From 1bba129074b812a354eccfdd9cc69b233789dc6c Mon Sep 17 00:00:00 2001
From: Tom Willemse <tom@ryuslash.org>
Date: Sun, 14 Aug 2022 22:27:35 -0700
Subject: [PATCH] Chapter 29.2

---
 clox/src/compiler.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index f14666c..599ad1b 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -71,6 +71,7 @@ typedef struct Compiler {
 
 typedef struct ClassCompiler {
   struct ClassCompiler *enclosing;
+  bool hasSuperclass;
 } ClassCompiler;
 
 static int resolveUpvalue(Compiler *, Token *);
@@ -478,6 +479,13 @@ static void variable(bool canAssign) {
   namedVariable(parser.previous, canAssign);
 }
 
+static Token syntheticToken(const char *text) {
+  Token token;
+  token.start = text;
+  token.length = (int)strlen(text);
+  return token;
+}
+
 static void classDeclaration() {
   consume(TOKEN_IDENTIFIER, "Expect class name");
   Token className = parser.previous;
@@ -488,6 +496,7 @@ static void classDeclaration() {
   defineVariable(nameConstant);
 
   ClassCompiler classCompiler;
+  classCompiler.hasSuperclass = false;
   classCompiler.enclosing = currentClass;
   currentClass = &classCompiler;
 
@@ -499,8 +508,13 @@ static void classDeclaration() {
       error("A class can't inherit from itself.");
     }
 
+    beginScope();
+    addLocal(syntheticToken("super"));
+    defineVariable(0);
+
     namedVariable(className, false);
     emitByte(OP_INHERIT);
+    classCompiler.hasSuperclass = true;
   }
 
   namedVariable(className, false);
@@ -511,6 +525,10 @@ static void classDeclaration() {
   consume(TOKEN_RIGHT_BRACE, "Expect '}' after class body.");
   emitByte(OP_POP);
 
+  if (classCompiler.hasSuperclass) {
+    endScope();
+  }
+
   currentClass = currentClass->enclosing;
 }