Struct NSUndoManager 

pub struct NSUndoManager<T> { /* private fields */ }

Bounded ringbuffer undo/redo state manager (NSUndoManager equivalent).

Implementations

impl<T: Clone + PartialEq> NSUndoManager<T>

pub fn new() -> Self

Creates a new NSUndoManager with default capacity (DEFAULT_UNDO_CAPACITY = 50).

pub fn with_capacity(capacity: usize) -> Self

Creates a new NSUndoManager with a custom maximum capacity.

pub fn capacity(&self) -> usize

Maximum snapshot capacity.

pub fn undo_count(&self) -> usize

Number of recorded undo steps available.

pub fn redo_count(&self) -> usize

Number of recorded redo steps available.

pub fn can_undo(&self) -> bool

Returns true if an undo operation can be performed.

pub fn can_redo(&self) -> bool

Returns true if a redo operation can be performed.

pub fn is_grouping(&self) -> bool

Returns true if a coalesced undo group is currently open.

pub fn peek_undo(&self) -> Option<&T>

Non-destructively inspects the most recent undo snapshot.

pub fn peek_redo(&self) -> Option<&T>

Non-destructively inspects the most recent redo snapshot.

pub fn begin_grouping(&mut self, initial_state: T)

Begins a coalesced undo group (such as a continuous slider or canvas drag).

While a group is active, intermediate Self::push_snapshot calls are ignored until Self::end_grouping commits the net state transition as a single undo step.

pub fn end_grouping(&mut self, final_state: &T) -> bool

Ends the active coalesced undo group and records a single undo snapshot if final_state differs from the group’s initial_state.

pub fn push_snapshot(&mut self, state: T)

Records a new state snapshot on the undo stack.

In accordance with SPEC-008 §2.2:

1. Ignores intermediate snapshots while a coalesced group (begin_grouping) is active.
2. Deduplicates consecutive identical snapshots (no-op protection).
3. Drops the oldest entry if the undo stack exceeds capacity.
4. Unconditionally clears the redo stack.

pub fn undo(&mut self, current_state: &mut T) -> bool

Performs an undo operation:

• Pushes *current_state onto the redo stack.
• Restores *current_state from the most recent undo snapshot.
• Returns true if state was restored, or false if undo_stack was empty.

pub fn redo(&mut self, current_state: &mut T) -> bool

Performs a redo operation:

• Pushes *current_state onto the undo stack.
• Restores *current_state from the most recent redo snapshot.
• Returns true if state was restored, or false if redo_stack was empty.

pub fn clear(&mut self)

Clears all undo and redo history.

pub fn validate_invariants(&self) -> Result<(), String>

Validates all NSUndoManager structural invariants (GL-1015 §3.5):

1. capacity >= 1
2. undo_stack.len() <= capacity and redo_stack.len() <= capacity
3. Zero consecutive identical snapshots in undo_stack

Trait Implementations

impl<T: Clone> Clone for NSUndoManager<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for NSUndoManager<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Clone + PartialEq> Default for NSUndoManager<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: Eq> Eq for NSUndoManager<T>

impl<T: PartialEq> PartialEq for NSUndoManager<T>

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<T: PartialEq> StructuralPartialEq for NSUndoManager<T>