From eeff5e273f22aa28e81ab080e9ffdce85ac394b8 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 22 Oct 2021 09:59:31 +0200
Subject: Prepare skeleton for bytecode interpreter

---
 src/treewalk/objects.h | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 src/treewalk/objects.h

(limited to 'src/treewalk/objects.h')

diff --git a/src/treewalk/objects.h b/src/treewalk/objects.h
new file mode 100644
index 0000000..ed623eb
--- /dev/null
+++ b/src/treewalk/objects.h
@@ -0,0 +1,75 @@
+#ifndef BDL_OBJECTS_H
+#define BDL_OBJECTS_H
+
+#include "string_view.h"
+
+typedef enum ObjectType {
+    OBJ_TYPE_FIXNUM,
+    OBJ_TYPE_BOOL,
+    OBJ_TYPE_NIL,
+    OBJ_TYPE_SYMBOL,
+    OBJ_TYPE_STRING,
+    OBJ_TYPE_PAIR,
+    OBJ_TYPE_PROCEDURE,
+    OBJ_TYPE_LAMBDA,
+    OBJ_TYPE_ERR,
+} ObjectType;
+
+struct Environment;
+
+typedef struct Object {
+    ObjectType type;
+    bool marked;
+    union {
+        // OBJ_TYPE_FIXNUM
+        ssize_t fixnum;
+
+        // OBJ_TYPE_STRING
+        struct {
+            char *string;
+        };
+
+        // OBJ_TYPE_PAIR
+        struct {
+            struct Object *car;
+            struct Object *cdr;
+        };
+
+        // OBJ_TYPE_SYMBOL
+        struct {
+            char *symbol;
+        };
+
+        // OBJ_TYPE_PROCEDURE
+        struct Object *(*proc)(struct Environment *env, struct Object *args);
+
+        // OBJ_TYPE_LAMBDA
+        struct {
+            struct Object *params;
+            struct Object *body;
+            struct Environment *env;
+        };
+    };
+} Object;
+
+// Object constructors.
+Object * make_fixnum(ssize_t num);
+Object * make_procedure(Object *(*proc)(struct Environment *, Object *args));
+Object * make_pair(Object *car, Object *cdr);
+Object * make_symbol(StringView sv);
+Object * make_string(void);
+void append_string(Object *obj, const StringView sv);
+
+// Object representation.
+void display(Object *root);
+void display_pair(Object *root);
+
+// Object comparison.
+bool obj_eq(const Object *a, const Object* b);
+
+// Utility macros.
+#define DEBUG_OBJ(MSG,OBJ) printf((MSG)); display(OBJ); printf("\n");
+#define PRINT_OBJ(OBJ) display(OBJ); printf("\n");
+#define MAKE_SYM(STR) make_symbol((StringView){(STR), sizeof(STR) - 1})
+
+#endif // BDL_OBJECTS_H
-- 
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