chore: extend sitemap builder instead of adapter

README.md

@@ -596,7 +596,7 @@ SiteMaps.generate(config_file: "config/sitemap.rb")
 
 ## Mixins
 
-You can use mixins to extend the sitemap builder with additional methods. The mixins can be used to define common methods that will be used in multiple processes. Make sure they are thread-safe, otherwise I recommend to define them in the process block.
+You can use mixins to extend the sitemap builder with additional methods. The mixins can be used to define common methods that will be used in multiple processes.
 
 ```ruby
 module MyMixin
@@ -610,10 +610,10 @@ module MyMixin
 end
 
 SiteMaps.use(:file_system) do
-  include_module(MyMixin)
+  extend_processes_with(MyMixin)
   process do |s|
-    repository.posts.each do |post|
-      s.add(post_path(post), priority: 0.8)
+    s.repository.posts.each do |post|
+      s.add(s.post_path(post), priority: 0.8)
     end
   end
 end
@@ -622,11 +622,9 @@ end
 We already have a built-in mixin for Rails applications that provides the url helpers through the `route` method.
 
 ```ruby
-SiteMaps.use(:file_system) do
-  include_module(SiteMaps::Mixins::Rails)
   process do |s|
-    s.add(route.root_path, priority: 1.0)
-    s.add(route.about_path, priority: 0.9)
+    s.add(s.route.root_path, priority: 1.0)
+    s.add(s.route.about_path, priority: 0.9)
   end
 end
 ```

lib/site_maps/adapters/adapter.rb

@@ -13,11 +13,12 @@ def config_class
     end
 
     def_delegators :config, :fetch_sitemap_index_links
-    attr_reader :sitemap_index, :processes
+    attr_reader :sitemap_index, :processes, :process_mixins
 
     def initialize(**options, &block)
       @config = SiteMaps.config.becomes(self.class.config_class, **options)
       @processes = Concurrent::Hash.new
+      @process_mixins = Concurrent::Array.new
       reset!
       instance_exec(&block) if block
     end
@@ -68,8 +69,8 @@ def repo
       @repo ||= SiteMaps::AtomicRepository.new(config.url)
     end
 
-    def include_module(mod)
-      extend(mod)
+    def extend_processes_with(mod)
+      @process_mixins << mod
     end
 
     def reset!

lib/site_maps/runner.rb

@@ -64,6 +64,7 @@ def run
                   location: process.location(**kwargs),
                   notification_payload: { process: process }
                 )
+                adapter.process_mixins.each { |mixin| builder.extend(mixin) }
                 process.call(builder, **kwargs)
                 builder.finalize!
               end

spec/site_maps/adapters/adapter_spec.rb

@@ -197,7 +197,7 @@
     end
   end
 
-  describe "#include_module" do
+  describe "#extend_processes_with" do
     let(:adapter) { described_class.new }
     let(:mod) do
       Module.new do
@@ -208,8 +208,8 @@ def foo
     end
 
     it "includes the module" do
-      adapter.include_module(mod)
-      expect(adapter).to respond_to(:foo)
+      adapter.extend_processes_with(mod)
+      expect(adapter.process_mixins).to include(mod)
     end
   end
 end

spec/site_maps/runner_spec.rb

@@ -275,6 +275,37 @@
         )
       end
     end
+
+    context "when the adapter has a process mixin" do
+      let(:adapter) do
+        SiteMaps.use(:noop) do
+          config.url = "https://example.com/sitemap.xml"
+          extend_processes_with(Module.new do
+            def add_post(year:)
+              add("/posts/#{year}/index.html")
+            end
+          end)
+
+          process(:posts, "posts/%{year}/sitemap.xml", year: 2024) do |s, year:|
+            s.add_post(year: year)
+          end
+        end
+      end
+
+      it "extends the process with the mixin" do
+        runner.enqueue(:posts, year: 2024)
+
+        process = adapter.processes[:posts]
+        allow(process).to receive(:call).and_call_original
+
+        expect { runner.run }.not_to raise_error
+
+        expect(process).to have_received(:call).with(
+          an_instance_of(SiteMaps::SitemapBuilder),
+          year: 2024
+        )
+      end
+    end
   end
 
   describe "#preload_sitemap_index_links?" do