From d785e5fcef4e0ec9a2d58bab57b73c6caa8b8f09 Mon Sep 17 00:00:00 2001
From: Jonathan Mast <jon@jonmast.com>
Date: Sun, 26 Jan 2020 12:08:00 -0500
Subject: [PATCH] Add support for rendering with block instead of partial

Add a `render` macro to the ComponentHelper, which takes a block that is
used to render the component instead of using the partial.

This is mainly useful for small components that will be rendered many
times, the overhead of rendering the partial can be quite significant.
---
 .../frontend/components/no_template/no_template.js       | 1 +
 .../frontend/components/no_template/no_template.scss     | 2 ++
 .../components/no_template/no_template_component.rb      | 9 +++++++++
 lib/komponent/component_helper.rb                        | 6 ++++++
 lib/komponent/component_renderer.rb                      | 6 +++++-
 test/komponent/component_test.rb                         | 2 +-
 test/komponent/komponent_helper_test.rb                  | 7 +++++++
 7 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 fixtures/my_app/frontend/components/no_template/no_template.js
 create mode 100644 fixtures/my_app/frontend/components/no_template/no_template.scss
 create mode 100644 fixtures/my_app/frontend/components/no_template/no_template_component.rb

diff --git a/fixtures/my_app/frontend/components/no_template/no_template.js b/fixtures/my_app/frontend/components/no_template/no_template.js
new file mode 100644
index 0000000..36fc60f
--- /dev/null
+++ b/fixtures/my_app/frontend/components/no_template/no_template.js
@@ -0,0 +1 @@
+import "./no_template.scss";
diff --git a/fixtures/my_app/frontend/components/no_template/no_template.scss b/fixtures/my_app/frontend/components/no_template/no_template.scss
new file mode 100644
index 0000000..d035f78
--- /dev/null
+++ b/fixtures/my_app/frontend/components/no_template/no_template.scss
@@ -0,0 +1,2 @@
+.no-template {
+}
diff --git a/fixtures/my_app/frontend/components/no_template/no_template_component.rb b/fixtures/my_app/frontend/components/no_template/no_template_component.rb
new file mode 100644
index 0000000..2e93b11
--- /dev/null
+++ b/fixtures/my_app/frontend/components/no_template/no_template_component.rb
@@ -0,0 +1,9 @@
+module NoTemplateComponent
+  extend ComponentHelper
+
+  render do |block|
+    content_tag :div, class: "no-template #{@additional_class}" do
+      block.call
+    end
+  end
+end
diff --git a/lib/komponent/component_helper.rb b/lib/komponent/component_helper.rb
index 6f5c476..2c8d387 100644
--- a/lib/komponent/component_helper.rb
+++ b/lib/komponent/component_helper.rb
@@ -10,4 +10,10 @@ def property(name, options = {})
   def self.extended(component)
     component.properties = {}
   end
+
+  def render(&block)
+    @render_block = block
+  end
+
+  attr_reader :render_block
 end
diff --git a/lib/komponent/component_renderer.rb b/lib/komponent/component_renderer.rb
index f343ebf..56dc3d9 100644
--- a/lib/komponent/component_renderer.rb
+++ b/lib/komponent/component_renderer.rb
@@ -76,7 +76,11 @@ def _render(component, locals = {}, options = {}, &block)
         define_singleton_method(:block_given_to_component) { block }
       end
 
-      @context.render("components/#{component}/#{parts.join('_')}", &block)
+      if component_module.respond_to?(:render_block) && component_module.render_block
+        @context.instance_exec(block, &component_module.render_block)
+      else
+        @context.render("components/#{component}/#{parts.join('_')}", &block)
+      end
     end
 
     def resolved_component_path(component)
diff --git a/test/komponent/component_test.rb b/test/komponent/component_test.rb
index 7f42214..1df8881 100644
--- a/test/komponent/component_test.rb
+++ b/test/komponent/component_test.rb
@@ -7,7 +7,7 @@ def test_all_returns_components
     all = Komponent::Component.all
 
     assert all.is_a?(Hash)
-    assert_equal all.count, 13
+    assert_equal all.count, 14
     assert all["foo"].is_a?(Komponent::Component)
   end
 
diff --git a/test/komponent/komponent_helper_test.rb b/test/komponent/komponent_helper_test.rb
index bc3f4a9..dab97cb 100644
--- a/test/komponent/komponent_helper_test.rb
+++ b/test/komponent/komponent_helper_test.rb
@@ -88,6 +88,7 @@ def test_helper_lists_components
         'genius_button',
         'hello',
         'namespaced/button',
+        'no_template',
         'partial/universe',
         'partial/universe_button',
         'ping',
@@ -108,4 +109,10 @@ def test_helper_renders_with_doc
 }</code></pre>),
       component_with_doc('all', world: "🌎", sunglasses: "😎").chomp
   end
+
+  def test_helper_renders_without_template
+    assert_equal \
+      %(<div class="no-template classy">🌎</div>),
+      component('no_template', additional_class: "classy") { "🌎" }.chomp
+  end
 end