#undo #redo

undo

Provides undo-redo functionality with dynamic dispatch and automatic command merging

75 releases (35 breaking)

✓ Uses Rust 2018 edition

0.36.0 Aug 1, 2019
0.35.0 Jul 2, 2019
0.34.0 May 14, 2019
0.32.0 Mar 25, 2019
0.2.4 Dec 26, 2016

#36 in Data structures

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658 downloads per month

MIT/Apache

109KB
2.5K SLoC

undo

Travis Crates.io Docs

Provides undo-redo functionality with dynamic dispatch and automatic command merging.

It is an implementation of the command pattern, where all modifications are done by creating objects of commands that applies the modifications. All commands knows how to undo the changes it applies, and by using the provided data structures it is easy to apply, undo, and redo changes made to a receiver. Both linear and non-linear undo-redo functionality is provided through the Record and History data structures. This library provides more or less the same functionality as the redo library but is more focused on ease of use instead of performance.

Contents

  • Command provides the base functionality for all commands.
  • Record provides linear undo-redo functionality.
  • History provides non-linear undo-redo functionality that allows you to jump between different branches.
  • Queue wraps a Record or History and extends them with queue functionality.
  • Checkpoint wraps a Record or History and extends them with checkpoint functionality.
  • Configurable display formatting is provided when the display feature is enabled.
  • Time stamps and time travel is provided when the chrono feature is enabled.

Concepts

  • Commands can be chained before they are applied using the Chain structure. This makes it easy to build complex operations from smaller ones by combining them into a single command that can be applied, undone, and redone in a single step.
  • Commands can be merged after being applied to the data-structures by implementing the merge method on the command. This allows smaller changes made gradually to be merged into larger operations that can be undone and redone in a single step.
  • The receiver can be marked as being saved to disk and the data-structures can track the saved state and tell the user when it changes.
  • The amount of changes being tracked can be configured by the user so only the n most recent changes are stored.

Examples

Add this to Cargo.toml:

[dependencies]
undo = "0.36"

And this to main.rs:

use undo::{Command, Record};

struct Add(char);

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

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

fn main() -> undo::Result {
    let mut record = Record::default();
    record.apply(Add('a'))?;
    record.apply(Add('b'))?;
    record.apply(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.as_receiver(), "abc");
    Ok(())
}

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Dependencies

~761KB