diff -r f77d2230e87c -r d384df40c8e7 src/edithistory.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/edithistory.h	Wed Sep 22 00:25:31 2021 +0300
@@ -0,0 +1,53 @@
+#pragma once
+#include "main.h"
+#include "model.h"
+#include "modeleditcontext.h"
+
+class AbstractHistoryEntry
+{
+public:
+	virtual void undo(Model::EditContext& editContext) = 0;
+	virtual void redo(Model::EditContext& editContext) = 0;
+};
+
+class InsertHistoryEntry : public AbstractHistoryEntry
+{
+public:
+	InsertHistoryEntry(int position, const QString& code) :
+		position{position},
+		code{code} {}
+	void undo(Model::EditContext& editContext) override;
+	void redo(Model::EditContext& editContext) override;
+protected:
+	int position;
+	QString code;
+};
+
+class DeleteHistoryEntry : public InsertHistoryEntry
+{
+public:
+	void undo(Model::EditContext& editContext) override;
+	void redo(Model::EditContext& editContext) override;
+};
+
+class EditHistoryEntry : public AbstractHistoryEntry
+{
+public:
+	EditHistoryEntry(int position, const QString& codeBefore, const QString& codeAfter) :
+		position{position},
+		codeBefore{codeBefore},
+		codeAfter{codeAfter} {}
+	void undo(Model::EditContext& editContext) override;
+	void redo(Model::EditContext& editContext) override;
+private:
+	int position;
+	QString codeBefore;
+	QString codeAfter;
+};
+
+class EditHistory
+{
+public:
+	using Changeset = QVector<std::unique_ptr<AbstractHistoryEntry>>;
+	EditHistory();
+};
\ No newline at end of file