Implement Herb::Visitor in Ruby gem

Author: marcoroth

.gitignore

@@ -93,6 +93,7 @@ javascript/packages/node/extension/nodes.cpp
 javascript/packages/node/extension/nodes.h
 lib/herb/ast/nodes.rb
 lib/herb/errors.rb
+lib/herb/visitor.rb
 sig/serialized_ast_nodes.rbs
 sig/serialized_ast_errors.rbs
 src/ast_nodes.c

lib/herb.rb

@@ -24,6 +24,8 @@
 
 require_relative "herb/version"
 
+require_relative "herb/visitor"
+
 begin
   major, minor, _patch = RUBY_VERSION.split(".") #: [String, String, String]
   require_relative "herb/#{major}.#{minor}/herb"

lib/herb/ast/node.rb

@@ -75,6 +75,18 @@ def inspect_array(array, item_name: "item", prefix: "    ")
       def tree_inspect(_indent = 0)
         raise NotImplementedError
       end
+
+      #: (Visitor) -> void
+      def accept(_visitor)
+        raise NoMethodError, "undefined method `accept' for #{inspect}"
+      end
+
+      #: () -> Array[Herb::AST::Node]
+      def child_nodes
+        raise NoMethodError, "undefined method `child_nodes' for #{inspect}"
+      end
+
+      alias deconstruct child_nodes
     end
   end
 end

lib/herb/parse_result.rb

@@ -26,5 +26,10 @@ def success?
     def pretty_errors
       JSON.pretty_generate(errors + value.errors)
     end
+
+    #: (Visitor) -> void
+    def visit(visitor)
+      value.accept(visitor)
+    end
   end
 end

sig/herb/ast/node.rbs

@@ -32,6 +32,14 @@ module Herb
 
       # : (?Integer) -> String
       def tree_inspect: (?Integer) -> String
+
+      # : (Visitor) -> void
+      def accept: (Visitor) -> void
+
+      # : () -> Array[Herb::AST::Node]
+      def child_nodes: () -> Array[Herb::AST::Node]
+
+      alias deconstruct child_nodes
     end
   end
 end