13.3.1

ruby/lib/lox/expr.rb

@@ -18,6 +18,7 @@ module Lox
     expr :Literal, :value
     expr :Logical, :left, :op, :right
     expr :Set, :object, :name, :value
+    expr :Super, :keyword, :method
     expr :This, :keyword
     expr :Unary, :op, :right
     expr :Variable, :name

ruby/lib/lox/parser.rb

@@ -316,6 +316,14 @@ module Lox
       return Expr::Literal.new(true) if match?(:TRUE)
       return Expr::Literal.new(nil) if match?(:NIL)
       return Expr::Literal.new(prev.literal) if match?(:NUMBER, :STRING)
+
+      if match?(:SUPER)
+        keyword = prev
+        consume!(:DOT, "Expect '.' after 'super'.")
+        method = consume!(:IDENTIFIER, "Expect superclass method name.")
+        return Expr::Super.new(keyword, method)
+      end
+
       return Expr::This.new(prev) if match?(:THIS)
       return Expr::Variable.new(prev) if match?(:IDENTIFIER)
 

ruby/test/lox/test_interpreter.rb

@@ -484,6 +484,28 @@ class TestInterpreter < Lox::Test
     SRC
   end
 
+  def test_calling_superclass_methods
+    assert_interpreted <<~OUT, <<~SRC
+      Fry until golden brown.
+      Pipe full of custard and coat with chocolate.
+    OUT
+      class Doughnut {
+        cook() {
+          print "Fry until golden brown.";
+        }
+      }
+
+      class BostonCream < Doughnut {
+        cook() {
+          super.cook();
+          print "Pipe full of custard and coat with chocolate.";
+        }
+      }
+
+      BostonCream().cook();
+    SRC
+  end
+
   private
 
   def assert_interpreted(expected, src)