CommandStack

@MainActor final class CommandStack

Overview

The CommandStack provides centralised command execution with full undo/redo capabilities. It maintains separate stacks for undo and redo operations, ensuring thread-safe access to command history and execution state.

Overview

The CommandStack follows a traditional undo/redo model:

• Execution: Commands are executed and added to the undo stack

• Undo: Commands are popped from undo stack and moved to redo stack

• Redo: Commands are popped from redo stack and moved back to undo stack

• Flush: Both stacks can be cleared to reset command history

Concurrency Model

The CommandStack is implemented as an actor to ensure thread-safe access to command stacks and execution state. All command operations are serialised through the actor’s message queue, preventing race conditions and ensuring consistent state transitions.

Example Usage

let commandStack = CommandStack(maxHistorySize: 100)

let result = try await commandStack.execute(setCommand)
try await commandStack.undo()  // Reverses the set command
try await commandStack.redo()  // Re-applies the set command