-          raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
-          as.to_sym
-        end
-      end
-
       def find_template(path, locals)
         prefixes = path.include?(?/) ? [] : @lookup_context.prefixes
         @lookup_context.find_template(path, prefixes, true, locals, @details)
@@ -377,11 +368,16 @@ module ActionView
         end
       end
 
-      def retrieve_variable(path, as)
-        variable = as || begin
-          base = path[-1] == "/" ? "" : File.basename(path)
-          raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
-          $1.to_sym
+      def retrieve_variable(path)
+        variable = if as = @options[:as]
+          raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
+          as.to_sym
+        else
+          begin
+            base = path[-1] == "/" ? "" : File.basename(path)
+            raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
+            $1.to_sym
+          end
         end
         [variable]
       end
@@ -453,24 +449,22 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, options, block)
-      as = as_variable(options)
-
       @options = options
 
       @locals  = options[:locals] || {}
       @details = extract_details(options)
       @path    = partial
 
-      @collection = build_collection_iterator(collection, partial, as, context)
+      @collection = build_collection_iterator(collection, partial, context)
 
       if options[:cached] && !partial
         raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
       end
 
-      template = find_template(partial, template_keys(partial, as)) if partial
+      template = find_template(partial, template_keys(partial)) if partial
 
       if !block && (layout = options[:layout])
-        layout = find_template(layout.to_s, template_keys(partial, as))
+        layout = find_template(layout.to_s, template_keys(partial))
       end
 
       render_collection(context, template, layout)
@@ -488,11 +482,11 @@ module ActionView
     end
 
     private
-      def template_keys(path, as)
-        super + retrieve_variable(path, as)
+      def template_keys(path)
+        super + retrieve_variable(path)
       end
 
-      def retrieve_variable(path, as)
+      def retrieve_variable(path)
         vars = super
         variable = vars.first
         vars << :"#{variable}_counter"
@@ -500,12 +494,12 @@ module ActionView
         vars
       end
 
-      def build_collection_iterator(collection, path, as, context)
+      def build_collection_iterator(collection, path, context)
         if path
-          SameCollectionIterator.new(collection, path, retrieve_variable(path, as))
+          SameCollectionIterator.new(collection, path, retrieve_variable(path))
         else
           paths = collection.map { |o| partial_path(o, context) }
-          paths.map! { |path| retrieve_variable(path, as).unshift(path) }
+          paths.map! { |path| retrieve_variable(path).unshift(path) }
           @path = nil
           MixedCollectionIterator.new(collection, paths)
         end
@@ -570,8 +564,8 @@ module ActionView
 
     private
 
-      def template_keys(path, as)
-        super + retrieve_variable(path, as)
+      def template_keys(path)
+        super + retrieve_variable(path)
       end
 
       def render_partial_template(view, locals, template, layout, block)

From f3dfd288214120bcdb9fd405cd0f2e8f842d4ea8 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:19:19 -0800
Subject: [PATCH 24/44] remove extra ivar set

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index d6f206c46f..4f658a65ae 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -500,7 +500,6 @@ module ActionView
         else
           paths = collection.map { |o| partial_path(o, context) }
           paths.map! { |path| retrieve_variable(path).unshift(path) }
-          @path = nil
           MixedCollectionIterator.new(collection, paths)
         end
       end

From ef6e03d5b120e4b263755fe88ea9983608eaf1ba Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:33:27 -0800
Subject: [PATCH 25/44] Move options ivar assignment in to the superclass

---
 .../action_view/renderer/abstract_renderer.rb | 21 ++++++
 .../action_view/renderer/partial_renderer.rb  | 66 +++++++------------
 .../lib/action_view/renderer/renderer.rb      | 20 +++---
 .../collection_cache_association_loading.rb   |  4 +-
 4 files changed, 56 insertions(+), 55 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index 3738ac8c26..4b2d4854ae 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -27,6 +27,27 @@ module ActionView
       raise NotImplementedError
     end
 
+    module ObjectRendering # :nodoc:
+      private
+        def template_keys(path)
+          super + retrieve_variable(path)
+        end
+
+        def retrieve_variable(path)
+          variable = if as = @options[:as]
+            raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
+            as.to_sym
+          else
+            begin
+              base = path[-1] == "/" ? "" : File.basename(path)
+              raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
+              $1.to_sym
+            end
+          end
+          [variable]
+        end
+    end
+
     class RenderedCollection # :nodoc:
       def self.empty(format)
         EmptyCollection.new format
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 4f658a65ae..d266eaff61 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -286,15 +286,15 @@ module ActionView
       h[k] = Concurrent::Map.new
     end
 
-    def initialize(*)
-      super
+    def initialize(lookup_context, options)
+      super(lookup_context)
+      @options = options
       @context_prefix = @lookup_context.prefixes.first
     end
 
-    def render(partial, context, options, block)
-      @options = options
-      @locals  = options[:locals] || {}
-      @details = extract_details(options)
+    def render(partial, context, block)
+      @locals  = @options[:locals] || {}
+      @details = extract_details(@options)
       @path    = partial
 
       template = find_template(@path, template_keys(@path))
@@ -307,7 +307,7 @@ module ActionView
     end
 
     private
-      def template_keys(path)
+      def template_keys(_)
         @locals.keys
       end
 
@@ -368,20 +368,6 @@ module ActionView
         end
       end
 
-      def retrieve_variable(path)
-        variable = if as = @options[:as]
-          raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
-          as.to_sym
-        else
-          begin
-            base = path[-1] == "/" ? "" : File.basename(path)
-            raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
-            $1.to_sym
-          end
-        end
-        [variable]
-      end
-
       IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
                                  "make sure your partial name starts with underscore."
 
@@ -399,6 +385,8 @@ module ActionView
   end
 
   class CollectionRenderer < PartialRenderer
+    include ObjectRendering
+
     class CollectionIterator # :nodoc:
       include Enumerable
 
@@ -448,44 +436,38 @@ module ActionView
       end
     end
 
-    def render_collection_with_partial(collection, partial, context, options, block)
-      @options = options
-
-      @locals  = options[:locals] || {}
-      @details = extract_details(options)
+    def render_collection_with_partial(collection, partial, context, block)
+      @locals  = @options[:locals] || {}
+      @details = extract_details(@options)
       @path    = partial
 
       @collection = build_collection_iterator(collection, partial, context)
 
-      if options[:cached] && !partial
+      if @options[:cached] && !partial
         raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
       end
 
       template = find_template(partial, template_keys(partial)) if partial
 
-      if !block && (layout = options[:layout])
+      if !block && (layout = @options[:layout])
         layout = find_template(layout.to_s, template_keys(partial))
       end
 
       render_collection(context, template, layout)
     end
 
-    def render_collection_derive_partial(collection, context, options, block)
+    def render_collection_derive_partial(collection, context, block)
       paths = collection.map { |o| partial_path(o, context) }
 
       if paths.uniq.length == 1
         # Homogeneous
-        render_collection_with_partial(collection, paths.first, context, options, block)
+        render_collection_with_partial(collection, paths.first, context, block)
       else
-        render_collection_with_partial(collection, nil, context, options, block)
+        render_collection_with_partial(collection, nil, context, block)
       end
     end
 
     private
-      def template_keys(path)
-        super + retrieve_variable(path)
-      end
-
       def retrieve_variable(path)
         vars = super
         variable = vars.first
@@ -551,22 +533,20 @@ module ActionView
   end
 
   class ObjectRenderer < PartialRenderer
-    def render_object_with_partial(object, partial, context, options, block)
+    include ObjectRendering
+
+    def render_object_with_partial(object, partial, context, block)
       @object = object
-      render(partial, context, options, block)
+      render(partial, context, block)
     end
 
-    def render_object_derive_partial(object, context, options, block)
+    def render_object_derive_partial(object, context, block)
       path = partial_path(object, context)
-      render_object_with_partial(object, path, context, options, block)
+      render_object_with_partial(object, path, context, block)
     end
 
     private
 
-      def template_keys(path)
-        super + retrieve_variable(path)
-      end
-
       def render_partial_template(view, locals, template, layout, block)
         as     = template.variable
         locals[as] = @object
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index bf619c03db..b30306388f 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -77,17 +77,17 @@ module ActionView
 
           if collection
             # Collection + Partial
-            renderer = CollectionRenderer.new(@lookup_context)
-            renderer.render_collection_with_partial(collection, partial, context, options, block)
+            renderer = CollectionRenderer.new(@lookup_context, options)
+            renderer.render_collection_with_partial(collection, partial, context, block)
           else
             if options.key?(:object)
               # Object + Partial
-              renderer = ObjectRenderer.new(@lookup_context)
-              renderer.render_object_with_partial(options[:object], partial, context, options, block)
+              renderer = ObjectRenderer.new(@lookup_context, options)
+              renderer.render_object_with_partial(options[:object], partial, context, block)
             else
               # Partial
-              renderer = PartialRenderer.new(@lookup_context)
-              renderer.render(partial, context, options, block)
+              renderer = PartialRenderer.new(@lookup_context, options)
+              renderer.render(partial, context, block)
             end
           end
         else
@@ -95,12 +95,12 @@ module ActionView
 
           if collection
             # Collection + Derived Partial
-            renderer = CollectionRenderer.new(@lookup_context)
-            renderer.render_collection_derive_partial(collection, context, options, block)
+            renderer = CollectionRenderer.new(@lookup_context, options)
+            renderer.render_collection_derive_partial(collection, context, block)
           else
             # Object + Derived Partial
-            renderer = ObjectRenderer.new(@lookup_context)
-            renderer.render_object_derive_partial(partial, context, options, block)
+            renderer = ObjectRenderer.new(@lookup_context, options)
+            renderer.render_object_derive_partial(partial, context, block)
           end
         end
       end
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
index 766f25beed..28e84c0563 100644
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
@@ -3,10 +3,10 @@
 module ActiveRecord
   module Railties # :nodoc:
     module CollectionCacheAssociationLoading #:nodoc:
-      def render_collection_with_partial(collection, partial, context, options, block)
+      def render_collection_with_partial(collection, partial, context, block)
         @relation = nil
 
-        return super unless options[:cached]
+        return super unless @options[:cached]
 
         @relation = get_relation(collection)
 

From 7210adb7ecec40ef9a7e149bda23a3d905f684e9 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:35:03 -0800
Subject: [PATCH 26/44] move locals and details ivar set in to initialize

---
 actionview/lib/action_view/renderer/partial_renderer.rb | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index d266eaff61..48bfd89a47 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -289,12 +289,12 @@ module ActionView
     def initialize(lookup_context, options)
       super(lookup_context)
       @options = options
+      @locals  = @options[:locals] || {}
+      @details = extract_details(@options)
       @context_prefix = @lookup_context.prefixes.first
     end
 
     def render(partial, context, block)
-      @locals  = @options[:locals] || {}
-      @details = extract_details(@options)
       @path    = partial
 
       template = find_template(@path, template_keys(@path))
@@ -437,8 +437,6 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, block)
-      @locals  = @options[:locals] || {}
-      @details = extract_details(@options)
       @path    = partial
 
       @collection = build_collection_iterator(collection, partial, context)

From 17fb6f0503d8c8c8f72ef6d3358611f181dec4ad Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:42:42 -0800
Subject: [PATCH 27/44] Move `partial_path` to ObjectRendering

Partial paths are only required for deriving template info for rendering
objects, which is only the case for the object renderer and the
collection renderer
---
 .../action_view/renderer/abstract_renderer.rb | 34 +++++++++++++++++++
 .../action_view/renderer/partial_renderer.rb  | 33 ++----------------
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index 4b2d4854ae..6aa3b4d166 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "concurrent/map"
+
 module ActionView
   # This class defines the interface for a renderer. Each class that
   # subclasses +AbstractRenderer+ is used by the base +Renderer+ class to
@@ -28,6 +30,15 @@ module ActionView
     end
 
     module ObjectRendering # :nodoc:
+      PREFIXED_PARTIAL_NAMES = Concurrent::Map.new do |h, k|
+        h[k] = Concurrent::Map.new
+      end
+
+      def initialize(lookup_context, options)
+        super
+        @context_prefix = lookup_context.prefixes.first
+      end
+
       private
         def template_keys(path)
           super + retrieve_variable(path)
@@ -46,6 +57,29 @@ module ActionView
           end
           [variable]
         end
+
+        # Obtains the path to where the object's partial is located. If the object
+        # responds to +to_partial_path+, then +to_partial_path+ will be called and
+        # will provide the path. If the object does not respond to +to_partial_path+,
+        # then an +ArgumentError+ is raised.
+        #
+        # If +prefix_partial_path_with_controller_namespace+ is true, then this
+        # method will prefix the partial paths with a namespace.
+        def partial_path(object, view)
+          object = object.to_model if object.respond_to?(:to_model)
+
+          path = if object.respond_to?(:to_partial_path)
+            object.to_partial_path
+          else
+            raise ArgumentError.new("'#{object.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.")
+          end
+
+          if view.prefix_partial_path_with_controller_namespace
+            PREFIXED_PARTIAL_NAMES[@context_prefix][path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
+          else
+            path
+          end
+        end
     end
 
     class RenderedCollection # :nodoc:
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 48bfd89a47..6f408d2494 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require "concurrent/map"
 require "action_view/renderer/partial_renderer/collection_caching"
 
 module ActionView
@@ -282,25 +281,20 @@ module ActionView
   class PartialRenderer < AbstractRenderer
     include CollectionCaching
 
-    PREFIXED_PARTIAL_NAMES = Concurrent::Map.new do |h, k|
-      h[k] = Concurrent::Map.new
-    end
-
     def initialize(lookup_context, options)
       super(lookup_context)
       @options = options
       @locals  = @options[:locals] || {}
       @details = extract_details(@options)
-      @context_prefix = @lookup_context.prefixes.first
     end
 
     def render(partial, context, block)
       @path    = partial
 
-      template = find_template(@path, template_keys(@path))
+      template = find_template(partial, template_keys(partial))
 
       if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(@path))
+        layout = find_template(layout.to_s, template_keys(partial))
       end
 
       render_partial_template(context, @locals, template, layout, block)
@@ -328,29 +322,6 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
 
-      # Obtains the path to where the object's partial is located. If the object
-      # responds to +to_partial_path+, then +to_partial_path+ will be called and
-      # will provide the path. If the object does not respond to +to_partial_path+,
-      # then an +ArgumentError+ is raised.
-      #
-      # If +prefix_partial_path_with_controller_namespace+ is true, then this
-      # method will prefix the partial paths with a namespace.
-      def partial_path(object, view)
-        object = object.to_model if object.respond_to?(:to_model)
-
-        path = if object.respond_to?(:to_partial_path)
-          object.to_partial_path
-        else
-          raise ArgumentError.new("'#{object.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.")
-        end
-
-        if view.prefix_partial_path_with_controller_namespace
-          PREFIXED_PARTIAL_NAMES[@context_prefix][path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
-        else
-          path
-        end
-      end
-
       def merge_prefix_into_object_path(prefix, object_path)
         if prefix.include?(?/) && object_path.include?(?/)
           prefixes = []

From 51f50a923e4ae73235f7ae3c846b56332d53ca89 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 16:44:35 -0800
Subject: [PATCH 28/44] path ivar is not required

---
 .../lib/action_view/renderer/partial_renderer.rb       | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 6f408d2494..45cd12ac41 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -289,8 +289,6 @@ module ActionView
     end
 
     def render(partial, context, block)
-      @path    = partial
-
       template = find_template(partial, template_keys(partial))
 
       if !block && (layout = @options[:layout])
@@ -408,8 +406,6 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, block)
-      @path    = partial
-
       @collection = build_collection_iterator(collection, partial, context)
 
       if @options[:cached] && !partial
@@ -422,7 +418,7 @@ module ActionView
         layout = find_template(layout.to_s, template_keys(partial))
       end
 
-      render_collection(context, template, layout)
+      render_collection(context, template, partial, layout)
     end
 
     def render_collection_derive_partial(collection, context, block)
@@ -455,8 +451,8 @@ module ActionView
         end
       end
 
-      def render_collection(view, template, layout)
-        identifier = (template && template.identifier) || @path
+      def render_collection(view, template, path, layout)
+        identifier = (template && template.identifier) || path
         instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
           spacer = if @options.key?(:spacer_template)
             spacer_template = find_template(@options[:spacer_template], @locals.keys)

From 2105fec0176940f1f202dbf2250d7ca8b3d595d5 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 17:14:18 -0800
Subject: [PATCH 29/44] Merging path prefixes is only done in object /
 collection rendering

---
 .../action_view/renderer/abstract_renderer.rb   | 17 +++++++++++++++++
 .../action_view/renderer/partial_renderer.rb    | 17 -----------------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index 6aa3b4d166..ded47da68b 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -80,6 +80,23 @@ module ActionView
             path
           end
         end
+
+        def merge_prefix_into_object_path(prefix, object_path)
+          if prefix.include?(?/) && object_path.include?(?/)
+            prefixes = []
+            prefix_array = File.dirname(prefix).split("/")
+            object_path_array = object_path.split("/")[0..-3] # skip model dir & partial
+
+            prefix_array.each_with_index do |dir, index|
+              break if dir == object_path_array[index]
+              prefixes << dir
+            end
+
+            (prefixes << object_path).join("/")
+          else
+            object_path
+          end
+        end
     end
 
     class RenderedCollection # :nodoc:
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 45cd12ac41..077a372f67 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -320,23 +320,6 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
 
-      def merge_prefix_into_object_path(prefix, object_path)
-        if prefix.include?(?/) && object_path.include?(?/)
-          prefixes = []
-          prefix_array = File.dirname(prefix).split("/")
-          object_path_array = object_path.split("/")[0..-3] # skip model dir & partial
-
-          prefix_array.each_with_index do |dir, index|
-            break if dir == object_path_array[index]
-            prefixes << dir
-          end
-
-          (prefixes << object_path).join("/")
-        else
-          object_path
-        end
-      end
-
       IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
                                  "make sure your partial name starts with underscore."
 

From f0429dbc303b43c73558a4866f66db7bf9250a5c Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 26 Feb 2020 17:14:37 -0800
Subject: [PATCH 30/44] Make extracting details cheaper

Details are only used if the user specifies a format or local, etc when
rendering a template.  This is a fairly uncommon thing to do, so lets
make it cheaper when there are no details specified
---
 .../lib/action_view/renderer/abstract_renderer.rb      | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index ded47da68b..0604176323 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -146,12 +146,18 @@ module ActionView
     end
 
     private
+      NO_DETAILS = {}.freeze
+
       def extract_details(options) # :doc:
-        @lookup_context.registered_details.each_with_object({}) do |key, details|
+        details = nil
+        @lookup_context.registered_details.each do |key|
           value = options[key]
 
-          details[key] = Array(value) if value
+          if value
+            (details ||= {})[key] = Array(value)
+          end
         end
+        details || NO_DETAILS
       end
 
       def instrument(name, **options) # :doc:

From dbd8860096461c38f62e5e8ca846513a1246e4d0 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 12:49:53 -0800
Subject: [PATCH 31/44] move object specific stuff in to the object processing
 code

---
 .../lib/action_view/renderer/abstract_renderer.rb | 15 +++++++++++++++
 .../lib/action_view/renderer/partial_renderer.rb  | 15 ---------------
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index 0604176323..d86265b6c2 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -58,6 +58,21 @@ module ActionView
           [variable]
         end
 
+        IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
+                                   "make sure your partial name starts with underscore."
+
+        OPTION_AS_ERROR_MESSAGE  = "The value (%s) of the option `as` is not a valid Ruby identifier; " \
+                                   "make sure it starts with lowercase letter, " \
+                                   "and is followed by any combination of letters, numbers and underscores."
+
+        def raise_invalid_identifier(path)
+          raise ArgumentError, IDENTIFIER_ERROR_MESSAGE % path
+        end
+
+        def raise_invalid_option_as(as)
+          raise ArgumentError, OPTION_AS_ERROR_MESSAGE % as
+        end
+
         # Obtains the path to where the object's partial is located. If the object
         # responds to +to_partial_path+, then +to_partial_path+ will be called and
         # will provide the path. If the object does not respond to +to_partial_path+,
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 077a372f67..3c1d1f610c 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -319,21 +319,6 @@ module ActionView
         prefixes = path.include?(?/) ? [] : @lookup_context.prefixes
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
-
-      IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
-                                 "make sure your partial name starts with underscore."
-
-      OPTION_AS_ERROR_MESSAGE  = "The value (%s) of the option `as` is not a valid Ruby identifier; " \
-                                 "make sure it starts with lowercase letter, " \
-                                 "and is followed by any combination of letters, numbers and underscores."
-
-      def raise_invalid_identifier(path)
-        raise ArgumentError.new(IDENTIFIER_ERROR_MESSAGE % (path))
-      end
-
-      def raise_invalid_option_as(as)
-        raise ArgumentError.new(OPTION_AS_ERROR_MESSAGE % (as))
-      end
   end
 
   class CollectionRenderer < PartialRenderer

From 665a355ed8d2b366d2a5fb96ffd9e4c26f361d87 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 12:50:02 -0800
Subject: [PATCH 32/44] We don't need this private method

---
 .../lib/action_view/renderer/renderer.rb      | 68 +++++++++----------
 1 file changed, 32 insertions(+), 36 deletions(-)

diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index b30306388f..d9973c7ebe 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -65,46 +65,42 @@ module ActionView
     end
 
     def render_partial_to_object(context, options, &block) #:nodoc:
-      make_renderer(options, context, block)
+      partial = options[:partial]
+      if String === partial
+        collection = collection_from_options(options)
+
+        if collection
+          # Collection + Partial
+          renderer = CollectionRenderer.new(@lookup_context, options)
+          renderer.render_collection_with_partial(collection, partial, context, block)
+        else
+          if options.key?(:object)
+            # Object + Partial
+            renderer = ObjectRenderer.new(@lookup_context, options)
+            renderer.render_object_with_partial(options[:object], partial, context, block)
+          else
+            # Partial
+            renderer = PartialRenderer.new(@lookup_context, options)
+            renderer.render(partial, context, block)
+          end
+        end
+      else
+        collection = collection_from_object(partial) || collection_from_options(options)
+
+        if collection
+          # Collection + Derived Partial
+          renderer = CollectionRenderer.new(@lookup_context, options)
+          renderer.render_collection_derive_partial(collection, context, block)
+        else
+          # Object + Derived Partial
+          renderer = ObjectRenderer.new(@lookup_context, options)
+          renderer.render_object_derive_partial(partial, context, block)
+        end
+      end
     end
 
     private
 
-      def make_renderer(options, context, block)
-        partial = options[:partial]
-        if String === partial
-          collection = collection_from_options(options)
-
-          if collection
-            # Collection + Partial
-            renderer = CollectionRenderer.new(@lookup_context, options)
-            renderer.render_collection_with_partial(collection, partial, context, block)
-          else
-            if options.key?(:object)
-              # Object + Partial
-              renderer = ObjectRenderer.new(@lookup_context, options)
-              renderer.render_object_with_partial(options[:object], partial, context, block)
-            else
-              # Partial
-              renderer = PartialRenderer.new(@lookup_context, options)
-              renderer.render(partial, context, block)
-            end
-          end
-        else
-          collection = collection_from_object(partial) || collection_from_options(options)
-
-          if collection
-            # Collection + Derived Partial
-            renderer = CollectionRenderer.new(@lookup_context, options)
-            renderer.render_collection_derive_partial(collection, context, block)
-          else
-            # Object + Derived Partial
-            renderer = ObjectRenderer.new(@lookup_context, options)
-            renderer.render_object_derive_partial(partial, context, block)
-          end
-        end
-      end
-
       def collection_from_options(options)
         if options.key?(:collection)
           collection = options[:collection]

From a85494dc0cba9f29e40ee910005b343ba8225434 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 12:55:04 -0800
Subject: [PATCH 33/44] Move renderers in to their own files

We don't need to keep all of these in the partial renderer file
---
 actionview/lib/action_view.rb                 |   4 +-
 .../renderer/collection_renderer.rb           | 176 ++++++++++++++++
 .../action_view/renderer/object_renderer.rb   |  25 +++
 .../action_view/renderer/partial_renderer.rb  | 193 ------------------
 4 files changed, 203 insertions(+), 195 deletions(-)
 create mode 100644 actionview/lib/action_view/renderer/collection_renderer.rb
 create mode 100644 actionview/lib/action_view/renderer/object_renderer.rb

diff --git a/actionview/lib/action_view.rb b/actionview/lib/action_view.rb
index fd14094792..a7876e4cfa 100644
--- a/actionview/lib/action_view.rb
+++ b/actionview/lib/action_view.rb
@@ -51,8 +51,8 @@ module ActionView
       autoload :Renderer
       autoload :AbstractRenderer
       autoload :PartialRenderer
-      autoload :CollectionRenderer, "action_view/renderer/partial_renderer"
-      autoload :ObjectRenderer, "action_view/renderer/partial_renderer"
+      autoload :CollectionRenderer
+      autoload :ObjectRenderer
       autoload :TemplateRenderer
       autoload :StreamingTemplateRenderer
     end
diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
new file mode 100644
index 0000000000..c074a762de
--- /dev/null
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -0,0 +1,176 @@
+# frozen_string_literal: true
+
+require "action_view/renderer/partial_renderer"
+
+module ActionView
+  class PartialIteration
+    # The number of iterations that will be done by the partial.
+    attr_reader :size
+
+    # The current iteration of the partial.
+    attr_reader :index
+
+    def initialize(size)
+      @size  = size
+      @index = 0
+    end
+
+    # Check if this is the first iteration of the partial.
+    def first?
+      index == 0
+    end
+
+    # Check if this is the last iteration of the partial.
+    def last?
+      index == size - 1
+    end
+
+    def iterate! # :nodoc:
+      @index += 1
+    end
+  end
+
+  class CollectionRenderer < PartialRenderer # :nodoc:
+    include ObjectRendering
+
+    class CollectionIterator # :nodoc:
+      include Enumerable
+
+      attr_reader :collection
+
+      def initialize(collection)
+        @collection = collection
+      end
+
+      def each(&blk)
+        @collection.each(&blk)
+      end
+
+      def size
+        @collection.size
+      end
+    end
+
+    class SameCollectionIterator < CollectionIterator # :nodoc:
+      def initialize(collection, path, variables)
+        super(collection)
+        @path      = path
+        @variables = variables
+      end
+
+      def from_collection(collection)
+        return collection if collection == self
+        self.class.new(collection, @path, @variables)
+      end
+
+      def each_with_info
+        return enum_for(:each_with_info) unless block_given?
+        variables = [@path] + @variables
+        @collection.each { |o| yield(o, variables) }
+      end
+    end
+
+    class MixedCollectionIterator < CollectionIterator # :nodoc:
+      def initialize(collection, paths)
+        super(collection)
+        @paths = paths
+      end
+
+      def each_with_info
+        return enum_for(:each_with_info) unless block_given?
+        collection.each_with_index { |o, i| yield(o, @paths[i]) }
+      end
+    end
+
+    def render_collection_with_partial(collection, partial, context, block)
+      @collection = build_collection_iterator(collection, partial, context)
+
+      if @options[:cached] && !partial
+        raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
+      end
+
+      template = find_template(partial, template_keys(partial)) if partial
+
+      if !block && (layout = @options[:layout])
+        layout = find_template(layout.to_s, template_keys(partial))
+      end
+
+      render_collection(context, template, partial, layout)
+    end
+
+    def render_collection_derive_partial(collection, context, block)
+      paths = collection.map { |o| partial_path(o, context) }
+
+      if paths.uniq.length == 1
+        # Homogeneous
+        render_collection_with_partial(collection, paths.first, context, block)
+      else
+        render_collection_with_partial(collection, nil, context, block)
+      end
+    end
+
+    private
+      def retrieve_variable(path)
+        vars = super
+        variable = vars.first
+        vars << :"#{variable}_counter"
+        vars << :"#{variable}_iteration"
+        vars
+      end
+
+      def build_collection_iterator(collection, path, context)
+        if path
+          SameCollectionIterator.new(collection, path, retrieve_variable(path))
+        else
+          paths = collection.map { |o| partial_path(o, context) }
+          paths.map! { |path| retrieve_variable(path).unshift(path) }
+          MixedCollectionIterator.new(collection, paths)
+        end
+      end
+
+      def render_collection(view, template, path, layout)
+        identifier = (template && template.identifier) || path
+        instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
+          spacer = if @options.key?(:spacer_template)
+            spacer_template = find_template(@options[:spacer_template], @locals.keys)
+            build_rendered_template(spacer_template.render(view, @locals), spacer_template)
+          else
+            RenderedTemplate::EMPTY_SPACER
+          end
+
+          collection_body = if template
+            cache_collection_render(payload, view, template, @collection) do |collection|
+              collection_with_template(view, template, layout, collection)
+            end
+          else
+            collection_with_template(view, nil, layout, @collection)
+          end
+
+          return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
+
+          build_rendered_collection(collection_body, spacer)
+        end
+      end
+
+      def collection_with_template(view, template, layout, collection)
+        locals = @locals
+        cache = template || {}
+
+        partial_iteration = PartialIteration.new(collection.size)
+
+        collection.each_with_info.map do |object, (path, as, counter, iteration)|
+          index = partial_iteration.index
+
+          locals[as]        = object
+          locals[counter]   = index
+          locals[iteration] = partial_iteration
+
+          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
+          content = _template.render(view, locals)
+          content = layout.render(view, locals) { content } if layout
+          partial_iteration.iterate!
+          build_rendered_template(content, _template)
+        end
+      end
+  end
+end
diff --git a/actionview/lib/action_view/renderer/object_renderer.rb b/actionview/lib/action_view/renderer/object_renderer.rb
new file mode 100644
index 0000000000..f0e73a8b7e
--- /dev/null
+++ b/actionview/lib/action_view/renderer/object_renderer.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module ActionView
+  class ObjectRenderer < PartialRenderer # :nodoc:
+    include ObjectRendering
+
+    def render_object_with_partial(object, partial, context, block)
+      @object = object
+      render(partial, context, block)
+    end
+
+    def render_object_derive_partial(object, context, block)
+      path = partial_path(object, context)
+      render_object_with_partial(object, path, context, block)
+    end
+
+    private
+
+      def render_partial_template(view, locals, template, layout, block)
+        as     = template.variable
+        locals[as] = @object
+        super(view, locals, template, layout, block)
+      end
+  end
+end
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 3c1d1f610c..5a3af00454 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -3,33 +3,6 @@
 require "action_view/renderer/partial_renderer/collection_caching"
 
 module ActionView
-  class PartialIteration
-    # The number of iterations that will be done by the partial.
-    attr_reader :size
-
-    # The current iteration of the partial.
-    attr_reader :index
-
-    def initialize(size)
-      @size  = size
-      @index = 0
-    end
-
-    # Check if this is the first iteration of the partial.
-    def first?
-      index == 0
-    end
-
-    # Check if this is the last iteration of the partial.
-    def last?
-      index == size - 1
-    end
-
-    def iterate! # :nodoc:
-      @index += 1
-    end
-  end
-
   # = Action View Partials
   #
   # There's also a convenience method for rendering sub templates within the current controller that depends on a
@@ -320,170 +293,4 @@ module ActionView
         @lookup_context.find_template(path, prefixes, true, locals, @details)
       end
   end
-
-  class CollectionRenderer < PartialRenderer
-    include ObjectRendering
-
-    class CollectionIterator # :nodoc:
-      include Enumerable
-
-      attr_reader :collection
-
-      def initialize(collection)
-        @collection = collection
-      end
-
-      def each(&blk)
-        @collection.each(&blk)
-      end
-
-      def size
-        @collection.size
-      end
-    end
-
-    class SameCollectionIterator < CollectionIterator # :nodoc:
-      def initialize(collection, path, variables)
-        super(collection)
-        @path      = path
-        @variables = variables
-      end
-
-      def from_collection(collection)
-        return collection if collection == self
-        self.class.new(collection, @path, @variables)
-      end
-
-      def each_with_info
-        return enum_for(:each_with_info) unless block_given?
-        variables = [@path] + @variables
-        @collection.each { |o| yield(o, variables) }
-      end
-    end
-
-    class MixedCollectionIterator < CollectionIterator # :nodoc:
-      def initialize(collection, paths)
-        super(collection)
-        @paths = paths
-      end
-
-      def each_with_info
-        return enum_for(:each_with_info) unless block_given?
-        collection.each_with_index { |o, i| yield(o, @paths[i]) }
-      end
-    end
-
-    def render_collection_with_partial(collection, partial, context, block)
-      @collection = build_collection_iterator(collection, partial, context)
-
-      if @options[:cached] && !partial
-        raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
-      end
-
-      template = find_template(partial, template_keys(partial)) if partial
-
-      if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(partial))
-      end
-
-      render_collection(context, template, partial, layout)
-    end
-
-    def render_collection_derive_partial(collection, context, block)
-      paths = collection.map { |o| partial_path(o, context) }
-
-      if paths.uniq.length == 1
-        # Homogeneous
-        render_collection_with_partial(collection, paths.first, context, block)
-      else
-        render_collection_with_partial(collection, nil, context, block)
-      end
-    end
-
-    private
-      def retrieve_variable(path)
-        vars = super
-        variable = vars.first
-        vars << :"#{variable}_counter"
-        vars << :"#{variable}_iteration"
-        vars
-      end
-
-      def build_collection_iterator(collection, path, context)
-        if path
-          SameCollectionIterator.new(collection, path, retrieve_variable(path))
-        else
-          paths = collection.map { |o| partial_path(o, context) }
-          paths.map! { |path| retrieve_variable(path).unshift(path) }
-          MixedCollectionIterator.new(collection, paths)
-        end
-      end
-
-      def render_collection(view, template, path, layout)
-        identifier = (template && template.identifier) || path
-        instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
-          spacer = if @options.key?(:spacer_template)
-            spacer_template = find_template(@options[:spacer_template], @locals.keys)
-            build_rendered_template(spacer_template.render(view, @locals), spacer_template)
-          else
-            RenderedTemplate::EMPTY_SPACER
-          end
-
-          collection_body = if template
-            cache_collection_render(payload, view, template, @collection) do |collection|
-              collection_with_template(view, template, layout, collection)
-            end
-          else
-            collection_with_template(view, nil, layout, @collection)
-          end
-
-          return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?
-
-          build_rendered_collection(collection_body, spacer)
-        end
-      end
-
-      def collection_with_template(view, template, layout, collection)
-        locals = @locals
-        cache = template || {}
-
-        partial_iteration = PartialIteration.new(collection.size)
-
-        collection.each_with_info.map do |object, (path, as, counter, iteration)|
-          index = partial_iteration.index
-
-          locals[as]        = object
-          locals[counter]   = index
-          locals[iteration] = partial_iteration
-
-          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
-          content = _template.render(view, locals)
-          content = layout.render(view, locals) { content } if layout
-          partial_iteration.iterate!
-          build_rendered_template(content, _template)
-        end
-      end
-  end
-
-  class ObjectRenderer < PartialRenderer
-    include ObjectRendering
-
-    def render_object_with_partial(object, partial, context, block)
-      @object = object
-      render(partial, context, block)
-    end
-
-    def render_object_derive_partial(object, context, block)
-      path = partial_path(object, context)
-      render_object_with_partial(object, path, context, block)
-    end
-
-    private
-
-      def render_partial_template(view, locals, template, layout, block)
-        as     = template.variable
-        locals[as] = @object
-        super(view, locals, template, layout, block)
-      end
-  end
 end

From 76ea105ca1e9c14d0bce9ddb330369792f720438 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 13:14:09 -0800
Subject: [PATCH 34/44] remove collection ivar

---
 .../lib/action_view/renderer/collection_renderer.rb  | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index c074a762de..8b5274a562 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -83,7 +83,7 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, block)
-      @collection = build_collection_iterator(collection, partial, context)
+      collection = build_collection_iterator(collection, partial, context)
 
       if @options[:cached] && !partial
         raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
@@ -95,7 +95,7 @@ module ActionView
         layout = find_template(layout.to_s, template_keys(partial))
       end
 
-      render_collection(context, template, partial, layout)
+      render_collection(collection, context, template, partial, layout)
     end
 
     def render_collection_derive_partial(collection, context, block)
@@ -128,9 +128,9 @@ module ActionView
         end
       end
 
-      def render_collection(view, template, path, layout)
+      def render_collection(collection, view, template, path, layout)
         identifier = (template && template.identifier) || path
-        instrument(:collection, identifier: identifier, count: @collection.size) do |payload|
+        instrument(:collection, identifier: identifier, count: collection.size) do |payload|
           spacer = if @options.key?(:spacer_template)
             spacer_template = find_template(@options[:spacer_template], @locals.keys)
             build_rendered_template(spacer_template.render(view, @locals), spacer_template)
@@ -139,11 +139,11 @@ module ActionView
           end
 
           collection_body = if template
-            cache_collection_render(payload, view, template, @collection) do |collection|
+            cache_collection_render(payload, view, template, collection) do |collection|
               collection_with_template(view, template, layout, collection)
             end
           else
-            collection_with_template(view, nil, layout, @collection)
+            collection_with_template(view, nil, layout, collection)
           end
 
           return RenderedCollection.empty(@lookup_context.formats.first) if collection_body.empty?

From 266e34973e1e78e487cf035b319ce8e7e3e7e4bd Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 13:15:56 -0800
Subject: [PATCH 35/44] Remove conditional

Only one case can possibly be missing a partial.  We can move the cache
check to that branch and eliminate the conditional
---
 .../lib/action_view/renderer/collection_renderer.rb       | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 8b5274a562..82e61bdf1a 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -85,10 +85,6 @@ module ActionView
     def render_collection_with_partial(collection, partial, context, block)
       collection = build_collection_iterator(collection, partial, context)
 
-      if @options[:cached] && !partial
-        raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
-      end
-
       template = find_template(partial, template_keys(partial)) if partial
 
       if !block && (layout = @options[:layout])
@@ -105,6 +101,10 @@ module ActionView
         # Homogeneous
         render_collection_with_partial(collection, paths.first, context, block)
       else
+        if @options[:cached]
+          raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
+        end
+
         render_collection_with_partial(collection, nil, context, block)
       end
     end

From 7c0dea18ce6593416b1242973b0695e06b64d657 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 13:20:34 -0800
Subject: [PATCH 36/44] Reduce iterations for non-homogeneous collections

We only need to iterate over the paths twice (this was doing it 3 times)
---
 .../renderer/collection_renderer.rb           | 30 +++++++------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 82e61bdf1a..76bb6b6b13 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -83,15 +83,9 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, block)
-      collection = build_collection_iterator(collection, partial, context)
+      collection = SameCollectionIterator.new(collection, partial, retrieve_variable(partial))
 
-      template = find_template(partial, template_keys(partial)) if partial
-
-      if !block && (layout = @options[:layout])
-        layout = find_template(layout.to_s, template_keys(partial))
-      end
-
-      render_collection(collection, context, template, partial, layout)
+      render_collection(collection, context, partial, block)
     end
 
     def render_collection_derive_partial(collection, context, block)
@@ -105,7 +99,9 @@ module ActionView
           raise NotImplementedError, "render caching requires a template. Please specify a partial when rendering"
         end
 
-        render_collection_with_partial(collection, nil, context, block)
+        paths.map! { |path| retrieve_variable(path).unshift(path) }
+        collection = MixedCollectionIterator.new(collection, paths)
+        render_collection(collection, context, nil, block)
       end
     end
 
@@ -118,17 +114,13 @@ module ActionView
         vars
       end
 
-      def build_collection_iterator(collection, path, context)
-        if path
-          SameCollectionIterator.new(collection, path, retrieve_variable(path))
-        else
-          paths = collection.map { |o| partial_path(o, context) }
-          paths.map! { |path| retrieve_variable(path).unshift(path) }
-          MixedCollectionIterator.new(collection, paths)
-        end
-      end
+      def render_collection(collection, view, path, block)
+        template = find_template(path, template_keys(path)) if path
+
+        if !block && (layout = @options[:layout])
+          layout = find_template(layout.to_s, template_keys(path))
+        end
 
-      def render_collection(collection, view, template, path, layout)
         identifier = (template && template.identifier) || path
         instrument(:collection, identifier: identifier, count: collection.size) do |payload|
           spacer = if @options.key?(:spacer_template)

From 78a28b7c4706e65de29e9744e6eecbce10baf633 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 13:52:53 -0800
Subject: [PATCH 37/44] always lookup template from path cache

---
 actionview/lib/action_view/renderer/collection_renderer.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 76bb6b6b13..39ab7e20b4 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -146,7 +146,7 @@ module ActionView
 
       def collection_with_template(view, template, layout, collection)
         locals = @locals
-        cache = template || {}
+        cache = {}
 
         partial_iteration = PartialIteration.new(collection.size)
 
@@ -157,7 +157,8 @@ module ActionView
           locals[counter]   = index
           locals[iteration] = partial_iteration
 
-          _template = template || (cache[path] ||= find_template(path, @locals.keys + [as, counter, iteration]))
+          _template = (cache[path] ||= (template || find_template(path, @locals.keys + [as, counter, iteration])))
+
           content = _template.render(view, locals)
           content = layout.render(view, locals) { content } if layout
           partial_iteration.iterate!

From 374c1b29409bd34aea22c38fab4356b7909f93c7 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 14:12:09 -0800
Subject: [PATCH 38/44] fix require

---
 actionview/test/template/partial_iteration_test.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/actionview/test/template/partial_iteration_test.rb b/actionview/test/template/partial_iteration_test.rb
index 1c3c566667..0ed995f7f2 100644
--- a/actionview/test/template/partial_iteration_test.rb
+++ b/actionview/test/template/partial_iteration_test.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "abstract_unit"
-require "action_view/renderer/partial_renderer"
+require "action_view/renderer/collection_renderer"
 
 class PartialIterationTest < ActiveSupport::TestCase
   def test_has_size_and_index

From 8d539bde7b7bd2d2347b804f935f7df7a7ce2e15 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 15:01:52 -0800
Subject: [PATCH 39/44] Move around local variable derivation

This reduces object allocations in collection rendering
---
 .../action_view/renderer/abstract_renderer.rb |  9 ++----
 .../renderer/collection_renderer.rb           | 28 +++++++++----------
 .../action_view/renderer/object_renderer.rb   |  3 ++
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/actionview/lib/action_view/renderer/abstract_renderer.rb b/actionview/lib/action_view/renderer/abstract_renderer.rb
index d86265b6c2..797f23b092 100644
--- a/actionview/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionview/lib/action_view/renderer/abstract_renderer.rb
@@ -40,12 +40,8 @@ module ActionView
       end
 
       private
-        def template_keys(path)
-          super + retrieve_variable(path)
-        end
-
-        def retrieve_variable(path)
-          variable = if as = @options[:as]
+        def local_variable(path)
+          if as = @options[:as]
             raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
             as.to_sym
           else
@@ -55,7 +51,6 @@ module ActionView
               $1.to_sym
             end
           end
-          [variable]
         end
 
         IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 39ab7e20b4..5e37efa641 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -83,9 +83,16 @@ module ActionView
     end
 
     def render_collection_with_partial(collection, partial, context, block)
-      collection = SameCollectionIterator.new(collection, partial, retrieve_variable(partial))
+      iter_vars  = retrieve_variable(partial)
+      collection = SameCollectionIterator.new(collection, partial, iter_vars)
 
-      render_collection(collection, context, partial, block)
+      template = find_template(partial, @locals.keys + iter_vars)
+
+      layout = if !block && (layout = @options[:layout])
+         find_template(layout.to_s, @locals.keys + iter_vars)
+      end
+
+      render_collection(collection, context, partial, template, layout, block)
     end
 
     def render_collection_derive_partial(collection, context, block)
@@ -101,26 +108,17 @@ module ActionView
 
         paths.map! { |path| retrieve_variable(path).unshift(path) }
         collection = MixedCollectionIterator.new(collection, paths)
-        render_collection(collection, context, nil, block)
+        render_collection(collection, context, nil, nil, nil, block)
       end
     end
 
     private
       def retrieve_variable(path)
-        vars = super
-        variable = vars.first
-        vars << :"#{variable}_counter"
-        vars << :"#{variable}_iteration"
-        vars
+        variable = local_variable(path)
+        [variable, :"#{variable}_counter", :"#{variable}_iteration"]
       end
 
-      def render_collection(collection, view, path, block)
-        template = find_template(path, template_keys(path)) if path
-
-        if !block && (layout = @options[:layout])
-          layout = find_template(layout.to_s, template_keys(path))
-        end
-
+      def render_collection(collection, view, path, template, layout, block)
         identifier = (template && template.identifier) || path
         instrument(:collection, identifier: identifier, count: collection.size) do |payload|
           spacer = if @options.key?(:spacer_template)
diff --git a/actionview/lib/action_view/renderer/object_renderer.rb b/actionview/lib/action_view/renderer/object_renderer.rb
index f0e73a8b7e..b6ba1cbc7a 100644
--- a/actionview/lib/action_view/renderer/object_renderer.rb
+++ b/actionview/lib/action_view/renderer/object_renderer.rb
@@ -15,6 +15,9 @@ module ActionView
     end
 
     private
+      def template_keys(path)
+        super + [local_variable(path)]
+      end
 
       def render_partial_template(view, locals, template, layout, block)
         as     = template.variable

From 4a4a8be06400f166b0a4062b9ca952a35e62f8d2 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 15:38:20 -0800
Subject: [PATCH 40/44] make the cops happy

---
 actionview/lib/action_view/renderer/collection_renderer.rb | 6 +++---
 actionview/lib/action_view/renderer/renderer.rb            | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 5e37efa641..9c4e4409c4 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -89,7 +89,7 @@ module ActionView
       template = find_template(partial, @locals.keys + iter_vars)
 
       layout = if !block && (layout = @options[:layout])
-         find_template(layout.to_s, @locals.keys + iter_vars)
+        find_template(layout.to_s, @locals.keys + iter_vars)
       end
 
       render_collection(collection, context, partial, template, layout, block)
@@ -129,8 +129,8 @@ module ActionView
           end
 
           collection_body = if template
-            cache_collection_render(payload, view, template, collection) do |collection|
-              collection_with_template(view, template, layout, collection)
+            cache_collection_render(payload, view, template, collection) do |filtered_collection|
+              collection_with_template(view, template, layout, filtered_collection)
             end
           else
             collection_with_template(view, nil, layout, collection)
diff --git a/actionview/lib/action_view/renderer/renderer.rb b/actionview/lib/action_view/renderer/renderer.rb
index d9973c7ebe..b9278adafd 100644
--- a/actionview/lib/action_view/renderer/renderer.rb
+++ b/actionview/lib/action_view/renderer/renderer.rb
@@ -100,7 +100,6 @@ module ActionView
     end
 
     private
-
       def collection_from_options(options)
         if options.key?(:collection)
           collection = options[:collection]

From 72e0d04a4bdb56db85e7c5fe4bd61d2162c7ffe5 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 27 Feb 2020 16:54:50 -0800
Subject: [PATCH 41/44] Fix issue in ActionText

ActionText was using `render` in a way that ActionView didn't have tests
for.  This is a fix for it.
---
 .../lib/action_view/renderer/object_renderer.rb    | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/object_renderer.rb b/actionview/lib/action_view/renderer/object_renderer.rb
index b6ba1cbc7a..12c5bb59dc 100644
--- a/actionview/lib/action_view/renderer/object_renderer.rb
+++ b/actionview/lib/action_view/renderer/object_renderer.rb
@@ -4,8 +4,15 @@ module ActionView
   class ObjectRenderer < PartialRenderer # :nodoc:
     include ObjectRendering
 
+    def initialize(lookup_context, options)
+      super
+      @object     = nil
+      @local_name = nil
+    end
+
     def render_object_with_partial(object, partial, context, block)
-      @object = object
+      @object     = object
+      @local_name = local_variable(partial)
       render(partial, context, block)
     end
 
@@ -16,12 +23,11 @@ module ActionView
 
     private
       def template_keys(path)
-        super + [local_variable(path)]
+        super + [@local_name]
       end
 
       def render_partial_template(view, locals, template, layout, block)
-        as     = template.variable
-        locals[as] = @object
+        locals[@local_name || template.variable] = @object
         super(view, locals, template, layout, block)
       end
   end

From 49adb7f4c61de8cbb02c4a207dbd56093d99e795 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Fri, 28 Feb 2020 09:23:22 -0800
Subject: [PATCH 42/44] pull preloading behavior in to the collection renderer

---
 .../renderer/collection_renderer.rb           | 26 +++++++++++++-
 .../activerecord/multifetch_cache_test.rb     |  3 --
 activerecord/lib/active_record/railtie.rb     |  7 ----
 .../collection_cache_association_loading.rb   | 35 -------------------
 4 files changed, 25 insertions(+), 46 deletions(-)
 delete mode 100644 activerecord/lib/active_record/railties/collection_cache_association_loading.rb

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index 9c4e4409c4..b175088640 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -70,6 +70,24 @@ module ActionView
       end
     end
 
+    class PreloadCollectionIterator < SameCollectionIterator # :nodoc:
+      def initialize(collection, path, variables, relation)
+        super(collection, path, variables)
+        relation.skip_preloading! unless relation.loaded?
+        @relation = relation
+      end
+
+      def from_collection(collection)
+        self.class.new(collection, @path, @variables, @relation)
+      end
+
+      def each_with_info
+        return super unless block_given?
+        @relation.preload_associations(@collection)
+        super
+      end
+    end
+
     class MixedCollectionIterator < CollectionIterator # :nodoc:
       def initialize(collection, paths)
         super(collection)
@@ -84,7 +102,13 @@ module ActionView
 
     def render_collection_with_partial(collection, partial, context, block)
       iter_vars  = retrieve_variable(partial)
-      collection = SameCollectionIterator.new(collection, partial, iter_vars)
+
+      collection = if collection.respond_to?(:preload_associations)
+        PreloadCollectionIterator.new(collection, partial, iter_vars, collection)
+      else
+        SameCollectionIterator.new(collection, partial, iter_vars)
+      end
+
 
       template = find_template(partial, @locals.keys + iter_vars)
 
diff --git a/actionview/test/activerecord/multifetch_cache_test.rb b/actionview/test/activerecord/multifetch_cache_test.rb
index 3e4782bc86..577615361a 100644
--- a/actionview/test/activerecord/multifetch_cache_test.rb
+++ b/actionview/test/activerecord/multifetch_cache_test.rb
@@ -1,9 +1,6 @@
 # frozen_string_literal: true
 
 require "active_record_unit"
-require "active_record/railties/collection_cache_association_loading"
-
-ActionView::CollectionRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
 
 class MultifetchCacheTest < ActiveRecordTestCase
   fixtures :topics, :replies
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 9bae89a7ae..cef94e3d1c 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -221,13 +221,6 @@ To keep using the current cache store, you can turn off cache versioning entirel
       end
     end
 
-    initializer "active_record.collection_cache_association_loading" do
-      require "active_record/railties/collection_cache_association_loading"
-      ActiveSupport.on_load(:action_view) do
-        ActionView::CollectionRenderer.prepend(ActiveRecord::Railties::CollectionCacheAssociationLoading)
-      end
-    end
-
     initializer "active_record.set_reloader_hooks" do
       ActiveSupport.on_load(:active_record) do
         ActiveSupport::Reloader.before_class_unload do
diff --git a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb b/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
deleted file mode 100644
index 28e84c0563..0000000000
--- a/activerecord/lib/active_record/railties/collection_cache_association_loading.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-# frozen_string_literal: true
-
-module ActiveRecord
-  module Railties # :nodoc:
-    module CollectionCacheAssociationLoading #:nodoc:
-      def render_collection_with_partial(collection, partial, context, block)
-        @relation = nil
-
-        return super unless @options[:cached]
-
-        @relation = get_relation(collection)
-
-        super
-      end
-
-      def get_relation(relation)
-        if relation && relation.is_a?(ActiveRecord::Relation) && !relation.loaded?
-          relation.skip_preloading!
-          relation
-        end
-      end
-
-      def relation_from_options(partial, collection)
-        relation = partial if partial.is_a?(ActiveRecord::Relation)
-        relation ||= collection if collection.is_a?(ActiveRecord::Relation)
-        get_relation(relation)
-      end
-
-      def collection_with_template(_, _, _, collection)
-        @relation.preload_associations(collection.collection) if @relation
-        super
-      end
-    end
-  end
-end

From a15339ff6527ba2310cb578da2d8e7e0d6b6014e Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Fri, 28 Feb 2020 09:25:25 -0800
Subject: [PATCH 43/44] remove usless attr_reader

---
 actionview/lib/action_view/renderer/collection_renderer.rb | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/actionview/lib/action_view/renderer/collection_renderer.rb b/actionview/lib/action_view/renderer/collection_renderer.rb
index b175088640..c5f69e83d0 100644
--- a/actionview/lib/action_view/renderer/collection_renderer.rb
+++ b/actionview/lib/action_view/renderer/collection_renderer.rb
@@ -36,8 +36,6 @@ module ActionView
     class CollectionIterator # :nodoc:
       include Enumerable
 
-      attr_reader :collection
-
       def initialize(collection)
         @collection = collection
       end
@@ -59,7 +57,6 @@ module ActionView
       end
 
       def from_collection(collection)
-        return collection if collection == self
         self.class.new(collection, @path, @variables)
       end
 
@@ -96,7 +93,7 @@ module ActionView
 
       def each_with_info
         return enum_for(:each_with_info) unless block_given?
-        collection.each_with_index { |o, i| yield(o, @paths[i]) }
+        @collection.each_with_index { |o, i| yield(o, @paths[i]) }
       end
     end
 

From d7bd84bc1148539b9d5c7a72d7b2c535986e6192 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Mon, 23 Mar 2020 17:08:17 -0700
Subject: [PATCH 44/44] Remove out-of-date comments

---
 .../renderer/partial_renderer/collection_caching.rb       | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
index 4cf94cd6e2..49011d2f43 100644
--- a/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb
@@ -33,16 +33,8 @@ module ActionView
         instrumentation_payload[:cache_hits] = cached_partials.size
 
         # Extract the items for the keys that are not found
-        # Set the uncached values to instance variable @collection
-        # which is used by the caller
         collection = keyed_collection.reject { |key, _| cached_partials.key?(key) }.values
 
-        # If all elements are already in cache then
-        # rendered partials will be an empty array
-        #
-        # If the cache is missing elements then
-        # the block will be called against the remaining items
-        # in the @collection.
         rendered_partials = collection.empty? ? [] : yield(collection_iterator.from_collection(collection))
 
         index = 0