From ba52787271b246255b8788942cdb74560f840bfe Mon Sep 17 00:00:00 2001
From: Tom Willemse <tom@ryuslash.org>
Date: Mon, 6 Sep 2021 02:24:56 -0700
Subject: [PATCH] Chapter 19.1 - 19.2

---
 clox/src/CMakeLists.txt |  1 +
 clox/src/object.h       | 32 ++++++++++++++++++++++++++++++++
 clox/src/value.h        |  8 ++++++++
 3 files changed, 41 insertions(+)
 create mode 100644 clox/src/object.h

diff --git a/clox/src/CMakeLists.txt b/clox/src/CMakeLists.txt
index af21222..e46b989 100644
--- a/clox/src/CMakeLists.txt
+++ b/clox/src/CMakeLists.txt
@@ -14,6 +14,7 @@ add_executable(Lox
   compiler.c
   scanner.h
   scanner.c
+  object.h
   main.c)
 
 install(TARGETS Lox)
diff --git a/clox/src/object.h b/clox/src/object.h
new file mode 100644
index 0000000..7ab8f3a
--- /dev/null
+++ b/clox/src/object.h
@@ -0,0 +1,32 @@
+#ifndef OBJECT_H
+#define OBJECT_H
+
+#include "common.h"
+#include "value.h"
+
+#define OBJ_TYPE(value) (AS_OBJ(value)->type)
+
+#define IS_STRING(value) isObjType(value, OBJ_STRING)
+
+#define AS_STRING(value) ((ObjString *)AS_OBJ(value))
+#define AS_CSTRING(value) (((ObjString *)AS_OBJ(value))->chars)
+
+typedef enum {
+  OBJ_STRING,
+} ObjType;
+
+struct Obj {
+  ObjType type;
+};
+
+struct ObjString {
+  Obj obj;
+  int length;
+  char *chars;
+};
+
+static inline bool isObjType(Value value, ObjType type) {
+  return IS_OBJ(value) && AS_OBJ(value)->type == type;
+}
+
+#endif
diff --git a/clox/src/value.h b/clox/src/value.h
index 96df347..6896bea 100644
--- a/clox/src/value.h
+++ b/clox/src/value.h
@@ -3,10 +3,14 @@
 
 #include "common.h"
 
+typedef struct Obj Obj;
+typedef struct ObjString ObjString;
+
 typedef enum {
   VAL_BOOL,
   VAL_NIL,
   VAL_NUMBER,
+  VAL_OBJ,
 } ValueType;
 
 typedef struct {
@@ -14,19 +18,23 @@ typedef struct {
   union {
     bool boolean;
     double number;
+    Obj *obj;
   } as;
 } Value;
 
 #define IS_BOOL(value) ((value).type == VAL_BOOL)
 #define IS_NIL(value) ((value).type == VAL_NIL)
 #define IS_NUMBER(value) ((value).type == VAL_NUMBER)
+#define IS_OBJ(value) ((value).type == VAL_OBJ)
 
+#define AS_OBJ(value) ((value).as.obj)
 #define AS_BOOL(value) ((value).as.boolean)
 #define AS_NUMBER(value) ((value).as.number)
 
 #define BOOL_VAL(value) ((Value){VAL_BOOL, {.boolean = value}})
 #define NIL_VAL ((Value){VAL_NIL, {.number = 0}})
 #define NUMBER_VAL(value) ((Value){VAL_NUMBER, {.number = value}})
+#define OBJ_VAL(value) ((Value){VAL_OBJ, {.obj = (Obj *)object}})
 
 typedef struct {
   int capacity;