From 62858b60e43803477e898c7993e109a94701ce70 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Sun, 14 Aug 2022 19:56:32 -0700
Subject: Chapter 28.5

---
 clox/src/chunk.h    |  1 +
 clox/src/compiler.c |  4 ++++
 clox/src/debug.c    | 11 +++++++++++
 clox/src/vm.c       | 36 ++++++++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+)

diff --git a/clox/src/chunk.h b/clox/src/chunk.h
index 9c75c1d..690fffd 100644
--- a/clox/src/chunk.h
+++ b/clox/src/chunk.h
@@ -33,6 +33,7 @@ typedef enum {
   OP_JUMP_IF_FALSE,
   OP_LOOP,
   OP_CALL,
+  OP_INVOKE,
   OP_CLOSURE,
   OP_CLOSE_UPVALUE,
   OP_RETURN,
diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index 18ad4a7..bfa0a96 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -335,6 +335,10 @@ static void dot(bool canAssign) {
   if (canAssign && match(TOKEN_EQUAL)) {
     expression();
     emitBytes(OP_SET_PROPERTY, name);
+  } else if (match(TOKEN_LEFT_PAREN)) {
+    uint8_t argCount = argumentList();
+    emitBytes(OP_INVOKE, name);
+    emitByte(argCount);
   } else {
     emitBytes(OP_GET_PROPERTY, name);
   }
diff --git a/clox/src/debug.c b/clox/src/debug.c
index 74be178..079f0e9 100644
--- a/clox/src/debug.c
+++ b/clox/src/debug.c
@@ -20,6 +20,15 @@ static int constantInstruction(const char *name, Chunk *chunk, int offset) {
   return offset + 2;
 }
 
+static int invokeInstruction(const char *name, Chunk *chunk, int offset) {
+  uint8_t constant = chunk->code[offset + 1];
+  uint8_t argCount = chunk->code[offset + 2];
+  printf("%-16s (%d args) %4d '", name, argCount, constant);
+  printValue(chunk->constants.values[constant]);
+  printf("'\n'");
+  return offset + 3;
+}
+
 static int simpleInstruction(const char *name, int offset) {
   printf("%s\n", name);
   return offset + 1;
@@ -105,6 +114,8 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return jumpInstruction("OP_LOOP", -1, chunk, offset);
   case OP_CALL:
     return byteInstruction("OP_CALL", chunk, offset);
+  case OP_INVOKE:
+    return invokeInstruction("OP_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 d248609..b5cb1cc 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -146,6 +146,33 @@ static bool callValue(Value callee, int argCount) {
   return false;
 }
 
+static bool invokeFromClass(ObjClass *klass, ObjString *name, int argCount) {
+  Value method;
+  if (!tableGet(&klass->methods, name, &method)) {
+    runtimeError("Undefined property '%s'.", name->chars);
+    return false;
+  }
+  return call(AS_CLOSURE(method), argCount);
+}
+
+static bool invoke(ObjString *name, int argCount) {
+  Value receiver = peek(argCount);
+
+  if (!IS_INSTANCE(receiver)) {
+    runtimeError("Only instances have methods.");
+    return false;
+  }
+
+  ObjInstance *instance = AS_INSTANCE(receiver);
+
+  Value value;
+  if (tableGet(&instance->fields, name, &value)) {
+    vm.stackTop[-argCount - 1] = value;
+    return callValue(value, argCount);
+  }
+  return invokeFromClass(instance->klass, name, argCount);
+}
+
 static bool bindMethod(ObjClass *klass, ObjString *name) {
   Value method;
   if (!tableGet(&klass->methods, name, &method)) {
@@ -424,6 +451,15 @@ static InterpretResult run() {
       frame = &vm.frames[vm.frameCount - 1];
       break;
     }
+    case OP_INVOKE: {
+      ObjString *method = READ_STRING();
+      int argCount = READ_BYTE();
+      if (!invoke(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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