Optimize render_each and each_part default local selection on Ruby 3+/!Windows

This uses an allocationless and regexp-free approach for symbols
and strings that do not have slashes or periods. This is about 3x
faster.

This support requires Ruby 3 for the Symbol#name usage and does
not work correctly on Windows (where \ can be a file separator),
so fallback to the previous code in other cases.

Author: jeremyevans

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Optimize render_each and each_part default local selection on Ruby 3+/!Windows (jeremyevans)
+
 * Optimize render_each and each_part template selection when freezing app with :assume_fixed_locals render plugin option (jeremyevans)
 
 === 3.93.0 (2025-06-12)

lib/roda/plugins/render_each.rb

@@ -152,10 +152,31 @@ def render_each(enum, template, opts=(no_opts = true; optimized_template = _cach
 
         private
 
-        # The default local variable name to use for the template, if the :local option
-        # is not used when calling render_each.
-        def render_each_default_local(template)
-          File.basename(template.to_s).sub(/\..+\z/, '').to_sym
+        if File.basename("a/b") == "b" && File.basename("a\\b") == "a\\b" && RUBY_VERSION >= '3'
+          # The default local variable name to use for the template, if the :local option
+          # is not used when calling render_each.
+          def render_each_default_local(template)
+            # Optimize to avoid allocations when possible
+            template = case template
+            when Symbol
+              s = template.name
+              return template unless s.include?("/") || s.include?(".")
+              s
+            when String
+              return template.to_sym unless template.include?("/") || template.include?(".")
+              template
+            else
+              template.to_s
+            end
+
+            File.basename(template).sub(/\..+\z/, '').to_sym
+          end
+        # :nocov:
+        else
+          def render_each_default_local(template)
+            File.basename(template.to_s).sub(/\..+\z/, '').to_sym
+          end
+        # :nocov:
         end
 
         if Render::COMPILED_METHOD_SUPPORT

spec/plugin/render_each_spec.rb

@@ -48,7 +48,7 @@ def o.to_s; 'each' end
           end
 
           r.is 'g' do
-            render_each([1,2,3], "each.foo")
+            render_each([1,2,3], :"each.foo")
           end
 
           r.is 'h' do