Struct History 

pub struct History { /* private fields */ }

An undo/redo history recorded as inverse operations in a value-backed ledger.

Implementations

impl History

pub fn new() -> Self

An empty history.

pub fn commit<T: Transport>( &mut self, transport: &mut T, resource: &Symbol, new_value: Expr, ) -> Result<()>

Commit a new value for resource through transport, recording the forward and inverse operations. Clears the redo stack.

pub fn undo<T: Transport>( &mut self, transport: &mut T, ) -> Result<Option<Symbol>>

Undo the most recent edit by replaying its inverse operation. Returns the resource that changed, or None if there is nothing to undo.

pub fn redo<T: Transport>( &mut self, transport: &mut T, ) -> Result<Option<Symbol>>

Redo the most recently undone edit by replaying its forward operation.

pub fn can_undo(&self) -> bool

Whether there is an edit to undo.

pub fn can_redo(&self) -> bool

Whether there is an edit to redo.

pub fn as_value(&self) -> Expr

The ledger as a value: the ordered list of recorded operations (the object edit history / session event log).

Trait Implementations

impl Default for History

fn default() -> History

Returns the “default value” for a type.