1 files changed, 24 insertions, 1 deletions
diff --git a/src/com/craftinginterpreters/lox/Resolver.java b/src/com/craftinginterpreters/lox/Resolver.java
index dc7332b..fe3a641 100644
--- a/src/com/craftinginterpreters/lox/Resolver.java
+++ b/src/com/craftinginterpreters/lox/Resolver.java
@@ -19,7 +19,7 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
     }
 
     private enum ClassType {
-        NONE, CLASS
+        NONE, CLASS, SUBCLASS
     }
 
     private ClassType currentClass = ClassType.NONE;
@@ -51,9 +51,16 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
         }
 
         if (stmt.superclass != null) {
+            currentClass = ClassType.SUBCLASS;
+
             resolve(stmt.superclass);
         }
 
+        if (stmt.superclass != null) {
+            beginScope();
+            scopes.peek().put("super", true);
+        }
+
         beginScope();
         scopes.peek().put("this", true);
 
@@ -67,6 +74,10 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
 
         endScope();
 
+        if (stmt.superclass != null) {
+            endScope();
+        }
+
         currentClass = enclosingClass;
         return null;
     }
@@ -184,6 +195,18 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
     }
 
     @Override
+    public Void visitSuperExpr(Expr.Super expr) {
+        if (currentClass == ClassType.NONE) {
+            Lox.error(expr.keyword, "Can't use 'super' outside of a class.");
+        } else if (currentClass != ClassType.SUBCLASS) {
+            Lox.error(expr.keyword, "Can't use 'super' in a class with no superclass.");
+        }
+
+        resolveLocal(expr, expr.keyword);
+        return null;
+    }
+
+    @Override
     public Void visitThisExpr(Expr.This expr) {
         if (currentClass == ClassType.NONE) {
             Lox.error(expr.keyword, "Can't use 'this' outside of a class.");