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::{Context as _, Result};
  15use clock::LOCAL_BRANCH_REPLICA_ID;
  16pub use clock::ReplicaId;
  17use collections::{HashMap, HashSet};
  18use locator::Locator;
  19use operation_queue::OperationQueue;
  20pub use patch::Patch;
  21use postage::{oneshot, prelude::*};
  22
  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, LazyLock},
  36    time::{Duration, Instant},
  37};
  38pub use subscription::*;
  39pub use sum_tree::Bias;
  40use sum_tree::{FilterCursor, SumTree, TreeMap, TreeSet};
  41use undo_map::UndoMap;
  42
  43#[cfg(any(test, feature = "test-support"))]
  44use util::RandomCharIter;
  45
  46static LINE_SEPARATORS_REGEX: LazyLock<Regex> =
  47    LazyLock::new(|| Regex::new(r"\r\n|\r").expect("Failed to create LINE_SEPARATORS_REGEX"));
  48
  49pub type TransactionId = clock::Lamport;
  50
  51pub struct Buffer {
  52    snapshot: BufferSnapshot,
  53    history: History,
  54    deferred_ops: OperationQueue<Operation>,
  55    deferred_replicas: HashSet<ReplicaId>,
  56    pub lamport_clock: clock::Lamport,
  57    subscriptions: Topic,
  58    edit_id_resolvers: HashMap<clock::Lamport, Vec<oneshot::Sender<()>>>,
  59    wait_for_version_txs: Vec<(clock::Global, oneshot::Sender<()>)>,
  60}
  61
  62#[repr(transparent)]
  63#[derive(Clone, Copy, Debug, Hash, PartialEq, PartialOrd, Ord, Eq)]
  64pub struct BufferId(NonZeroU64);
  65
  66impl Display for BufferId {
  67    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  68        write!(f, "{}", self.0)
  69    }
  70}
  71
  72impl From<NonZeroU64> for BufferId {
  73    fn from(id: NonZeroU64) -> Self {
  74        BufferId(id)
  75    }
  76}
  77
  78impl BufferId {
  79    /// Returns Err if `id` is outside of BufferId domain.
  80    pub fn new(id: u64) -> anyhow::Result<Self> {
  81        let id = NonZeroU64::new(id).context("Buffer id cannot be 0.")?;
  82        Ok(Self(id))
  83    }
  84
  85    /// Increments this buffer id, returning the old value.
  86    /// So that's a post-increment operator in disguise.
  87    pub fn next(&mut self) -> Self {
  88        let old = *self;
  89        self.0 = self.0.saturating_add(1);
  90        old
  91    }
  92
  93    pub fn to_proto(self) -> u64 {
  94        self.into()
  95    }
  96}
  97
  98impl From<BufferId> for u64 {
  99    fn from(id: BufferId) -> Self {
 100        id.0.get()
 101    }
 102}
 103
 104#[derive(Clone)]
 105pub struct BufferSnapshot {
 106    replica_id: ReplicaId,
 107    remote_id: BufferId,
 108    visible_text: Rope,
 109    deleted_text: Rope,
 110    line_ending: LineEnding,
 111    undo_map: UndoMap,
 112    fragments: SumTree<Fragment>,
 113    insertions: SumTree<InsertionFragment>,
 114    insertion_slices: TreeSet<InsertionSlice>,
 115    pub version: clock::Global,
 116}
 117
 118#[derive(Clone, Debug)]
 119pub struct HistoryEntry {
 120    transaction: Transaction,
 121    first_edit_at: Instant,
 122    last_edit_at: Instant,
 123    suppress_grouping: bool,
 124}
 125
 126#[derive(Clone, Debug)]
 127pub struct Transaction {
 128    pub id: TransactionId,
 129    pub edit_ids: Vec<clock::Lamport>,
 130    pub start: clock::Global,
 131}
 132
 133impl Transaction {
 134    pub fn merge_in(&mut self, other: Transaction) {
 135        self.edit_ids.extend(other.edit_ids);
 136    }
 137}
 138
 139impl HistoryEntry {
 140    pub fn transaction_id(&self) -> TransactionId {
 141        self.transaction.id
 142    }
 143}
 144
 145struct History {
 146    base_text: Rope,
 147    operations: TreeMap<clock::Lamport, Operation>,
 148    undo_stack: Vec<HistoryEntry>,
 149    redo_stack: Vec<HistoryEntry>,
 150    transaction_depth: usize,
 151    group_interval: Duration,
 152}
 153
 154#[derive(Clone, Debug, Eq, PartialEq)]
 155struct InsertionSlice {
 156    edit_id: clock::Lamport,
 157    insertion_id: clock::Lamport,
 158    range: Range<usize>,
 159}
 160
 161impl Ord for InsertionSlice {
 162    fn cmp(&self, other: &Self) -> Ordering {
 163        self.edit_id
 164            .cmp(&other.edit_id)
 165            .then_with(|| self.insertion_id.cmp(&other.insertion_id))
 166            .then_with(|| self.range.start.cmp(&other.range.start))
 167            .then_with(|| self.range.end.cmp(&other.range.end))
 168    }
 169}
 170
 171impl PartialOrd for InsertionSlice {
 172    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
 173        Some(self.cmp(other))
 174    }
 175}
 176
 177impl InsertionSlice {
 178    fn from_fragment(edit_id: clock::Lamport, fragment: &Fragment) -> Self {
 179        Self {
 180            edit_id,
 181            insertion_id: fragment.timestamp,
 182            range: fragment.insertion_offset..fragment.insertion_offset + fragment.len,
 183        }
 184    }
 185}
 186
 187impl History {
 188    pub fn new(base_text: Rope) -> Self {
 189        Self {
 190            base_text,
 191            operations: Default::default(),
 192            undo_stack: Vec::new(),
 193            redo_stack: Vec::new(),
 194            transaction_depth: 0,
 195            // Don't group transactions in tests unless we opt in, because it's a footgun.
 196            #[cfg(any(test, feature = "test-support"))]
 197            group_interval: Duration::ZERO,
 198            #[cfg(not(any(test, feature = "test-support")))]
 199            group_interval: Duration::from_millis(300),
 200        }
 201    }
 202
 203    fn push(&mut self, op: Operation) {
 204        self.operations.insert(op.timestamp(), op);
 205    }
 206
 207    fn start_transaction(
 208        &mut self,
 209        start: clock::Global,
 210        now: Instant,
 211        clock: &mut clock::Lamport,
 212    ) -> Option<TransactionId> {
 213        self.transaction_depth += 1;
 214        if self.transaction_depth == 1 {
 215            let id = clock.tick();
 216            self.undo_stack.push(HistoryEntry {
 217                transaction: Transaction {
 218                    id,
 219                    start,
 220                    edit_ids: Default::default(),
 221                },
 222                first_edit_at: now,
 223                last_edit_at: now,
 224                suppress_grouping: false,
 225            });
 226            Some(id)
 227        } else {
 228            None
 229        }
 230    }
 231
 232    fn end_transaction(&mut self, now: Instant) -> Option<&HistoryEntry> {
 233        assert_ne!(self.transaction_depth, 0);
 234        self.transaction_depth -= 1;
 235        if self.transaction_depth == 0 {
 236            if self
 237                .undo_stack
 238                .last()
 239                .unwrap()
 240                .transaction
 241                .edit_ids
 242                .is_empty()
 243            {
 244                self.undo_stack.pop();
 245                None
 246            } else {
 247                self.redo_stack.clear();
 248                let entry = self.undo_stack.last_mut().unwrap();
 249                entry.last_edit_at = now;
 250                Some(entry)
 251            }
 252        } else {
 253            None
 254        }
 255    }
 256
 257    fn group(&mut self) -> Option<TransactionId> {
 258        let mut count = 0;
 259        let mut entries = self.undo_stack.iter();
 260        if let Some(mut entry) = entries.next_back() {
 261            while let Some(prev_entry) = entries.next_back() {
 262                if !prev_entry.suppress_grouping
 263                    && entry.first_edit_at - prev_entry.last_edit_at < self.group_interval
 264                {
 265                    entry = prev_entry;
 266                    count += 1;
 267                } else {
 268                    break;
 269                }
 270            }
 271        }
 272        self.group_trailing(count)
 273    }
 274
 275    fn group_until(&mut self, transaction_id: TransactionId) {
 276        let mut count = 0;
 277        for entry in self.undo_stack.iter().rev() {
 278            if entry.transaction_id() == transaction_id {
 279                self.group_trailing(count);
 280                break;
 281            } else if entry.suppress_grouping {
 282                break;
 283            } else {
 284                count += 1;
 285            }
 286        }
 287    }
 288
 289    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
 290        let new_len = self.undo_stack.len() - n;
 291        let (entries_to_keep, entries_to_merge) = self.undo_stack.split_at_mut(new_len);
 292        if let Some(last_entry) = entries_to_keep.last_mut() {
 293            for entry in &*entries_to_merge {
 294                for edit_id in &entry.transaction.edit_ids {
 295                    last_entry.transaction.edit_ids.push(*edit_id);
 296                }
 297            }
 298
 299            if let Some(entry) = entries_to_merge.last_mut() {
 300                last_entry.last_edit_at = entry.last_edit_at;
 301            }
 302        }
 303
 304        self.undo_stack.truncate(new_len);
 305        self.undo_stack.last().map(|e| e.transaction.id)
 306    }
 307
 308    fn finalize_last_transaction(&mut self) -> Option<&Transaction> {
 309        self.undo_stack.last_mut().map(|entry| {
 310            entry.suppress_grouping = true;
 311            &entry.transaction
 312        })
 313    }
 314
 315    fn push_transaction(&mut self, transaction: Transaction, now: Instant) {
 316        assert_eq!(self.transaction_depth, 0);
 317        self.undo_stack.push(HistoryEntry {
 318            transaction,
 319            first_edit_at: now,
 320            last_edit_at: now,
 321            suppress_grouping: false,
 322        });
 323    }
 324
 325    /// Differs from `push_transaction` in that it does not clear the redo
 326    /// stack. Intended to be used to create a parent transaction to merge
 327    /// potential child transactions into.
 328    ///
 329    /// The caller is responsible for removing it from the undo history using
 330    /// `forget_transaction` if no edits are merged into it. Otherwise, if edits
 331    /// are merged into this transaction, the caller is responsible for ensuring
 332    /// the redo stack is cleared. The easiest way to ensure the redo stack is
 333    /// cleared is to create transactions with the usual `start_transaction` and
 334    /// `end_transaction` methods and merging the resulting transactions into
 335    /// the transaction created by this method
 336    fn push_empty_transaction(
 337        &mut self,
 338        start: clock::Global,
 339        now: Instant,
 340        clock: &mut clock::Lamport,
 341    ) -> TransactionId {
 342        assert_eq!(self.transaction_depth, 0);
 343        let id = clock.tick();
 344        let transaction = Transaction {
 345            id,
 346            start,
 347            edit_ids: Vec::new(),
 348        };
 349        self.undo_stack.push(HistoryEntry {
 350            transaction,
 351            first_edit_at: now,
 352            last_edit_at: now,
 353            suppress_grouping: false,
 354        });
 355        id
 356    }
 357
 358    fn push_undo(&mut self, op_id: clock::Lamport) {
 359        assert_ne!(self.transaction_depth, 0);
 360        if let Some(Operation::Edit(_)) = self.operations.get(&op_id) {
 361            let last_transaction = self.undo_stack.last_mut().unwrap();
 362            last_transaction.transaction.edit_ids.push(op_id);
 363        }
 364    }
 365
 366    fn pop_undo(&mut self) -> Option<&HistoryEntry> {
 367        assert_eq!(self.transaction_depth, 0);
 368        if let Some(entry) = self.undo_stack.pop() {
 369            self.redo_stack.push(entry);
 370            self.redo_stack.last()
 371        } else {
 372            None
 373        }
 374    }
 375
 376    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&HistoryEntry> {
 377        assert_eq!(self.transaction_depth, 0);
 378
 379        let entry_ix = self
 380            .undo_stack
 381            .iter()
 382            .rposition(|entry| entry.transaction.id == transaction_id)?;
 383        let entry = self.undo_stack.remove(entry_ix);
 384        self.redo_stack.push(entry);
 385        self.redo_stack.last()
 386    }
 387
 388    fn remove_from_undo_until(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
 389        assert_eq!(self.transaction_depth, 0);
 390
 391        let redo_stack_start_len = self.redo_stack.len();
 392        if let Some(entry_ix) = self
 393            .undo_stack
 394            .iter()
 395            .rposition(|entry| entry.transaction.id == transaction_id)
 396        {
 397            self.redo_stack
 398                .extend(self.undo_stack.drain(entry_ix..).rev());
 399        }
 400        &self.redo_stack[redo_stack_start_len..]
 401    }
 402
 403    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
 404        assert_eq!(self.transaction_depth, 0);
 405        if let Some(entry_ix) = self
 406            .undo_stack
 407            .iter()
 408            .rposition(|entry| entry.transaction.id == transaction_id)
 409        {
 410            Some(self.undo_stack.remove(entry_ix).transaction)
 411        } else if let Some(entry_ix) = self
 412            .redo_stack
 413            .iter()
 414            .rposition(|entry| entry.transaction.id == transaction_id)
 415        {
 416            Some(self.redo_stack.remove(entry_ix).transaction)
 417        } else {
 418            None
 419        }
 420    }
 421
 422    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
 423        let entry = self
 424            .undo_stack
 425            .iter()
 426            .rfind(|entry| entry.transaction.id == transaction_id)
 427            .or_else(|| {
 428                self.redo_stack
 429                    .iter()
 430                    .rfind(|entry| entry.transaction.id == transaction_id)
 431            })?;
 432        Some(&entry.transaction)
 433    }
 434
 435    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
 436        let entry = self
 437            .undo_stack
 438            .iter_mut()
 439            .rfind(|entry| entry.transaction.id == transaction_id)
 440            .or_else(|| {
 441                self.redo_stack
 442                    .iter_mut()
 443                    .rfind(|entry| entry.transaction.id == transaction_id)
 444            })?;
 445        Some(&mut entry.transaction)
 446    }
 447
 448    fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
 449        if let Some(transaction) = self.forget(transaction) {
 450            if let Some(destination) = self.transaction_mut(destination) {
 451                destination.edit_ids.extend(transaction.edit_ids);
 452            }
 453        }
 454    }
 455
 456    fn pop_redo(&mut self) -> Option<&HistoryEntry> {
 457        assert_eq!(self.transaction_depth, 0);
 458        if let Some(entry) = self.redo_stack.pop() {
 459            self.undo_stack.push(entry);
 460            self.undo_stack.last()
 461        } else {
 462            None
 463        }
 464    }
 465
 466    fn remove_from_redo(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
 467        assert_eq!(self.transaction_depth, 0);
 468
 469        let undo_stack_start_len = self.undo_stack.len();
 470        if let Some(entry_ix) = self
 471            .redo_stack
 472            .iter()
 473            .rposition(|entry| entry.transaction.id == transaction_id)
 474        {
 475            self.undo_stack
 476                .extend(self.redo_stack.drain(entry_ix..).rev());
 477        }
 478        &self.undo_stack[undo_stack_start_len..]
 479    }
 480}
 481
 482struct Edits<'a, D: TextDimension, F: FnMut(&FragmentSummary) -> bool> {
 483    visible_cursor: rope::Cursor<'a>,
 484    deleted_cursor: rope::Cursor<'a>,
 485    fragments_cursor: Option<FilterCursor<'a, F, Fragment, FragmentTextSummary>>,
 486    undos: &'a UndoMap,
 487    since: &'a clock::Global,
 488    old_end: D,
 489    new_end: D,
 490    range: Range<(&'a Locator, usize)>,
 491    buffer_id: BufferId,
 492}
 493
 494#[derive(Clone, Debug, Default, Eq, PartialEq)]
 495pub struct Edit<D> {
 496    pub old: Range<D>,
 497    pub new: Range<D>,
 498}
 499
 500impl<D> Edit<D>
 501where
 502    D: Sub<D, Output = D> + PartialEq + Copy,
 503{
 504    pub fn old_len(&self) -> D {
 505        self.old.end - self.old.start
 506    }
 507
 508    pub fn new_len(&self) -> D {
 509        self.new.end - self.new.start
 510    }
 511
 512    pub fn is_empty(&self) -> bool {
 513        self.old.start == self.old.end && self.new.start == self.new.end
 514    }
 515}
 516
 517impl<D1, D2> Edit<(D1, D2)> {
 518    pub fn flatten(self) -> (Edit<D1>, Edit<D2>) {
 519        (
 520            Edit {
 521                old: self.old.start.0..self.old.end.0,
 522                new: self.new.start.0..self.new.end.0,
 523            },
 524            Edit {
 525                old: self.old.start.1..self.old.end.1,
 526                new: self.new.start.1..self.new.end.1,
 527            },
 528        )
 529    }
 530}
 531
 532#[derive(Eq, PartialEq, Clone, Debug)]
 533pub struct Fragment {
 534    pub id: Locator,
 535    pub timestamp: clock::Lamport,
 536    pub insertion_offset: usize,
 537    pub len: usize,
 538    pub visible: bool,
 539    pub deletions: HashSet<clock::Lamport>,
 540    pub max_undos: clock::Global,
 541}
 542
 543#[derive(Eq, PartialEq, Clone, Debug)]
 544pub struct FragmentSummary {
 545    text: FragmentTextSummary,
 546    max_id: Locator,
 547    max_version: clock::Global,
 548    min_insertion_version: clock::Global,
 549    max_insertion_version: clock::Global,
 550}
 551
 552#[derive(Copy, Default, Clone, Debug, PartialEq, Eq)]
 553struct FragmentTextSummary {
 554    visible: usize,
 555    deleted: usize,
 556}
 557
 558impl<'a> sum_tree::Dimension<'a, FragmentSummary> for FragmentTextSummary {
 559    fn zero(_: &Option<clock::Global>) -> Self {
 560        Default::default()
 561    }
 562
 563    fn add_summary(&mut self, summary: &'a FragmentSummary, _: &Option<clock::Global>) {
 564        self.visible += summary.text.visible;
 565        self.deleted += summary.text.deleted;
 566    }
 567}
 568
 569#[derive(Eq, PartialEq, Clone, Debug)]
 570struct InsertionFragment {
 571    timestamp: clock::Lamport,
 572    split_offset: usize,
 573    fragment_id: Locator,
 574}
 575
 576#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
 577struct InsertionFragmentKey {
 578    timestamp: clock::Lamport,
 579    split_offset: usize,
 580}
 581
 582#[derive(Clone, Debug, Eq, PartialEq)]
 583pub enum Operation {
 584    Edit(EditOperation),
 585    Undo(UndoOperation),
 586}
 587
 588#[derive(Clone, Debug, Eq, PartialEq)]
 589pub struct EditOperation {
 590    pub timestamp: clock::Lamport,
 591    pub version: clock::Global,
 592    pub ranges: Vec<Range<FullOffset>>,
 593    pub new_text: Vec<Arc<str>>,
 594}
 595
 596#[derive(Clone, Debug, Eq, PartialEq)]
 597pub struct UndoOperation {
 598    pub timestamp: clock::Lamport,
 599    pub version: clock::Global,
 600    pub counts: HashMap<clock::Lamport, u32>,
 601}
 602
 603/// Stores information about the indentation of a line (tabs and spaces).
 604#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 605pub struct LineIndent {
 606    pub tabs: u32,
 607    pub spaces: u32,
 608    pub line_blank: bool,
 609}
 610
 611impl LineIndent {
 612    pub fn from_chunks(chunks: &mut Chunks) -> Self {
 613        let mut tabs = 0;
 614        let mut spaces = 0;
 615        let mut line_blank = true;
 616
 617        'outer: while let Some(chunk) = chunks.peek() {
 618            for ch in chunk.chars() {
 619                if ch == '\t' {
 620                    tabs += 1;
 621                } else if ch == ' ' {
 622                    spaces += 1;
 623                } else {
 624                    if ch != '\n' {
 625                        line_blank = false;
 626                    }
 627                    break 'outer;
 628                }
 629            }
 630
 631            chunks.next();
 632        }
 633
 634        Self {
 635            tabs,
 636            spaces,
 637            line_blank,
 638        }
 639    }
 640
 641    /// Constructs a new `LineIndent` which only contains spaces.
 642    pub fn spaces(spaces: u32) -> Self {
 643        Self {
 644            tabs: 0,
 645            spaces,
 646            line_blank: true,
 647        }
 648    }
 649
 650    /// Constructs a new `LineIndent` which only contains tabs.
 651    pub fn tabs(tabs: u32) -> Self {
 652        Self {
 653            tabs,
 654            spaces: 0,
 655            line_blank: true,
 656        }
 657    }
 658
 659    /// Indicates whether the line is empty.
 660    pub fn is_line_empty(&self) -> bool {
 661        self.tabs == 0 && self.spaces == 0 && self.line_blank
 662    }
 663
 664    /// Indicates whether the line is blank (contains only whitespace).
 665    pub fn is_line_blank(&self) -> bool {
 666        self.line_blank
 667    }
 668
 669    /// Returns the number of indentation characters (tabs or spaces).
 670    pub fn raw_len(&self) -> u32 {
 671        self.tabs + self.spaces
 672    }
 673
 674    /// Returns the number of indentation characters (tabs or spaces), taking tab size into account.
 675    pub fn len(&self, tab_size: u32) -> u32 {
 676        self.tabs * tab_size + self.spaces
 677    }
 678}
 679
 680impl From<&str> for LineIndent {
 681    fn from(value: &str) -> Self {
 682        Self::from_iter(value.chars())
 683    }
 684}
 685
 686impl FromIterator<char> for LineIndent {
 687    fn from_iter<T: IntoIterator<Item = char>>(chars: T) -> Self {
 688        let mut tabs = 0;
 689        let mut spaces = 0;
 690        let mut line_blank = true;
 691        for c in chars {
 692            if c == '\t' {
 693                tabs += 1;
 694            } else if c == ' ' {
 695                spaces += 1;
 696            } else {
 697                if c != '\n' {
 698                    line_blank = false;
 699                }
 700                break;
 701            }
 702        }
 703        Self {
 704            tabs,
 705            spaces,
 706            line_blank,
 707        }
 708    }
 709}
 710
 711impl Buffer {
 712    pub fn new(replica_id: u16, remote_id: BufferId, base_text: impl Into<String>) -> Buffer {
 713        let mut base_text = base_text.into();
 714        let line_ending = LineEnding::detect(&base_text);
 715        LineEnding::normalize(&mut base_text);
 716        Self::new_normalized(replica_id, remote_id, line_ending, Rope::from(base_text))
 717    }
 718
 719    pub fn new_normalized(
 720        replica_id: u16,
 721        remote_id: BufferId,
 722        line_ending: LineEnding,
 723        normalized: Rope,
 724    ) -> Buffer {
 725        let history = History::new(normalized);
 726        let mut fragments = SumTree::new(&None);
 727        let mut insertions = SumTree::default();
 728
 729        let mut lamport_clock = clock::Lamport::new(replica_id);
 730        let mut version = clock::Global::new();
 731
 732        let visible_text = history.base_text.clone();
 733        if !visible_text.is_empty() {
 734            let insertion_timestamp = clock::Lamport {
 735                replica_id: 0,
 736                value: 1,
 737            };
 738            lamport_clock.observe(insertion_timestamp);
 739            version.observe(insertion_timestamp);
 740            let fragment_id = Locator::between(&Locator::min(), &Locator::max());
 741            let fragment = Fragment {
 742                id: fragment_id,
 743                timestamp: insertion_timestamp,
 744                insertion_offset: 0,
 745                len: visible_text.len(),
 746                visible: true,
 747                deletions: Default::default(),
 748                max_undos: Default::default(),
 749            };
 750            insertions.push(InsertionFragment::new(&fragment), &());
 751            fragments.push(fragment, &None);
 752        }
 753
 754        Buffer {
 755            snapshot: BufferSnapshot {
 756                replica_id,
 757                remote_id,
 758                visible_text,
 759                deleted_text: Rope::new(),
 760                line_ending,
 761                fragments,
 762                insertions,
 763                version,
 764                undo_map: Default::default(),
 765                insertion_slices: Default::default(),
 766            },
 767            history,
 768            deferred_ops: OperationQueue::new(),
 769            deferred_replicas: HashSet::default(),
 770            lamport_clock,
 771            subscriptions: Default::default(),
 772            edit_id_resolvers: Default::default(),
 773            wait_for_version_txs: Default::default(),
 774        }
 775    }
 776
 777    pub fn version(&self) -> clock::Global {
 778        self.version.clone()
 779    }
 780
 781    pub fn snapshot(&self) -> BufferSnapshot {
 782        self.snapshot.clone()
 783    }
 784
 785    pub fn branch(&self) -> Self {
 786        Self {
 787            snapshot: self.snapshot.clone(),
 788            history: History::new(self.base_text().clone()),
 789            deferred_ops: OperationQueue::new(),
 790            deferred_replicas: HashSet::default(),
 791            lamport_clock: clock::Lamport::new(LOCAL_BRANCH_REPLICA_ID),
 792            subscriptions: Default::default(),
 793            edit_id_resolvers: Default::default(),
 794            wait_for_version_txs: Default::default(),
 795        }
 796    }
 797
 798    pub fn replica_id(&self) -> ReplicaId {
 799        self.lamport_clock.replica_id
 800    }
 801
 802    pub fn remote_id(&self) -> BufferId {
 803        self.remote_id
 804    }
 805
 806    pub fn deferred_ops_len(&self) -> usize {
 807        self.deferred_ops.len()
 808    }
 809
 810    pub fn transaction_group_interval(&self) -> Duration {
 811        self.history.group_interval
 812    }
 813
 814    pub fn edit<R, I, S, T>(&mut self, edits: R) -> Operation
 815    where
 816        R: IntoIterator<IntoIter = I>,
 817        I: ExactSizeIterator<Item = (Range<S>, T)>,
 818        S: ToOffset,
 819        T: Into<Arc<str>>,
 820    {
 821        let edits = edits
 822            .into_iter()
 823            .map(|(range, new_text)| (range, new_text.into()));
 824
 825        self.start_transaction();
 826        let timestamp = self.lamport_clock.tick();
 827        let operation = Operation::Edit(self.apply_local_edit(edits, timestamp));
 828
 829        self.history.push(operation.clone());
 830        self.history.push_undo(operation.timestamp());
 831        self.snapshot.version.observe(operation.timestamp());
 832        self.end_transaction();
 833        operation
 834    }
 835
 836    fn apply_local_edit<S: ToOffset, T: Into<Arc<str>>>(
 837        &mut self,
 838        edits: impl ExactSizeIterator<Item = (Range<S>, T)>,
 839        timestamp: clock::Lamport,
 840    ) -> EditOperation {
 841        let mut edits_patch = Patch::default();
 842        let mut edit_op = EditOperation {
 843            timestamp,
 844            version: self.version(),
 845            ranges: Vec::with_capacity(edits.len()),
 846            new_text: Vec::with_capacity(edits.len()),
 847        };
 848        let mut new_insertions = Vec::new();
 849        let mut insertion_offset = 0;
 850        let mut insertion_slices = Vec::new();
 851
 852        let mut edits = edits
 853            .map(|(range, new_text)| (range.to_offset(&*self), new_text))
 854            .peekable();
 855
 856        let mut new_ropes =
 857            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
 858        let mut old_fragments = self.fragments.cursor::<FragmentTextSummary>(&None);
 859        let mut new_fragments = old_fragments.slice(&edits.peek().unwrap().0.start, Bias::Right);
 860        new_ropes.append(new_fragments.summary().text);
 861
 862        let mut fragment_start = old_fragments.start().visible;
 863        for (range, new_text) in edits {
 864            let new_text = LineEnding::normalize_arc(new_text.into());
 865            let fragment_end = old_fragments.end().visible;
 866
 867            // If the current fragment ends before this range, then jump ahead to the first fragment
 868            // that extends past the start of this range, reusing any intervening fragments.
 869            if fragment_end < range.start {
 870                // If the current fragment has been partially consumed, then consume the rest of it
 871                // and advance to the next fragment before slicing.
 872                if fragment_start > old_fragments.start().visible {
 873                    if fragment_end > fragment_start {
 874                        let mut suffix = old_fragments.item().unwrap().clone();
 875                        suffix.len = fragment_end - fragment_start;
 876                        suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 877                        new_insertions.push(InsertionFragment::insert_new(&suffix));
 878                        new_ropes.push_fragment(&suffix, suffix.visible);
 879                        new_fragments.push(suffix, &None);
 880                    }
 881                    old_fragments.next();
 882                }
 883
 884                let slice = old_fragments.slice(&range.start, Bias::Right);
 885                new_ropes.append(slice.summary().text);
 886                new_fragments.append(slice, &None);
 887                fragment_start = old_fragments.start().visible;
 888            }
 889
 890            let full_range_start = FullOffset(range.start + old_fragments.start().deleted);
 891
 892            // Preserve any portion of the current fragment that precedes this range.
 893            if fragment_start < range.start {
 894                let mut prefix = old_fragments.item().unwrap().clone();
 895                prefix.len = range.start - fragment_start;
 896                prefix.insertion_offset += fragment_start - old_fragments.start().visible;
 897                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
 898                new_insertions.push(InsertionFragment::insert_new(&prefix));
 899                new_ropes.push_fragment(&prefix, prefix.visible);
 900                new_fragments.push(prefix, &None);
 901                fragment_start = range.start;
 902            }
 903
 904            // Insert the new text before any existing fragments within the range.
 905            if !new_text.is_empty() {
 906                let new_start = new_fragments.summary().text.visible;
 907
 908                let fragment = Fragment {
 909                    id: Locator::between(
 910                        &new_fragments.summary().max_id,
 911                        old_fragments
 912                            .item()
 913                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
 914                    ),
 915                    timestamp,
 916                    insertion_offset,
 917                    len: new_text.len(),
 918                    deletions: Default::default(),
 919                    max_undos: Default::default(),
 920                    visible: true,
 921                };
 922                edits_patch.push(Edit {
 923                    old: fragment_start..fragment_start,
 924                    new: new_start..new_start + new_text.len(),
 925                });
 926                insertion_slices.push(InsertionSlice::from_fragment(timestamp, &fragment));
 927                new_insertions.push(InsertionFragment::insert_new(&fragment));
 928                new_ropes.push_str(new_text.as_ref());
 929                new_fragments.push(fragment, &None);
 930                insertion_offset += new_text.len();
 931            }
 932
 933            // Advance through every fragment that intersects this range, marking the intersecting
 934            // portions as deleted.
 935            while fragment_start < range.end {
 936                let fragment = old_fragments.item().unwrap();
 937                let fragment_end = old_fragments.end().visible;
 938                let mut intersection = fragment.clone();
 939                let intersection_end = cmp::min(range.end, fragment_end);
 940                if fragment.visible {
 941                    intersection.len = intersection_end - fragment_start;
 942                    intersection.insertion_offset += fragment_start - old_fragments.start().visible;
 943                    intersection.id =
 944                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
 945                    intersection.deletions.insert(timestamp);
 946                    intersection.visible = false;
 947                }
 948                if intersection.len > 0 {
 949                    if fragment.visible && !intersection.visible {
 950                        let new_start = new_fragments.summary().text.visible;
 951                        edits_patch.push(Edit {
 952                            old: fragment_start..intersection_end,
 953                            new: new_start..new_start,
 954                        });
 955                        insertion_slices
 956                            .push(InsertionSlice::from_fragment(timestamp, &intersection));
 957                    }
 958                    new_insertions.push(InsertionFragment::insert_new(&intersection));
 959                    new_ropes.push_fragment(&intersection, fragment.visible);
 960                    new_fragments.push(intersection, &None);
 961                    fragment_start = intersection_end;
 962                }
 963                if fragment_end <= range.end {
 964                    old_fragments.next();
 965                }
 966            }
 967
 968            let full_range_end = FullOffset(range.end + old_fragments.start().deleted);
 969            edit_op.ranges.push(full_range_start..full_range_end);
 970            edit_op.new_text.push(new_text);
 971        }
 972
 973        // If the current fragment has been partially consumed, then consume the rest of it
 974        // and advance to the next fragment before slicing.
 975        if fragment_start > old_fragments.start().visible {
 976            let fragment_end = old_fragments.end().visible;
 977            if fragment_end > fragment_start {
 978                let mut suffix = old_fragments.item().unwrap().clone();
 979                suffix.len = fragment_end - fragment_start;
 980                suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 981                new_insertions.push(InsertionFragment::insert_new(&suffix));
 982                new_ropes.push_fragment(&suffix, suffix.visible);
 983                new_fragments.push(suffix, &None);
 984            }
 985            old_fragments.next();
 986        }
 987
 988        let suffix = old_fragments.suffix();
 989        new_ropes.append(suffix.summary().text);
 990        new_fragments.append(suffix, &None);
 991        let (visible_text, deleted_text) = new_ropes.finish();
 992        drop(old_fragments);
 993
 994        self.snapshot.fragments = new_fragments;
 995        self.snapshot.insertions.edit(new_insertions, &());
 996        self.snapshot.visible_text = visible_text;
 997        self.snapshot.deleted_text = deleted_text;
 998        self.subscriptions.publish_mut(&edits_patch);
 999        self.snapshot.insertion_slices.extend(insertion_slices);
1000        edit_op
1001    }
1002
1003    pub fn set_line_ending(&mut self, line_ending: LineEnding) {
1004        self.snapshot.line_ending = line_ending;
1005    }
1006
1007    pub fn apply_ops<I: IntoIterator<Item = Operation>>(&mut self, ops: I) {
1008        let mut deferred_ops = Vec::new();
1009        for op in ops {
1010            self.history.push(op.clone());
1011            if self.can_apply_op(&op) {
1012                self.apply_op(op);
1013            } else {
1014                self.deferred_replicas.insert(op.replica_id());
1015                deferred_ops.push(op);
1016            }
1017        }
1018        self.deferred_ops.insert(deferred_ops);
1019        self.flush_deferred_ops();
1020    }
1021
1022    fn apply_op(&mut self, op: Operation) {
1023        match op {
1024            Operation::Edit(edit) => {
1025                if !self.version.observed(edit.timestamp) {
1026                    self.apply_remote_edit(
1027                        &edit.version,
1028                        &edit.ranges,
1029                        &edit.new_text,
1030                        edit.timestamp,
1031                    );
1032                    self.snapshot.version.observe(edit.timestamp);
1033                    self.lamport_clock.observe(edit.timestamp);
1034                    self.resolve_edit(edit.timestamp);
1035                }
1036            }
1037            Operation::Undo(undo) => {
1038                if !self.version.observed(undo.timestamp) {
1039                    self.apply_undo(&undo);
1040                    self.snapshot.version.observe(undo.timestamp);
1041                    self.lamport_clock.observe(undo.timestamp);
1042                }
1043            }
1044        }
1045        self.wait_for_version_txs.retain_mut(|(version, tx)| {
1046            if self.snapshot.version().observed_all(version) {
1047                tx.try_send(()).ok();
1048                false
1049            } else {
1050                true
1051            }
1052        });
1053    }
1054
1055    fn apply_remote_edit(
1056        &mut self,
1057        version: &clock::Global,
1058        ranges: &[Range<FullOffset>],
1059        new_text: &[Arc<str>],
1060        timestamp: clock::Lamport,
1061    ) {
1062        if ranges.is_empty() {
1063            return;
1064        }
1065
1066        let edits = ranges.iter().zip(new_text.iter());
1067        let mut edits_patch = Patch::default();
1068        let mut insertion_slices = Vec::new();
1069        let cx = Some(version.clone());
1070        let mut new_insertions = Vec::new();
1071        let mut insertion_offset = 0;
1072        let mut new_ropes =
1073            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
1074        let mut old_fragments = self.fragments.cursor::<(VersionedFullOffset, usize)>(&cx);
1075        let mut new_fragments =
1076            old_fragments.slice(&VersionedFullOffset::Offset(ranges[0].start), Bias::Left);
1077        new_ropes.append(new_fragments.summary().text);
1078
1079        let mut fragment_start = old_fragments.start().0.full_offset();
1080        for (range, new_text) in edits {
1081            let fragment_end = old_fragments.end().0.full_offset();
1082
1083            // If the current fragment ends before this range, then jump ahead to the first fragment
1084            // that extends past the start of this range, reusing any intervening fragments.
1085            if fragment_end < range.start {
1086                // If the current fragment has been partially consumed, then consume the rest of it
1087                // and advance to the next fragment before slicing.
1088                if fragment_start > old_fragments.start().0.full_offset() {
1089                    if fragment_end > fragment_start {
1090                        let mut suffix = old_fragments.item().unwrap().clone();
1091                        suffix.len = fragment_end.0 - fragment_start.0;
1092                        suffix.insertion_offset +=
1093                            fragment_start - old_fragments.start().0.full_offset();
1094                        new_insertions.push(InsertionFragment::insert_new(&suffix));
1095                        new_ropes.push_fragment(&suffix, suffix.visible);
1096                        new_fragments.push(suffix, &None);
1097                    }
1098                    old_fragments.next();
1099                }
1100
1101                let slice =
1102                    old_fragments.slice(&VersionedFullOffset::Offset(range.start), Bias::Left);
1103                new_ropes.append(slice.summary().text);
1104                new_fragments.append(slice, &None);
1105                fragment_start = old_fragments.start().0.full_offset();
1106            }
1107
1108            // If we are at the end of a non-concurrent fragment, advance to the next one.
1109            let fragment_end = old_fragments.end().0.full_offset();
1110            if fragment_end == range.start && fragment_end > fragment_start {
1111                let mut fragment = old_fragments.item().unwrap().clone();
1112                fragment.len = fragment_end.0 - fragment_start.0;
1113                fragment.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1114                new_insertions.push(InsertionFragment::insert_new(&fragment));
1115                new_ropes.push_fragment(&fragment, fragment.visible);
1116                new_fragments.push(fragment, &None);
1117                old_fragments.next();
1118                fragment_start = old_fragments.start().0.full_offset();
1119            }
1120
1121            // Skip over insertions that are concurrent to this edit, but have a lower lamport
1122            // timestamp.
1123            while let Some(fragment) = old_fragments.item() {
1124                if fragment_start == range.start && fragment.timestamp > timestamp {
1125                    new_ropes.push_fragment(fragment, fragment.visible);
1126                    new_fragments.push(fragment.clone(), &None);
1127                    old_fragments.next();
1128                    debug_assert_eq!(fragment_start, range.start);
1129                } else {
1130                    break;
1131                }
1132            }
1133            debug_assert!(fragment_start <= range.start);
1134
1135            // Preserve any portion of the current fragment that precedes this range.
1136            if fragment_start < range.start {
1137                let mut prefix = old_fragments.item().unwrap().clone();
1138                prefix.len = range.start.0 - fragment_start.0;
1139                prefix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1140                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
1141                new_insertions.push(InsertionFragment::insert_new(&prefix));
1142                fragment_start = range.start;
1143                new_ropes.push_fragment(&prefix, prefix.visible);
1144                new_fragments.push(prefix, &None);
1145            }
1146
1147            // Insert the new text before any existing fragments within the range.
1148            if !new_text.is_empty() {
1149                let mut old_start = old_fragments.start().1;
1150                if old_fragments.item().map_or(false, |f| f.visible) {
1151                    old_start += fragment_start.0 - old_fragments.start().0.full_offset().0;
1152                }
1153                let new_start = new_fragments.summary().text.visible;
1154                let fragment = Fragment {
1155                    id: Locator::between(
1156                        &new_fragments.summary().max_id,
1157                        old_fragments
1158                            .item()
1159                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
1160                    ),
1161                    timestamp,
1162                    insertion_offset,
1163                    len: new_text.len(),
1164                    deletions: Default::default(),
1165                    max_undos: Default::default(),
1166                    visible: true,
1167                };
1168                edits_patch.push(Edit {
1169                    old: old_start..old_start,
1170                    new: new_start..new_start + new_text.len(),
1171                });
1172                insertion_slices.push(InsertionSlice::from_fragment(timestamp, &fragment));
1173                new_insertions.push(InsertionFragment::insert_new(&fragment));
1174                new_ropes.push_str(new_text);
1175                new_fragments.push(fragment, &None);
1176                insertion_offset += new_text.len();
1177            }
1178
1179            // Advance through every fragment that intersects this range, marking the intersecting
1180            // portions as deleted.
1181            while fragment_start < range.end {
1182                let fragment = old_fragments.item().unwrap();
1183                let fragment_end = old_fragments.end().0.full_offset();
1184                let mut intersection = fragment.clone();
1185                let intersection_end = cmp::min(range.end, fragment_end);
1186                if fragment.was_visible(version, &self.undo_map) {
1187                    intersection.len = intersection_end.0 - fragment_start.0;
1188                    intersection.insertion_offset +=
1189                        fragment_start - old_fragments.start().0.full_offset();
1190                    intersection.id =
1191                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
1192                    intersection.deletions.insert(timestamp);
1193                    intersection.visible = false;
1194                    insertion_slices.push(InsertionSlice::from_fragment(timestamp, &intersection));
1195                }
1196                if intersection.len > 0 {
1197                    if fragment.visible && !intersection.visible {
1198                        let old_start = old_fragments.start().1
1199                            + (fragment_start.0 - old_fragments.start().0.full_offset().0);
1200                        let new_start = new_fragments.summary().text.visible;
1201                        edits_patch.push(Edit {
1202                            old: old_start..old_start + intersection.len,
1203                            new: new_start..new_start,
1204                        });
1205                    }
1206                    new_insertions.push(InsertionFragment::insert_new(&intersection));
1207                    new_ropes.push_fragment(&intersection, fragment.visible);
1208                    new_fragments.push(intersection, &None);
1209                    fragment_start = intersection_end;
1210                }
1211                if fragment_end <= range.end {
1212                    old_fragments.next();
1213                }
1214            }
1215        }
1216
1217        // If the current fragment has been partially consumed, then consume the rest of it
1218        // and advance to the next fragment before slicing.
1219        if fragment_start > old_fragments.start().0.full_offset() {
1220            let fragment_end = old_fragments.end().0.full_offset();
1221            if fragment_end > fragment_start {
1222                let mut suffix = old_fragments.item().unwrap().clone();
1223                suffix.len = fragment_end.0 - fragment_start.0;
1224                suffix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1225                new_insertions.push(InsertionFragment::insert_new(&suffix));
1226                new_ropes.push_fragment(&suffix, suffix.visible);
1227                new_fragments.push(suffix, &None);
1228            }
1229            old_fragments.next();
1230        }
1231
1232        let suffix = old_fragments.suffix();
1233        new_ropes.append(suffix.summary().text);
1234        new_fragments.append(suffix, &None);
1235        let (visible_text, deleted_text) = new_ropes.finish();
1236        drop(old_fragments);
1237
1238        self.snapshot.fragments = new_fragments;
1239        self.snapshot.visible_text = visible_text;
1240        self.snapshot.deleted_text = deleted_text;
1241        self.snapshot.insertions.edit(new_insertions, &());
1242        self.snapshot.insertion_slices.extend(insertion_slices);
1243        self.subscriptions.publish_mut(&edits_patch)
1244    }
1245
1246    fn fragment_ids_for_edits<'a>(
1247        &'a self,
1248        edit_ids: impl Iterator<Item = &'a clock::Lamport>,
1249    ) -> Vec<&'a Locator> {
1250        // Get all of the insertion slices changed by the given edits.
1251        let mut insertion_slices = Vec::new();
1252        for edit_id in edit_ids {
1253            let insertion_slice = InsertionSlice {
1254                edit_id: *edit_id,
1255                insertion_id: clock::Lamport::default(),
1256                range: 0..0,
1257            };
1258            let slices = self
1259                .snapshot
1260                .insertion_slices
1261                .iter_from(&insertion_slice)
1262                .take_while(|slice| slice.edit_id == *edit_id);
1263            insertion_slices.extend(slices)
1264        }
1265        insertion_slices
1266            .sort_unstable_by_key(|s| (s.insertion_id, s.range.start, Reverse(s.range.end)));
1267
1268        // Get all of the fragments corresponding to these insertion slices.
1269        let mut fragment_ids = Vec::new();
1270        let mut insertions_cursor = self.insertions.cursor::<InsertionFragmentKey>(&());
1271        for insertion_slice in &insertion_slices {
1272            if insertion_slice.insertion_id != insertions_cursor.start().timestamp
1273                || insertion_slice.range.start > insertions_cursor.start().split_offset
1274            {
1275                insertions_cursor.seek_forward(
1276                    &InsertionFragmentKey {
1277                        timestamp: insertion_slice.insertion_id,
1278                        split_offset: insertion_slice.range.start,
1279                    },
1280                    Bias::Left,
1281                );
1282            }
1283            while let Some(item) = insertions_cursor.item() {
1284                if item.timestamp != insertion_slice.insertion_id
1285                    || item.split_offset >= insertion_slice.range.end
1286                {
1287                    break;
1288                }
1289                fragment_ids.push(&item.fragment_id);
1290                insertions_cursor.next();
1291            }
1292        }
1293        fragment_ids.sort_unstable();
1294        fragment_ids
1295    }
1296
1297    fn apply_undo(&mut self, undo: &UndoOperation) {
1298        self.snapshot.undo_map.insert(undo);
1299
1300        let mut edits = Patch::default();
1301        let mut old_fragments = self.fragments.cursor::<(Option<&Locator>, usize)>(&None);
1302        let mut new_fragments = SumTree::new(&None);
1303        let mut new_ropes =
1304            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
1305
1306        for fragment_id in self.fragment_ids_for_edits(undo.counts.keys()) {
1307            let preceding_fragments = old_fragments.slice(&Some(fragment_id), Bias::Left);
1308            new_ropes.append(preceding_fragments.summary().text);
1309            new_fragments.append(preceding_fragments, &None);
1310
1311            if let Some(fragment) = old_fragments.item() {
1312                let mut fragment = fragment.clone();
1313                let fragment_was_visible = fragment.visible;
1314
1315                fragment.visible = fragment.is_visible(&self.undo_map);
1316                fragment.max_undos.observe(undo.timestamp);
1317
1318                let old_start = old_fragments.start().1;
1319                let new_start = new_fragments.summary().text.visible;
1320                if fragment_was_visible && !fragment.visible {
1321                    edits.push(Edit {
1322                        old: old_start..old_start + fragment.len,
1323                        new: new_start..new_start,
1324                    });
1325                } else if !fragment_was_visible && fragment.visible {
1326                    edits.push(Edit {
1327                        old: old_start..old_start,
1328                        new: new_start..new_start + fragment.len,
1329                    });
1330                }
1331                new_ropes.push_fragment(&fragment, fragment_was_visible);
1332                new_fragments.push(fragment, &None);
1333
1334                old_fragments.next();
1335            }
1336        }
1337
1338        let suffix = old_fragments.suffix();
1339        new_ropes.append(suffix.summary().text);
1340        new_fragments.append(suffix, &None);
1341
1342        drop(old_fragments);
1343        let (visible_text, deleted_text) = new_ropes.finish();
1344        self.snapshot.fragments = new_fragments;
1345        self.snapshot.visible_text = visible_text;
1346        self.snapshot.deleted_text = deleted_text;
1347        self.subscriptions.publish_mut(&edits);
1348    }
1349
1350    fn flush_deferred_ops(&mut self) {
1351        self.deferred_replicas.clear();
1352        let mut deferred_ops = Vec::new();
1353        for op in self.deferred_ops.drain().iter().cloned() {
1354            if self.can_apply_op(&op) {
1355                self.apply_op(op);
1356            } else {
1357                self.deferred_replicas.insert(op.replica_id());
1358                deferred_ops.push(op);
1359            }
1360        }
1361        self.deferred_ops.insert(deferred_ops);
1362    }
1363
1364    fn can_apply_op(&self, op: &Operation) -> bool {
1365        if self.deferred_replicas.contains(&op.replica_id()) {
1366            false
1367        } else {
1368            self.version.observed_all(match op {
1369                Operation::Edit(edit) => &edit.version,
1370                Operation::Undo(undo) => &undo.version,
1371            })
1372        }
1373    }
1374
1375    pub fn has_deferred_ops(&self) -> bool {
1376        !self.deferred_ops.is_empty()
1377    }
1378
1379    pub fn peek_undo_stack(&self) -> Option<&HistoryEntry> {
1380        self.history.undo_stack.last()
1381    }
1382
1383    pub fn peek_redo_stack(&self) -> Option<&HistoryEntry> {
1384        self.history.redo_stack.last()
1385    }
1386
1387    pub fn start_transaction(&mut self) -> Option<TransactionId> {
1388        self.start_transaction_at(Instant::now())
1389    }
1390
1391    pub fn start_transaction_at(&mut self, now: Instant) -> Option<TransactionId> {
1392        self.history
1393            .start_transaction(self.version.clone(), now, &mut self.lamport_clock)
1394    }
1395
1396    pub fn end_transaction(&mut self) -> Option<(TransactionId, clock::Global)> {
1397        self.end_transaction_at(Instant::now())
1398    }
1399
1400    pub fn end_transaction_at(&mut self, now: Instant) -> Option<(TransactionId, clock::Global)> {
1401        if let Some(entry) = self.history.end_transaction(now) {
1402            let since = entry.transaction.start.clone();
1403            let id = self.history.group().unwrap();
1404            Some((id, since))
1405        } else {
1406            None
1407        }
1408    }
1409
1410    pub fn finalize_last_transaction(&mut self) -> Option<&Transaction> {
1411        self.history.finalize_last_transaction()
1412    }
1413
1414    pub fn group_until_transaction(&mut self, transaction_id: TransactionId) {
1415        self.history.group_until(transaction_id);
1416    }
1417
1418    pub fn base_text(&self) -> &Rope {
1419        &self.history.base_text
1420    }
1421
1422    pub fn operations(&self) -> &TreeMap<clock::Lamport, Operation> {
1423        &self.history.operations
1424    }
1425
1426    pub fn undo(&mut self) -> Option<(TransactionId, Operation)> {
1427        if let Some(entry) = self.history.pop_undo() {
1428            let transaction = entry.transaction.clone();
1429            let transaction_id = transaction.id;
1430            let op = self.undo_or_redo(transaction);
1431            Some((transaction_id, op))
1432        } else {
1433            None
1434        }
1435    }
1436
1437    pub fn undo_transaction(&mut self, transaction_id: TransactionId) -> Option<Operation> {
1438        let transaction = self
1439            .history
1440            .remove_from_undo(transaction_id)?
1441            .transaction
1442            .clone();
1443        Some(self.undo_or_redo(transaction))
1444    }
1445
1446    pub fn undo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1447        let transactions = self
1448            .history
1449            .remove_from_undo_until(transaction_id)
1450            .iter()
1451            .map(|entry| entry.transaction.clone())
1452            .collect::<Vec<_>>();
1453
1454        transactions
1455            .into_iter()
1456            .map(|transaction| self.undo_or_redo(transaction))
1457            .collect()
1458    }
1459
1460    pub fn forget_transaction(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
1461        self.history.forget(transaction_id)
1462    }
1463
1464    pub fn get_transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
1465        self.history.transaction(transaction_id)
1466    }
1467
1468    pub fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
1469        self.history.merge_transactions(transaction, destination);
1470    }
1471
1472    pub fn redo(&mut self) -> Option<(TransactionId, Operation)> {
1473        if let Some(entry) = self.history.pop_redo() {
1474            let transaction = entry.transaction.clone();
1475            let transaction_id = transaction.id;
1476            let op = self.undo_or_redo(transaction);
1477            Some((transaction_id, op))
1478        } else {
1479            None
1480        }
1481    }
1482
1483    pub fn redo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1484        let transactions = self
1485            .history
1486            .remove_from_redo(transaction_id)
1487            .iter()
1488            .map(|entry| entry.transaction.clone())
1489            .collect::<Vec<_>>();
1490
1491        transactions
1492            .into_iter()
1493            .map(|transaction| self.undo_or_redo(transaction))
1494            .collect()
1495    }
1496
1497    fn undo_or_redo(&mut self, transaction: Transaction) -> Operation {
1498        let mut counts = HashMap::default();
1499        for edit_id in transaction.edit_ids {
1500            counts.insert(edit_id, self.undo_map.undo_count(edit_id).saturating_add(1));
1501        }
1502
1503        let operation = self.undo_operations(counts);
1504        self.history.push(operation.clone());
1505        operation
1506    }
1507
1508    pub fn undo_operations(&mut self, counts: HashMap<clock::Lamport, u32>) -> Operation {
1509        let timestamp = self.lamport_clock.tick();
1510        let version = self.version();
1511        self.snapshot.version.observe(timestamp);
1512        let undo = UndoOperation {
1513            timestamp,
1514            version,
1515            counts,
1516        };
1517        self.apply_undo(&undo);
1518        Operation::Undo(undo)
1519    }
1520
1521    pub fn push_transaction(&mut self, transaction: Transaction, now: Instant) {
1522        self.history.push_transaction(transaction, now);
1523    }
1524
1525    /// Differs from `push_transaction` in that it does not clear the redo stack.
1526    /// The caller responsible for
1527    /// Differs from `push_transaction` in that it does not clear the redo
1528    /// stack. Intended to be used to create a parent transaction to merge
1529    /// potential child transactions into.
1530    ///
1531    /// The caller is responsible for removing it from the undo history using
1532    /// `forget_transaction` if no edits are merged into it. Otherwise, if edits
1533    /// are merged into this transaction, the caller is responsible for ensuring
1534    /// the redo stack is cleared. The easiest way to ensure the redo stack is
1535    /// cleared is to create transactions with the usual `start_transaction` and
1536    /// `end_transaction` methods and merging the resulting transactions into
1537    /// the transaction created by this method
1538    pub fn push_empty_transaction(&mut self, now: Instant) -> TransactionId {
1539        self.history
1540            .push_empty_transaction(self.version.clone(), now, &mut self.lamport_clock)
1541    }
1542
1543    pub fn edited_ranges_for_transaction_id<D>(
1544        &self,
1545        transaction_id: TransactionId,
1546    ) -> impl '_ + Iterator<Item = Range<D>>
1547    where
1548        D: TextDimension,
1549    {
1550        self.history
1551            .transaction(transaction_id)
1552            .into_iter()
1553            .flat_map(|transaction| self.edited_ranges_for_transaction(transaction))
1554    }
1555
1556    pub fn edited_ranges_for_edit_ids<'a, D>(
1557        &'a self,
1558        edit_ids: impl IntoIterator<Item = &'a clock::Lamport>,
1559    ) -> impl 'a + Iterator<Item = Range<D>>
1560    where
1561        D: TextDimension,
1562    {
1563        // get fragment ranges
1564        let mut cursor = self.fragments.cursor::<(Option<&Locator>, usize)>(&None);
1565        let offset_ranges = self
1566            .fragment_ids_for_edits(edit_ids.into_iter())
1567            .into_iter()
1568            .filter_map(move |fragment_id| {
1569                cursor.seek_forward(&Some(fragment_id), Bias::Left);
1570                let fragment = cursor.item()?;
1571                let start_offset = cursor.start().1;
1572                let end_offset = start_offset + if fragment.visible { fragment.len } else { 0 };
1573                Some(start_offset..end_offset)
1574            });
1575
1576        // combine adjacent ranges
1577        let mut prev_range: Option<Range<usize>> = None;
1578        let disjoint_ranges = offset_ranges
1579            .map(Some)
1580            .chain([None])
1581            .filter_map(move |range| {
1582                if let Some((range, prev_range)) = range.as_ref().zip(prev_range.as_mut()) {
1583                    if prev_range.end == range.start {
1584                        prev_range.end = range.end;
1585                        return None;
1586                    }
1587                }
1588                let result = prev_range.clone();
1589                prev_range = range;
1590                result
1591            });
1592
1593        // convert to the desired text dimension.
1594        let mut position = D::zero(&());
1595        let mut rope_cursor = self.visible_text.cursor(0);
1596        disjoint_ranges.map(move |range| {
1597            position.add_assign(&rope_cursor.summary(range.start));
1598            let start = position;
1599            position.add_assign(&rope_cursor.summary(range.end));
1600            let end = position;
1601            start..end
1602        })
1603    }
1604
1605    pub fn edited_ranges_for_transaction<'a, D>(
1606        &'a self,
1607        transaction: &'a Transaction,
1608    ) -> impl 'a + Iterator<Item = Range<D>>
1609    where
1610        D: TextDimension,
1611    {
1612        self.edited_ranges_for_edit_ids(&transaction.edit_ids)
1613    }
1614
1615    pub fn subscribe(&mut self) -> Subscription {
1616        self.subscriptions.subscribe()
1617    }
1618
1619    pub fn wait_for_edits<It: IntoIterator<Item = clock::Lamport>>(
1620        &mut self,
1621        edit_ids: It,
1622    ) -> impl 'static + Future<Output = Result<()>> + use<It> {
1623        let mut futures = Vec::new();
1624        for edit_id in edit_ids {
1625            if !self.version.observed(edit_id) {
1626                let (tx, rx) = oneshot::channel();
1627                self.edit_id_resolvers.entry(edit_id).or_default().push(tx);
1628                futures.push(rx);
1629            }
1630        }
1631
1632        async move {
1633            for mut future in futures {
1634                if future.recv().await.is_none() {
1635                    anyhow::bail!("gave up waiting for edits");
1636                }
1637            }
1638            Ok(())
1639        }
1640    }
1641
1642    pub fn wait_for_anchors<It: IntoIterator<Item = Anchor>>(
1643        &mut self,
1644        anchors: It,
1645    ) -> impl 'static + Future<Output = Result<()>> + use<It> {
1646        let mut futures = Vec::new();
1647        for anchor in anchors {
1648            if !self.version.observed(anchor.timestamp)
1649                && anchor != Anchor::MAX
1650                && anchor != Anchor::MIN
1651            {
1652                let (tx, rx) = oneshot::channel();
1653                self.edit_id_resolvers
1654                    .entry(anchor.timestamp)
1655                    .or_default()
1656                    .push(tx);
1657                futures.push(rx);
1658            }
1659        }
1660
1661        async move {
1662            for mut future in futures {
1663                if future.recv().await.is_none() {
1664                    anyhow::bail!("gave up waiting for anchors");
1665                }
1666            }
1667            Ok(())
1668        }
1669    }
1670
1671    pub fn wait_for_version(
1672        &mut self,
1673        version: clock::Global,
1674    ) -> impl Future<Output = Result<()>> + use<> {
1675        let mut rx = None;
1676        if !self.snapshot.version.observed_all(&version) {
1677            let channel = oneshot::channel();
1678            self.wait_for_version_txs.push((version, channel.0));
1679            rx = Some(channel.1);
1680        }
1681        async move {
1682            if let Some(mut rx) = rx {
1683                if rx.recv().await.is_none() {
1684                    anyhow::bail!("gave up waiting for version");
1685                }
1686            }
1687            Ok(())
1688        }
1689    }
1690
1691    pub fn give_up_waiting(&mut self) {
1692        self.edit_id_resolvers.clear();
1693        self.wait_for_version_txs.clear();
1694    }
1695
1696    fn resolve_edit(&mut self, edit_id: clock::Lamport) {
1697        for mut tx in self
1698            .edit_id_resolvers
1699            .remove(&edit_id)
1700            .into_iter()
1701            .flatten()
1702        {
1703            tx.try_send(()).ok();
1704        }
1705    }
1706}
1707
1708#[cfg(any(test, feature = "test-support"))]
1709impl Buffer {
1710    #[track_caller]
1711    pub fn edit_via_marked_text(&mut self, marked_string: &str) {
1712        let edits = self.edits_for_marked_text(marked_string);
1713        self.edit(edits);
1714    }
1715
1716    #[track_caller]
1717    pub fn edits_for_marked_text(&self, marked_string: &str) -> Vec<(Range<usize>, String)> {
1718        let old_text = self.text();
1719        let (new_text, mut ranges) = util::test::marked_text_ranges(marked_string, false);
1720        if ranges.is_empty() {
1721            ranges.push(0..new_text.len());
1722        }
1723
1724        assert_eq!(
1725            old_text[..ranges[0].start],
1726            new_text[..ranges[0].start],
1727            "invalid edit"
1728        );
1729
1730        let mut delta = 0;
1731        let mut edits = Vec::new();
1732        let mut ranges = ranges.into_iter().peekable();
1733
1734        while let Some(inserted_range) = ranges.next() {
1735            let new_start = inserted_range.start;
1736            let old_start = (new_start as isize - delta) as usize;
1737
1738            let following_text = if let Some(next_range) = ranges.peek() {
1739                &new_text[inserted_range.end..next_range.start]
1740            } else {
1741                &new_text[inserted_range.end..]
1742            };
1743
1744            let inserted_len = inserted_range.len();
1745            let deleted_len = old_text[old_start..]
1746                .find(following_text)
1747                .expect("invalid edit");
1748
1749            let old_range = old_start..old_start + deleted_len;
1750            edits.push((old_range, new_text[inserted_range].to_string()));
1751            delta += inserted_len as isize - deleted_len as isize;
1752        }
1753
1754        assert_eq!(
1755            old_text.len() as isize + delta,
1756            new_text.len() as isize,
1757            "invalid edit"
1758        );
1759
1760        edits
1761    }
1762
1763    pub fn check_invariants(&self) {
1764        // Ensure every fragment is ordered by locator in the fragment tree and corresponds
1765        // to an insertion fragment in the insertions tree.
1766        let mut prev_fragment_id = Locator::min();
1767        for fragment in self.snapshot.fragments.items(&None) {
1768            assert!(fragment.id > prev_fragment_id);
1769            prev_fragment_id = fragment.id.clone();
1770
1771            let insertion_fragment = self
1772                .snapshot
1773                .insertions
1774                .get(
1775                    &InsertionFragmentKey {
1776                        timestamp: fragment.timestamp,
1777                        split_offset: fragment.insertion_offset,
1778                    },
1779                    &(),
1780                )
1781                .unwrap();
1782            assert_eq!(
1783                insertion_fragment.fragment_id, fragment.id,
1784                "fragment: {:?}\ninsertion: {:?}",
1785                fragment, insertion_fragment
1786            );
1787        }
1788
1789        let mut cursor = self.snapshot.fragments.cursor::<Option<&Locator>>(&None);
1790        for insertion_fragment in self.snapshot.insertions.cursor::<()>(&()) {
1791            cursor.seek(&Some(&insertion_fragment.fragment_id), Bias::Left);
1792            let fragment = cursor.item().unwrap();
1793            assert_eq!(insertion_fragment.fragment_id, fragment.id);
1794            assert_eq!(insertion_fragment.split_offset, fragment.insertion_offset);
1795        }
1796
1797        let fragment_summary = self.snapshot.fragments.summary();
1798        assert_eq!(
1799            fragment_summary.text.visible,
1800            self.snapshot.visible_text.len()
1801        );
1802        assert_eq!(
1803            fragment_summary.text.deleted,
1804            self.snapshot.deleted_text.len()
1805        );
1806
1807        assert!(!self.text().contains("\r\n"));
1808    }
1809
1810    pub fn set_group_interval(&mut self, group_interval: Duration) {
1811        self.history.group_interval = group_interval;
1812    }
1813
1814    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
1815        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
1816        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
1817        start..end
1818    }
1819
1820    pub fn get_random_edits<T>(
1821        &self,
1822        rng: &mut T,
1823        edit_count: usize,
1824    ) -> Vec<(Range<usize>, Arc<str>)>
1825    where
1826        T: rand::Rng,
1827    {
1828        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1829        let mut last_end = None;
1830        for _ in 0..edit_count {
1831            if last_end.map_or(false, |last_end| last_end >= self.len()) {
1832                break;
1833            }
1834            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1835            let range = self.random_byte_range(new_start, rng);
1836            last_end = Some(range.end);
1837
1838            let new_text_len = rng.gen_range(0..10);
1839            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1840
1841            edits.push((range, new_text.into()));
1842        }
1843        edits
1844    }
1845
1846    pub fn randomly_edit<T>(
1847        &mut self,
1848        rng: &mut T,
1849        edit_count: usize,
1850    ) -> (Vec<(Range<usize>, Arc<str>)>, Operation)
1851    where
1852        T: rand::Rng,
1853    {
1854        let mut edits = self.get_random_edits(rng, edit_count);
1855        log::info!("mutating buffer {} with {:?}", self.replica_id, edits);
1856
1857        let op = self.edit(edits.iter().cloned());
1858        if let Operation::Edit(edit) = &op {
1859            assert_eq!(edits.len(), edit.new_text.len());
1860            for (edit, new_text) in edits.iter_mut().zip(&edit.new_text) {
1861                edit.1 = new_text.clone();
1862            }
1863        } else {
1864            unreachable!()
1865        }
1866
1867        (edits, op)
1868    }
1869
1870    pub fn randomly_undo_redo(&mut self, rng: &mut impl rand::Rng) -> Vec<Operation> {
1871        use rand::prelude::*;
1872
1873        let mut ops = Vec::new();
1874        for _ in 0..rng.gen_range(1..=5) {
1875            if let Some(entry) = self.history.undo_stack.choose(rng) {
1876                let transaction = entry.transaction.clone();
1877                log::info!(
1878                    "undoing buffer {} transaction {:?}",
1879                    self.replica_id,
1880                    transaction
1881                );
1882                ops.push(self.undo_or_redo(transaction));
1883            }
1884        }
1885        ops
1886    }
1887}
1888
1889impl Deref for Buffer {
1890    type Target = BufferSnapshot;
1891
1892    fn deref(&self) -> &Self::Target {
1893        &self.snapshot
1894    }
1895}
1896
1897impl BufferSnapshot {
1898    pub fn as_rope(&self) -> &Rope {
1899        &self.visible_text
1900    }
1901
1902    pub fn rope_for_version(&self, version: &clock::Global) -> Rope {
1903        let mut rope = Rope::new();
1904
1905        let mut cursor = self
1906            .fragments
1907            .filter::<_, FragmentTextSummary>(&None, move |summary| {
1908                !version.observed_all(&summary.max_version)
1909            });
1910        cursor.next();
1911
1912        let mut visible_cursor = self.visible_text.cursor(0);
1913        let mut deleted_cursor = self.deleted_text.cursor(0);
1914
1915        while let Some(fragment) = cursor.item() {
1916            if cursor.start().visible > visible_cursor.offset() {
1917                let text = visible_cursor.slice(cursor.start().visible);
1918                rope.append(text);
1919            }
1920
1921            if fragment.was_visible(version, &self.undo_map) {
1922                if fragment.visible {
1923                    let text = visible_cursor.slice(cursor.end().visible);
1924                    rope.append(text);
1925                } else {
1926                    deleted_cursor.seek_forward(cursor.start().deleted);
1927                    let text = deleted_cursor.slice(cursor.end().deleted);
1928                    rope.append(text);
1929                }
1930            } else if fragment.visible {
1931                visible_cursor.seek_forward(cursor.end().visible);
1932            }
1933
1934            cursor.next();
1935        }
1936
1937        if cursor.start().visible > visible_cursor.offset() {
1938            let text = visible_cursor.slice(cursor.start().visible);
1939            rope.append(text);
1940        }
1941
1942        rope
1943    }
1944
1945    pub fn remote_id(&self) -> BufferId {
1946        self.remote_id
1947    }
1948
1949    pub fn replica_id(&self) -> ReplicaId {
1950        self.replica_id
1951    }
1952
1953    pub fn row_count(&self) -> u32 {
1954        self.max_point().row + 1
1955    }
1956
1957    pub fn len(&self) -> usize {
1958        self.visible_text.len()
1959    }
1960
1961    pub fn is_empty(&self) -> bool {
1962        self.len() == 0
1963    }
1964
1965    pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
1966        self.chars_at(0)
1967    }
1968
1969    pub fn chars_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = char> + '_ {
1970        self.text_for_range(range).flat_map(str::chars)
1971    }
1972
1973    pub fn reversed_chars_for_range<T: ToOffset>(
1974        &self,
1975        range: Range<T>,
1976    ) -> impl Iterator<Item = char> + '_ {
1977        self.reversed_chunks_in_range(range)
1978            .flat_map(|chunk| chunk.chars().rev())
1979    }
1980
1981    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1982    where
1983        T: ToOffset,
1984    {
1985        let position = position.to_offset(self);
1986        position == self.clip_offset(position, Bias::Left)
1987            && self
1988                .bytes_in_range(position..self.len())
1989                .flatten()
1990                .copied()
1991                .take(needle.len())
1992                .eq(needle.bytes())
1993    }
1994
1995    pub fn common_prefix_at<T>(&self, position: T, needle: &str) -> Range<T>
1996    where
1997        T: ToOffset + TextDimension,
1998    {
1999        let offset = position.to_offset(self);
2000        let common_prefix_len = needle
2001            .char_indices()
2002            .map(|(index, _)| index)
2003            .chain([needle.len()])
2004            .take_while(|&len| len <= offset)
2005            .filter(|&len| {
2006                let left = self
2007                    .chars_for_range(offset - len..offset)
2008                    .flat_map(char::to_lowercase);
2009                let right = needle[..len].chars().flat_map(char::to_lowercase);
2010                left.eq(right)
2011            })
2012            .last()
2013            .unwrap_or(0);
2014        let start_offset = offset - common_prefix_len;
2015        let start = self.text_summary_for_range(0..start_offset);
2016        start..position
2017    }
2018
2019    pub fn text(&self) -> String {
2020        self.visible_text.to_string()
2021    }
2022
2023    pub fn line_ending(&self) -> LineEnding {
2024        self.line_ending
2025    }
2026
2027    pub fn deleted_text(&self) -> String {
2028        self.deleted_text.to_string()
2029    }
2030
2031    pub fn fragments(&self) -> impl Iterator<Item = &Fragment> {
2032        self.fragments.iter()
2033    }
2034
2035    pub fn text_summary(&self) -> TextSummary {
2036        self.visible_text.summary()
2037    }
2038
2039    pub fn max_point(&self) -> Point {
2040        self.visible_text.max_point()
2041    }
2042
2043    pub fn max_point_utf16(&self) -> PointUtf16 {
2044        self.visible_text.max_point_utf16()
2045    }
2046
2047    pub fn point_to_offset(&self, point: Point) -> usize {
2048        self.visible_text.point_to_offset(point)
2049    }
2050
2051    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2052        self.visible_text.point_utf16_to_offset(point)
2053    }
2054
2055    pub fn unclipped_point_utf16_to_offset(&self, point: Unclipped<PointUtf16>) -> usize {
2056        self.visible_text.unclipped_point_utf16_to_offset(point)
2057    }
2058
2059    pub fn unclipped_point_utf16_to_point(&self, point: Unclipped<PointUtf16>) -> Point {
2060        self.visible_text.unclipped_point_utf16_to_point(point)
2061    }
2062
2063    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
2064        self.visible_text.offset_utf16_to_offset(offset)
2065    }
2066
2067    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2068        self.visible_text.offset_to_offset_utf16(offset)
2069    }
2070
2071    pub fn offset_to_point(&self, offset: usize) -> Point {
2072        self.visible_text.offset_to_point(offset)
2073    }
2074
2075    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2076        self.visible_text.offset_to_point_utf16(offset)
2077    }
2078
2079    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2080        self.visible_text.point_to_point_utf16(point)
2081    }
2082
2083    pub fn version(&self) -> &clock::Global {
2084        &self.version
2085    }
2086
2087    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2088        let offset = position.to_offset(self);
2089        self.visible_text.chars_at(offset)
2090    }
2091
2092    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2093        let offset = position.to_offset(self);
2094        self.visible_text.reversed_chars_at(offset)
2095    }
2096
2097    pub fn reversed_chunks_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Chunks<'_> {
2098        let range = range.start.to_offset(self)..range.end.to_offset(self);
2099        self.visible_text.reversed_chunks_in_range(range)
2100    }
2101
2102    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
2103        let start = range.start.to_offset(self);
2104        let end = range.end.to_offset(self);
2105        self.visible_text.bytes_in_range(start..end)
2106    }
2107
2108    pub fn reversed_bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
2109        let start = range.start.to_offset(self);
2110        let end = range.end.to_offset(self);
2111        self.visible_text.reversed_bytes_in_range(start..end)
2112    }
2113
2114    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> Chunks<'_> {
2115        let start = range.start.to_offset(self);
2116        let end = range.end.to_offset(self);
2117        self.visible_text.chunks_in_range(start..end)
2118    }
2119
2120    pub fn line_len(&self, row: u32) -> u32 {
2121        let row_start_offset = Point::new(row, 0).to_offset(self);
2122        let row_end_offset = if row >= self.max_point().row {
2123            self.len()
2124        } else {
2125            Point::new(row + 1, 0).to_offset(self) - 1
2126        };
2127        (row_end_offset - row_start_offset) as u32
2128    }
2129
2130    pub fn line_indents_in_row_range(
2131        &self,
2132        row_range: Range<u32>,
2133    ) -> impl Iterator<Item = (u32, LineIndent)> + '_ {
2134        let start = Point::new(row_range.start, 0).to_offset(self);
2135        let end = Point::new(row_range.end, self.line_len(row_range.end)).to_offset(self);
2136
2137        let mut chunks = self.as_rope().chunks_in_range(start..end);
2138        let mut row = row_range.start;
2139        let mut done = false;
2140        std::iter::from_fn(move || {
2141            if done {
2142                None
2143            } else {
2144                let indent = (row, LineIndent::from_chunks(&mut chunks));
2145                done = !chunks.next_line();
2146                row += 1;
2147                Some(indent)
2148            }
2149        })
2150    }
2151
2152    /// Returns the line indents in the given row range, exclusive of end row, in reversed order.
2153    pub fn reversed_line_indents_in_row_range(
2154        &self,
2155        row_range: Range<u32>,
2156    ) -> impl Iterator<Item = (u32, LineIndent)> + '_ {
2157        let start = Point::new(row_range.start, 0).to_offset(self);
2158
2159        let end_point;
2160        let end;
2161        if row_range.end > row_range.start {
2162            end_point = Point::new(row_range.end - 1, self.line_len(row_range.end - 1));
2163            end = end_point.to_offset(self);
2164        } else {
2165            end_point = Point::new(row_range.start, 0);
2166            end = start;
2167        };
2168
2169        let mut chunks = self.as_rope().chunks_in_range(start..end);
2170        // Move the cursor to the start of the last line if it's not empty.
2171        chunks.seek(end);
2172        if end_point.column > 0 {
2173            chunks.prev_line();
2174        }
2175
2176        let mut row = end_point.row;
2177        let mut done = false;
2178        std::iter::from_fn(move || {
2179            if done {
2180                None
2181            } else {
2182                let initial_offset = chunks.offset();
2183                let indent = (row, LineIndent::from_chunks(&mut chunks));
2184                if chunks.offset() > initial_offset {
2185                    chunks.prev_line();
2186                }
2187                done = !chunks.prev_line();
2188                if !done {
2189                    row -= 1;
2190                }
2191
2192                Some(indent)
2193            }
2194        })
2195    }
2196
2197    pub fn line_indent_for_row(&self, row: u32) -> LineIndent {
2198        LineIndent::from_iter(self.chars_at(Point::new(row, 0)))
2199    }
2200
2201    pub fn is_line_blank(&self, row: u32) -> bool {
2202        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
2203            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
2204    }
2205
2206    pub fn text_summary_for_range<D, O: ToOffset>(&self, range: Range<O>) -> D
2207    where
2208        D: TextDimension,
2209    {
2210        self.visible_text
2211            .cursor(range.start.to_offset(self))
2212            .summary(range.end.to_offset(self))
2213    }
2214
2215    pub fn summaries_for_anchors<'a, D, A>(&'a self, anchors: A) -> impl 'a + Iterator<Item = D>
2216    where
2217        D: 'a + TextDimension,
2218        A: 'a + IntoIterator<Item = &'a Anchor>,
2219    {
2220        let anchors = anchors.into_iter();
2221        self.summaries_for_anchors_with_payload::<D, _, ()>(anchors.map(|a| (a, ())))
2222            .map(|d| d.0)
2223    }
2224
2225    pub fn summaries_for_anchors_with_payload<'a, D, A, T>(
2226        &'a self,
2227        anchors: A,
2228    ) -> impl 'a + Iterator<Item = (D, T)>
2229    where
2230        D: 'a + TextDimension,
2231        A: 'a + IntoIterator<Item = (&'a Anchor, T)>,
2232    {
2233        let anchors = anchors.into_iter();
2234        let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(&());
2235        let mut fragment_cursor = self.fragments.cursor::<(Option<&Locator>, usize)>(&None);
2236        let mut text_cursor = self.visible_text.cursor(0);
2237        let mut position = D::zero(&());
2238
2239        anchors.map(move |(anchor, payload)| {
2240            if *anchor == Anchor::MIN {
2241                return (D::zero(&()), payload);
2242            } else if *anchor == Anchor::MAX {
2243                return (D::from_text_summary(&self.visible_text.summary()), payload);
2244            }
2245
2246            let anchor_key = InsertionFragmentKey {
2247                timestamp: anchor.timestamp,
2248                split_offset: anchor.offset,
2249            };
2250            insertion_cursor.seek(&anchor_key, anchor.bias);
2251            if let Some(insertion) = insertion_cursor.item() {
2252                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2253                if comparison == Ordering::Greater
2254                    || (anchor.bias == Bias::Left
2255                        && comparison == Ordering::Equal
2256                        && anchor.offset > 0)
2257                {
2258                    insertion_cursor.prev();
2259                }
2260            } else {
2261                insertion_cursor.prev();
2262            }
2263            let insertion = insertion_cursor.item().expect("invalid insertion");
2264            assert_eq!(insertion.timestamp, anchor.timestamp, "invalid insertion");
2265
2266            fragment_cursor.seek_forward(&Some(&insertion.fragment_id), Bias::Left);
2267            let fragment = fragment_cursor.item().unwrap();
2268            let mut fragment_offset = fragment_cursor.start().1;
2269            if fragment.visible {
2270                fragment_offset += anchor.offset - insertion.split_offset;
2271            }
2272
2273            position.add_assign(&text_cursor.summary(fragment_offset));
2274            (position, payload)
2275        })
2276    }
2277
2278    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2279    where
2280        D: TextDimension,
2281    {
2282        self.text_summary_for_range(0..self.offset_for_anchor(anchor))
2283    }
2284
2285    pub fn offset_for_anchor(&self, anchor: &Anchor) -> usize {
2286        if *anchor == Anchor::MIN {
2287            0
2288        } else if *anchor == Anchor::MAX {
2289            self.visible_text.len()
2290        } else {
2291            debug_assert!(anchor.buffer_id == Some(self.remote_id));
2292            let anchor_key = InsertionFragmentKey {
2293                timestamp: anchor.timestamp,
2294                split_offset: anchor.offset,
2295            };
2296            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(&());
2297            insertion_cursor.seek(&anchor_key, anchor.bias);
2298            if let Some(insertion) = insertion_cursor.item() {
2299                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2300                if comparison == Ordering::Greater
2301                    || (anchor.bias == Bias::Left
2302                        && comparison == Ordering::Equal
2303                        && anchor.offset > 0)
2304                {
2305                    insertion_cursor.prev();
2306                }
2307            } else {
2308                insertion_cursor.prev();
2309            }
2310
2311            let Some(insertion) = insertion_cursor
2312                .item()
2313                .filter(|insertion| insertion.timestamp == anchor.timestamp)
2314            else {
2315                panic!(
2316                    "invalid anchor {:?}. buffer id: {}, version: {:?}",
2317                    anchor, self.remote_id, self.version
2318                );
2319            };
2320
2321            let mut fragment_cursor = self.fragments.cursor::<(Option<&Locator>, usize)>(&None);
2322            fragment_cursor.seek(&Some(&insertion.fragment_id), Bias::Left);
2323            let fragment = fragment_cursor.item().unwrap();
2324            let mut fragment_offset = fragment_cursor.start().1;
2325            if fragment.visible {
2326                fragment_offset += anchor.offset - insertion.split_offset;
2327            }
2328            fragment_offset
2329        }
2330    }
2331
2332    fn fragment_id_for_anchor(&self, anchor: &Anchor) -> &Locator {
2333        self.try_fragment_id_for_anchor(anchor).unwrap_or_else(|| {
2334            panic!(
2335                "invalid anchor {:?}. buffer id: {}, version: {:?}",
2336                anchor, self.remote_id, self.version,
2337            )
2338        })
2339    }
2340
2341    fn try_fragment_id_for_anchor(&self, anchor: &Anchor) -> Option<&Locator> {
2342        if *anchor == Anchor::MIN {
2343            Some(Locator::min_ref())
2344        } else if *anchor == Anchor::MAX {
2345            Some(Locator::max_ref())
2346        } else {
2347            let anchor_key = InsertionFragmentKey {
2348                timestamp: anchor.timestamp,
2349                split_offset: anchor.offset,
2350            };
2351            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(&());
2352            insertion_cursor.seek(&anchor_key, anchor.bias);
2353            if let Some(insertion) = insertion_cursor.item() {
2354                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2355                if comparison == Ordering::Greater
2356                    || (anchor.bias == Bias::Left
2357                        && comparison == Ordering::Equal
2358                        && anchor.offset > 0)
2359                {
2360                    insertion_cursor.prev();
2361                }
2362            } else {
2363                insertion_cursor.prev();
2364            }
2365
2366            insertion_cursor
2367                .item()
2368                .filter(|insertion| {
2369                    !cfg!(debug_assertions) || insertion.timestamp == anchor.timestamp
2370                })
2371                .map(|insertion| &insertion.fragment_id)
2372        }
2373    }
2374
2375    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2376        self.anchor_at(position, Bias::Left)
2377    }
2378
2379    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2380        self.anchor_at(position, Bias::Right)
2381    }
2382
2383    pub fn anchor_at<T: ToOffset>(&self, position: T, bias: Bias) -> Anchor {
2384        self.anchor_at_offset(position.to_offset(self), bias)
2385    }
2386
2387    fn anchor_at_offset(&self, offset: usize, bias: Bias) -> Anchor {
2388        if bias == Bias::Left && offset == 0 {
2389            Anchor::MIN
2390        } else if bias == Bias::Right && offset == self.len() {
2391            Anchor::MAX
2392        } else {
2393            let mut fragment_cursor = self.fragments.cursor::<usize>(&None);
2394            fragment_cursor.seek(&offset, bias);
2395            let fragment = fragment_cursor.item().unwrap();
2396            let overshoot = offset - *fragment_cursor.start();
2397            Anchor {
2398                timestamp: fragment.timestamp,
2399                offset: fragment.insertion_offset + overshoot,
2400                bias,
2401                buffer_id: Some(self.remote_id),
2402            }
2403        }
2404    }
2405
2406    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2407        *anchor == Anchor::MIN
2408            || *anchor == Anchor::MAX
2409            || (Some(self.remote_id) == anchor.buffer_id && self.version.observed(anchor.timestamp))
2410    }
2411
2412    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2413        self.visible_text.clip_offset(offset, bias)
2414    }
2415
2416    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2417        self.visible_text.clip_point(point, bias)
2418    }
2419
2420    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2421        self.visible_text.clip_offset_utf16(offset, bias)
2422    }
2423
2424    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2425        self.visible_text.clip_point_utf16(point, bias)
2426    }
2427
2428    pub fn edits_since<'a, D>(
2429        &'a self,
2430        since: &'a clock::Global,
2431    ) -> impl 'a + Iterator<Item = Edit<D>>
2432    where
2433        D: TextDimension + Ord,
2434    {
2435        self.edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2436    }
2437
2438    pub fn anchored_edits_since<'a, D>(
2439        &'a self,
2440        since: &'a clock::Global,
2441    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2442    where
2443        D: TextDimension + Ord,
2444    {
2445        self.anchored_edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2446    }
2447
2448    pub fn edits_since_in_range<'a, D>(
2449        &'a self,
2450        since: &'a clock::Global,
2451        range: Range<Anchor>,
2452    ) -> impl 'a + Iterator<Item = Edit<D>>
2453    where
2454        D: TextDimension + Ord,
2455    {
2456        self.anchored_edits_since_in_range(since, range)
2457            .map(|item| item.0)
2458    }
2459
2460    pub fn anchored_edits_since_in_range<'a, D>(
2461        &'a self,
2462        since: &'a clock::Global,
2463        range: Range<Anchor>,
2464    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2465    where
2466        D: TextDimension + Ord,
2467    {
2468        let fragments_cursor = if *since == self.version {
2469            None
2470        } else {
2471            let mut cursor = self.fragments.filter(&None, move |summary| {
2472                !since.observed_all(&summary.max_version)
2473            });
2474            cursor.next();
2475            Some(cursor)
2476        };
2477        let mut cursor = self
2478            .fragments
2479            .cursor::<(Option<&Locator>, FragmentTextSummary)>(&None);
2480
2481        let start_fragment_id = self.fragment_id_for_anchor(&range.start);
2482        cursor.seek(&Some(start_fragment_id), Bias::Left);
2483        let mut visible_start = cursor.start().1.visible;
2484        let mut deleted_start = cursor.start().1.deleted;
2485        if let Some(fragment) = cursor.item() {
2486            let overshoot = range.start.offset - fragment.insertion_offset;
2487            if fragment.visible {
2488                visible_start += overshoot;
2489            } else {
2490                deleted_start += overshoot;
2491            }
2492        }
2493        let end_fragment_id = self.fragment_id_for_anchor(&range.end);
2494
2495        Edits {
2496            visible_cursor: self.visible_text.cursor(visible_start),
2497            deleted_cursor: self.deleted_text.cursor(deleted_start),
2498            fragments_cursor,
2499            undos: &self.undo_map,
2500            since,
2501            old_end: D::zero(&()),
2502            new_end: D::zero(&()),
2503            range: (start_fragment_id, range.start.offset)..(end_fragment_id, range.end.offset),
2504            buffer_id: self.remote_id,
2505        }
2506    }
2507
2508    pub fn has_edits_since_in_range(&self, since: &clock::Global, range: Range<Anchor>) -> bool {
2509        if *since != self.version {
2510            let start_fragment_id = self.fragment_id_for_anchor(&range.start);
2511            let end_fragment_id = self.fragment_id_for_anchor(&range.end);
2512            let mut cursor = self.fragments.filter::<_, usize>(&None, move |summary| {
2513                !since.observed_all(&summary.max_version)
2514            });
2515            cursor.next();
2516            while let Some(fragment) = cursor.item() {
2517                if fragment.id > *end_fragment_id {
2518                    break;
2519                }
2520                if fragment.id > *start_fragment_id {
2521                    let was_visible = fragment.was_visible(since, &self.undo_map);
2522                    let is_visible = fragment.visible;
2523                    if was_visible != is_visible {
2524                        return true;
2525                    }
2526                }
2527                cursor.next();
2528            }
2529        }
2530        false
2531    }
2532
2533    pub fn has_edits_since(&self, since: &clock::Global) -> bool {
2534        if *since != self.version {
2535            let mut cursor = self.fragments.filter::<_, usize>(&None, move |summary| {
2536                !since.observed_all(&summary.max_version)
2537            });
2538            cursor.next();
2539            while let Some(fragment) = cursor.item() {
2540                let was_visible = fragment.was_visible(since, &self.undo_map);
2541                let is_visible = fragment.visible;
2542                if was_visible != is_visible {
2543                    return true;
2544                }
2545                cursor.next();
2546            }
2547        }
2548        false
2549    }
2550
2551    pub fn range_to_version(&self, range: Range<usize>, version: &clock::Global) -> Range<usize> {
2552        let mut offsets = self.offsets_to_version([range.start, range.end], version);
2553        offsets.next().unwrap()..offsets.next().unwrap()
2554    }
2555
2556    /// Converts the given sequence of offsets into their corresponding offsets
2557    /// at a prior version of this buffer.
2558    pub fn offsets_to_version<'a>(
2559        &'a self,
2560        offsets: impl 'a + IntoIterator<Item = usize>,
2561        version: &'a clock::Global,
2562    ) -> impl 'a + Iterator<Item = usize> {
2563        let mut edits = self.edits_since(version).peekable();
2564        let mut last_old_end = 0;
2565        let mut last_new_end = 0;
2566        offsets.into_iter().map(move |new_offset| {
2567            while let Some(edit) = edits.peek() {
2568                if edit.new.start > new_offset {
2569                    break;
2570                }
2571
2572                if edit.new.end <= new_offset {
2573                    last_new_end = edit.new.end;
2574                    last_old_end = edit.old.end;
2575                    edits.next();
2576                    continue;
2577                }
2578
2579                let overshoot = new_offset - edit.new.start;
2580                return (edit.old.start + overshoot).min(edit.old.end);
2581            }
2582
2583            last_old_end + new_offset.saturating_sub(last_new_end)
2584        })
2585    }
2586}
2587
2588struct RopeBuilder<'a> {
2589    old_visible_cursor: rope::Cursor<'a>,
2590    old_deleted_cursor: rope::Cursor<'a>,
2591    new_visible: Rope,
2592    new_deleted: Rope,
2593}
2594
2595impl<'a> RopeBuilder<'a> {
2596    fn new(old_visible_cursor: rope::Cursor<'a>, old_deleted_cursor: rope::Cursor<'a>) -> Self {
2597        Self {
2598            old_visible_cursor,
2599            old_deleted_cursor,
2600            new_visible: Rope::new(),
2601            new_deleted: Rope::new(),
2602        }
2603    }
2604
2605    fn append(&mut self, len: FragmentTextSummary) {
2606        self.push(len.visible, true, true);
2607        self.push(len.deleted, false, false);
2608    }
2609
2610    fn push_fragment(&mut self, fragment: &Fragment, was_visible: bool) {
2611        debug_assert!(fragment.len > 0);
2612        self.push(fragment.len, was_visible, fragment.visible)
2613    }
2614
2615    fn push(&mut self, len: usize, was_visible: bool, is_visible: bool) {
2616        let text = if was_visible {
2617            self.old_visible_cursor
2618                .slice(self.old_visible_cursor.offset() + len)
2619        } else {
2620            self.old_deleted_cursor
2621                .slice(self.old_deleted_cursor.offset() + len)
2622        };
2623        if is_visible {
2624            self.new_visible.append(text);
2625        } else {
2626            self.new_deleted.append(text);
2627        }
2628    }
2629
2630    fn push_str(&mut self, text: &str) {
2631        self.new_visible.push(text);
2632    }
2633
2634    fn finish(mut self) -> (Rope, Rope) {
2635        self.new_visible.append(self.old_visible_cursor.suffix());
2636        self.new_deleted.append(self.old_deleted_cursor.suffix());
2637        (self.new_visible, self.new_deleted)
2638    }
2639}
2640
2641impl<D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator for Edits<'_, D, F> {
2642    type Item = (Edit<D>, Range<Anchor>);
2643
2644    fn next(&mut self) -> Option<Self::Item> {
2645        let mut pending_edit: Option<Self::Item> = None;
2646        let cursor = self.fragments_cursor.as_mut()?;
2647
2648        while let Some(fragment) = cursor.item() {
2649            if fragment.id < *self.range.start.0 {
2650                cursor.next();
2651                continue;
2652            } else if fragment.id > *self.range.end.0 {
2653                break;
2654            }
2655
2656            if cursor.start().visible > self.visible_cursor.offset() {
2657                let summary = self.visible_cursor.summary(cursor.start().visible);
2658                self.old_end.add_assign(&summary);
2659                self.new_end.add_assign(&summary);
2660            }
2661
2662            if pending_edit
2663                .as_ref()
2664                .map_or(false, |(change, _)| change.new.end < self.new_end)
2665            {
2666                break;
2667            }
2668
2669            let start_anchor = Anchor {
2670                timestamp: fragment.timestamp,
2671                offset: fragment.insertion_offset,
2672                bias: Bias::Right,
2673                buffer_id: Some(self.buffer_id),
2674            };
2675            let end_anchor = Anchor {
2676                timestamp: fragment.timestamp,
2677                offset: fragment.insertion_offset + fragment.len,
2678                bias: Bias::Left,
2679                buffer_id: Some(self.buffer_id),
2680            };
2681
2682            if !fragment.was_visible(self.since, self.undos) && fragment.visible {
2683                let mut visible_end = cursor.end().visible;
2684                if fragment.id == *self.range.end.0 {
2685                    visible_end = cmp::min(
2686                        visible_end,
2687                        cursor.start().visible + (self.range.end.1 - fragment.insertion_offset),
2688                    );
2689                }
2690
2691                let fragment_summary = self.visible_cursor.summary(visible_end);
2692                let mut new_end = self.new_end;
2693                new_end.add_assign(&fragment_summary);
2694                if let Some((edit, range)) = pending_edit.as_mut() {
2695                    edit.new.end = new_end;
2696                    range.end = end_anchor;
2697                } else {
2698                    pending_edit = Some((
2699                        Edit {
2700                            old: self.old_end..self.old_end,
2701                            new: self.new_end..new_end,
2702                        },
2703                        start_anchor..end_anchor,
2704                    ));
2705                }
2706
2707                self.new_end = new_end;
2708            } else if fragment.was_visible(self.since, self.undos) && !fragment.visible {
2709                let mut deleted_end = cursor.end().deleted;
2710                if fragment.id == *self.range.end.0 {
2711                    deleted_end = cmp::min(
2712                        deleted_end,
2713                        cursor.start().deleted + (self.range.end.1 - fragment.insertion_offset),
2714                    );
2715                }
2716
2717                if cursor.start().deleted > self.deleted_cursor.offset() {
2718                    self.deleted_cursor.seek_forward(cursor.start().deleted);
2719                }
2720                let fragment_summary = self.deleted_cursor.summary(deleted_end);
2721                let mut old_end = self.old_end;
2722                old_end.add_assign(&fragment_summary);
2723                if let Some((edit, range)) = pending_edit.as_mut() {
2724                    edit.old.end = old_end;
2725                    range.end = end_anchor;
2726                } else {
2727                    pending_edit = Some((
2728                        Edit {
2729                            old: self.old_end..old_end,
2730                            new: self.new_end..self.new_end,
2731                        },
2732                        start_anchor..end_anchor,
2733                    ));
2734                }
2735
2736                self.old_end = old_end;
2737            }
2738
2739            cursor.next();
2740        }
2741
2742        pending_edit
2743    }
2744}
2745
2746impl Fragment {
2747    fn is_visible(&self, undos: &UndoMap) -> bool {
2748        !undos.is_undone(self.timestamp) && self.deletions.iter().all(|d| undos.is_undone(*d))
2749    }
2750
2751    fn was_visible(&self, version: &clock::Global, undos: &UndoMap) -> bool {
2752        (version.observed(self.timestamp) && !undos.was_undone(self.timestamp, version))
2753            && self
2754                .deletions
2755                .iter()
2756                .all(|d| !version.observed(*d) || undos.was_undone(*d, version))
2757    }
2758}
2759
2760impl sum_tree::Item for Fragment {
2761    type Summary = FragmentSummary;
2762
2763    fn summary(&self, _cx: &Option<clock::Global>) -> Self::Summary {
2764        let mut max_version = clock::Global::new();
2765        max_version.observe(self.timestamp);
2766        for deletion in &self.deletions {
2767            max_version.observe(*deletion);
2768        }
2769        max_version.join(&self.max_undos);
2770
2771        let mut min_insertion_version = clock::Global::new();
2772        min_insertion_version.observe(self.timestamp);
2773        let max_insertion_version = min_insertion_version.clone();
2774        if self.visible {
2775            FragmentSummary {
2776                max_id: self.id.clone(),
2777                text: FragmentTextSummary {
2778                    visible: self.len,
2779                    deleted: 0,
2780                },
2781                max_version,
2782                min_insertion_version,
2783                max_insertion_version,
2784            }
2785        } else {
2786            FragmentSummary {
2787                max_id: self.id.clone(),
2788                text: FragmentTextSummary {
2789                    visible: 0,
2790                    deleted: self.len,
2791                },
2792                max_version,
2793                min_insertion_version,
2794                max_insertion_version,
2795            }
2796        }
2797    }
2798}
2799
2800impl sum_tree::Summary for FragmentSummary {
2801    type Context = Option<clock::Global>;
2802
2803    fn zero(_cx: &Self::Context) -> Self {
2804        Default::default()
2805    }
2806
2807    fn add_summary(&mut self, other: &Self, _: &Self::Context) {
2808        self.max_id.assign(&other.max_id);
2809        self.text.visible += &other.text.visible;
2810        self.text.deleted += &other.text.deleted;
2811        self.max_version.join(&other.max_version);
2812        self.min_insertion_version
2813            .meet(&other.min_insertion_version);
2814        self.max_insertion_version
2815            .join(&other.max_insertion_version);
2816    }
2817}
2818
2819impl Default for FragmentSummary {
2820    fn default() -> Self {
2821        FragmentSummary {
2822            max_id: Locator::min(),
2823            text: FragmentTextSummary::default(),
2824            max_version: clock::Global::new(),
2825            min_insertion_version: clock::Global::new(),
2826            max_insertion_version: clock::Global::new(),
2827        }
2828    }
2829}
2830
2831impl sum_tree::Item for InsertionFragment {
2832    type Summary = InsertionFragmentKey;
2833
2834    fn summary(&self, _cx: &()) -> Self::Summary {
2835        InsertionFragmentKey {
2836            timestamp: self.timestamp,
2837            split_offset: self.split_offset,
2838        }
2839    }
2840}
2841
2842impl sum_tree::KeyedItem for InsertionFragment {
2843    type Key = InsertionFragmentKey;
2844
2845    fn key(&self) -> Self::Key {
2846        sum_tree::Item::summary(self, &())
2847    }
2848}
2849
2850impl InsertionFragment {
2851    fn new(fragment: &Fragment) -> Self {
2852        Self {
2853            timestamp: fragment.timestamp,
2854            split_offset: fragment.insertion_offset,
2855            fragment_id: fragment.id.clone(),
2856        }
2857    }
2858
2859    fn insert_new(fragment: &Fragment) -> sum_tree::Edit<Self> {
2860        sum_tree::Edit::Insert(Self::new(fragment))
2861    }
2862}
2863
2864impl sum_tree::Summary for InsertionFragmentKey {
2865    type Context = ();
2866
2867    fn zero(_cx: &()) -> Self {
2868        Default::default()
2869    }
2870
2871    fn add_summary(&mut self, summary: &Self, _: &()) {
2872        *self = *summary;
2873    }
2874}
2875
2876#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
2877pub struct FullOffset(pub usize);
2878
2879impl ops::AddAssign<usize> for FullOffset {
2880    fn add_assign(&mut self, rhs: usize) {
2881        self.0 += rhs;
2882    }
2883}
2884
2885impl ops::Add<usize> for FullOffset {
2886    type Output = Self;
2887
2888    fn add(mut self, rhs: usize) -> Self::Output {
2889        self += rhs;
2890        self
2891    }
2892}
2893
2894impl ops::Sub for FullOffset {
2895    type Output = usize;
2896
2897    fn sub(self, rhs: Self) -> Self::Output {
2898        self.0 - rhs.0
2899    }
2900}
2901
2902impl sum_tree::Dimension<'_, FragmentSummary> for usize {
2903    fn zero(_: &Option<clock::Global>) -> Self {
2904        Default::default()
2905    }
2906
2907    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2908        *self += summary.text.visible;
2909    }
2910}
2911
2912impl sum_tree::Dimension<'_, FragmentSummary> for FullOffset {
2913    fn zero(_: &Option<clock::Global>) -> Self {
2914        Default::default()
2915    }
2916
2917    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2918        self.0 += summary.text.visible + summary.text.deleted;
2919    }
2920}
2921
2922impl<'a> sum_tree::Dimension<'a, FragmentSummary> for Option<&'a Locator> {
2923    fn zero(_: &Option<clock::Global>) -> Self {
2924        Default::default()
2925    }
2926
2927    fn add_summary(&mut self, summary: &'a FragmentSummary, _: &Option<clock::Global>) {
2928        *self = Some(&summary.max_id);
2929    }
2930}
2931
2932impl sum_tree::SeekTarget<'_, FragmentSummary, FragmentTextSummary> for usize {
2933    fn cmp(
2934        &self,
2935        cursor_location: &FragmentTextSummary,
2936        _: &Option<clock::Global>,
2937    ) -> cmp::Ordering {
2938        Ord::cmp(self, &cursor_location.visible)
2939    }
2940}
2941
2942#[derive(Copy, Clone, Debug, Eq, PartialEq)]
2943enum VersionedFullOffset {
2944    Offset(FullOffset),
2945    Invalid,
2946}
2947
2948impl VersionedFullOffset {
2949    fn full_offset(&self) -> FullOffset {
2950        if let Self::Offset(position) = self {
2951            *position
2952        } else {
2953            panic!("invalid version")
2954        }
2955    }
2956}
2957
2958impl Default for VersionedFullOffset {
2959    fn default() -> Self {
2960        Self::Offset(Default::default())
2961    }
2962}
2963
2964impl<'a> sum_tree::Dimension<'a, FragmentSummary> for VersionedFullOffset {
2965    fn zero(_cx: &Option<clock::Global>) -> Self {
2966        Default::default()
2967    }
2968
2969    fn add_summary(&mut self, summary: &'a FragmentSummary, cx: &Option<clock::Global>) {
2970        if let Self::Offset(offset) = self {
2971            let version = cx.as_ref().unwrap();
2972            if version.observed_all(&summary.max_insertion_version) {
2973                *offset += summary.text.visible + summary.text.deleted;
2974            } else if version.observed_any(&summary.min_insertion_version) {
2975                *self = Self::Invalid;
2976            }
2977        }
2978    }
2979}
2980
2981impl sum_tree::SeekTarget<'_, FragmentSummary, Self> for VersionedFullOffset {
2982    fn cmp(&self, cursor_position: &Self, _: &Option<clock::Global>) -> cmp::Ordering {
2983        match (self, cursor_position) {
2984            (Self::Offset(a), Self::Offset(b)) => Ord::cmp(a, b),
2985            (Self::Offset(_), Self::Invalid) => cmp::Ordering::Less,
2986            (Self::Invalid, _) => unreachable!(),
2987        }
2988    }
2989}
2990
2991impl Operation {
2992    fn replica_id(&self) -> ReplicaId {
2993        operation_queue::Operation::lamport_timestamp(self).replica_id
2994    }
2995
2996    pub fn timestamp(&self) -> clock::Lamport {
2997        match self {
2998            Operation::Edit(edit) => edit.timestamp,
2999            Operation::Undo(undo) => undo.timestamp,
3000        }
3001    }
3002
3003    pub fn as_edit(&self) -> Option<&EditOperation> {
3004        match self {
3005            Operation::Edit(edit) => Some(edit),
3006            _ => None,
3007        }
3008    }
3009
3010    pub fn is_edit(&self) -> bool {
3011        matches!(self, Operation::Edit { .. })
3012    }
3013}
3014
3015impl operation_queue::Operation for Operation {
3016    fn lamport_timestamp(&self) -> clock::Lamport {
3017        match self {
3018            Operation::Edit(edit) => edit.timestamp,
3019            Operation::Undo(undo) => undo.timestamp,
3020        }
3021    }
3022}
3023
3024pub trait ToOffset {
3025    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize;
3026}
3027
3028impl ToOffset for Point {
3029    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3030        snapshot.point_to_offset(*self)
3031    }
3032}
3033
3034impl ToOffset for usize {
3035    #[track_caller]
3036    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3037        assert!(
3038            *self <= snapshot.len(),
3039            "offset {} is out of range, max allowed is {}",
3040            self,
3041            snapshot.len()
3042        );
3043        *self
3044    }
3045}
3046
3047impl ToOffset for Anchor {
3048    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3049        snapshot.summary_for_anchor(self)
3050    }
3051}
3052
3053impl<T: ToOffset> ToOffset for &T {
3054    fn to_offset(&self, content: &BufferSnapshot) -> usize {
3055        (*self).to_offset(content)
3056    }
3057}
3058
3059impl ToOffset for PointUtf16 {
3060    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3061        snapshot.point_utf16_to_offset(*self)
3062    }
3063}
3064
3065impl ToOffset for Unclipped<PointUtf16> {
3066    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3067        snapshot.unclipped_point_utf16_to_offset(*self)
3068    }
3069}
3070
3071pub trait ToPoint {
3072    fn to_point(&self, snapshot: &BufferSnapshot) -> Point;
3073}
3074
3075impl ToPoint for Anchor {
3076    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3077        snapshot.summary_for_anchor(self)
3078    }
3079}
3080
3081impl ToPoint for usize {
3082    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3083        snapshot.offset_to_point(*self)
3084    }
3085}
3086
3087impl ToPoint for Point {
3088    fn to_point(&self, _: &BufferSnapshot) -> Point {
3089        *self
3090    }
3091}
3092
3093impl ToPoint for Unclipped<PointUtf16> {
3094    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3095        snapshot.unclipped_point_utf16_to_point(*self)
3096    }
3097}
3098
3099pub trait ToPointUtf16 {
3100    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16;
3101}
3102
3103impl ToPointUtf16 for Anchor {
3104    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3105        snapshot.summary_for_anchor(self)
3106    }
3107}
3108
3109impl ToPointUtf16 for usize {
3110    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3111        snapshot.offset_to_point_utf16(*self)
3112    }
3113}
3114
3115impl ToPointUtf16 for PointUtf16 {
3116    fn to_point_utf16(&self, _: &BufferSnapshot) -> PointUtf16 {
3117        *self
3118    }
3119}
3120
3121impl ToPointUtf16 for Point {
3122    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3123        snapshot.point_to_point_utf16(*self)
3124    }
3125}
3126
3127pub trait ToOffsetUtf16 {
3128    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16;
3129}
3130
3131impl ToOffsetUtf16 for Anchor {
3132    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
3133        snapshot.summary_for_anchor(self)
3134    }
3135}
3136
3137impl ToOffsetUtf16 for usize {
3138    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
3139        snapshot.offset_to_offset_utf16(*self)
3140    }
3141}
3142
3143impl ToOffsetUtf16 for OffsetUtf16 {
3144    fn to_offset_utf16(&self, _snapshot: &BufferSnapshot) -> OffsetUtf16 {
3145        *self
3146    }
3147}
3148
3149pub trait FromAnchor {
3150    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self;
3151}
3152
3153impl FromAnchor for Anchor {
3154    fn from_anchor(anchor: &Anchor, _snapshot: &BufferSnapshot) -> Self {
3155        *anchor
3156    }
3157}
3158
3159impl FromAnchor for Point {
3160    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3161        snapshot.summary_for_anchor(anchor)
3162    }
3163}
3164
3165impl FromAnchor for PointUtf16 {
3166    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3167        snapshot.summary_for_anchor(anchor)
3168    }
3169}
3170
3171impl FromAnchor for usize {
3172    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3173        snapshot.summary_for_anchor(anchor)
3174    }
3175}
3176
3177#[derive(Clone, Copy, Debug, PartialEq)]
3178pub enum LineEnding {
3179    Unix,
3180    Windows,
3181}
3182
3183impl Default for LineEnding {
3184    fn default() -> Self {
3185        #[cfg(unix)]
3186        return Self::Unix;
3187
3188        #[cfg(not(unix))]
3189        return Self::Windows;
3190    }
3191}
3192
3193impl LineEnding {
3194    pub fn as_str(&self) -> &'static str {
3195        match self {
3196            LineEnding::Unix => "\n",
3197            LineEnding::Windows => "\r\n",
3198        }
3199    }
3200
3201    pub fn detect(text: &str) -> Self {
3202        let mut max_ix = cmp::min(text.len(), 1000);
3203        while !text.is_char_boundary(max_ix) {
3204            max_ix -= 1;
3205        }
3206
3207        if let Some(ix) = text[..max_ix].find(['\n']) {
3208            if ix > 0 && text.as_bytes()[ix - 1] == b'\r' {
3209                Self::Windows
3210            } else {
3211                Self::Unix
3212            }
3213        } else {
3214            Self::default()
3215        }
3216    }
3217
3218    pub fn normalize(text: &mut String) {
3219        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(text, "\n") {
3220            *text = replaced;
3221        }
3222    }
3223
3224    pub fn normalize_arc(text: Arc<str>) -> Arc<str> {
3225        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(&text, "\n") {
3226            replaced.into()
3227        } else {
3228            text
3229        }
3230    }
3231
3232    pub fn normalize_cow(text: Cow<str>) -> Cow<str> {
3233        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(&text, "\n") {
3234            replaced.into()
3235        } else {
3236            text
3237        }
3238    }
3239}