From a819a85209646cb7dba87c49e904dd47cc804133 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Fri, 12 Aug 2022 21:17:45 -0700
Subject: Chapter 27.2

---
 clox/src/chunk.h    |  1 +
 clox/src/compiler.c | 90 +++++++++++++++++++++++++++++++----------------------
 clox/src/debug.c    |  2 ++
 clox/src/vm.c       |  3 ++
 4 files changed, 58 insertions(+), 38 deletions(-)

(limited to 'clox/src')

diff --git a/clox/src/chunk.h b/clox/src/chunk.h
index e992c04..ae0ab72 100644
--- a/clox/src/chunk.h
+++ b/clox/src/chunk.h
@@ -34,6 +34,7 @@ typedef enum {
   OP_CLOSURE,
   OP_CLOSE_UPVALUE,
   OP_RETURN,
+  OP_CLASS,
 } OpCode;
 
 typedef struct {
diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index f31d015..b21a53d 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -362,6 +362,55 @@ static void function(FunctionType type) {
   }
 }
 
+static bool identifiersEqual(Token *a, Token *b) {
+  if (a->length != b->length)
+    return false;
+  return memcmp(a->start, b->start, a->length) == 0;
+}
+
+static void addLocal(Token name) {
+  if (current->localCount == UINT8_COUNT) {
+    error("Too many local variables in function.");
+    return;
+  }
+
+  Local *local = &current->locals[current->localCount++];
+  local->name = name;
+  local->depth = -1;
+  local->isCaptured = false;
+}
+
+static void declareVariable() {
+  if (current->scopeDepth == 0)
+    return;
+
+  Token *name = &parser.previous;
+  for (int i = current->localCount - 1; i >= 0; i--) {
+    Local *local = &current->locals[i];
+    if (local->depth != -1 && local->depth < current->scopeDepth) {
+      break;
+    }
+
+    if (identifiersEqual(name, &local->name)) {
+      error("Already a variable with this name in this scope.");
+    }
+  }
+
+  addLocal(*name);
+}
+
+static void classDeclaration() {
+  consume(TOKEN_IDENTIFIER, "Expect class name");
+  uint8_t nameConstant = identifierConstant(&parser.previous);
+  declareVariable();
+
+  emitBytes(OP_CLASS, nameConstant);
+  defineVariable(nameConstant);
+
+  consume(TOKEN_LEFT_BRACE, "Expect '{' before class body.");
+  consume(TOKEN_RIGHT_BRACE, "Expect '}' after class body.");
+}
+
 static void markInitialized() {
   if (current->scopeDepth == 0)
     return;
@@ -518,7 +567,9 @@ static void synchronize() {
 }
 
 static void declaration() {
-  if (match(TOKEN_FUN)) {
+  if (match(TOKEN_CLASS)) {
+    classDeclaration();
+  } else if (match(TOKEN_FUN)) {
     funDeclaration();
   } else if (match(TOKEN_VAR)) {
     varDeclaration();
@@ -701,12 +752,6 @@ static uint8_t identifierConstant(Token *name) {
   return makeConstant(OBJ_VAL(copyString(name->start, name->length)));
 }
 
-static bool identifiersEqual(Token *a, Token *b) {
-  if (a->length != b->length)
-    return false;
-  return memcmp(a->start, b->start, a->length) == 0;
-}
-
 static int resolveLocal(Compiler *compiler, Token *name) {
   for (int i = compiler->localCount - 1; i >= 0; i--) {
     Local *local = &compiler->locals[i];
@@ -759,37 +804,6 @@ static int resolveUpvalue(Compiler *compiler, Token *name) {
   return -1;
 }
 
-static void addLocal(Token name) {
-  if (current->localCount == UINT8_COUNT) {
-    error("Too many local variables in function.");
-    return;
-  }
-
-  Local *local = &current->locals[current->localCount++];
-  local->name = name;
-  local->depth = -1;
-  local->isCaptured = false;
-}
-
-static void declareVariable() {
-  if (current->scopeDepth == 0)
-    return;
-
-  Token *name = &parser.previous;
-  for (int i = current->localCount - 1; i >= 0; i--) {
-    Local *local = &current->locals[i];
-    if (local->depth != -1 && local->depth < current->scopeDepth) {
-      break;
-    }
-
-    if (identifiersEqual(name, &local->name)) {
-      error("Already a variable with this name in this scope.");
-    }
-  }
-
-  addLocal(*name);
-}
-
 static uint8_t parseVariable(const char *errorMessage) {
   consume(TOKEN_IDENTIFIER, errorMessage);
 
diff --git a/clox/src/debug.c b/clox/src/debug.c
index 750fdb9..a2c2c53 100644
--- a/clox/src/debug.c
+++ b/clox/src/debug.c
@@ -122,6 +122,8 @@ int disassembleInstruction(Chunk *chunk, int offset) {
     return simpleInstruction("OP_CLOSE_UPVALUE", offset);
   case OP_RETURN:
     return simpleInstruction("OP_RETURN", offset);
+  case OP_CLASS:
+    return constantInstruction("OP_CLASS", chunk, offset);
   default:
     printf("Unknown opcode %d\n", instruction);
     return offset + 1;
diff --git a/clox/src/vm.c b/clox/src/vm.c
index 601b128..37bf2d4 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -384,6 +384,9 @@ static InterpretResult run() {
       frame = &vm.frames[vm.frameCount - 1];
       break;
     }
+    case OP_CLASS:
+      push(OBJ_VAL(newClass(READ_STRING())));
+      break;
     }
   }
 
-- 
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