From eb978b27d01beb451340a35f26c0fcab414cef26 Mon Sep 17 00:00:00 2001
From: hmdne <54514036+hmdne@users.noreply.github.com>
Date: Tue, 15 Nov 2022 08:41:12 +0100
Subject: [PATCH] Add Opal::BuilderProcessors::RubyERBProcessor

---
 lib/opal/builder_processors.rb | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/lib/opal/builder_processors.rb b/lib/opal/builder_processors.rb
index 22b2ca8f41..35194e6254 100644
--- a/lib/opal/builder_processors.rb
+++ b/lib/opal/builder_processors.rb
@@ -114,6 +114,12 @@ def self.match?(other)
       end
     end
 
+    # This handler is for files named ".opalerb", which ought to
+    # first get compiled to Ruby code using ERB, then with Opal.
+    # Unlike below processors, OpalERBProcessor can be used to
+    # compile templates, which will in turn output HTML. Take
+    # a look at docs/templates.md to understand this subsystem
+    # better.
     class OpalERBProcessor < RubyProcessor
       handles :opalerb
 
@@ -133,6 +139,24 @@ def prepare(source, path)
       end
     end
 
+    # This handler is for files named ".rb.erb", which ought to
+    # first get preprocessed via ERB, then via Opal.
+    class RubyERBProcessor < RubyProcessor
+      handles :"rb.erb"
+
+      def compiled
+        @compiled ||= begin
+          @source = ::ERB.new(@source.to_s).result
+
+          compiler = compiler_for(@source, file: @filename)
+          compiler.compile
+          compiler
+        end
+      end
+    end
+
+    # This handler is for files named ".js.erb", which ought to
+    # first get preprocessed via ERB, then served verbatim as JS.
     class ERBProcessor < Processor
       handles :erb