add iterable

iterators.h

@@ -0,0 +1,68 @@
+#pragma once
+
+template <typename T>
+class Iterator {
+protected:
+	T* current;
+public:
+	explicit Iterator(T* ptr) : current(ptr) {}
+
+	T& operator*() const { return *current; }
+	T* operator->() const { return current; }
+
+	bool operator!=(const Iterator& other) const {
+		return current != other.current;
+	}
+
+	virtual Iterator& operator++() = 0;
+};
+
+template<typename T, typename Policy>
+class Traversal {
+	T* start;
+
+public:
+	explicit Traversal(T* start) : start(start) {}
+
+	Policy begin() const { return Policy(start); }
+	Policy end() const { return Policy(nullptr); }
+};
+
+template <typename T>
+struct IteratorForward : public Iterator<T> {
+	explicit IteratorForward(T* ptr) : Iterator<T>(first(ptr)) {}
+
+	static T* first(T* node) {
+		return node;
+	}
+
+	static T* next(T* node) {
+		return node ? node->get_next() : nullptr;
+	}
+
+	Iterator<T>& operator++() override {
+		this->current = next(this->current);
+		return *this;
+	}
+};
+
+template <typename T>
+struct IteratorBackward : public Iterator<T> {
+	explicit IteratorBackward(T* ptr) : Iterator<T>(first(ptr)) {}
+
+	static T* first(T* node) {
+		if (!node) return nullptr;
+		while (node->get_next()) node = node->get_next();
+		return node;
+	}
+
+	static T* next(T* node) {
+		return node ? node->get_prev() : nullptr;
+	}
+
+	Iterator<T>& operator++() override {
+		this->current = next(this->current);
+		return *this;
+	}
+};
+