Struct History 

pub struct History<S> { /* private fields */ }

the undo and redo steps of a state S

Implementations

impl<S: 'static> History<S>

pub fn new(limit: usize) -> Self

pub fn apply(&mut self, s: &mut S, edit: Box<dyn Edit<S>>)

run the edit and record it as the newest step (redo steps are gone)

pub fn record(&mut self, edit: Box<dyn Edit<S>>)

record an edit that was already applied

pub fn undo(&mut self, s: &mut S) -> bool

take the newest step back -> false when there is none

pub fn redo(&mut self, s: &mut S) -> bool

do the last undone step again -> false when there is none

pub fn can_undo(&self) -> bool

pub fn can_redo(&self) -> bool

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

the label of the step undo would take back

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

the label of the step redo would do again

pub fn undo_value(&self) -> Option<&dyn Any>

the step undo would take back as data (Edit::value; None for a group): the app can see what kind of edit it is before it runs

pub fn redo_value(&self) -> Option<&dyn Any>

the step redo would do again as data (Edit::value)

pub fn group_begin(&mut self, label: &str)

the following edits are one step (nested groups join the outer one)

pub fn group_end(&mut self)

close the group of group_begin (an empty group records nothing)

pub fn mark_saved(&mut self)

the state is saved now (dirty() false until the next change)

pub fn mark_unsaved(&mut self)

the state counts as unsaved until the next mark_saved (a copy recovered after a crash)

pub fn dirty(&self) -> bool

the state differs from the saved one

pub fn clear(&mut self)

forget every step (the current state counts as saved when it was)

pub fn len(&self) -> usize

the number of undo steps

pub fn is_empty(&self) -> bool