text.rs

   1mod anchor;
   2pub mod locator;
   3#[cfg(any(test, feature = "test-support"))]
   4pub mod network;
   5pub mod operation_queue;
   6mod patch;
   7mod selection;
   8pub mod subscription;
   9#[cfg(test)]
  10mod tests;
  11mod undo_map;
  12
  13pub use anchor::*;
  14use anyhow::{anyhow, Context as _, Result};
  15pub use clock::ReplicaId;
  16use collections::{HashMap, HashSet};
  17use locator::Locator;
  18use operation_queue::OperationQueue;
  19pub use patch::Patch;
  20use postage::{oneshot, prelude::*};
  21
  22use lazy_static::lazy_static;
  23use regex::Regex;
  24pub use rope::*;
  25pub use selection::*;
  26use std::{
  27    borrow::Cow,
  28    cmp::{self, Ordering, Reverse},
  29    fmt::Display,
  30    future::Future,
  31    iter::Iterator,
  32    num::NonZeroU64,
  33    ops::{self, Deref, Range, Sub},
  34    str,
  35    sync::Arc,
  36    time::{Duration, Instant},
  37};
  38pub use subscription::*;
  39pub use sum_tree::Bias;
  40use sum_tree::{FilterCursor, SumTree, TreeMap};
  41use undo_map::UndoMap;
  42use util::ResultExt;
  43
  44#[cfg(any(test, feature = "test-support"))]
  45use util::RandomCharIter;
  46
  47lazy_static! {
  48    static ref LINE_SEPARATORS_REGEX: Regex = Regex::new("\r\n|\r|\u{2028}|\u{2029}").unwrap();
  49}
  50
  51pub type TransactionId = clock::Lamport;
  52
  53pub struct Buffer {
  54    snapshot: BufferSnapshot,
  55    history: History,
  56    deferred_ops: OperationQueue<Operation>,
  57    deferred_replicas: HashSet<ReplicaId>,
  58    pub lamport_clock: clock::Lamport,
  59    subscriptions: Topic,
  60    edit_id_resolvers: HashMap<clock::Lamport, Vec<oneshot::Sender<()>>>,
  61    wait_for_version_txs: Vec<(clock::Global, oneshot::Sender<()>)>,
  62}
  63
  64#[repr(transparent)]
  65#[derive(Clone, Copy, Debug, Hash, PartialEq, PartialOrd, Ord, Eq)]
  66pub struct BufferId(NonZeroU64);
  67
  68impl Display for BufferId {
  69    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  70        write!(f, "{}", self.0)
  71    }
  72}
  73
  74impl BufferId {
  75    /// Returns Err if `id` is outside of BufferId domain.
  76    pub fn new(id: u64) -> anyhow::Result<Self> {
  77        let id = NonZeroU64::new(id).context("Buffer id cannot be 0.")?;
  78        Ok(Self(id))
  79    }
  80    /// Increments this buffer id, returning the old value.
  81    /// So that's a post-increment operator in disguise.
  82    pub fn next(&mut self) -> Self {
  83        let old = *self;
  84        self.0 = self.0.saturating_add(1);
  85        old
  86    }
  87}
  88impl From<BufferId> for u64 {
  89    fn from(id: BufferId) -> Self {
  90        id.0.get()
  91    }
  92}
  93
  94#[derive(Clone)]
  95pub struct BufferSnapshot {
  96    replica_id: ReplicaId,
  97    remote_id: BufferId,
  98    visible_text: Rope,
  99    deleted_text: Rope,
 100    line_ending: LineEnding,
 101    undo_map: UndoMap,
 102    fragments: SumTree<Fragment>,
 103    insertions: SumTree<InsertionFragment>,
 104    pub version: clock::Global,
 105}
 106
 107#[derive(Clone, Debug)]
 108pub struct HistoryEntry {
 109    transaction: Transaction,
 110    first_edit_at: Instant,
 111    last_edit_at: Instant,
 112    suppress_grouping: bool,
 113}
 114
 115#[derive(Clone, Debug)]
 116pub struct Transaction {
 117    pub id: TransactionId,
 118    pub edit_ids: Vec<clock::Lamport>,
 119    pub start: clock::Global,
 120}
 121
 122impl HistoryEntry {
 123    pub fn transaction_id(&self) -> TransactionId {
 124        self.transaction.id
 125    }
 126}
 127
 128struct History {
 129    base_text: Rope,
 130    operations: TreeMap<clock::Lamport, Operation>,
 131    insertion_slices: HashMap<clock::Lamport, Vec<InsertionSlice>>,
 132    undo_stack: Vec<HistoryEntry>,
 133    redo_stack: Vec<HistoryEntry>,
 134    transaction_depth: usize,
 135    group_interval: Duration,
 136}
 137
 138#[derive(Clone, Debug)]
 139struct InsertionSlice {
 140    insertion_id: clock::Lamport,
 141    range: Range<usize>,
 142}
 143
 144impl History {
 145    pub fn new(base_text: Rope) -> Self {
 146        Self {
 147            base_text,
 148            operations: Default::default(),
 149            insertion_slices: Default::default(),
 150            undo_stack: Vec::new(),
 151            redo_stack: Vec::new(),
 152            transaction_depth: 0,
 153            // Don't group transactions in tests unless we opt in, because it's a footgun.
 154            #[cfg(any(test, feature = "test-support"))]
 155            group_interval: Duration::ZERO,
 156            #[cfg(not(any(test, feature = "test-support")))]
 157            group_interval: Duration::from_millis(300),
 158        }
 159    }
 160
 161    fn push(&mut self, op: Operation) {
 162        self.operations.insert(op.timestamp(), op);
 163    }
 164
 165    fn start_transaction(
 166        &mut self,
 167        start: clock::Global,
 168        now: Instant,
 169        clock: &mut clock::Lamport,
 170    ) -> Option<TransactionId> {
 171        self.transaction_depth += 1;
 172        if self.transaction_depth == 1 {
 173            let id = clock.tick();
 174            self.undo_stack.push(HistoryEntry {
 175                transaction: Transaction {
 176                    id,
 177                    start,
 178                    edit_ids: Default::default(),
 179                },
 180                first_edit_at: now,
 181                last_edit_at: now,
 182                suppress_grouping: false,
 183            });
 184            Some(id)
 185        } else {
 186            None
 187        }
 188    }
 189
 190    fn end_transaction(&mut self, now: Instant) -> Option<&HistoryEntry> {
 191        assert_ne!(self.transaction_depth, 0);
 192        self.transaction_depth -= 1;
 193        if self.transaction_depth == 0 {
 194            if self
 195                .undo_stack
 196                .last()
 197                .unwrap()
 198                .transaction
 199                .edit_ids
 200                .is_empty()
 201            {
 202                self.undo_stack.pop();
 203                None
 204            } else {
 205                self.redo_stack.clear();
 206                let entry = self.undo_stack.last_mut().unwrap();
 207                entry.last_edit_at = now;
 208                Some(entry)
 209            }
 210        } else {
 211            None
 212        }
 213    }
 214
 215    fn group(&mut self) -> Option<TransactionId> {
 216        let mut count = 0;
 217        let mut entries = self.undo_stack.iter();
 218        if let Some(mut entry) = entries.next_back() {
 219            while let Some(prev_entry) = entries.next_back() {
 220                if !prev_entry.suppress_grouping
 221                    && entry.first_edit_at - prev_entry.last_edit_at <= self.group_interval
 222                {
 223                    entry = prev_entry;
 224                    count += 1;
 225                } else {
 226                    break;
 227                }
 228            }
 229        }
 230        self.group_trailing(count)
 231    }
 232
 233    fn group_until(&mut self, transaction_id: TransactionId) {
 234        let mut count = 0;
 235        for entry in self.undo_stack.iter().rev() {
 236            if entry.transaction_id() == transaction_id {
 237                self.group_trailing(count);
 238                break;
 239            } else if entry.suppress_grouping {
 240                break;
 241            } else {
 242                count += 1;
 243            }
 244        }
 245    }
 246
 247    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
 248        let new_len = self.undo_stack.len() - n;
 249        let (entries_to_keep, entries_to_merge) = self.undo_stack.split_at_mut(new_len);
 250        if let Some(last_entry) = entries_to_keep.last_mut() {
 251            for entry in &*entries_to_merge {
 252                for edit_id in &entry.transaction.edit_ids {
 253                    last_entry.transaction.edit_ids.push(*edit_id);
 254                }
 255            }
 256
 257            if let Some(entry) = entries_to_merge.last_mut() {
 258                last_entry.last_edit_at = entry.last_edit_at;
 259            }
 260        }
 261
 262        self.undo_stack.truncate(new_len);
 263        self.undo_stack.last().map(|e| e.transaction.id)
 264    }
 265
 266    fn finalize_last_transaction(&mut self) -> Option<&Transaction> {
 267        self.undo_stack.last_mut().map(|entry| {
 268            entry.suppress_grouping = true;
 269            &entry.transaction
 270        })
 271    }
 272
 273    fn push_transaction(&mut self, transaction: Transaction, now: Instant) {
 274        assert_eq!(self.transaction_depth, 0);
 275        self.undo_stack.push(HistoryEntry {
 276            transaction,
 277            first_edit_at: now,
 278            last_edit_at: now,
 279            suppress_grouping: false,
 280        });
 281        self.redo_stack.clear();
 282    }
 283
 284    fn push_undo(&mut self, op_id: clock::Lamport) {
 285        assert_ne!(self.transaction_depth, 0);
 286        if let Some(Operation::Edit(_)) = self.operations.get(&op_id) {
 287            let last_transaction = self.undo_stack.last_mut().unwrap();
 288            last_transaction.transaction.edit_ids.push(op_id);
 289        }
 290    }
 291
 292    fn pop_undo(&mut self) -> Option<&HistoryEntry> {
 293        assert_eq!(self.transaction_depth, 0);
 294        if let Some(entry) = self.undo_stack.pop() {
 295            self.redo_stack.push(entry);
 296            self.redo_stack.last()
 297        } else {
 298            None
 299        }
 300    }
 301
 302    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&HistoryEntry> {
 303        assert_eq!(self.transaction_depth, 0);
 304
 305        let entry_ix = self
 306            .undo_stack
 307            .iter()
 308            .rposition(|entry| entry.transaction.id == transaction_id)?;
 309        let entry = self.undo_stack.remove(entry_ix);
 310        self.redo_stack.push(entry);
 311        self.redo_stack.last()
 312    }
 313
 314    fn remove_from_undo_until(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
 315        assert_eq!(self.transaction_depth, 0);
 316
 317        let redo_stack_start_len = self.redo_stack.len();
 318        if let Some(entry_ix) = self
 319            .undo_stack
 320            .iter()
 321            .rposition(|entry| entry.transaction.id == transaction_id)
 322        {
 323            self.redo_stack
 324                .extend(self.undo_stack.drain(entry_ix..).rev());
 325        }
 326        &self.redo_stack[redo_stack_start_len..]
 327    }
 328
 329    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
 330        assert_eq!(self.transaction_depth, 0);
 331        if let Some(entry_ix) = self
 332            .undo_stack
 333            .iter()
 334            .rposition(|entry| entry.transaction.id == transaction_id)
 335        {
 336            Some(self.undo_stack.remove(entry_ix).transaction)
 337        } else if let Some(entry_ix) = self
 338            .redo_stack
 339            .iter()
 340            .rposition(|entry| entry.transaction.id == transaction_id)
 341        {
 342            Some(self.redo_stack.remove(entry_ix).transaction)
 343        } else {
 344            None
 345        }
 346    }
 347
 348    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
 349        let entry = self
 350            .undo_stack
 351            .iter_mut()
 352            .rfind(|entry| entry.transaction.id == transaction_id)
 353            .or_else(|| {
 354                self.redo_stack
 355                    .iter_mut()
 356                    .rfind(|entry| entry.transaction.id == transaction_id)
 357            })?;
 358        Some(&mut entry.transaction)
 359    }
 360
 361    fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
 362        if let Some(transaction) = self.forget(transaction) {
 363            if let Some(destination) = self.transaction_mut(destination) {
 364                destination.edit_ids.extend(transaction.edit_ids);
 365            }
 366        }
 367    }
 368
 369    fn pop_redo(&mut self) -> Option<&HistoryEntry> {
 370        assert_eq!(self.transaction_depth, 0);
 371        if let Some(entry) = self.redo_stack.pop() {
 372            self.undo_stack.push(entry);
 373            self.undo_stack.last()
 374        } else {
 375            None
 376        }
 377    }
 378
 379    fn remove_from_redo(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
 380        assert_eq!(self.transaction_depth, 0);
 381
 382        let undo_stack_start_len = self.undo_stack.len();
 383        if let Some(entry_ix) = self
 384            .redo_stack
 385            .iter()
 386            .rposition(|entry| entry.transaction.id == transaction_id)
 387        {
 388            self.undo_stack
 389                .extend(self.redo_stack.drain(entry_ix..).rev());
 390        }
 391        &self.undo_stack[undo_stack_start_len..]
 392    }
 393}
 394
 395struct Edits<'a, D: TextDimension, F: FnMut(&FragmentSummary) -> bool> {
 396    visible_cursor: rope::Cursor<'a>,
 397    deleted_cursor: rope::Cursor<'a>,
 398    fragments_cursor: Option<FilterCursor<'a, F, Fragment, FragmentTextSummary>>,
 399    undos: &'a UndoMap,
 400    since: &'a clock::Global,
 401    old_end: D,
 402    new_end: D,
 403    range: Range<(&'a Locator, usize)>,
 404    buffer_id: BufferId,
 405}
 406
 407#[derive(Clone, Debug, Default, Eq, PartialEq)]
 408pub struct Edit<D> {
 409    pub old: Range<D>,
 410    pub new: Range<D>,
 411}
 412
 413impl<D> Edit<D>
 414where
 415    D: Sub<D, Output = D> + PartialEq + Copy,
 416{
 417    pub fn old_len(&self) -> D {
 418        self.old.end - self.old.start
 419    }
 420
 421    pub fn new_len(&self) -> D {
 422        self.new.end - self.new.start
 423    }
 424
 425    pub fn is_empty(&self) -> bool {
 426        self.old.start == self.old.end && self.new.start == self.new.end
 427    }
 428}
 429
 430impl<D1, D2> Edit<(D1, D2)> {
 431    pub fn flatten(self) -> (Edit<D1>, Edit<D2>) {
 432        (
 433            Edit {
 434                old: self.old.start.0..self.old.end.0,
 435                new: self.new.start.0..self.new.end.0,
 436            },
 437            Edit {
 438                old: self.old.start.1..self.old.end.1,
 439                new: self.new.start.1..self.new.end.1,
 440            },
 441        )
 442    }
 443}
 444
 445#[derive(Eq, PartialEq, Clone, Debug)]
 446pub struct Fragment {
 447    pub id: Locator,
 448    pub timestamp: clock::Lamport,
 449    pub insertion_offset: usize,
 450    pub len: usize,
 451    pub visible: bool,
 452    pub deletions: HashSet<clock::Lamport>,
 453    pub max_undos: clock::Global,
 454}
 455
 456#[derive(Eq, PartialEq, Clone, Debug)]
 457pub struct FragmentSummary {
 458    text: FragmentTextSummary,
 459    max_id: Locator,
 460    max_version: clock::Global,
 461    min_insertion_version: clock::Global,
 462    max_insertion_version: clock::Global,
 463}
 464
 465#[derive(Copy, Default, Clone, Debug, PartialEq, Eq)]
 466struct FragmentTextSummary {
 467    visible: usize,
 468    deleted: usize,
 469}
 470
 471impl<'a> sum_tree::Dimension<'a, FragmentSummary> for FragmentTextSummary {
 472    fn add_summary(&mut self, summary: &'a FragmentSummary, _: &Option<clock::Global>) {
 473        self.visible += summary.text.visible;
 474        self.deleted += summary.text.deleted;
 475    }
 476}
 477
 478#[derive(Eq, PartialEq, Clone, Debug)]
 479struct InsertionFragment {
 480    timestamp: clock::Lamport,
 481    split_offset: usize,
 482    fragment_id: Locator,
 483}
 484
 485#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
 486struct InsertionFragmentKey {
 487    timestamp: clock::Lamport,
 488    split_offset: usize,
 489}
 490
 491#[derive(Clone, Debug, Eq, PartialEq)]
 492pub enum Operation {
 493    Edit(EditOperation),
 494    Undo(UndoOperation),
 495}
 496
 497#[derive(Clone, Debug, Eq, PartialEq)]
 498pub struct EditOperation {
 499    pub timestamp: clock::Lamport,
 500    pub version: clock::Global,
 501    pub ranges: Vec<Range<FullOffset>>,
 502    pub new_text: Vec<Arc<str>>,
 503}
 504
 505#[derive(Clone, Debug, Eq, PartialEq)]
 506pub struct UndoOperation {
 507    pub timestamp: clock::Lamport,
 508    pub version: clock::Global,
 509    pub counts: HashMap<clock::Lamport, u32>,
 510}
 511
 512impl Buffer {
 513    pub fn new(replica_id: u16, remote_id: BufferId, mut base_text: String) -> Buffer {
 514        let line_ending = LineEnding::detect(&base_text);
 515        LineEnding::normalize(&mut base_text);
 516
 517        let history = History::new(Rope::from(base_text.as_ref()));
 518        let mut fragments = SumTree::new();
 519        let mut insertions = SumTree::new();
 520
 521        let mut lamport_clock = clock::Lamport::new(replica_id);
 522        let mut version = clock::Global::new();
 523
 524        let visible_text = history.base_text.clone();
 525        if !visible_text.is_empty() {
 526            let insertion_timestamp = clock::Lamport {
 527                replica_id: 0,
 528                value: 1,
 529            };
 530            lamport_clock.observe(insertion_timestamp);
 531            version.observe(insertion_timestamp);
 532            let fragment_id = Locator::between(&Locator::min(), &Locator::max());
 533            let fragment = Fragment {
 534                id: fragment_id,
 535                timestamp: insertion_timestamp,
 536                insertion_offset: 0,
 537                len: visible_text.len(),
 538                visible: true,
 539                deletions: Default::default(),
 540                max_undos: Default::default(),
 541            };
 542            insertions.push(InsertionFragment::new(&fragment), &());
 543            fragments.push(fragment, &None);
 544        }
 545
 546        Buffer {
 547            snapshot: BufferSnapshot {
 548                replica_id,
 549                remote_id,
 550                visible_text,
 551                deleted_text: Rope::new(),
 552                line_ending,
 553                fragments,
 554                insertions,
 555                version,
 556                undo_map: Default::default(),
 557            },
 558            history,
 559            deferred_ops: OperationQueue::new(),
 560            deferred_replicas: HashSet::default(),
 561            lamport_clock,
 562            subscriptions: Default::default(),
 563            edit_id_resolvers: Default::default(),
 564            wait_for_version_txs: Default::default(),
 565        }
 566    }
 567
 568    pub fn version(&self) -> clock::Global {
 569        self.version.clone()
 570    }
 571
 572    pub fn snapshot(&self) -> BufferSnapshot {
 573        self.snapshot.clone()
 574    }
 575
 576    pub fn replica_id(&self) -> ReplicaId {
 577        self.lamport_clock.replica_id
 578    }
 579
 580    pub fn remote_id(&self) -> BufferId {
 581        self.remote_id
 582    }
 583
 584    pub fn deferred_ops_len(&self) -> usize {
 585        self.deferred_ops.len()
 586    }
 587
 588    pub fn transaction_group_interval(&self) -> Duration {
 589        self.history.group_interval
 590    }
 591
 592    pub fn edit<R, I, S, T>(&mut self, edits: R) -> Operation
 593    where
 594        R: IntoIterator<IntoIter = I>,
 595        I: ExactSizeIterator<Item = (Range<S>, T)>,
 596        S: ToOffset,
 597        T: Into<Arc<str>>,
 598    {
 599        let edits = edits
 600            .into_iter()
 601            .map(|(range, new_text)| (range, new_text.into()));
 602
 603        self.start_transaction();
 604        let timestamp = self.lamport_clock.tick();
 605        let operation = Operation::Edit(self.apply_local_edit(edits, timestamp));
 606
 607        self.history.push(operation.clone());
 608        self.history.push_undo(operation.timestamp());
 609        self.snapshot.version.observe(operation.timestamp());
 610        self.end_transaction();
 611        operation
 612    }
 613
 614    fn apply_local_edit<S: ToOffset, T: Into<Arc<str>>>(
 615        &mut self,
 616        edits: impl ExactSizeIterator<Item = (Range<S>, T)>,
 617        timestamp: clock::Lamport,
 618    ) -> EditOperation {
 619        let mut edits_patch = Patch::default();
 620        let mut edit_op = EditOperation {
 621            timestamp,
 622            version: self.version(),
 623            ranges: Vec::with_capacity(edits.len()),
 624            new_text: Vec::with_capacity(edits.len()),
 625        };
 626        let mut new_insertions = Vec::new();
 627        let mut insertion_offset = 0;
 628        let mut insertion_slices = Vec::new();
 629
 630        let mut edits = edits
 631            .map(|(range, new_text)| (range.to_offset(&*self), new_text))
 632            .peekable();
 633
 634        let mut new_ropes =
 635            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
 636        let mut old_fragments = self.fragments.cursor::<FragmentTextSummary>();
 637        let mut new_fragments =
 638            old_fragments.slice(&edits.peek().unwrap().0.start, Bias::Right, &None);
 639        new_ropes.append(new_fragments.summary().text);
 640
 641        let mut fragment_start = old_fragments.start().visible;
 642        for (range, new_text) in edits {
 643            let new_text = LineEnding::normalize_arc(new_text.into());
 644            let fragment_end = old_fragments.end(&None).visible;
 645
 646            // If the current fragment ends before this range, then jump ahead to the first fragment
 647            // that extends past the start of this range, reusing any intervening fragments.
 648            if fragment_end < range.start {
 649                // If the current fragment has been partially consumed, then consume the rest of it
 650                // and advance to the next fragment before slicing.
 651                if fragment_start > old_fragments.start().visible {
 652                    if fragment_end > fragment_start {
 653                        let mut suffix = old_fragments.item().unwrap().clone();
 654                        suffix.len = fragment_end - fragment_start;
 655                        suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 656                        new_insertions.push(InsertionFragment::insert_new(&suffix));
 657                        new_ropes.push_fragment(&suffix, suffix.visible);
 658                        new_fragments.push(suffix, &None);
 659                    }
 660                    old_fragments.next(&None);
 661                }
 662
 663                let slice = old_fragments.slice(&range.start, Bias::Right, &None);
 664                new_ropes.append(slice.summary().text);
 665                new_fragments.append(slice, &None);
 666                fragment_start = old_fragments.start().visible;
 667            }
 668
 669            let full_range_start = FullOffset(range.start + old_fragments.start().deleted);
 670
 671            // Preserve any portion of the current fragment that precedes this range.
 672            if fragment_start < range.start {
 673                let mut prefix = old_fragments.item().unwrap().clone();
 674                prefix.len = range.start - fragment_start;
 675                prefix.insertion_offset += fragment_start - old_fragments.start().visible;
 676                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
 677                new_insertions.push(InsertionFragment::insert_new(&prefix));
 678                new_ropes.push_fragment(&prefix, prefix.visible);
 679                new_fragments.push(prefix, &None);
 680                fragment_start = range.start;
 681            }
 682
 683            // Insert the new text before any existing fragments within the range.
 684            if !new_text.is_empty() {
 685                let new_start = new_fragments.summary().text.visible;
 686
 687                let fragment = Fragment {
 688                    id: Locator::between(
 689                        &new_fragments.summary().max_id,
 690                        old_fragments
 691                            .item()
 692                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
 693                    ),
 694                    timestamp,
 695                    insertion_offset,
 696                    len: new_text.len(),
 697                    deletions: Default::default(),
 698                    max_undos: Default::default(),
 699                    visible: true,
 700                };
 701                edits_patch.push(Edit {
 702                    old: fragment_start..fragment_start,
 703                    new: new_start..new_start + new_text.len(),
 704                });
 705                insertion_slices.push(fragment.insertion_slice());
 706                new_insertions.push(InsertionFragment::insert_new(&fragment));
 707                new_ropes.push_str(new_text.as_ref());
 708                new_fragments.push(fragment, &None);
 709                insertion_offset += new_text.len();
 710            }
 711
 712            // Advance through every fragment that intersects this range, marking the intersecting
 713            // portions as deleted.
 714            while fragment_start < range.end {
 715                let fragment = old_fragments.item().unwrap();
 716                let fragment_end = old_fragments.end(&None).visible;
 717                let mut intersection = fragment.clone();
 718                let intersection_end = cmp::min(range.end, fragment_end);
 719                if fragment.visible {
 720                    intersection.len = intersection_end - fragment_start;
 721                    intersection.insertion_offset += fragment_start - old_fragments.start().visible;
 722                    intersection.id =
 723                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
 724                    intersection.deletions.insert(timestamp);
 725                    intersection.visible = false;
 726                }
 727                if intersection.len > 0 {
 728                    if fragment.visible && !intersection.visible {
 729                        let new_start = new_fragments.summary().text.visible;
 730                        edits_patch.push(Edit {
 731                            old: fragment_start..intersection_end,
 732                            new: new_start..new_start,
 733                        });
 734                        insertion_slices.push(intersection.insertion_slice());
 735                    }
 736                    new_insertions.push(InsertionFragment::insert_new(&intersection));
 737                    new_ropes.push_fragment(&intersection, fragment.visible);
 738                    new_fragments.push(intersection, &None);
 739                    fragment_start = intersection_end;
 740                }
 741                if fragment_end <= range.end {
 742                    old_fragments.next(&None);
 743                }
 744            }
 745
 746            let full_range_end = FullOffset(range.end + old_fragments.start().deleted);
 747            edit_op.ranges.push(full_range_start..full_range_end);
 748            edit_op.new_text.push(new_text);
 749        }
 750
 751        // If the current fragment has been partially consumed, then consume the rest of it
 752        // and advance to the next fragment before slicing.
 753        if fragment_start > old_fragments.start().visible {
 754            let fragment_end = old_fragments.end(&None).visible;
 755            if fragment_end > fragment_start {
 756                let mut suffix = old_fragments.item().unwrap().clone();
 757                suffix.len = fragment_end - fragment_start;
 758                suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 759                new_insertions.push(InsertionFragment::insert_new(&suffix));
 760                new_ropes.push_fragment(&suffix, suffix.visible);
 761                new_fragments.push(suffix, &None);
 762            }
 763            old_fragments.next(&None);
 764        }
 765
 766        let suffix = old_fragments.suffix(&None);
 767        new_ropes.append(suffix.summary().text);
 768        new_fragments.append(suffix, &None);
 769        let (visible_text, deleted_text) = new_ropes.finish();
 770        drop(old_fragments);
 771
 772        self.snapshot.fragments = new_fragments;
 773        self.snapshot.insertions.edit(new_insertions, &());
 774        self.snapshot.visible_text = visible_text;
 775        self.snapshot.deleted_text = deleted_text;
 776        self.subscriptions.publish_mut(&edits_patch);
 777        self.history
 778            .insertion_slices
 779            .insert(timestamp, insertion_slices);
 780        edit_op
 781    }
 782
 783    pub fn set_line_ending(&mut self, line_ending: LineEnding) {
 784        self.snapshot.line_ending = line_ending;
 785    }
 786
 787    pub fn apply_ops<I: IntoIterator<Item = Operation>>(&mut self, ops: I) -> Result<()> {
 788        let mut deferred_ops = Vec::new();
 789        for op in ops {
 790            self.history.push(op.clone());
 791            if self.can_apply_op(&op) {
 792                self.apply_op(op)?;
 793            } else {
 794                self.deferred_replicas.insert(op.replica_id());
 795                deferred_ops.push(op);
 796            }
 797        }
 798        self.deferred_ops.insert(deferred_ops);
 799        self.flush_deferred_ops()?;
 800        Ok(())
 801    }
 802
 803    fn apply_op(&mut self, op: Operation) -> Result<()> {
 804        match op {
 805            Operation::Edit(edit) => {
 806                if !self.version.observed(edit.timestamp) {
 807                    self.apply_remote_edit(
 808                        &edit.version,
 809                        &edit.ranges,
 810                        &edit.new_text,
 811                        edit.timestamp,
 812                    );
 813                    self.snapshot.version.observe(edit.timestamp);
 814                    self.lamport_clock.observe(edit.timestamp);
 815                    self.resolve_edit(edit.timestamp);
 816                }
 817            }
 818            Operation::Undo(undo) => {
 819                if !self.version.observed(undo.timestamp) {
 820                    self.apply_undo(&undo)?;
 821                    self.snapshot.version.observe(undo.timestamp);
 822                    self.lamport_clock.observe(undo.timestamp);
 823                }
 824            }
 825        }
 826        self.wait_for_version_txs.retain_mut(|(version, tx)| {
 827            if self.snapshot.version().observed_all(version) {
 828                tx.try_send(()).ok();
 829                false
 830            } else {
 831                true
 832            }
 833        });
 834        Ok(())
 835    }
 836
 837    fn apply_remote_edit(
 838        &mut self,
 839        version: &clock::Global,
 840        ranges: &[Range<FullOffset>],
 841        new_text: &[Arc<str>],
 842        timestamp: clock::Lamport,
 843    ) {
 844        if ranges.is_empty() {
 845            return;
 846        }
 847
 848        let edits = ranges.iter().zip(new_text.iter());
 849        let mut edits_patch = Patch::default();
 850        let mut insertion_slices = Vec::new();
 851        let cx = Some(version.clone());
 852        let mut new_insertions = Vec::new();
 853        let mut insertion_offset = 0;
 854        let mut new_ropes =
 855            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
 856        let mut old_fragments = self.fragments.cursor::<(VersionedFullOffset, usize)>();
 857        let mut new_fragments = old_fragments.slice(
 858            &VersionedFullOffset::Offset(ranges[0].start),
 859            Bias::Left,
 860            &cx,
 861        );
 862        new_ropes.append(new_fragments.summary().text);
 863
 864        let mut fragment_start = old_fragments.start().0.full_offset();
 865        for (range, new_text) in edits {
 866            let fragment_end = old_fragments.end(&cx).0.full_offset();
 867
 868            // If the current fragment ends before this range, then jump ahead to the first fragment
 869            // that extends past the start of this range, reusing any intervening fragments.
 870            if fragment_end < range.start {
 871                // If the current fragment has been partially consumed, then consume the rest of it
 872                // and advance to the next fragment before slicing.
 873                if fragment_start > old_fragments.start().0.full_offset() {
 874                    if fragment_end > fragment_start {
 875                        let mut suffix = old_fragments.item().unwrap().clone();
 876                        suffix.len = fragment_end.0 - fragment_start.0;
 877                        suffix.insertion_offset +=
 878                            fragment_start - old_fragments.start().0.full_offset();
 879                        new_insertions.push(InsertionFragment::insert_new(&suffix));
 880                        new_ropes.push_fragment(&suffix, suffix.visible);
 881                        new_fragments.push(suffix, &None);
 882                    }
 883                    old_fragments.next(&cx);
 884                }
 885
 886                let slice =
 887                    old_fragments.slice(&VersionedFullOffset::Offset(range.start), Bias::Left, &cx);
 888                new_ropes.append(slice.summary().text);
 889                new_fragments.append(slice, &None);
 890                fragment_start = old_fragments.start().0.full_offset();
 891            }
 892
 893            // If we are at the end of a non-concurrent fragment, advance to the next one.
 894            let fragment_end = old_fragments.end(&cx).0.full_offset();
 895            if fragment_end == range.start && fragment_end > fragment_start {
 896                let mut fragment = old_fragments.item().unwrap().clone();
 897                fragment.len = fragment_end.0 - fragment_start.0;
 898                fragment.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
 899                new_insertions.push(InsertionFragment::insert_new(&fragment));
 900                new_ropes.push_fragment(&fragment, fragment.visible);
 901                new_fragments.push(fragment, &None);
 902                old_fragments.next(&cx);
 903                fragment_start = old_fragments.start().0.full_offset();
 904            }
 905
 906            // Skip over insertions that are concurrent to this edit, but have a lower lamport
 907            // timestamp.
 908            while let Some(fragment) = old_fragments.item() {
 909                if fragment_start == range.start && fragment.timestamp > timestamp {
 910                    new_ropes.push_fragment(fragment, fragment.visible);
 911                    new_fragments.push(fragment.clone(), &None);
 912                    old_fragments.next(&cx);
 913                    debug_assert_eq!(fragment_start, range.start);
 914                } else {
 915                    break;
 916                }
 917            }
 918            debug_assert!(fragment_start <= range.start);
 919
 920            // Preserve any portion of the current fragment that precedes this range.
 921            if fragment_start < range.start {
 922                let mut prefix = old_fragments.item().unwrap().clone();
 923                prefix.len = range.start.0 - fragment_start.0;
 924                prefix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
 925                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
 926                new_insertions.push(InsertionFragment::insert_new(&prefix));
 927                fragment_start = range.start;
 928                new_ropes.push_fragment(&prefix, prefix.visible);
 929                new_fragments.push(prefix, &None);
 930            }
 931
 932            // Insert the new text before any existing fragments within the range.
 933            if !new_text.is_empty() {
 934                let mut old_start = old_fragments.start().1;
 935                if old_fragments.item().map_or(false, |f| f.visible) {
 936                    old_start += fragment_start.0 - old_fragments.start().0.full_offset().0;
 937                }
 938                let new_start = new_fragments.summary().text.visible;
 939                let fragment = Fragment {
 940                    id: Locator::between(
 941                        &new_fragments.summary().max_id,
 942                        old_fragments
 943                            .item()
 944                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
 945                    ),
 946                    timestamp,
 947                    insertion_offset,
 948                    len: new_text.len(),
 949                    deletions: Default::default(),
 950                    max_undos: Default::default(),
 951                    visible: true,
 952                };
 953                edits_patch.push(Edit {
 954                    old: old_start..old_start,
 955                    new: new_start..new_start + new_text.len(),
 956                });
 957                insertion_slices.push(fragment.insertion_slice());
 958                new_insertions.push(InsertionFragment::insert_new(&fragment));
 959                new_ropes.push_str(new_text);
 960                new_fragments.push(fragment, &None);
 961                insertion_offset += new_text.len();
 962            }
 963
 964            // Advance through every fragment that intersects this range, marking the intersecting
 965            // portions as deleted.
 966            while fragment_start < range.end {
 967                let fragment = old_fragments.item().unwrap();
 968                let fragment_end = old_fragments.end(&cx).0.full_offset();
 969                let mut intersection = fragment.clone();
 970                let intersection_end = cmp::min(range.end, fragment_end);
 971                if fragment.was_visible(version, &self.undo_map) {
 972                    intersection.len = intersection_end.0 - fragment_start.0;
 973                    intersection.insertion_offset +=
 974                        fragment_start - old_fragments.start().0.full_offset();
 975                    intersection.id =
 976                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
 977                    intersection.deletions.insert(timestamp);
 978                    intersection.visible = false;
 979                    insertion_slices.push(intersection.insertion_slice());
 980                }
 981                if intersection.len > 0 {
 982                    if fragment.visible && !intersection.visible {
 983                        let old_start = old_fragments.start().1
 984                            + (fragment_start.0 - old_fragments.start().0.full_offset().0);
 985                        let new_start = new_fragments.summary().text.visible;
 986                        edits_patch.push(Edit {
 987                            old: old_start..old_start + intersection.len,
 988                            new: new_start..new_start,
 989                        });
 990                    }
 991                    new_insertions.push(InsertionFragment::insert_new(&intersection));
 992                    new_ropes.push_fragment(&intersection, fragment.visible);
 993                    new_fragments.push(intersection, &None);
 994                    fragment_start = intersection_end;
 995                }
 996                if fragment_end <= range.end {
 997                    old_fragments.next(&cx);
 998                }
 999            }
1000        }
1001
1002        // If the current fragment has been partially consumed, then consume the rest of it
1003        // and advance to the next fragment before slicing.
1004        if fragment_start > old_fragments.start().0.full_offset() {
1005            let fragment_end = old_fragments.end(&cx).0.full_offset();
1006            if fragment_end > fragment_start {
1007                let mut suffix = old_fragments.item().unwrap().clone();
1008                suffix.len = fragment_end.0 - fragment_start.0;
1009                suffix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1010                new_insertions.push(InsertionFragment::insert_new(&suffix));
1011                new_ropes.push_fragment(&suffix, suffix.visible);
1012                new_fragments.push(suffix, &None);
1013            }
1014            old_fragments.next(&cx);
1015        }
1016
1017        let suffix = old_fragments.suffix(&cx);
1018        new_ropes.append(suffix.summary().text);
1019        new_fragments.append(suffix, &None);
1020        let (visible_text, deleted_text) = new_ropes.finish();
1021        drop(old_fragments);
1022
1023        self.snapshot.fragments = new_fragments;
1024        self.snapshot.visible_text = visible_text;
1025        self.snapshot.deleted_text = deleted_text;
1026        self.snapshot.insertions.edit(new_insertions, &());
1027        self.history
1028            .insertion_slices
1029            .insert(timestamp, insertion_slices);
1030        self.subscriptions.publish_mut(&edits_patch)
1031    }
1032
1033    fn fragment_ids_for_edits<'a>(
1034        &'a self,
1035        edit_ids: impl Iterator<Item = &'a clock::Lamport>,
1036    ) -> Vec<&'a Locator> {
1037        // Get all of the insertion slices changed by the given edits.
1038        let mut insertion_slices = Vec::new();
1039        for edit_id in edit_ids {
1040            if let Some(slices) = self.history.insertion_slices.get(edit_id) {
1041                insertion_slices.extend_from_slice(slices)
1042            }
1043        }
1044        insertion_slices
1045            .sort_unstable_by_key(|s| (s.insertion_id, s.range.start, Reverse(s.range.end)));
1046
1047        // Get all of the fragments corresponding to these insertion slices.
1048        let mut fragment_ids = Vec::new();
1049        let mut insertions_cursor = self.insertions.cursor::<InsertionFragmentKey>();
1050        for insertion_slice in &insertion_slices {
1051            if insertion_slice.insertion_id != insertions_cursor.start().timestamp
1052                || insertion_slice.range.start > insertions_cursor.start().split_offset
1053            {
1054                insertions_cursor.seek_forward(
1055                    &InsertionFragmentKey {
1056                        timestamp: insertion_slice.insertion_id,
1057                        split_offset: insertion_slice.range.start,
1058                    },
1059                    Bias::Left,
1060                    &(),
1061                );
1062            }
1063            while let Some(item) = insertions_cursor.item() {
1064                if item.timestamp != insertion_slice.insertion_id
1065                    || item.split_offset >= insertion_slice.range.end
1066                {
1067                    break;
1068                }
1069                fragment_ids.push(&item.fragment_id);
1070                insertions_cursor.next(&());
1071            }
1072        }
1073        fragment_ids.sort_unstable();
1074        fragment_ids
1075    }
1076
1077    fn apply_undo(&mut self, undo: &UndoOperation) -> Result<()> {
1078        self.snapshot.undo_map.insert(undo);
1079
1080        let mut edits = Patch::default();
1081        let mut old_fragments = self.fragments.cursor::<(Option<&Locator>, usize)>();
1082        let mut new_fragments = SumTree::new();
1083        let mut new_ropes =
1084            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
1085
1086        for fragment_id in self.fragment_ids_for_edits(undo.counts.keys()) {
1087            let preceding_fragments = old_fragments.slice(&Some(fragment_id), Bias::Left, &None);
1088            new_ropes.append(preceding_fragments.summary().text);
1089            new_fragments.append(preceding_fragments, &None);
1090
1091            if let Some(fragment) = old_fragments.item() {
1092                let mut fragment = fragment.clone();
1093                let fragment_was_visible = fragment.visible;
1094
1095                fragment.visible = fragment.is_visible(&self.undo_map);
1096                fragment.max_undos.observe(undo.timestamp);
1097
1098                let old_start = old_fragments.start().1;
1099                let new_start = new_fragments.summary().text.visible;
1100                if fragment_was_visible && !fragment.visible {
1101                    edits.push(Edit {
1102                        old: old_start..old_start + fragment.len,
1103                        new: new_start..new_start,
1104                    });
1105                } else if !fragment_was_visible && fragment.visible {
1106                    edits.push(Edit {
1107                        old: old_start..old_start,
1108                        new: new_start..new_start + fragment.len,
1109                    });
1110                }
1111                new_ropes.push_fragment(&fragment, fragment_was_visible);
1112                new_fragments.push(fragment, &None);
1113
1114                old_fragments.next(&None);
1115            }
1116        }
1117
1118        let suffix = old_fragments.suffix(&None);
1119        new_ropes.append(suffix.summary().text);
1120        new_fragments.append(suffix, &None);
1121
1122        drop(old_fragments);
1123        let (visible_text, deleted_text) = new_ropes.finish();
1124        self.snapshot.fragments = new_fragments;
1125        self.snapshot.visible_text = visible_text;
1126        self.snapshot.deleted_text = deleted_text;
1127        self.subscriptions.publish_mut(&edits);
1128        Ok(())
1129    }
1130
1131    fn flush_deferred_ops(&mut self) -> Result<()> {
1132        self.deferred_replicas.clear();
1133        let mut deferred_ops = Vec::new();
1134        for op in self.deferred_ops.drain().iter().cloned() {
1135            if self.can_apply_op(&op) {
1136                self.apply_op(op)?;
1137            } else {
1138                self.deferred_replicas.insert(op.replica_id());
1139                deferred_ops.push(op);
1140            }
1141        }
1142        self.deferred_ops.insert(deferred_ops);
1143        Ok(())
1144    }
1145
1146    fn can_apply_op(&self, op: &Operation) -> bool {
1147        if self.deferred_replicas.contains(&op.replica_id()) {
1148            false
1149        } else {
1150            self.version.observed_all(match op {
1151                Operation::Edit(edit) => &edit.version,
1152                Operation::Undo(undo) => &undo.version,
1153            })
1154        }
1155    }
1156
1157    pub fn peek_undo_stack(&self) -> Option<&HistoryEntry> {
1158        self.history.undo_stack.last()
1159    }
1160
1161    pub fn peek_redo_stack(&self) -> Option<&HistoryEntry> {
1162        self.history.redo_stack.last()
1163    }
1164
1165    pub fn start_transaction(&mut self) -> Option<TransactionId> {
1166        self.start_transaction_at(Instant::now())
1167    }
1168
1169    pub fn start_transaction_at(&mut self, now: Instant) -> Option<TransactionId> {
1170        self.history
1171            .start_transaction(self.version.clone(), now, &mut self.lamport_clock)
1172    }
1173
1174    pub fn end_transaction(&mut self) -> Option<(TransactionId, clock::Global)> {
1175        self.end_transaction_at(Instant::now())
1176    }
1177
1178    pub fn end_transaction_at(&mut self, now: Instant) -> Option<(TransactionId, clock::Global)> {
1179        if let Some(entry) = self.history.end_transaction(now) {
1180            let since = entry.transaction.start.clone();
1181            let id = self.history.group().unwrap();
1182            Some((id, since))
1183        } else {
1184            None
1185        }
1186    }
1187
1188    pub fn finalize_last_transaction(&mut self) -> Option<&Transaction> {
1189        self.history.finalize_last_transaction()
1190    }
1191
1192    pub fn group_until_transaction(&mut self, transaction_id: TransactionId) {
1193        self.history.group_until(transaction_id);
1194    }
1195
1196    pub fn base_text(&self) -> &Rope {
1197        &self.history.base_text
1198    }
1199
1200    pub fn operations(&self) -> &TreeMap<clock::Lamport, Operation> {
1201        &self.history.operations
1202    }
1203
1204    pub fn undo(&mut self) -> Option<(TransactionId, Operation)> {
1205        if let Some(entry) = self.history.pop_undo() {
1206            let transaction = entry.transaction.clone();
1207            let transaction_id = transaction.id;
1208            let op = self.undo_or_redo(transaction).unwrap();
1209            Some((transaction_id, op))
1210        } else {
1211            None
1212        }
1213    }
1214
1215    pub fn undo_transaction(&mut self, transaction_id: TransactionId) -> Option<Operation> {
1216        let transaction = self
1217            .history
1218            .remove_from_undo(transaction_id)?
1219            .transaction
1220            .clone();
1221        self.undo_or_redo(transaction).log_err()
1222    }
1223
1224    pub fn undo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1225        let transactions = self
1226            .history
1227            .remove_from_undo_until(transaction_id)
1228            .iter()
1229            .map(|entry| entry.transaction.clone())
1230            .collect::<Vec<_>>();
1231
1232        transactions
1233            .into_iter()
1234            .map(|transaction| self.undo_or_redo(transaction).unwrap())
1235            .collect()
1236    }
1237
1238    pub fn forget_transaction(&mut self, transaction_id: TransactionId) {
1239        self.history.forget(transaction_id);
1240    }
1241
1242    pub fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
1243        self.history.merge_transactions(transaction, destination);
1244    }
1245
1246    pub fn redo(&mut self) -> Option<(TransactionId, Operation)> {
1247        if let Some(entry) = self.history.pop_redo() {
1248            let transaction = entry.transaction.clone();
1249            let transaction_id = transaction.id;
1250            let op = self.undo_or_redo(transaction).unwrap();
1251            Some((transaction_id, op))
1252        } else {
1253            None
1254        }
1255    }
1256
1257    pub fn redo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1258        let transactions = self
1259            .history
1260            .remove_from_redo(transaction_id)
1261            .iter()
1262            .map(|entry| entry.transaction.clone())
1263            .collect::<Vec<_>>();
1264
1265        transactions
1266            .into_iter()
1267            .map(|transaction| self.undo_or_redo(transaction).unwrap())
1268            .collect()
1269    }
1270
1271    fn undo_or_redo(&mut self, transaction: Transaction) -> Result<Operation> {
1272        let mut counts = HashMap::default();
1273        for edit_id in transaction.edit_ids {
1274            counts.insert(edit_id, self.undo_map.undo_count(edit_id) + 1);
1275        }
1276
1277        let undo = UndoOperation {
1278            timestamp: self.lamport_clock.tick(),
1279            version: self.version(),
1280            counts,
1281        };
1282        self.apply_undo(&undo)?;
1283        self.snapshot.version.observe(undo.timestamp);
1284        let operation = Operation::Undo(undo);
1285        self.history.push(operation.clone());
1286        Ok(operation)
1287    }
1288
1289    pub fn push_transaction(&mut self, transaction: Transaction, now: Instant) {
1290        self.history.push_transaction(transaction, now);
1291        self.history.finalize_last_transaction();
1292    }
1293
1294    pub fn edited_ranges_for_transaction<'a, D>(
1295        &'a self,
1296        transaction: &'a Transaction,
1297    ) -> impl 'a + Iterator<Item = Range<D>>
1298    where
1299        D: TextDimension,
1300    {
1301        // get fragment ranges
1302        let mut cursor = self.fragments.cursor::<(Option<&Locator>, usize)>();
1303        let offset_ranges = self
1304            .fragment_ids_for_edits(transaction.edit_ids.iter())
1305            .into_iter()
1306            .filter_map(move |fragment_id| {
1307                cursor.seek_forward(&Some(fragment_id), Bias::Left, &None);
1308                let fragment = cursor.item()?;
1309                let start_offset = cursor.start().1;
1310                let end_offset = start_offset + if fragment.visible { fragment.len } else { 0 };
1311                Some(start_offset..end_offset)
1312            });
1313
1314        // combine adjacent ranges
1315        let mut prev_range: Option<Range<usize>> = None;
1316        let disjoint_ranges = offset_ranges
1317            .map(Some)
1318            .chain([None])
1319            .filter_map(move |range| {
1320                if let Some((range, prev_range)) = range.as_ref().zip(prev_range.as_mut()) {
1321                    if prev_range.end == range.start {
1322                        prev_range.end = range.end;
1323                        return None;
1324                    }
1325                }
1326                let result = prev_range.clone();
1327                prev_range = range;
1328                result
1329            });
1330
1331        // convert to the desired text dimension.
1332        let mut position = D::default();
1333        let mut rope_cursor = self.visible_text.cursor(0);
1334        disjoint_ranges.map(move |range| {
1335            position.add_assign(&rope_cursor.summary(range.start));
1336            let start = position.clone();
1337            position.add_assign(&rope_cursor.summary(range.end));
1338            let end = position.clone();
1339            start..end
1340        })
1341    }
1342
1343    pub fn subscribe(&mut self) -> Subscription {
1344        self.subscriptions.subscribe()
1345    }
1346
1347    pub fn wait_for_edits(
1348        &mut self,
1349        edit_ids: impl IntoIterator<Item = clock::Lamport>,
1350    ) -> impl 'static + Future<Output = Result<()>> {
1351        let mut futures = Vec::new();
1352        for edit_id in edit_ids {
1353            if !self.version.observed(edit_id) {
1354                let (tx, rx) = oneshot::channel();
1355                self.edit_id_resolvers.entry(edit_id).or_default().push(tx);
1356                futures.push(rx);
1357            }
1358        }
1359
1360        async move {
1361            for mut future in futures {
1362                if future.recv().await.is_none() {
1363                    Err(anyhow!("gave up waiting for edits"))?;
1364                }
1365            }
1366            Ok(())
1367        }
1368    }
1369
1370    pub fn wait_for_anchors(
1371        &mut self,
1372        anchors: impl IntoIterator<Item = Anchor>,
1373    ) -> impl 'static + Future<Output = Result<()>> {
1374        let mut futures = Vec::new();
1375        for anchor in anchors {
1376            if !self.version.observed(anchor.timestamp)
1377                && anchor != Anchor::MAX
1378                && anchor != Anchor::MIN
1379            {
1380                let (tx, rx) = oneshot::channel();
1381                self.edit_id_resolvers
1382                    .entry(anchor.timestamp)
1383                    .or_default()
1384                    .push(tx);
1385                futures.push(rx);
1386            }
1387        }
1388
1389        async move {
1390            for mut future in futures {
1391                if future.recv().await.is_none() {
1392                    Err(anyhow!("gave up waiting for anchors"))?;
1393                }
1394            }
1395            Ok(())
1396        }
1397    }
1398
1399    pub fn wait_for_version(&mut self, version: clock::Global) -> impl Future<Output = Result<()>> {
1400        let mut rx = None;
1401        if !self.snapshot.version.observed_all(&version) {
1402            let channel = oneshot::channel();
1403            self.wait_for_version_txs.push((version, channel.0));
1404            rx = Some(channel.1);
1405        }
1406        async move {
1407            if let Some(mut rx) = rx {
1408                if rx.recv().await.is_none() {
1409                    Err(anyhow!("gave up waiting for version"))?;
1410                }
1411            }
1412            Ok(())
1413        }
1414    }
1415
1416    pub fn give_up_waiting(&mut self) {
1417        self.edit_id_resolvers.clear();
1418        self.wait_for_version_txs.clear();
1419    }
1420
1421    fn resolve_edit(&mut self, edit_id: clock::Lamport) {
1422        for mut tx in self
1423            .edit_id_resolvers
1424            .remove(&edit_id)
1425            .into_iter()
1426            .flatten()
1427        {
1428            tx.try_send(()).ok();
1429        }
1430    }
1431}
1432
1433#[cfg(any(test, feature = "test-support"))]
1434impl Buffer {
1435    pub fn edit_via_marked_text(&mut self, marked_string: &str) {
1436        let edits = self.edits_for_marked_text(marked_string);
1437        self.edit(edits);
1438    }
1439
1440    pub fn edits_for_marked_text(&self, marked_string: &str) -> Vec<(Range<usize>, String)> {
1441        let old_text = self.text();
1442        let (new_text, mut ranges) = util::test::marked_text_ranges(marked_string, false);
1443        if ranges.is_empty() {
1444            ranges.push(0..new_text.len());
1445        }
1446
1447        assert_eq!(
1448            old_text[..ranges[0].start],
1449            new_text[..ranges[0].start],
1450            "invalid edit"
1451        );
1452
1453        let mut delta = 0;
1454        let mut edits = Vec::new();
1455        let mut ranges = ranges.into_iter().peekable();
1456
1457        while let Some(inserted_range) = ranges.next() {
1458            let new_start = inserted_range.start;
1459            let old_start = (new_start as isize - delta) as usize;
1460
1461            let following_text = if let Some(next_range) = ranges.peek() {
1462                &new_text[inserted_range.end..next_range.start]
1463            } else {
1464                &new_text[inserted_range.end..]
1465            };
1466
1467            let inserted_len = inserted_range.len();
1468            let deleted_len = old_text[old_start..]
1469                .find(following_text)
1470                .expect("invalid edit");
1471
1472            let old_range = old_start..old_start + deleted_len;
1473            edits.push((old_range, new_text[inserted_range].to_string()));
1474            delta += inserted_len as isize - deleted_len as isize;
1475        }
1476
1477        assert_eq!(
1478            old_text.len() as isize + delta,
1479            new_text.len() as isize,
1480            "invalid edit"
1481        );
1482
1483        edits
1484    }
1485
1486    pub fn check_invariants(&self) {
1487        // Ensure every fragment is ordered by locator in the fragment tree and corresponds
1488        // to an insertion fragment in the insertions tree.
1489        let mut prev_fragment_id = Locator::min();
1490        for fragment in self.snapshot.fragments.items(&None) {
1491            assert!(fragment.id > prev_fragment_id);
1492            prev_fragment_id = fragment.id.clone();
1493
1494            let insertion_fragment = self
1495                .snapshot
1496                .insertions
1497                .get(
1498                    &InsertionFragmentKey {
1499                        timestamp: fragment.timestamp,
1500                        split_offset: fragment.insertion_offset,
1501                    },
1502                    &(),
1503                )
1504                .unwrap();
1505            assert_eq!(
1506                insertion_fragment.fragment_id, fragment.id,
1507                "fragment: {:?}\ninsertion: {:?}",
1508                fragment, insertion_fragment
1509            );
1510        }
1511
1512        let mut cursor = self.snapshot.fragments.cursor::<Option<&Locator>>();
1513        for insertion_fragment in self.snapshot.insertions.cursor::<()>() {
1514            cursor.seek(&Some(&insertion_fragment.fragment_id), Bias::Left, &None);
1515            let fragment = cursor.item().unwrap();
1516            assert_eq!(insertion_fragment.fragment_id, fragment.id);
1517            assert_eq!(insertion_fragment.split_offset, fragment.insertion_offset);
1518        }
1519
1520        let fragment_summary = self.snapshot.fragments.summary();
1521        assert_eq!(
1522            fragment_summary.text.visible,
1523            self.snapshot.visible_text.len()
1524        );
1525        assert_eq!(
1526            fragment_summary.text.deleted,
1527            self.snapshot.deleted_text.len()
1528        );
1529
1530        assert!(!self.text().contains("\r\n"));
1531    }
1532
1533    pub fn set_group_interval(&mut self, group_interval: Duration) {
1534        self.history.group_interval = group_interval;
1535    }
1536
1537    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
1538        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
1539        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
1540        start..end
1541    }
1542
1543    pub fn get_random_edits<T>(
1544        &self,
1545        rng: &mut T,
1546        edit_count: usize,
1547    ) -> Vec<(Range<usize>, Arc<str>)>
1548    where
1549        T: rand::Rng,
1550    {
1551        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1552        let mut last_end = None;
1553        for _ in 0..edit_count {
1554            if last_end.map_or(false, |last_end| last_end >= self.len()) {
1555                break;
1556            }
1557            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1558            let range = self.random_byte_range(new_start, rng);
1559            last_end = Some(range.end);
1560
1561            let new_text_len = rng.gen_range(0..10);
1562            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1563
1564            edits.push((range, new_text.into()));
1565        }
1566        edits
1567    }
1568
1569    pub fn randomly_edit<T>(
1570        &mut self,
1571        rng: &mut T,
1572        edit_count: usize,
1573    ) -> (Vec<(Range<usize>, Arc<str>)>, Operation)
1574    where
1575        T: rand::Rng,
1576    {
1577        let mut edits = self.get_random_edits(rng, edit_count);
1578        log::info!("mutating buffer {} with {:?}", self.replica_id, edits);
1579
1580        let op = self.edit(edits.iter().cloned());
1581        if let Operation::Edit(edit) = &op {
1582            assert_eq!(edits.len(), edit.new_text.len());
1583            for (edit, new_text) in edits.iter_mut().zip(&edit.new_text) {
1584                edit.1 = new_text.clone();
1585            }
1586        } else {
1587            unreachable!()
1588        }
1589
1590        (edits, op)
1591    }
1592
1593    pub fn randomly_undo_redo(&mut self, rng: &mut impl rand::Rng) -> Vec<Operation> {
1594        use rand::prelude::*;
1595
1596        let mut ops = Vec::new();
1597        for _ in 0..rng.gen_range(1..=5) {
1598            if let Some(entry) = self.history.undo_stack.choose(rng) {
1599                let transaction = entry.transaction.clone();
1600                log::info!(
1601                    "undoing buffer {} transaction {:?}",
1602                    self.replica_id,
1603                    transaction
1604                );
1605                ops.push(self.undo_or_redo(transaction).unwrap());
1606            }
1607        }
1608        ops
1609    }
1610}
1611
1612impl Deref for Buffer {
1613    type Target = BufferSnapshot;
1614
1615    fn deref(&self) -> &Self::Target {
1616        &self.snapshot
1617    }
1618}
1619
1620impl BufferSnapshot {
1621    pub fn as_rope(&self) -> &Rope {
1622        &self.visible_text
1623    }
1624
1625    pub fn remote_id(&self) -> BufferId {
1626        self.remote_id
1627    }
1628
1629    pub fn replica_id(&self) -> ReplicaId {
1630        self.replica_id
1631    }
1632
1633    pub fn row_count(&self) -> u32 {
1634        self.max_point().row + 1
1635    }
1636
1637    pub fn len(&self) -> usize {
1638        self.visible_text.len()
1639    }
1640
1641    pub fn is_empty(&self) -> bool {
1642        self.len() == 0
1643    }
1644
1645    pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
1646        self.chars_at(0)
1647    }
1648
1649    pub fn chars_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = char> + '_ {
1650        self.text_for_range(range).flat_map(str::chars)
1651    }
1652
1653    pub fn reversed_chars_for_range<T: ToOffset>(
1654        &self,
1655        range: Range<T>,
1656    ) -> impl Iterator<Item = char> + '_ {
1657        self.reversed_chunks_in_range(range)
1658            .flat_map(|chunk| chunk.chars().rev())
1659    }
1660
1661    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1662    where
1663        T: ToOffset,
1664    {
1665        let position = position.to_offset(self);
1666        position == self.clip_offset(position, Bias::Left)
1667            && self
1668                .bytes_in_range(position..self.len())
1669                .flatten()
1670                .copied()
1671                .take(needle.len())
1672                .eq(needle.bytes())
1673    }
1674
1675    pub fn common_prefix_at<T>(&self, position: T, needle: &str) -> Range<T>
1676    where
1677        T: ToOffset + TextDimension,
1678    {
1679        let offset = position.to_offset(self);
1680        let common_prefix_len = needle
1681            .char_indices()
1682            .map(|(index, _)| index)
1683            .chain([needle.len()])
1684            .take_while(|&len| len <= offset)
1685            .filter(|&len| {
1686                let left = self
1687                    .chars_for_range(offset - len..offset)
1688                    .flat_map(char::to_lowercase);
1689                let right = needle[..len].chars().flat_map(char::to_lowercase);
1690                left.eq(right)
1691            })
1692            .last()
1693            .unwrap_or(0);
1694        let start_offset = offset - common_prefix_len;
1695        let start = self.text_summary_for_range(0..start_offset);
1696        start..position
1697    }
1698
1699    pub fn text(&self) -> String {
1700        self.visible_text.to_string()
1701    }
1702
1703    pub fn line_ending(&self) -> LineEnding {
1704        self.line_ending
1705    }
1706
1707    pub fn deleted_text(&self) -> String {
1708        self.deleted_text.to_string()
1709    }
1710
1711    pub fn fragments(&self) -> impl Iterator<Item = &Fragment> {
1712        self.fragments.iter()
1713    }
1714
1715    pub fn text_summary(&self) -> TextSummary {
1716        self.visible_text.summary()
1717    }
1718
1719    pub fn max_point(&self) -> Point {
1720        self.visible_text.max_point()
1721    }
1722
1723    pub fn max_point_utf16(&self) -> PointUtf16 {
1724        self.visible_text.max_point_utf16()
1725    }
1726
1727    pub fn point_to_offset(&self, point: Point) -> usize {
1728        self.visible_text.point_to_offset(point)
1729    }
1730
1731    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1732        self.visible_text.point_utf16_to_offset(point)
1733    }
1734
1735    pub fn unclipped_point_utf16_to_offset(&self, point: Unclipped<PointUtf16>) -> usize {
1736        self.visible_text.unclipped_point_utf16_to_offset(point)
1737    }
1738
1739    pub fn unclipped_point_utf16_to_point(&self, point: Unclipped<PointUtf16>) -> Point {
1740        self.visible_text.unclipped_point_utf16_to_point(point)
1741    }
1742
1743    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
1744        self.visible_text.offset_utf16_to_offset(offset)
1745    }
1746
1747    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
1748        self.visible_text.offset_to_offset_utf16(offset)
1749    }
1750
1751    pub fn offset_to_point(&self, offset: usize) -> Point {
1752        self.visible_text.offset_to_point(offset)
1753    }
1754
1755    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
1756        self.visible_text.offset_to_point_utf16(offset)
1757    }
1758
1759    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
1760        self.visible_text.point_to_point_utf16(point)
1761    }
1762
1763    pub fn version(&self) -> &clock::Global {
1764        &self.version
1765    }
1766
1767    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1768        let offset = position.to_offset(self);
1769        self.visible_text.chars_at(offset)
1770    }
1771
1772    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1773        let offset = position.to_offset(self);
1774        self.visible_text.reversed_chars_at(offset)
1775    }
1776
1777    pub fn reversed_chunks_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Chunks {
1778        let range = range.start.to_offset(self)..range.end.to_offset(self);
1779        self.visible_text.reversed_chunks_in_range(range)
1780    }
1781
1782    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
1783        let start = range.start.to_offset(self);
1784        let end = range.end.to_offset(self);
1785        self.visible_text.bytes_in_range(start..end)
1786    }
1787
1788    pub fn reversed_bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
1789        let start = range.start.to_offset(self);
1790        let end = range.end.to_offset(self);
1791        self.visible_text.reversed_bytes_in_range(start..end)
1792    }
1793
1794    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> Chunks<'_> {
1795        let start = range.start.to_offset(self);
1796        let end = range.end.to_offset(self);
1797        self.visible_text.chunks_in_range(start..end)
1798    }
1799
1800    pub fn line_len(&self, row: u32) -> u32 {
1801        let row_start_offset = Point::new(row, 0).to_offset(self);
1802        let row_end_offset = if row >= self.max_point().row {
1803            self.len()
1804        } else {
1805            Point::new(row + 1, 0).to_offset(self) - 1
1806        };
1807        (row_end_offset - row_start_offset) as u32
1808    }
1809
1810    pub fn is_line_blank(&self, row: u32) -> bool {
1811        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1812            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1813    }
1814
1815    pub fn text_summary_for_range<D, O: ToOffset>(&self, range: Range<O>) -> D
1816    where
1817        D: TextDimension,
1818    {
1819        self.visible_text
1820            .cursor(range.start.to_offset(self))
1821            .summary(range.end.to_offset(self))
1822    }
1823
1824    pub fn summaries_for_anchors<'a, D, A>(&'a self, anchors: A) -> impl 'a + Iterator<Item = D>
1825    where
1826        D: 'a + TextDimension,
1827        A: 'a + IntoIterator<Item = &'a Anchor>,
1828    {
1829        let anchors = anchors.into_iter();
1830        self.summaries_for_anchors_with_payload::<D, _, ()>(anchors.map(|a| (a, ())))
1831            .map(|d| d.0)
1832    }
1833
1834    pub fn summaries_for_anchors_with_payload<'a, D, A, T>(
1835        &'a self,
1836        anchors: A,
1837    ) -> impl 'a + Iterator<Item = (D, T)>
1838    where
1839        D: 'a + TextDimension,
1840        A: 'a + IntoIterator<Item = (&'a Anchor, T)>,
1841    {
1842        let anchors = anchors.into_iter();
1843        let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>();
1844        let mut fragment_cursor = self.fragments.cursor::<(Option<&Locator>, usize)>();
1845        let mut text_cursor = self.visible_text.cursor(0);
1846        let mut position = D::default();
1847
1848        anchors.map(move |(anchor, payload)| {
1849            if *anchor == Anchor::MIN {
1850                return (D::default(), payload);
1851            } else if *anchor == Anchor::MAX {
1852                return (D::from_text_summary(&self.visible_text.summary()), payload);
1853            }
1854
1855            let anchor_key = InsertionFragmentKey {
1856                timestamp: anchor.timestamp,
1857                split_offset: anchor.offset,
1858            };
1859            insertion_cursor.seek(&anchor_key, anchor.bias, &());
1860            if let Some(insertion) = insertion_cursor.item() {
1861                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
1862                if comparison == Ordering::Greater
1863                    || (anchor.bias == Bias::Left
1864                        && comparison == Ordering::Equal
1865                        && anchor.offset > 0)
1866                {
1867                    insertion_cursor.prev(&());
1868                }
1869            } else {
1870                insertion_cursor.prev(&());
1871            }
1872            let insertion = insertion_cursor.item().expect("invalid insertion");
1873            assert_eq!(insertion.timestamp, anchor.timestamp, "invalid insertion");
1874
1875            fragment_cursor.seek_forward(&Some(&insertion.fragment_id), Bias::Left, &None);
1876            let fragment = fragment_cursor.item().unwrap();
1877            let mut fragment_offset = fragment_cursor.start().1;
1878            if fragment.visible {
1879                fragment_offset += anchor.offset - insertion.split_offset;
1880            }
1881
1882            position.add_assign(&text_cursor.summary(fragment_offset));
1883            (position.clone(), payload)
1884        })
1885    }
1886
1887    fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1888    where
1889        D: TextDimension,
1890    {
1891        if *anchor == Anchor::MIN {
1892            D::default()
1893        } else if *anchor == Anchor::MAX {
1894            D::from_text_summary(&self.visible_text.summary())
1895        } else {
1896            let anchor_key = InsertionFragmentKey {
1897                timestamp: anchor.timestamp,
1898                split_offset: anchor.offset,
1899            };
1900            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>();
1901            insertion_cursor.seek(&anchor_key, anchor.bias, &());
1902            if let Some(insertion) = insertion_cursor.item() {
1903                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
1904                if comparison == Ordering::Greater
1905                    || (anchor.bias == Bias::Left
1906                        && comparison == Ordering::Equal
1907                        && anchor.offset > 0)
1908                {
1909                    insertion_cursor.prev(&());
1910                }
1911            } else {
1912                insertion_cursor.prev(&());
1913            }
1914
1915            let Some(insertion) = insertion_cursor
1916                .item()
1917                .filter(|insertion| insertion.timestamp == anchor.timestamp)
1918            else {
1919                panic!(
1920                    "invalid anchor {:?}. buffer id: {}, version: {:?}",
1921                    anchor, self.remote_id, self.version
1922                );
1923            };
1924
1925            let mut fragment_cursor = self.fragments.cursor::<(Option<&Locator>, usize)>();
1926            fragment_cursor.seek(&Some(&insertion.fragment_id), Bias::Left, &None);
1927            let fragment = fragment_cursor.item().unwrap();
1928            let mut fragment_offset = fragment_cursor.start().1;
1929            if fragment.visible {
1930                fragment_offset += anchor.offset - insertion.split_offset;
1931            }
1932            self.text_summary_for_range(0..fragment_offset)
1933        }
1934    }
1935
1936    fn fragment_id_for_anchor(&self, anchor: &Anchor) -> &Locator {
1937        if *anchor == Anchor::MIN {
1938            Locator::min_ref()
1939        } else if *anchor == Anchor::MAX {
1940            Locator::max_ref()
1941        } else {
1942            let anchor_key = InsertionFragmentKey {
1943                timestamp: anchor.timestamp,
1944                split_offset: anchor.offset,
1945            };
1946            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>();
1947            insertion_cursor.seek(&anchor_key, anchor.bias, &());
1948            if let Some(insertion) = insertion_cursor.item() {
1949                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
1950                if comparison == Ordering::Greater
1951                    || (anchor.bias == Bias::Left
1952                        && comparison == Ordering::Equal
1953                        && anchor.offset > 0)
1954                {
1955                    insertion_cursor.prev(&());
1956                }
1957            } else {
1958                insertion_cursor.prev(&());
1959            }
1960
1961            let Some(insertion) = insertion_cursor.item().filter(|insertion| {
1962                if cfg!(debug_assertions) {
1963                    insertion.timestamp == anchor.timestamp
1964                } else {
1965                    true
1966                }
1967            }) else {
1968                panic!(
1969                    "invalid anchor {:?}. buffer id: {}, version: {:?}",
1970                    anchor, self.remote_id, self.version
1971                );
1972            };
1973
1974            &insertion.fragment_id
1975        }
1976    }
1977
1978    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1979        self.anchor_at(position, Bias::Left)
1980    }
1981
1982    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1983        self.anchor_at(position, Bias::Right)
1984    }
1985
1986    pub fn anchor_at<T: ToOffset>(&self, position: T, bias: Bias) -> Anchor {
1987        self.anchor_at_offset(position.to_offset(self), bias)
1988    }
1989
1990    fn anchor_at_offset(&self, offset: usize, bias: Bias) -> Anchor {
1991        if bias == Bias::Left && offset == 0 {
1992            Anchor::MIN
1993        } else if bias == Bias::Right && offset == self.len() {
1994            Anchor::MAX
1995        } else {
1996            let mut fragment_cursor = self.fragments.cursor::<usize>();
1997            fragment_cursor.seek(&offset, bias, &None);
1998            let fragment = fragment_cursor.item().unwrap();
1999            let overshoot = offset - *fragment_cursor.start();
2000            Anchor {
2001                timestamp: fragment.timestamp,
2002                offset: fragment.insertion_offset + overshoot,
2003                bias,
2004                buffer_id: Some(self.remote_id),
2005            }
2006        }
2007    }
2008
2009    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2010        *anchor == Anchor::MIN
2011            || *anchor == Anchor::MAX
2012            || (Some(self.remote_id) == anchor.buffer_id && self.version.observed(anchor.timestamp))
2013    }
2014
2015    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2016        self.visible_text.clip_offset(offset, bias)
2017    }
2018
2019    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2020        self.visible_text.clip_point(point, bias)
2021    }
2022
2023    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2024        self.visible_text.clip_offset_utf16(offset, bias)
2025    }
2026
2027    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2028        self.visible_text.clip_point_utf16(point, bias)
2029    }
2030
2031    pub fn edits_since<'a, D>(
2032        &'a self,
2033        since: &'a clock::Global,
2034    ) -> impl 'a + Iterator<Item = Edit<D>>
2035    where
2036        D: TextDimension + Ord,
2037    {
2038        self.edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2039    }
2040
2041    pub fn anchored_edits_since<'a, D>(
2042        &'a self,
2043        since: &'a clock::Global,
2044    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2045    where
2046        D: TextDimension + Ord,
2047    {
2048        self.anchored_edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2049    }
2050
2051    pub fn edits_since_in_range<'a, D>(
2052        &'a self,
2053        since: &'a clock::Global,
2054        range: Range<Anchor>,
2055    ) -> impl 'a + Iterator<Item = Edit<D>>
2056    where
2057        D: TextDimension + Ord,
2058    {
2059        self.anchored_edits_since_in_range(since, range)
2060            .map(|item| item.0)
2061    }
2062
2063    pub fn anchored_edits_since_in_range<'a, D>(
2064        &'a self,
2065        since: &'a clock::Global,
2066        range: Range<Anchor>,
2067    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2068    where
2069        D: TextDimension + Ord,
2070    {
2071        let fragments_cursor = if *since == self.version {
2072            None
2073        } else {
2074            let mut cursor = self
2075                .fragments
2076                .filter(move |summary| !since.observed_all(&summary.max_version));
2077            cursor.next(&None);
2078            Some(cursor)
2079        };
2080        let mut cursor = self
2081            .fragments
2082            .cursor::<(Option<&Locator>, FragmentTextSummary)>();
2083
2084        let start_fragment_id = self.fragment_id_for_anchor(&range.start);
2085        cursor.seek(&Some(start_fragment_id), Bias::Left, &None);
2086        let mut visible_start = cursor.start().1.visible;
2087        let mut deleted_start = cursor.start().1.deleted;
2088        if let Some(fragment) = cursor.item() {
2089            let overshoot = range.start.offset - fragment.insertion_offset;
2090            if fragment.visible {
2091                visible_start += overshoot;
2092            } else {
2093                deleted_start += overshoot;
2094            }
2095        }
2096        let end_fragment_id = self.fragment_id_for_anchor(&range.end);
2097
2098        Edits {
2099            visible_cursor: self.visible_text.cursor(visible_start),
2100            deleted_cursor: self.deleted_text.cursor(deleted_start),
2101            fragments_cursor,
2102            undos: &self.undo_map,
2103            since,
2104            old_end: Default::default(),
2105            new_end: Default::default(),
2106            range: (start_fragment_id, range.start.offset)..(end_fragment_id, range.end.offset),
2107            buffer_id: self.remote_id,
2108        }
2109    }
2110}
2111
2112struct RopeBuilder<'a> {
2113    old_visible_cursor: rope::Cursor<'a>,
2114    old_deleted_cursor: rope::Cursor<'a>,
2115    new_visible: Rope,
2116    new_deleted: Rope,
2117}
2118
2119impl<'a> RopeBuilder<'a> {
2120    fn new(old_visible_cursor: rope::Cursor<'a>, old_deleted_cursor: rope::Cursor<'a>) -> Self {
2121        Self {
2122            old_visible_cursor,
2123            old_deleted_cursor,
2124            new_visible: Rope::new(),
2125            new_deleted: Rope::new(),
2126        }
2127    }
2128
2129    fn append(&mut self, len: FragmentTextSummary) {
2130        self.push(len.visible, true, true);
2131        self.push(len.deleted, false, false);
2132    }
2133
2134    fn push_fragment(&mut self, fragment: &Fragment, was_visible: bool) {
2135        debug_assert!(fragment.len > 0);
2136        self.push(fragment.len, was_visible, fragment.visible)
2137    }
2138
2139    fn push(&mut self, len: usize, was_visible: bool, is_visible: bool) {
2140        let text = if was_visible {
2141            self.old_visible_cursor
2142                .slice(self.old_visible_cursor.offset() + len)
2143        } else {
2144            self.old_deleted_cursor
2145                .slice(self.old_deleted_cursor.offset() + len)
2146        };
2147        if is_visible {
2148            self.new_visible.append(text);
2149        } else {
2150            self.new_deleted.append(text);
2151        }
2152    }
2153
2154    fn push_str(&mut self, text: &str) {
2155        self.new_visible.push(text);
2156    }
2157
2158    fn finish(mut self) -> (Rope, Rope) {
2159        self.new_visible.append(self.old_visible_cursor.suffix());
2160        self.new_deleted.append(self.old_deleted_cursor.suffix());
2161        (self.new_visible, self.new_deleted)
2162    }
2163}
2164
2165impl<'a, D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator for Edits<'a, D, F> {
2166    type Item = (Edit<D>, Range<Anchor>);
2167
2168    fn next(&mut self) -> Option<Self::Item> {
2169        let mut pending_edit: Option<Self::Item> = None;
2170        let cursor = self.fragments_cursor.as_mut()?;
2171
2172        while let Some(fragment) = cursor.item() {
2173            if fragment.id < *self.range.start.0 {
2174                cursor.next(&None);
2175                continue;
2176            } else if fragment.id > *self.range.end.0 {
2177                break;
2178            }
2179
2180            if cursor.start().visible > self.visible_cursor.offset() {
2181                let summary = self.visible_cursor.summary(cursor.start().visible);
2182                self.old_end.add_assign(&summary);
2183                self.new_end.add_assign(&summary);
2184            }
2185
2186            if pending_edit
2187                .as_ref()
2188                .map_or(false, |(change, _)| change.new.end < self.new_end)
2189            {
2190                break;
2191            }
2192
2193            let start_anchor = Anchor {
2194                timestamp: fragment.timestamp,
2195                offset: fragment.insertion_offset,
2196                bias: Bias::Right,
2197                buffer_id: Some(self.buffer_id),
2198            };
2199            let end_anchor = Anchor {
2200                timestamp: fragment.timestamp,
2201                offset: fragment.insertion_offset + fragment.len,
2202                bias: Bias::Left,
2203                buffer_id: Some(self.buffer_id),
2204            };
2205
2206            if !fragment.was_visible(self.since, self.undos) && fragment.visible {
2207                let mut visible_end = cursor.end(&None).visible;
2208                if fragment.id == *self.range.end.0 {
2209                    visible_end = cmp::min(
2210                        visible_end,
2211                        cursor.start().visible + (self.range.end.1 - fragment.insertion_offset),
2212                    );
2213                }
2214
2215                let fragment_summary = self.visible_cursor.summary(visible_end);
2216                let mut new_end = self.new_end.clone();
2217                new_end.add_assign(&fragment_summary);
2218                if let Some((edit, range)) = pending_edit.as_mut() {
2219                    edit.new.end = new_end.clone();
2220                    range.end = end_anchor;
2221                } else {
2222                    pending_edit = Some((
2223                        Edit {
2224                            old: self.old_end.clone()..self.old_end.clone(),
2225                            new: self.new_end.clone()..new_end.clone(),
2226                        },
2227                        start_anchor..end_anchor,
2228                    ));
2229                }
2230
2231                self.new_end = new_end;
2232            } else if fragment.was_visible(self.since, self.undos) && !fragment.visible {
2233                let mut deleted_end = cursor.end(&None).deleted;
2234                if fragment.id == *self.range.end.0 {
2235                    deleted_end = cmp::min(
2236                        deleted_end,
2237                        cursor.start().deleted + (self.range.end.1 - fragment.insertion_offset),
2238                    );
2239                }
2240
2241                if cursor.start().deleted > self.deleted_cursor.offset() {
2242                    self.deleted_cursor.seek_forward(cursor.start().deleted);
2243                }
2244                let fragment_summary = self.deleted_cursor.summary(deleted_end);
2245                let mut old_end = self.old_end.clone();
2246                old_end.add_assign(&fragment_summary);
2247                if let Some((edit, range)) = pending_edit.as_mut() {
2248                    edit.old.end = old_end.clone();
2249                    range.end = end_anchor;
2250                } else {
2251                    pending_edit = Some((
2252                        Edit {
2253                            old: self.old_end.clone()..old_end.clone(),
2254                            new: self.new_end.clone()..self.new_end.clone(),
2255                        },
2256                        start_anchor..end_anchor,
2257                    ));
2258                }
2259
2260                self.old_end = old_end;
2261            }
2262
2263            cursor.next(&None);
2264        }
2265
2266        pending_edit
2267    }
2268}
2269
2270impl Fragment {
2271    fn insertion_slice(&self) -> InsertionSlice {
2272        InsertionSlice {
2273            insertion_id: self.timestamp,
2274            range: self.insertion_offset..self.insertion_offset + self.len,
2275        }
2276    }
2277
2278    fn is_visible(&self, undos: &UndoMap) -> bool {
2279        !undos.is_undone(self.timestamp) && self.deletions.iter().all(|d| undos.is_undone(*d))
2280    }
2281
2282    fn was_visible(&self, version: &clock::Global, undos: &UndoMap) -> bool {
2283        (version.observed(self.timestamp) && !undos.was_undone(self.timestamp, version))
2284            && self
2285                .deletions
2286                .iter()
2287                .all(|d| !version.observed(*d) || undos.was_undone(*d, version))
2288    }
2289}
2290
2291impl sum_tree::Item for Fragment {
2292    type Summary = FragmentSummary;
2293
2294    fn summary(&self) -> Self::Summary {
2295        let mut max_version = clock::Global::new();
2296        max_version.observe(self.timestamp);
2297        for deletion in &self.deletions {
2298            max_version.observe(*deletion);
2299        }
2300        max_version.join(&self.max_undos);
2301
2302        let mut min_insertion_version = clock::Global::new();
2303        min_insertion_version.observe(self.timestamp);
2304        let max_insertion_version = min_insertion_version.clone();
2305        if self.visible {
2306            FragmentSummary {
2307                max_id: self.id.clone(),
2308                text: FragmentTextSummary {
2309                    visible: self.len,
2310                    deleted: 0,
2311                },
2312                max_version,
2313                min_insertion_version,
2314                max_insertion_version,
2315            }
2316        } else {
2317            FragmentSummary {
2318                max_id: self.id.clone(),
2319                text: FragmentTextSummary {
2320                    visible: 0,
2321                    deleted: self.len,
2322                },
2323                max_version,
2324                min_insertion_version,
2325                max_insertion_version,
2326            }
2327        }
2328    }
2329}
2330
2331impl sum_tree::Summary for FragmentSummary {
2332    type Context = Option<clock::Global>;
2333
2334    fn add_summary(&mut self, other: &Self, _: &Self::Context) {
2335        self.max_id.assign(&other.max_id);
2336        self.text.visible += &other.text.visible;
2337        self.text.deleted += &other.text.deleted;
2338        self.max_version.join(&other.max_version);
2339        self.min_insertion_version
2340            .meet(&other.min_insertion_version);
2341        self.max_insertion_version
2342            .join(&other.max_insertion_version);
2343    }
2344}
2345
2346impl Default for FragmentSummary {
2347    fn default() -> Self {
2348        FragmentSummary {
2349            max_id: Locator::min(),
2350            text: FragmentTextSummary::default(),
2351            max_version: clock::Global::new(),
2352            min_insertion_version: clock::Global::new(),
2353            max_insertion_version: clock::Global::new(),
2354        }
2355    }
2356}
2357
2358impl sum_tree::Item for InsertionFragment {
2359    type Summary = InsertionFragmentKey;
2360
2361    fn summary(&self) -> Self::Summary {
2362        InsertionFragmentKey {
2363            timestamp: self.timestamp,
2364            split_offset: self.split_offset,
2365        }
2366    }
2367}
2368
2369impl sum_tree::KeyedItem for InsertionFragment {
2370    type Key = InsertionFragmentKey;
2371
2372    fn key(&self) -> Self::Key {
2373        sum_tree::Item::summary(self)
2374    }
2375}
2376
2377impl InsertionFragment {
2378    fn new(fragment: &Fragment) -> Self {
2379        Self {
2380            timestamp: fragment.timestamp,
2381            split_offset: fragment.insertion_offset,
2382            fragment_id: fragment.id.clone(),
2383        }
2384    }
2385
2386    fn insert_new(fragment: &Fragment) -> sum_tree::Edit<Self> {
2387        sum_tree::Edit::Insert(Self::new(fragment))
2388    }
2389}
2390
2391impl sum_tree::Summary for InsertionFragmentKey {
2392    type Context = ();
2393
2394    fn add_summary(&mut self, summary: &Self, _: &()) {
2395        *self = *summary;
2396    }
2397}
2398
2399#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
2400pub struct FullOffset(pub usize);
2401
2402impl ops::AddAssign<usize> for FullOffset {
2403    fn add_assign(&mut self, rhs: usize) {
2404        self.0 += rhs;
2405    }
2406}
2407
2408impl ops::Add<usize> for FullOffset {
2409    type Output = Self;
2410
2411    fn add(mut self, rhs: usize) -> Self::Output {
2412        self += rhs;
2413        self
2414    }
2415}
2416
2417impl ops::Sub for FullOffset {
2418    type Output = usize;
2419
2420    fn sub(self, rhs: Self) -> Self::Output {
2421        self.0 - rhs.0
2422    }
2423}
2424
2425impl<'a> sum_tree::Dimension<'a, FragmentSummary> for usize {
2426    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2427        *self += summary.text.visible;
2428    }
2429}
2430
2431impl<'a> sum_tree::Dimension<'a, FragmentSummary> for FullOffset {
2432    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2433        self.0 += summary.text.visible + summary.text.deleted;
2434    }
2435}
2436
2437impl<'a> sum_tree::Dimension<'a, FragmentSummary> for Option<&'a Locator> {
2438    fn add_summary(&mut self, summary: &'a FragmentSummary, _: &Option<clock::Global>) {
2439        *self = Some(&summary.max_id);
2440    }
2441}
2442
2443impl<'a> sum_tree::SeekTarget<'a, FragmentSummary, FragmentTextSummary> for usize {
2444    fn cmp(
2445        &self,
2446        cursor_location: &FragmentTextSummary,
2447        _: &Option<clock::Global>,
2448    ) -> cmp::Ordering {
2449        Ord::cmp(self, &cursor_location.visible)
2450    }
2451}
2452
2453#[derive(Copy, Clone, Debug, Eq, PartialEq)]
2454enum VersionedFullOffset {
2455    Offset(FullOffset),
2456    Invalid,
2457}
2458
2459impl VersionedFullOffset {
2460    fn full_offset(&self) -> FullOffset {
2461        if let Self::Offset(position) = self {
2462            *position
2463        } else {
2464            panic!("invalid version")
2465        }
2466    }
2467}
2468
2469impl Default for VersionedFullOffset {
2470    fn default() -> Self {
2471        Self::Offset(Default::default())
2472    }
2473}
2474
2475impl<'a> sum_tree::Dimension<'a, FragmentSummary> for VersionedFullOffset {
2476    fn add_summary(&mut self, summary: &'a FragmentSummary, cx: &Option<clock::Global>) {
2477        if let Self::Offset(offset) = self {
2478            let version = cx.as_ref().unwrap();
2479            if version.observed_all(&summary.max_insertion_version) {
2480                *offset += summary.text.visible + summary.text.deleted;
2481            } else if version.observed_any(&summary.min_insertion_version) {
2482                *self = Self::Invalid;
2483            }
2484        }
2485    }
2486}
2487
2488impl<'a> sum_tree::SeekTarget<'a, FragmentSummary, Self> for VersionedFullOffset {
2489    fn cmp(&self, cursor_position: &Self, _: &Option<clock::Global>) -> cmp::Ordering {
2490        match (self, cursor_position) {
2491            (Self::Offset(a), Self::Offset(b)) => Ord::cmp(a, b),
2492            (Self::Offset(_), Self::Invalid) => cmp::Ordering::Less,
2493            (Self::Invalid, _) => unreachable!(),
2494        }
2495    }
2496}
2497
2498impl Operation {
2499    fn replica_id(&self) -> ReplicaId {
2500        operation_queue::Operation::lamport_timestamp(self).replica_id
2501    }
2502
2503    pub fn timestamp(&self) -> clock::Lamport {
2504        match self {
2505            Operation::Edit(edit) => edit.timestamp,
2506            Operation::Undo(undo) => undo.timestamp,
2507        }
2508    }
2509
2510    pub fn as_edit(&self) -> Option<&EditOperation> {
2511        match self {
2512            Operation::Edit(edit) => Some(edit),
2513            _ => None,
2514        }
2515    }
2516
2517    pub fn is_edit(&self) -> bool {
2518        matches!(self, Operation::Edit { .. })
2519    }
2520}
2521
2522impl operation_queue::Operation for Operation {
2523    fn lamport_timestamp(&self) -> clock::Lamport {
2524        match self {
2525            Operation::Edit(edit) => edit.timestamp,
2526            Operation::Undo(undo) => undo.timestamp,
2527        }
2528    }
2529}
2530
2531pub trait ToOffset {
2532    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize;
2533}
2534
2535impl ToOffset for Point {
2536    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
2537        snapshot.point_to_offset(*self)
2538    }
2539}
2540
2541impl ToOffset for usize {
2542    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
2543        assert!(
2544            *self <= snapshot.len(),
2545            "offset {} is out of range, max allowed is {}",
2546            self,
2547            snapshot.len()
2548        );
2549        *self
2550    }
2551}
2552
2553impl ToOffset for Anchor {
2554    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
2555        snapshot.summary_for_anchor(self)
2556    }
2557}
2558
2559impl<'a, T: ToOffset> ToOffset for &'a T {
2560    fn to_offset(&self, content: &BufferSnapshot) -> usize {
2561        (*self).to_offset(content)
2562    }
2563}
2564
2565impl ToOffset for PointUtf16 {
2566    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
2567        snapshot.point_utf16_to_offset(*self)
2568    }
2569}
2570
2571impl ToOffset for Unclipped<PointUtf16> {
2572    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
2573        snapshot.unclipped_point_utf16_to_offset(*self)
2574    }
2575}
2576
2577pub trait ToPoint {
2578    fn to_point(&self, snapshot: &BufferSnapshot) -> Point;
2579}
2580
2581impl ToPoint for Anchor {
2582    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
2583        snapshot.summary_for_anchor(self)
2584    }
2585}
2586
2587impl ToPoint for usize {
2588    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
2589        snapshot.offset_to_point(*self)
2590    }
2591}
2592
2593impl ToPoint for Point {
2594    fn to_point(&self, _: &BufferSnapshot) -> Point {
2595        *self
2596    }
2597}
2598
2599impl ToPoint for Unclipped<PointUtf16> {
2600    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
2601        snapshot.unclipped_point_utf16_to_point(*self)
2602    }
2603}
2604
2605pub trait ToPointUtf16 {
2606    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16;
2607}
2608
2609impl ToPointUtf16 for Anchor {
2610    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
2611        snapshot.summary_for_anchor(self)
2612    }
2613}
2614
2615impl ToPointUtf16 for usize {
2616    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
2617        snapshot.offset_to_point_utf16(*self)
2618    }
2619}
2620
2621impl ToPointUtf16 for PointUtf16 {
2622    fn to_point_utf16(&self, _: &BufferSnapshot) -> PointUtf16 {
2623        *self
2624    }
2625}
2626
2627impl ToPointUtf16 for Point {
2628    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
2629        snapshot.point_to_point_utf16(*self)
2630    }
2631}
2632
2633pub trait ToOffsetUtf16 {
2634    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16;
2635}
2636
2637impl ToOffsetUtf16 for Anchor {
2638    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
2639        snapshot.summary_for_anchor(self)
2640    }
2641}
2642
2643impl ToOffsetUtf16 for usize {
2644    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
2645        snapshot.offset_to_offset_utf16(*self)
2646    }
2647}
2648
2649impl ToOffsetUtf16 for OffsetUtf16 {
2650    fn to_offset_utf16(&self, _snapshot: &BufferSnapshot) -> OffsetUtf16 {
2651        *self
2652    }
2653}
2654
2655pub trait FromAnchor {
2656    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self;
2657}
2658
2659impl FromAnchor for Point {
2660    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
2661        snapshot.summary_for_anchor(anchor)
2662    }
2663}
2664
2665impl FromAnchor for PointUtf16 {
2666    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
2667        snapshot.summary_for_anchor(anchor)
2668    }
2669}
2670
2671impl FromAnchor for usize {
2672    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
2673        snapshot.summary_for_anchor(anchor)
2674    }
2675}
2676
2677#[derive(Clone, Copy, Debug, PartialEq)]
2678pub enum LineEnding {
2679    Unix,
2680    Windows,
2681}
2682
2683impl Default for LineEnding {
2684    fn default() -> Self {
2685        #[cfg(unix)]
2686        return Self::Unix;
2687
2688        #[cfg(not(unix))]
2689        return Self::Windows;
2690    }
2691}
2692
2693impl LineEnding {
2694    pub fn as_str(&self) -> &'static str {
2695        match self {
2696            LineEnding::Unix => "\n",
2697            LineEnding::Windows => "\r\n",
2698        }
2699    }
2700
2701    pub fn detect(text: &str) -> Self {
2702        let mut max_ix = cmp::min(text.len(), 1000);
2703        while !text.is_char_boundary(max_ix) {
2704            max_ix -= 1;
2705        }
2706
2707        if let Some(ix) = text[..max_ix].find(['\n']) {
2708            if ix > 0 && text.as_bytes()[ix - 1] == b'\r' {
2709                Self::Windows
2710            } else {
2711                Self::Unix
2712            }
2713        } else {
2714            Self::default()
2715        }
2716    }
2717
2718    pub fn normalize(text: &mut String) {
2719        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(text, "\n") {
2720            *text = replaced;
2721        }
2722    }
2723
2724    pub fn normalize_arc(text: Arc<str>) -> Arc<str> {
2725        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(&text, "\n") {
2726            replaced.into()
2727        } else {
2728            text
2729        }
2730    }
2731}