Refactors rewriter into its own file

lib/namespacer.rb

@@ -9,42 +9,14 @@
 module Rubyists
   # Namespace for the namespacer tool
   module Namespacer
-    # Do the AST rewriting with the Rewriter class
-    class Rewriter < Parser::TreeRewriter
-      attr_accessor(:namespaces)
-
-      def initialize(namespaces)
-        super()
-        @namespaces = namespaces
-      end
-
-      def on_module(node)
-        _on_module(node)
-      end
-
-      def on_class(node)
-        _on_module(node)
-      end
-
-      private
-
-      def wrap(ast)
-        # Recursively wrap the AST in the namespace modules
-        namespaces.split('::').reverse.inject(ast) do |current_ast, ns|
-          # Create a module node with the current namespace part and the current AST
-          Parser::AST::Node.new(:module, [Parser::AST::Node.new(:const, [nil, ns.to_sym]), current_ast])
-        end
-      end
-
-      def _on_module(node)
-        return unless node.location.column.zero?
-
-        (ast, comments) = Unparser.parse_with_comments(node.location.expression.source)
-        replace(node.location.expression, Unparser.unparse(wrap(ast), comments))
-      end
-    end
-
-    # Wrap some namespace around top-level AST nodes of 'module' or 'class' type
+    require_relative 'namespacer/rewriter'
+
+    # Wrap some namespace(s) around top-level AST nodes of 'module' or 'class' type
+    #
+    # @param string_or_io [String, IO] The source code to namespace
+    # @param namespaces [String] The namespace(s) to wrap around the top-level AST nodes
+    #
+    # @return [String] The source code with the namespace(s) wrapped around the top-level AST nodes
     def self.namespace!(string_or_io, namespaces)
       buffer = Parser::Source::Buffer.new("(#{namespaces})")
       buffer.source = string_or_io.is_a?(IO) ? string_or_io.read : string_or_io

lib/namespacer/rewriter.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module Rubyists
+  module Namespacer
+    # Do the AST rewriting with the Rewriter class
+    class Rewriter < Parser::TreeRewriter
+      attr_accessor(:namespaces)
+
+      def initialize(namespaces)
+        super()
+        @namespaces = namespaces
+      end
+
+      def on_module(node)
+        _on_module(node)
+      end
+
+      def on_class(node)
+        _on_module(node)
+      end
+
+      private
+
+      def wrap(ast)
+        # Recursively wrap the AST in the namespace modules
+        namespaces.split('::').reverse.inject(ast) do |current_ast, ns|
+          # Create a module node with the current namespace part and the current AST
+          Parser::AST::Node.new(:module, [Parser::AST::Node.new(:const, [nil, ns.to_sym]), current_ast])
+        end
+      end
+
+      def _on_module(node)
+        return unless node.location.column.zero?
+
+        (ast, comments) = Unparser.parse_with_comments(node.location.expression.source)
+        replace(node.location.expression, Unparser.unparse(wrap(ast), comments))
+      end
+    end
+  end
+end