[UNSTABLE] Use duck typing for ASTLeaf/ASTNode checks. NEXT: Get `enum` and friends working

app/lib/celery_script/ast_leaf.rb

@@ -5,9 +5,26 @@
 # to do that. -RC
 module CeleryScript
   class AstLeaf < AstBase
+    FRIENDLY_ERRORS = CeleryScript::Checker::FRIENDLY_ERRORS
+    BAD_LEAF        = CeleryScript::Checker::BAD_LEAF
+
     attr_reader :kind, :value, :parent
     def initialize(parent, value, kind)
       @parent, @value, @kind = parent, value, kind
     end
+
+    def cross_check(corpus)
+      allowed = corpus.fetchArg(kind).allowed_values
+      unless allowed.any? { |spec| spec.valid?(self, corpus) }
+        message = (FRIENDLY_ERRORS.dig(kind, parent.kind) || BAD_LEAF) % {
+          kind:        kind,
+          parent_kind: parent.kind,
+          allowed:     "[#{allowed.map(&:name).join(", ")}]",
+          actual:      value.class
+        }
+        raise TypeCheckError, message
+      end
+    end
+
   end
 end

app/lib/celery_script/ast_node.rb

@@ -8,13 +8,10 @@ module CeleryScript
                            "no leaves here."
       LEAVES_NEED_KEYS   = "Tried to initialize a leaf without a key."
       NEVER              = :__NEVER__
+      FRIENDLY_ERRORS    = CeleryScript::Checker::FRIENDLY_ERRORS
+      BAD_LEAF           = CeleryScript::Checker::BAD_LEAF
 
-      def initialize(parent = nil,
-                     args:,
-                     body: nil,
-                     comment: "",
-                     kind:,
-                     uuid: nil)
+      def initialize(parent = nil, args:, body: nil, comment: "", kind:, uuid: nil)
           @comment, @kind, @parent = comment, kind, parent
 
           @args = args.map do |key, value|
@@ -46,5 +43,9 @@ module CeleryScript
         (hash[:args].is_a?(Hash)) &&
         (hash[:kind].is_a?(String))
       end
+
+      def cross_check(corpus)
+        print "🔥"
+      end
   end
 end

app/lib/celery_script/checker.rb

@@ -133,25 +133,7 @@ module CeleryScript
     # IDEA: Add a refinement to string class to allow it to quack like other
     #       special classes.
     def needs_new_name(node, arg_key = nil)
-      case node
-      when CeleryScript::AstNode
-        print "🔥"
-      when CeleryScript::AstLeaf
-        allowed = corpus.fetchArg(node.kind).allowed_values
-        unless allowed.any? { |spec| spec.valid?(node, corpus) }
-          actual      = node.value.class
-          kind        = node.kind
-          parent_kind = node.parent.kind
-
-          message = (FRIENDLY_ERRORS.dig(kind, parent_kind) || BAD_LEAF) % {
-            kind:        kind,
-            parent_kind: parent_kind,
-            allowed:     "[#{allowed.map(&:name).join(", ")}]",
-            actual:      actual
-          }
-          raise TypeCheckError, message
-        end
-      end
+      node.cross_check(corpus)
     end
 
     def validate_leaf_pairing(key, value)

app/lib/celery_script/corpus.rb

@@ -25,7 +25,7 @@ module CeleryScript
       end
 
       def valid?(node, corpus)
-        return corpus
+        return corpus # TODO: Clean this up to actually use encapsulation.
           .instance_variable_get(:@value_def_list)
           .fetch(value)
           .values