A simple mark-sweep implementation

src/MarkSweep.cpp

@@ -0,0 +1,84 @@
+#include <iostream> 
+#include <vector>
+#define HEAP_SIZE 65536 // Arbitrary for now, 2^16
+using namespace std;
+
+/* A simple mark and sweep algorithm */
+
+// Shouldn't be exposed. For now, it is
+struct ObjectHeader {
+    size_t size = sizeof(this);
+    bool marked = false;
+
+};
+
+struct Object : ObjectHeader {
+    char name; // should be something like id, but for testing sake its char
+    Object* child;
+    //Object(char name) {}
+    //Object(char name, Object* child) {}
+};
+
+// Representing the heap as a simple struct for now
+struct Heap {
+    Object heap_space[HEAP_SIZE];
+};
+
+// For now it assumes that it is given root objects from the start, no root finding included
+class MarkSweep {
+    public:
+        void mark(Object* obj) {
+            if (!markedBit(obj)) {
+                markBit(obj);
+                Object* ref = obj->child;
+                if (ref != nullptr) {
+                    mark(ref);
+                }
+            }
+        }
+
+        void sweep(vector<Object*> worklist) {
+            for (Object* obj: worklist) {
+                if (!markedBit(obj) && obj != nullptr) {
+                    delete obj;
+                }
+            }
+        }
+
+    private:
+        bool markedBit(Object* obj) {
+            return obj->marked;
+        }
+
+        void markBit(Object* obj) {
+            obj->marked = true;
+        }
+
+};
+
+int main() {
+    Object* b = new Object();
+    b->name = 'B';
+    b->child = nullptr;
+    Object* c = new Object();
+    c->name = 'C';
+    c->child = b; // c -> d
+    Object* d = new Object();
+    d->name = 'D';
+    d->child = nullptr;
+
+    //Heap* heap = new Heap{*c, *b, *d};
+    vector<Object*> worklist = {c, b, d};
+    MarkSweep* gc = new MarkSweep();
+
+    gc->mark(c);
+    cout << "Expected 1, got: " << b->marked << '\n';
+    cout << "Expected 1, got: " << c->marked << '\n';
+    cout << "Expected 0, got: " << d->marked << '\n';
+
+    gc->sweep(worklist); 
+    cout << b->name << '\n';
+    cout << c->name << '\n';
+    cout << d->name << '\n'; // The object at d is now deleted (freed)
+    return 0;
+}