1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462
//! A history tree of edit commands.
mod builder;
mod checkpoint;
mod display;
mod queue;
pub use builder::Builder;
pub use checkpoint::Checkpoint;
pub use display::Display;
pub use queue::Queue;
use crate::socket::Slot;
use crate::{At, Edit, Entry, Event, Record};
use alloc::collections::{BTreeMap, VecDeque};
use alloc::string::String;
use alloc::vec::Vec;
use core::fmt;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
/// A history tree of [`Edit`] commands.
///
/// Unlike [`Record`] which maintains a linear undo history,
/// [`History`] maintains an undo tree containing every edit made to the target.
///
/// See [this](https://github.com/evenorog/undo/blob/master/examples/history.rs)
/// example for an interactive view of the history tree.
///
/// # Examples
/// ```
/// # use undo::{Add, History};
/// let mut target = String::new();
/// let mut history = History::new();
///
/// history.edit(&mut target, Add('a'));
/// history.edit(&mut target, Add('b'));
/// history.edit(&mut target, Add('c'));
/// let abc = history.head();
///
/// history.undo(&mut target);
/// history.undo(&mut target);
/// assert_eq!(target, "a");
///
/// // Instead of discarding 'b' and 'c', a new branch is created.
/// history.edit(&mut target, Add('f'));
/// history.edit(&mut target, Add('g'));
/// assert_eq!(target, "afg");
///
/// // We can now switch back to the original branch.
/// history.go_to(&mut target, abc);
/// assert_eq!(target, "abc");
/// ```
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Clone, Debug)]
pub struct History<E, S = ()> {
root: usize,
next: usize,
saved: Option<At>,
record: Record<E, S>,
branches: BTreeMap<usize, Branch<E>>,
}
impl<E> History<E> {
/// Returns a new history.
pub fn new() -> History<E> {
History::builder().build()
}
}
impl<E, S> History<E, S> {
/// Returns a new history builder.
pub fn builder() -> Builder<E, S> {
Builder::default()
}
/// Reserves capacity for at least `additional` more edits.
///
/// # Panics
/// Panics if the new capacity overflows usize.
pub fn reserve(&mut self, additional: usize) {
self.record.reserve(additional);
}
/// Returns the capacity of the history.
pub fn capacity(&self) -> usize {
self.record.capacity()
}
/// Shrinks the capacity of the history as much as possible.
pub fn shrink_to_fit(&mut self) {
self.record.shrink_to_fit();
}
/// Returns the number of edits in the current branch of the history.
pub fn len(&self) -> usize {
self.record.len()
}
/// Returns `true` if the current branch of the history is empty.
pub fn is_empty(&self) -> bool {
self.record.is_empty()
}
/// Returns the limit of the history.
pub fn limit(&self) -> usize {
self.record.limit()
}
/// Sets how the event should be handled when the state changes.
pub fn connect(&mut self, slot: S) -> Option<S> {
self.record.connect(slot)
}
/// Removes and returns the slot if it exists.
pub fn disconnect(&mut self) -> Option<S> {
self.record.disconnect()
}
/// Returns `true` if the target is in a saved state, `false` otherwise.
pub fn is_saved(&self) -> bool {
self.record.is_saved()
}
/// Return the position of the saved state.
pub fn saved(&self) -> Option<At> {
self.record
.saved
.map(|index| At::new(self.root, index))
.or(self.saved)
}
/// Returns `true` if the history can undo.
pub fn can_undo(&self) -> bool {
self.record.can_undo()
}
/// Returns `true` if the history can redo.
pub fn can_redo(&self) -> bool {
self.record.can_redo()
}
/// Returns the current position in the history.
pub fn head(&self) -> At {
At::new(self.root, self.record.index)
}
/// Returns the head of the next branch in the history.
///
/// This will be the first edit that was stored in the branch.
/// This can be used in combination with [`History::go_to`] to go to the next branch.
pub fn next_branch_head(&self) -> Option<At> {
self.branches
.range(self.root + 1..)
.next()
.map(|(&id, branch)| At::new(id, branch.parent.index + 1))
}
/// Returns the head of the previous branch in the history.
///
/// This will be the first edit that was stored in the branch.
/// This can be used in combination with [`History::go_to`] to go to the previous branch.
pub fn prev_branch_head(&self) -> Option<At> {
self.branches
.range(..self.root)
.next_back()
.map(|(&id, branch)| At::new(id, branch.parent.index + 1))
}
/// Returns the entry at the index in the current root branch.
///
/// Use [History::get_branch] if you want to get entry from other branches.
pub fn get_entry(&self, index: usize) -> Option<&Entry<E>> {
self.record.get_entry(index)
}
/// Returns an iterator over the entries in the current root branch.
pub fn entries(&self) -> impl Iterator<Item = &Entry<E>> {
self.record.entries()
}
/// Returns the branch with the given id.
pub fn get_branch(&self, id: usize) -> Option<&Branch<E>> {
self.branches.get(&id)
}
/// Returns an iterator over the branches in the history.
///
/// This does not include the current root branch.
pub fn branches(&self) -> impl Iterator<Item = (&usize, &Branch<E>)> {
self.branches.iter()
}
/// Returns a queue.
pub fn queue(&mut self) -> Queue<E, S> {
Queue::from(self)
}
/// Returns a checkpoint.
pub fn checkpoint(&mut self) -> Checkpoint<E, S> {
Checkpoint::from(self)
}
/// Returns a structure for configurable formatting of the history.
pub fn display(&self) -> Display<E, S> {
Display::from(self)
}
fn rm_child_of(&mut self, at: At) {
// We need to check if any of the branches had the removed node as root.
let mut dead: Vec<_> = self
.branches
.iter()
.filter(|&(_, child)| child.parent == at)
.map(|(&id, _)| id)
.collect();
while let Some(parent) = dead.pop() {
// Remove the dead branch.
self.branches.remove(&parent).unwrap();
self.saved = self.saved.filter(|saved| saved.root != parent);
// Add the children of the dead branch so they are removed too.
dead.extend(
self.branches
.iter()
.filter(|&(_, child)| child.parent.root == parent)
.map(|(&id, _)| id),
)
}
}
fn mk_path(&mut self, mut to: usize) -> Option<impl Iterator<Item = (usize, Branch<E>)>> {
debug_assert_ne!(self.root, to);
let mut dest = self.branches.remove(&to)?;
let mut i = dest.parent.root;
let mut path = alloc::vec![(to, dest)];
while i != self.root {
dest = self.branches.remove(&i).unwrap();
to = i;
i = dest.parent.root;
path.push((to, dest));
}
Some(path.into_iter().rev())
}
}
impl<E, S: Slot> History<E, S> {
/// Marks the target as currently being in a saved or unsaved state.
pub fn set_saved(&mut self, saved: bool) {
self.saved = None;
self.record.set_saved(saved);
}
/// Removes all edits from the history without undoing them.
pub fn clear(&mut self) {
let old_root = self.root;
self.root = 0;
self.next = 1;
self.saved = None;
self.record.clear();
self.branches.clear();
self.record.socket.emit_if(old_root != 0, || Event::Root(0));
}
fn set_root(&mut self, new: At, rm_saved: Option<usize>) {
debug_assert_ne!(self.root, new.root);
// Update all branches that are now children of the new root.
//
// | | <- The old root is now a child of the new root.
// | | | | <- This branch is still a child of the old root.
// |/ |/
// | -> /
// o | o | <- This branch is now a child of the new root.
// |/ |/
// | |
//
// If we split at 'o' all branches that are children of 'o' or below should now
// be children of the new root. All branches that are above should still be
// children of the old root.
self.branches
.values_mut()
.filter(|child| child.parent.root == self.root && child.parent.index <= new.index)
.for_each(|child| child.parent.root = new.root);
match (self.saved, rm_saved) {
(Some(saved), None) if saved.root == new.root => {
self.saved = None;
self.record.saved = Some(saved.index);
}
(None, Some(saved)) => {
self.saved = Some(At::new(self.root, saved));
}
_ => (),
}
debug_assert_ne!(self.saved.map(|s| s.root), Some(new.root));
self.root = new.root;
self.record.socket.emit(|| Event::Root(new.root));
}
fn jump_to(&mut self, root: usize) {
let mut branch = self.branches.remove(&root).unwrap();
debug_assert_eq!(branch.parent, self.head());
let parent = At::new(root, self.record.index);
let (tail, rm_saved) = self.record.rm_tail();
self.record.entries.append(&mut branch.entries);
self.branches.insert(self.root, Branch::new(parent, tail));
self.set_root(parent, rm_saved);
}
}
impl<E: Edit, S: Slot> History<E, S> {
/// Pushes the [`Edit`] to the top of the history and executes its [`Edit::edit`] method.
pub fn edit(&mut self, target: &mut E::Target, edit: E) -> E::Output {
let head = self.head();
let (output, merged, tail, rm_saved) = self.record.edit_and_push(target, edit.into());
// Check if the limit has been reached.
if !merged && head.index == self.record.index {
let root = self.root;
self.rm_child_of(At::new(root, 0));
self.branches
.values_mut()
.filter(|child| child.parent.root == root)
.for_each(|child| child.parent.index -= 1);
}
// Handle new branch.
if !tail.is_empty() {
let new = self.next;
self.next += 1;
let parent = At::new(new, head.index);
self.branches.insert(head.root, Branch::new(parent, tail));
self.set_root(parent, rm_saved);
}
output
}
/// Calls the [`Edit::undo`] method for the active edit
/// and sets the previous one as the new active one.
pub fn undo(&mut self, target: &mut E::Target) -> Option<E::Output> {
self.record.undo(target)
}
/// Calls the [`Edit::redo`] method for the active edit
/// and sets the next one as the new active one.
pub fn redo(&mut self, target: &mut E::Target) -> Option<E::Output> {
self.record.redo(target)
}
/// Repeatedly calls [`Edit::undo`] or [`Edit::redo`] until the edit at `at` is reached.
pub fn go_to(&mut self, target: &mut E::Target, at: At) -> Vec<E::Output> {
let root = self.root;
if root == at.root {
return self.record.go_to(target, at.index);
}
// Walk the path from `root` to `branch`.
let mut outputs = Vec::new();
let Some(path) = self.mk_path(at.root) else {
return Vec::new();
};
for (new, branch) in path {
let mut outs = self.record.go_to(target, branch.parent.index);
outputs.append(&mut outs);
// Apply the edits in the branch and move older edits into their own branch.
for entry in branch.entries {
let index = self.record.index;
let (_, _, entries, rm_saved) = self.record.redo_and_push(target, entry);
if !entries.is_empty() {
let parent = At::new(new, index);
self.branches
.insert(self.root, Branch::new(parent, entries));
self.set_root(parent, rm_saved);
}
}
}
let mut outs = self.record.go_to(target, at.index);
outputs.append(&mut outs);
outputs
}
}
impl<E: fmt::Display, S> History<E, S> {
/// Returns the string of the edit which will be undone
/// in the next call to [`History::undo`].
pub fn undo_string(&self) -> Option<String> {
self.record.undo_string()
}
/// Returns the string of the edit which will be redone
/// in the next call to [`History::redo`].
pub fn redo_string(&self) -> Option<String> {
self.record.redo_string()
}
}
impl<E> Default for History<E> {
fn default() -> History<E> {
History::new()
}
}
impl<E, S> From<Record<E, S>> for History<E, S> {
fn from(record: Record<E, S>) -> Self {
History {
root: 0,
next: 1,
saved: None,
record,
branches: BTreeMap::new(),
}
}
}
impl<E, F> From<History<E, F>> for Record<E, F> {
fn from(history: History<E, F>) -> Record<E, F> {
history.record
}
}
/// A branch in the history.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Clone, Debug)]
pub struct Branch<E> {
parent: At,
entries: VecDeque<Entry<E>>,
}
impl<E> Branch<E> {
fn new(parent: At, entries: VecDeque<Entry<E>>) -> Branch<E> {
debug_assert!(!entries.is_empty());
Branch { parent, entries }
}
/// Returns the parent edit of the branch.
pub fn parent(&self) -> At {
self.parent
}
/// Returns the number of edits in the branch.
#[allow(clippy::len_without_is_empty)]
pub fn len(&self) -> usize {
self.entries.len()
}
/// Returns the edit at the index.
pub fn get_entry(&self, index: usize) -> Option<&Entry<E>> {
self.entries.get(index)
}
/// Returns an iterator over the edits in the branch.
pub fn entries(&self) -> impl Iterator<Item = &Entry<E>> {
self.entries.iter()
}
}