Struct History 

pub struct History {
    current: EditProject,
    undo: Vec<EditProject>,
    redo: Vec<EditProject>,
    limit: usize,
}

A bounded undo / redo stack wrapping a live EditProject.

Edits go through History::apply, which snapshots the project before each change. Because apply runs the operation on a clone and only commits when the project actually changed, apply then undo is guaranteed to restore the exact prior state — no fragile per-operation inverse derivation, and no-op operations never pollute the undo stack.

Fields

current: EditProject

undo: Vec<EditProject>

redo: Vec<EditProject>

limit: usize

Implementations

impl History

pub fn new(project: EditProject) -> Self

Wrap a project with an undo stack of the default depth.

pub fn with_limit(project: EditProject, limit: usize) -> Self

Wrap a project with an undo stack of at most limit steps (clamped to at least 1).

pub fn project(&self) -> &EditProject

The live project.

pub fn can_undo(&self) -> bool

Whether there is anything to undo.

pub fn can_redo(&self) -> bool

Whether there is anything to redo.

pub fn apply(&mut self, op: &EditOp) -> Result<(), EditError>

Apply an edit, recording it for undo if it changed anything.

Errors

Propagates EditError from EditProject::apply. On error the project is left unchanged (the operation runs on a clone that is discarded).

pub fn undo(&mut self) -> bool

Undo the last recorded change. Returns whether anything was undone (the boolean is an optional signal — undo is usually called for effect).

pub fn redo(&mut self) -> bool

Redo the last undone change. Returns whether anything was redone.

Trait Implementations

impl Clone for History

fn clone(&self) -> History

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for History

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

Formats the value using the given formatter.