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//! An undo-redo library with static dispatch and manual command merging. //! //! It uses the [command pattern] where the user modifies the receiver by //! applying commands on it. Since each command knows how to undo and redo //! the changes it applies to the receiver, the state of the receiver can //! be rolled forwards or backwards by calling undo or redo in the correct order. //! //! The [Record] and [History] provides functionality to store and keep track //! of the applied commands, and makes it easy to undo and redo changes. //! The Record provides a stack based undo-redo functionality, while the //! History provides a tree based undo-redo functionality where you can //! jump between different branches. //! //! 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. //! //! [command pattern]: https://en.wikipedia.org/wiki/Command_pattern //! [Record]: struct.Record.html //! [History]: struct.History.html //! [`merge!`]: macro.merge.html //! [`merge`]: trait.Command.html#method.merge #![deny( bad_style, bare_trait_objects, missing_debug_implementations, unused_import_braces, unused_qualifications, unsafe_code, unstable_features, )] #[macro_use] extern crate bitflags; extern crate colored; extern crate fnv; #[cfg(feature = "serde")] #[macro_use] extern crate serde; mod display; mod history; mod merge; mod record; mod signal; use std::{error::Error as StdError, fmt}; pub use display::Display; pub use history::{History, HistoryBuilder}; pub use record::{Record, RecordBuilder}; pub use signal::Signal; /// 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. /// /// Returns `Ok` if commands was merged and `Err` if not. /// /// # Examples /// ``` /// # use redo::*; /// #[derive(Debug)] /// 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) -> Result<(), Self> { /// self.0.push_str(&s); /// Ok(()) /// } /// } /// /// fn main() -> Result<(), Error<String, Add>> { /// 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.len(), 1); /// 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, cmd: Self) -> Result<(), Self> where Self: Sized, { Err(cmd) } } /// An error which holds the command that caused it. pub struct Error<R, C: Command<R>>(pub C, pub C::Error); impl<R, C: Command<R> + fmt::Debug> fmt::Debug for Error<R, C> where C::Error: fmt::Debug, { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.debug_tuple("Error") .field(&self.0) .field(&self.1) .finish() } } impl<R, C: Command<R>> fmt::Display for Error<R, C> where C::Error: fmt::Display, { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (&self.1 as &dyn fmt::Display).fmt(f) } } impl<R, C: Command<R>> StdError for Error<R, C> where C: fmt::Debug, C::Error: StdError, { #[inline] fn description(&self) -> &str { self.1.description() } #[inline] fn cause(&self) -> Option<&dyn StdError> { self.1.cause() } }