Struct UndoBuffer 

pub struct UndoBuffer { /* private fields */ }

Two-stack undo/redo history buffer.

Mirrors the C# UndoBuffer class: when a new action is added the redo stack is cleared (so a new branch cannot be redone). The undo stack is size-limited; the oldest entries are dropped when the limit is exceeded.

Implementations

impl UndoBuffer

pub fn new() -> Self

Create a new buffer with a default history limit of 200 entries.

pub fn with_max_undos(self, n: usize) -> Self

Set the maximum number of undo steps retained.

pub fn add(&mut self, cmd: Box<dyn UndoRedoCommand>)

Push cmd without executing it.

Use this when the action has already been applied to the state; the command only needs to know how to undo (and redo) it. Clears the redo stack.

pub fn add_and_do(&mut self, cmd: Box<dyn UndoRedoCommand>)

Execute cmd.do_it() and push it onto the undo stack.

Use this when the action has not yet been applied.

pub fn undo(&mut self)

Undo the most recent operation. No-op if the stack is empty.

pub fn redo(&mut self)

Redo the most recently undone operation. No-op if the redo stack is empty.

pub fn can_undo(&self) -> bool

Returns true if there is at least one operation that can be undone.

pub fn can_redo(&self) -> bool

Returns true if there is at least one operation that can be redone.

pub fn undo_name(&self) -> Option<&str>

Name of the operation that undo() would reverse, if any.

pub fn redo_name(&self) -> Option<&str>

Name of the operation that redo() would re-apply, if any.

pub fn clear_history(&mut self)

Discard all undo and redo history.

Trait Implementations

impl Default for UndoBuffer

fn default() -> Self

Returns the “default value” for a type.