feat(metal): implement base class for pure ruby components

lib/view_component.rb

@@ -7,6 +7,7 @@ module ViewComponent
   extend ActiveSupport::Autoload
 
   autoload :Base
+  autoload :Metal
   autoload :CaptureCompatibility
   autoload :Compiler
   autoload :CompileCache

lib/view_component/metal.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module ViewComponent
+  class Metal
+    undef :p
+
+    def self.tag_elements
+      @@tag_elements ||= ActionView::Helpers::TagHelper::TagBuilder.instance_methods(false)
+    end
+
+    def render_in(view_context)
+      raise ArgumentError, "#{self.class} does not support passing a block" if block_given?
+      @view_context = view_context
+      @view_context.with_output_buffer { call }.to_s
+    end
+
+    def plain(string)
+      @view_context.concat(string)
+    end
+
+    def method_missing(method, ...)
+      if self.class.tag_elements.include?(method)
+        @view_context.concat @view_context.tag.__send__(method, ...)
+      elsif @view_context.respond_to?(method, false)
+        @view_context.__send__(method, ...)
+      else
+        super
+      end
+    end
+
+    def respond_to_missing?(method, include_all = false)
+      return true if super
+      return true if self.class.tag_elements.include?(method)
+      @view_context.respond_to?(method, false)
+    end
+  end
+end

test/sandbox/app/components/metal_component.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class MetalComponent < ViewComponent::Metal
+  def call
+    button type: :button do
+      p "Hello"
+      span do
+        strong { " World" }
+      end
+    end
+  end
+end

test/sandbox/test/metal_test.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class MetalTest < ViewComponent::TestCase
+  test "it works" do
+    render_inline MetalComponent.new
+
+    assert_selector "button > span > strong"
+    assert_text "Hello World"
+  end
+end