Struct undo::History

pub struct History<R> { /* fields omitted */ }

A history of commands.

A history works like the Record but also provides branching, like vim's undo-tree.

Examples

#[derive(Debug)]
struct Add(char);

impl Command<String> for Add {
    fn apply(&mut self, s: &mut String) -> Result<(), Box<dyn Error + Send + Sync>> {
        s.push(self.0);
        Ok(())
    }

    fn undo(&mut self, s: &mut String) -> Result<(), Box<dyn Error + Send + Sync>> {
        self.0 = s.pop().ok_or("`s` is empty")?;
        Ok(())
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let mut history = History::default();
    history.apply(Add('a'))?;
    history.apply(Add('b'))?;
    history.apply(Add('c'))?;
    assert_eq!(history.as_receiver(), "abc");

    let root = history.root();
    history.go_to(root, 1).unwrap()?;
    assert_eq!(history.as_receiver(), "a");

    let abc = history.apply(Add('f'))?.unwrap();
    history.apply(Add('g'))?;
    assert_eq!(history.as_receiver(), "afg");

    history.go_to(abc, 3).unwrap()?;
    assert_eq!(history.as_receiver(), "abc");
    Ok(())
}

Methods

impl<R> History<R>

pub fn new(     receiver: impl Into<R> ) -> History<R>

Returns a new history.

pub fn builder() -> HistoryBuilder<R>

Returns a builder for a history.

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more commands.

Panics

Panics if the new capacity overflows usize.

pub fn capacity(&self) -> usize

Returns the capacity of the history.

pub fn len(&self) -> usize

Returns the number of commands in the current branch of the history.

pub fn is_empty(&self) -> bool

Returns true if the current branch of the history is empty.

pub fn limit(&self) -> usize

Returns the limit of the history.

pub fn set_limit(&mut self, limit: usize) -> usize

Sets the limit of the history and returns the new limit.

If this limit is reached it will start popping of commands at the beginning of the history when new commands are applied. No limit is set by default which means it may grow indefinitely.

If limit < len the first commands will be removed until len == limit. However, if the current active command is going to be removed, the limit is instead adjusted to len - active so the active command is not removed.

Panics

Panics if limit is 0.

pub fn set_signal(     &mut self,     f: impl FnMut(Signal) + Send + Sync + 'static )

Sets how the signal should be handled when the state changes.

pub fn can_undo(&self) -> bool

Returns true if the history can undo.

pub fn can_redo(&self) -> bool

Returns true if the history can redo.

pub fn set_saved(&mut self, saved: bool)

Marks the receiver as currently being in a saved or unsaved state.

pub fn is_saved(&self) -> bool

Returns true if the receiver is in a saved state, false otherwise.

pub fn root(&self) -> usize

Returns the current branch.

pub fn cursor(&self) -> usize

Returns the position of the current command.

pub fn clear(&mut self)

Removes all commands from the history without undoing them.

pub fn apply(     &mut self,     cmd: impl Command<R> + 'static ) -> Result<Option<usize>, Error<R>> where     R: 'static,

Pushes the command to the top of the history and executes its apply method. The command is merged with the previous top command if they have the same id.

Errors

If an error occur when executing apply the error is returned together with the command.

pub fn undo(&mut self) -> Option<Result<(), Error<R>>>

Calls the undo method for the active command and sets the previous one as the new active one.

Errors

If an error occur when executing undo the error is returned together with the command.

pub fn redo(&mut self) -> Option<Result<(), Error<R>>>

Calls the redo method for the active command and sets the next one as the new active one.

Errors

If an error occur when executing redo the error is returned together with the command.

pub fn go_to(     &mut self,     branch: usize,     cursor: usize ) -> Option<Result<usize, Error<R>>> where     R: 'static,

Repeatedly calls undo or redo until the command in branch at cursor is reached.

Errors

If an error occur when executing undo or redo the error is returned together with the command.

pub fn jump_to(     &mut self,     branch: usize,     cursor: usize ) -> Option<Result<usize, Error<R>>> where     R: 'static,

Jump directly to the command in branch at cursor and executes its undo or redo method.

This method can be used if the commands store the whole state of the receiver, and does not require the commands in between to be called to get the same result. Use go_to otherwise.

Errors

If an error occur when executing undo or redo the error is returned together with the command.

pub fn as_receiver(&self) -> &R

Returns a reference to the receiver.

pub fn as_mut_receiver(&mut self) -> &mut R

Returns a mutable reference to the receiver.

This method should only be used when doing changes that should not be able to be undone.

pub fn into_receiver(self) -> R

Consumes the history, returning the receiver.

pub fn commands(     &self ) -> impl Iterator<Item = &impl Command<R>>

Returns an iterator over the commands in the current branch.

Trait Implementations

impl<R: Debug> Debug for History<R>

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

Formats the value using the given formatter.

impl<R: Default> Default for History<R>

fn default() -> History<R>

Returns the "default value" for a type.

impl<R> AsRef<R> for History<R>

fn as_ref(&self) -> &R

Performs the conversion.

impl<R> AsMut<R> for History<R>

fn as_mut(&mut self) -> &mut R

Performs the conversion.

impl<R> From<R> for History<R>

fn from(receiver: R) -> History<R>

Performs the conversion.

impl<R> From<Record<R>> for History<R>

fn from(record: Record<R>) -> History<R>

Performs the conversion.

impl<R> From<History<R>> for Record<R>

fn from(history: History<R>) -> Record<R>

Performs the conversion.