From 69a9a95483ca23ee1a42554a9675a30a9d94cc30 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Sun, 14 Aug 2022 23:44:26 -0700
Subject: Chapter 29.3

---
 clox/src/chunk.h    |  2 ++
 clox/src/compiler.c | 25 ++++++++++++++++++++++++-
 clox/src/debug.c    |  4 ++++
 clox/src/vm.c       | 19 +++++++++++++++++++
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/clox/src/chunk.h b/clox/src/chunk.h
index 4810f38..1748adc 100644
--- a/clox/src/chunk.h
+++ b/clox/src/chunk.h
@@ -19,6 +19,7 @@ typedef enum {
   OP_SET_UPVALUE,
   OP_GET_PROPERTY,
   OP_SET_PROPERTY,
+  OP_GET_SUPER,
   OP_EQUAL,
   OP_GREATER,
   OP_LESS,
@@ -34,6 +35,7 @@ typedef enum {
   OP_LOOP,
   OP_CALL,
   OP_INVOKE,
+  OP_SUPER_INVOKE,
   OP_CLOSURE,
   OP_CLOSE_UPVALUE,
   OP_RETURN,
diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index 599ad1b..fd435d5 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -486,6 +486,29 @@ static Token syntheticToken(const char *text) {
   return token;
 }
 
+static void super_(bool canAssign) {
+  if (currentClass == NULL) {
+    error("Can't use 'super' outside of a class.");
+  } else if (!currentClass->hasSuperclass) {
+    error("Can't use 'super' in a class with no superclass.");
+  }
+
+  consume(TOKEN_DOT, "Expect '.' after 'super'.");
+  consume(TOKEN_IDENTIFIER, "Expect superclass method name.");
+  uint8_t name = identifierConstant(&parser.previous);
+
+  namedVariable(syntheticToken("this"), false);
+  if (match(TOKEN_LEFT_PAREN)) {
+    uint8_t argCount = argumentList();
+    namedVariable(syntheticToken("super"), false);
+    emitBytes(OP_SUPER_INVOKE, name);
+    emitByte(argCount);
+  } else {
+    namedVariable(syntheticToken("super"), false);
+    emitBytes(OP_GET_SUPER, name);
+  }
+}
+
 static void classDeclaration() {
   consume(TOKEN_IDENTIFIER, "Expect class name");
   Token className = parser.previous;
@@ -823,7 +846,7 @@ ParseRule rules[] = {
     [TOKEN_OR] = {NULL, or_, PREC_OR},
     [TOKEN_PRINT] = {NULL, NULL, PREC_NONE},
     [TOKEN_RETURN] = {NULL, NULL, PREC_NONE},
-    [TOKEN_SUPER] = {NULL, NULL, PREC_NONE},
+    [TOKEN_SUPER] = {super_, NULL, PREC_NONE},
     [TOKEN_THIS] = {this_, NULL, PREC_NONE},
     [TOKEN_TRUE] = {literal, NULL, PREC_NONE},
     [TOKEN_VAR] = {NULL, NULL, PREC_NONE},
diff --git a/clox/src/debug.c b/clox/src/debug.c
index 4a39811..b8e4a48 100644
--- a/clox/src/debug.c
+++ b/clox/src/debug.c
@@ -86,6 +86,8 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return constantInstruction("OP_GET_PROPERTY", chunk, offset);
   case OP_SET_PROPERTY:
     return constantInstruction("OP_SET_PROPERTY", chunk, offset);
+  case OP_GET_SUPER:
+    return constantInstruction("OP_GET_SUPER", chunk, offset);
   case OP_EQUAL:
     return simpleInstruction("OP_EQUAL", offset);
   case OP_GREATER:
@@ -116,6 +118,8 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return byteInstruction("OP_CALL", chunk, offset);
   case OP_INVOKE:
     return invokeInstruction("OP_INVOKE", chunk, offset);
+  case OP_SUPER_INVOKE:
+    return invokeInstruction("OP_SUPER_INVOKE", chunk, offset);
   case OP_CLOSURE: {
     offset++;
     uint8_t constant = chunk->code[offset++];
diff --git a/clox/src/vm.c b/clox/src/vm.c
index 8a6847e..47c9f29 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -379,6 +379,15 @@ static InterpretResult run() {
       push(value);
       break;
     }
+    case OP_GET_SUPER: {
+      ObjString *name = READ_STRING();
+      ObjClass *superclass = AS_CLASS(pop());
+
+      if (!bindMethod(superclass, name)) {
+        return INTERPRET_RUNTIME_ERROR;
+      }
+      break;
+    }
     case OP_EQUAL: {
       Value b = pop();
       Value a = pop();
@@ -460,6 +469,16 @@ static InterpretResult run() {
       frame = &vm.frames[vm.frameCount - 1];
       break;
     }
+    case OP_SUPER_INVOKE: {
+      ObjString *method = READ_STRING();
+      int argCount = READ_BYTE();
+      ObjClass *superclass = AS_CLASS(pop());
+      if (!invokeFromClass(superclass, method, argCount)) {
+        return INTERPRET_RUNTIME_ERROR;
+      }
+      frame = &vm.frames[vm.frameCount - 1];
+      break;
+    }
     case OP_CLOSURE: {
       ObjFunction *function = AS_FUNCTION(READ_CONSTANT());
       ObjClosure *closure = newClosure(function);
-- 
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