Add undo/redo infrastructure and buffer management additions.

UndoNode.h

@@ -0,0 +1,83 @@
+#ifndef KTE_UNDONODE_H
+#define KTE_UNDONODE_H
+
+#include <cstddef>
+#include <cstddef>
+
+
+enum UndoKind {
+	UNDO_INSERT,
+	UNDO_DELETE,
+};
+
+
+class UndoNode {
+public:
+	explicit UndoNode(const UndoKind kind, const size_t row, const size_t col)
+		: kind_(kind), row_(row), col_(col) {}
+
+
+	~UndoNode() = default;
+
+
+	[[nodiscard]] UndoKind Kind() const
+	{
+		return kind_;
+	}
+
+
+	[[nodiscard]] UndoNode *Next() const
+	{
+		return next_;
+	}
+
+
+	void Next(UndoNode *next)
+	{
+		next_ = next;
+	}
+
+
+	[[nodiscard]] UndoNode *Child() const
+	{
+		return child_;
+	}
+
+
+	void Child(UndoNode *child)
+	{
+		child_ = child;
+	}
+
+
+	void SetRowCol(const std::size_t row, const std::size_t col)
+	{
+		this->row_ = row;
+		this->col_ = col;
+	}
+
+
+	[[nodiscard]] std::size_t Row() const
+	{
+		return row_;
+	}
+
+
+	[[nodiscard]] std::size_t Col() const
+	{
+		return col_;
+	}
+
+
+	void DeleteNext() const;
+
+private:
+	[[maybe_unused]] UndoKind kind_;
+	[[maybe_unused]] UndoNode *next_{nullptr};
+	[[maybe_unused]] UndoNode *child_{nullptr};
+
+	[[maybe_unused]] std::size_t row_{}, col_{};
+};
+
+
+#endif // KTE_UNDONODE_H