Struct undo::record::Record

pub struct Record<'a, R> { /* fields omitted */ }

A record of commands.

The Record works mostly like a Stack, but it stores the commands instead of returning them when undoing. This means it can roll the receivers state backwards and forwards by using the undo and redo methods. In addition, the Record has an internal state that is either clean or dirty. A clean state means that the Record does not have any Commands to redo, while a dirty state means that it does. The user can give the Record a function that is called each time the state changes by using the config constructor.

Examples

use std::error::Error;
use undo::{Command, Record};

struct Add(char);

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

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

fn foo() -> Result<(), Box<Error>> {
    let mut record = Record::default();

    record.push(Add('a'))?;
    record.push(Add('b'))?;
    record.push(Add('c'))?;

    assert_eq!(record.as_receiver(), "abc");

    record.undo().unwrap()?;
    record.undo().unwrap()?;
    record.undo().unwrap()?;

    assert_eq!(record.as_receiver(), "");

    record.redo().unwrap()?;
    record.redo().unwrap()?;
    record.redo().unwrap()?;

    assert_eq!(record.into_receiver(), "abc");

    Ok(())
}

Methods

impl<'a, R> Record<'a, R>

fn new<T: Into<R>>(receiver: T) -> Record<'a, R>

Returns a new Record.

fn config<T: Into<R>>(receiver: T) -> Config<'a, R>

Returns a configurator for a Record.

Examples

let mut record = Record::config("")
    .capacity(2)
    .limit(2)
    .create();

record.push(Add('a'))?;
record.push(Add('b'))?;
record.push(Add('c'))?; // 'a' is removed from the record since limit is 2.

assert_eq!(record.as_receiver(), "abc");

record.undo().unwrap()?;
record.undo().unwrap()?;
assert!(record.undo().is_none());

assert_eq!(record.into_receiver(), "a");

fn limit(&self) -> Option<usize>

Returns the limit of the Record, or None if it has no limit.

fn capacity(&self) -> usize

Returns the number of commands the stack can hold without reallocating.

fn len(&self) -> usize

Returns the number of commands in the Record.

fn is_empty(&self) -> bool

Returns true if the Record is empty.

fn is_clean(&self) -> bool

Returns true if the state of the stack is clean, false otherwise.

fn is_dirty(&self) -> bool

Returns true if the state of the stack is dirty, false otherwise.

fn as_receiver(&self) -> &R

Returns a reference to the receiver.

fn into_receiver(self) -> R

Consumes the Record, returning the receiver.

fn push<C>(&mut self, cmd: C) -> Result<Commands<R>, Error<R>> where
    C: Command<R> + 'static,
    R: 'static, 

Pushes cmd to the top of the Record and executes its redo method. The command is merged with the previous top command if [merge] does not return None.

All commands above the active one are removed from the stack and returned as an iterator.

Errors

If an error occur when executing redo the error is returned together with the command, and the state of the stack is left unchanged.

Examples

let mut record = Record::default();

record.push(Add('a'))?;
record.push(Add('b'))?;
record.push(Add('c'))?;

assert_eq!(record.as_receiver(), "abc");

record.undo().unwrap()?;
record.undo().unwrap()?;
let mut bc = record.push(Add('e'))?;

assert_eq!(record.into_receiver(), "ae");
assert!(bc.next().is_some());
assert!(bc.next().is_some());
assert!(bc.next().is_none());

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 command that caused the error is removed from the record and returned together with the error.

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 command that caused the error is removed from the record and returned together with the error.

Trait Implementations

impl<'a, R: Default> Default for Record<'a, R>

fn default() -> Record<'a, R>

Returns the "default value" for a type.

impl<'a, R> AsRef<R> for Record<'a, R>

fn as_ref(&self) -> &R

Performs the conversion.

impl<'a, R: Debug> Debug for Record<'a, R>

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

Formats the value using the given formatter.