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//! Provides undo-redo functionality with static dispatch and manual 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 [undo] library //! but is more focused on performance and control instead of ease of use. //! //! # 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 through the [Display] structure. //! * Time stamps and time travel is provided when the `chrono` feature is enabled. //! * Serialization and deserialization is provided when the `serde` feature is enabled. //! //! # Concepts //! //! * Commands can be merged into a single command by implementing the [merge] method on the command. //! This allows smaller commands to be used to build more complex operations, or smaller incremental changes to be //! merged into larger changes 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`: //! //! ```toml //! [dependencies] //! redo = "0.32" //! ``` //! //! And this to `main.rs`: //! //! ``` //! use redo::{Command, Record}; //! //! struct Add(char); //! //! impl Command<String> for Add { //! type Error = &'static str; //! //! fn apply(&mut self, s: &mut String) -> Result<(), Self::Error> { //! s.push(self.0); //! Ok(()) //! } //! //! fn undo(&mut self, s: &mut String) -> Result<(), Self::Error> { //! self.0 = s.pop().ok_or("`s` is empty")?; //! Ok(()) //! } //! } //! //! fn main() -> Result<(), &'static str> { //! 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(()) //! } //! ``` //! //! [Command]: trait.Command.html //! [Record]: struct.Record.html //! [Timeline]: struct.Timeline.html //! [History]: struct.History.html //! [Queue]: struct.Queue.html //! [Checkpoint]: struct.Checkpoint.html //! [Display]: struct.Display.html //! [merge]: trait.Command.html#method.merge //! [undo]: https://github.com/evenorog/undo #![doc(html_root_url = "https://docs.rs/redo/latest")] #![deny( bad_style, bare_trait_objects, missing_debug_implementations, missing_docs, unused_import_braces, unsafe_code, unstable_features )] mod checkpoint; mod display; mod history; mod queue; mod record; #[cfg(feature = "chrono")] use chrono::{DateTime, Utc}; #[cfg(feature = "serde")] use serde::{Deserialize, Serialize}; use std::fmt; pub use self::{ checkpoint::Checkpoint, display::Display, history::{History, HistoryBuilder}, queue::Queue, record::{Record, RecordBuilder}, }; /// Base functionality for all commands. pub trait Command<R> { /// The error type. type Error; /// Applies the command on the receiver and returns `Ok` if everything went fine, /// and `Err` if something went wrong. fn apply(&mut self, receiver: &mut R) -> Result<(), Self::Error>; /// Restores the state of the receiver as it was before the command was applied /// and returns `Ok` if everything went fine, and `Err` if something went wrong. fn undo(&mut self, receiver: &mut R) -> Result<(), Self::Error>; /// Reapplies the command on the receiver and return `Ok` if everything went fine, /// and `Err` if something went wrong. /// /// The default implementation uses the [`apply`] implementation. /// /// [`apply`]: trait.Command.html#tymethod.apply #[inline] fn redo(&mut self, receiver: &mut R) -> Result<(), Self::Error> { self.apply(receiver) } /// Used for manual merging of two commands. /// /// # Examples /// ``` /// # use redo::{Command, Merge, Record}; /// struct Add(String); /// /// impl Command<String> for Add { /// type Error = (); /// /// fn apply(&mut self, s: &mut String) -> Result<(), ()> { /// s.push_str(&self.0); /// Ok(()) /// } /// /// fn undo(&mut self, s: &mut String) -> Result<(), ()> { /// let len = s.len() - self.0.len(); /// s.truncate(len); /// Ok(()) /// } /// /// fn merge(&mut self, Add(s): Self) -> Merge<Self> { /// self.0.push_str(&s); /// Merge::Yes /// } /// } /// /// fn main() -> Result<(), ()> { /// let mut record = Record::default(); /// // The `a`, `b`, and `c` commands are merged. /// record.apply(Add("a".into()))?; /// record.apply(Add("b".into()))?; /// record.apply(Add("c".into()))?; /// assert_eq!(record.as_receiver(), "abc"); /// // Calling `undo` once will undo all the merged commands. /// record.undo().unwrap()?; /// assert_eq!(record.as_receiver(), ""); /// // Calling `redo` once will redo all the merged commands. /// record.redo().unwrap()?; /// assert_eq!(record.as_receiver(), "abc"); /// Ok(()) /// } /// ``` #[inline] fn merge(&mut self, command: Self) -> Merge<Self> where Self: Sized, { Merge::No(command) } /// Says if the command is dead. /// /// A dead command will be removed the next time it becomes the current command. /// This can be used to remove command if for example executing it caused an error, /// and it needs to be removed. #[inline] fn is_dead(&self) -> bool { false } } /// The signal sent when the record, the history, or the receiver changes. /// /// When one of these states changes, they will send a corresponding signal to the user. /// For example, if the record can no longer redo any commands, it sends a `Redo(false)` /// signal to tell the user. #[derive(Copy, Clone, Debug, Hash, Ord, PartialOrd, Eq, PartialEq)] pub enum Signal { /// Says if the record can undo. /// /// This signal will be emitted when the records ability to undo changes. Undo(bool), /// Says if the record can redo. /// /// This signal will be emitted when the records ability to redo changes. Redo(bool), /// Says if the receiver is in a saved state. /// /// This signal will be emitted when the record enters or leaves its receivers saved state. Saved(bool), /// Says if the current command has changed. /// /// This signal will be emitted when the current command has changed. This includes /// when two commands have been merged, in which case `old == new`. Current { /// The old current command. old: usize, /// The new current command. new: usize, }, /// Says if the current branch, or root, has changed. /// /// This is only emitted from `History`. Root { /// The old root. old: usize, /// The new root. new: usize, }, } /// The result of merging two commands. #[derive(Copy, Clone, Debug, Hash, Ord, PartialOrd, Eq, PartialEq)] pub enum Merge<C> { /// The commands have been merged. Yes, /// The commands have not been merged. No(C), /// The two commands cancels each other out. This removes both commands. Annul, } /// A position in a history tree. #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] #[derive(Copy, Clone, Debug, Default, Hash, Ord, PartialOrd, Eq, PartialEq)] struct At { branch: usize, current: usize, } #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] #[derive(Debug, Clone)] struct Meta<C> { command: C, #[cfg(feature = "chrono")] timestamp: DateTime<Utc>, } impl<C> From<C> for Meta<C> { #[inline] fn from(command: C) -> Self { Meta { command, #[cfg(feature = "chrono")] timestamp: Utc::now(), } } } impl<R, C: Command<R>> Command<R> for Meta<C> { type Error = C::Error; #[inline] fn apply(&mut self, receiver: &mut R) -> Result<(), <Self as Command<R>>::Error> { self.command.apply(receiver) } #[inline] fn undo(&mut self, receiver: &mut R) -> Result<(), <Self as Command<R>>::Error> { self.command.undo(receiver) } #[inline] fn redo(&mut self, receiver: &mut R) -> Result<(), <Self as Command<R>>::Error> { self.command.redo(receiver) } #[inline] fn merge(&mut self, command: Self) -> Merge<Self> where Self: Sized, { match self.command.merge(command.command) { Merge::Yes => Merge::Yes, Merge::No(command) => Merge::No(Meta::from(command)), Merge::Annul => Merge::Annul, } } #[inline] fn is_dead(&self) -> bool { self.command.is_dead() } } impl<C: fmt::Display> fmt::Display for Meta<C> { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (&self.command as &dyn fmt::Display).fmt(f) } }