Crate undo

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

Contents

• Record provides a stack based undo-redo functionality.
• History provides a 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 = "0.30"

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(())
}

Macros

merge

Macro for merging commands.

Structs

Checkpoint	A checkpoint wrapper.
History	A history of commands.
HistoryBuilder	Builder for a History.
Merged	The result of merging commands.
Queue	A command queue wrapper.
Record	A record of commands.
RecordBuilder	Builder for a record.

Enums

Merge	Says if the command should merge with another command.
Signal	The signal sent when the record, the history, or the receiver changes.

Traits

Command

Base functionality for all commands.

Type Definitions

Result

A specialized Result type for undo-redo operations.