undo 0.31.1

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

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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.

Contents

  • Record provides stack based undo-redo functionality.
  • History provides tree based 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.
  • Commands can be merged using the merge! macro or the merge method. When two commands are merged, undoing and redoing them are done in a single step.
  • Configurable display formatting is provided when the display feature is enabled.
  • Time stamps and time travel is provided when the chrono feature is enabled.

Examples

Add this to Cargo.toml:

[dependencies]
undo = "0.31"

And this to main.rs:

use undo::{Command, Record};

#[derive(Debug)]
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.