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::Lamport;
  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::{Dimensions, 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            && let Some(destination) = self.transaction_mut(destination)
 451        {
 452            destination.edit_ids.extend(transaction.edit_ids);
 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, 'static, 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, 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: ReplicaId, 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: ReplicaId,
 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::new(ReplicaId::LOCAL);
 735            lamport_clock.observe(insertion_timestamp);
 736            version.observe(insertion_timestamp);
 737            let fragment_id = Locator::between(&Locator::min(), &Locator::max());
 738            let fragment = Fragment {
 739                id: fragment_id,
 740                timestamp: insertion_timestamp,
 741                insertion_offset: 0,
 742                len: visible_text.len(),
 743                visible: true,
 744                deletions: Default::default(),
 745                max_undos: Default::default(),
 746            };
 747            insertions.push(InsertionFragment::new(&fragment), ());
 748            fragments.push(fragment, &None);
 749        }
 750
 751        Buffer {
 752            snapshot: BufferSnapshot {
 753                replica_id,
 754                remote_id,
 755                visible_text,
 756                deleted_text: Rope::new(),
 757                line_ending,
 758                fragments,
 759                insertions,
 760                version,
 761                undo_map: Default::default(),
 762                insertion_slices: Default::default(),
 763            },
 764            history,
 765            deferred_ops: OperationQueue::new(),
 766            deferred_replicas: HashSet::default(),
 767            lamport_clock,
 768            subscriptions: Default::default(),
 769            edit_id_resolvers: Default::default(),
 770            wait_for_version_txs: Default::default(),
 771        }
 772    }
 773
 774    pub fn version(&self) -> clock::Global {
 775        self.version.clone()
 776    }
 777
 778    pub fn snapshot(&self) -> BufferSnapshot {
 779        self.snapshot.clone()
 780    }
 781
 782    pub fn branch(&self) -> Self {
 783        Self {
 784            snapshot: self.snapshot.clone(),
 785            history: History::new(self.base_text().clone()),
 786            deferred_ops: OperationQueue::new(),
 787            deferred_replicas: HashSet::default(),
 788            lamport_clock: clock::Lamport::new(ReplicaId::LOCAL_BRANCH),
 789            subscriptions: Default::default(),
 790            edit_id_resolvers: Default::default(),
 791            wait_for_version_txs: Default::default(),
 792        }
 793    }
 794
 795    pub fn replica_id(&self) -> ReplicaId {
 796        self.lamport_clock.replica_id
 797    }
 798
 799    pub fn remote_id(&self) -> BufferId {
 800        self.remote_id
 801    }
 802
 803    pub fn deferred_ops_len(&self) -> usize {
 804        self.deferred_ops.len()
 805    }
 806
 807    pub fn transaction_group_interval(&self) -> Duration {
 808        self.history.group_interval
 809    }
 810
 811    pub fn edit<R, I, S, T>(&mut self, edits: R) -> Operation
 812    where
 813        R: IntoIterator<IntoIter = I>,
 814        I: ExactSizeIterator<Item = (Range<S>, T)>,
 815        S: ToOffset,
 816        T: Into<Arc<str>>,
 817    {
 818        let edits = edits
 819            .into_iter()
 820            .map(|(range, new_text)| (range, new_text.into()));
 821
 822        self.start_transaction();
 823        let timestamp = self.lamport_clock.tick();
 824        let operation = Operation::Edit(self.apply_local_edit(edits, timestamp));
 825
 826        self.history.push(operation.clone());
 827        self.history.push_undo(operation.timestamp());
 828        self.snapshot.version.observe(operation.timestamp());
 829        self.end_transaction();
 830        operation
 831    }
 832
 833    fn apply_local_edit<S: ToOffset, T: Into<Arc<str>>>(
 834        &mut self,
 835        edits: impl ExactSizeIterator<Item = (Range<S>, T)>,
 836        timestamp: clock::Lamport,
 837    ) -> EditOperation {
 838        let mut edits_patch = Patch::default();
 839        let mut edit_op = EditOperation {
 840            timestamp,
 841            version: self.version(),
 842            ranges: Vec::with_capacity(edits.len()),
 843            new_text: Vec::with_capacity(edits.len()),
 844        };
 845        let mut new_insertions = Vec::new();
 846        let mut insertion_offset = 0;
 847        let mut insertion_slices = Vec::new();
 848
 849        let mut edits = edits
 850            .map(|(range, new_text)| (range.to_offset(&*self), new_text))
 851            .peekable();
 852
 853        let mut new_ropes =
 854            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
 855        let mut old_fragments = self.fragments.cursor::<FragmentTextSummary>(&None);
 856        let mut new_fragments = old_fragments.slice(&edits.peek().unwrap().0.start, Bias::Right);
 857        new_ropes.append(new_fragments.summary().text);
 858
 859        let mut fragment_start = old_fragments.start().visible;
 860        for (range, new_text) in edits {
 861            let new_text = LineEnding::normalize_arc(new_text.into());
 862            let fragment_end = old_fragments.end().visible;
 863
 864            // If the current fragment ends before this range, then jump ahead to the first fragment
 865            // that extends past the start of this range, reusing any intervening fragments.
 866            if fragment_end < range.start {
 867                // If the current fragment has been partially consumed, then consume the rest of it
 868                // and advance to the next fragment before slicing.
 869                if fragment_start > old_fragments.start().visible {
 870                    if fragment_end > fragment_start {
 871                        let mut suffix = old_fragments.item().unwrap().clone();
 872                        suffix.len = fragment_end - fragment_start;
 873                        suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 874                        new_insertions.push(InsertionFragment::insert_new(&suffix));
 875                        new_ropes.push_fragment(&suffix, suffix.visible);
 876                        new_fragments.push(suffix, &None);
 877                    }
 878                    old_fragments.next();
 879                }
 880
 881                let slice = old_fragments.slice(&range.start, Bias::Right);
 882                new_ropes.append(slice.summary().text);
 883                new_fragments.append(slice, &None);
 884                fragment_start = old_fragments.start().visible;
 885            }
 886
 887            let full_range_start = FullOffset(range.start + old_fragments.start().deleted);
 888
 889            // Preserve any portion of the current fragment that precedes this range.
 890            if fragment_start < range.start {
 891                let mut prefix = old_fragments.item().unwrap().clone();
 892                prefix.len = range.start - fragment_start;
 893                prefix.insertion_offset += fragment_start - old_fragments.start().visible;
 894                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
 895                new_insertions.push(InsertionFragment::insert_new(&prefix));
 896                new_ropes.push_fragment(&prefix, prefix.visible);
 897                new_fragments.push(prefix, &None);
 898                fragment_start = range.start;
 899            }
 900
 901            // Insert the new text before any existing fragments within the range.
 902            if !new_text.is_empty() {
 903                let new_start = new_fragments.summary().text.visible;
 904
 905                let fragment = Fragment {
 906                    id: Locator::between(
 907                        &new_fragments.summary().max_id,
 908                        old_fragments
 909                            .item()
 910                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
 911                    ),
 912                    timestamp,
 913                    insertion_offset,
 914                    len: new_text.len(),
 915                    deletions: Default::default(),
 916                    max_undos: Default::default(),
 917                    visible: true,
 918                };
 919                edits_patch.push(Edit {
 920                    old: fragment_start..fragment_start,
 921                    new: new_start..new_start + new_text.len(),
 922                });
 923                insertion_slices.push(InsertionSlice::from_fragment(timestamp, &fragment));
 924                new_insertions.push(InsertionFragment::insert_new(&fragment));
 925                new_ropes.push_str(new_text.as_ref());
 926                new_fragments.push(fragment, &None);
 927                insertion_offset += new_text.len();
 928            }
 929
 930            // Advance through every fragment that intersects this range, marking the intersecting
 931            // portions as deleted.
 932            while fragment_start < range.end {
 933                let fragment = old_fragments.item().unwrap();
 934                let fragment_end = old_fragments.end().visible;
 935                let mut intersection = fragment.clone();
 936                let intersection_end = cmp::min(range.end, fragment_end);
 937                if fragment.visible {
 938                    intersection.len = intersection_end - fragment_start;
 939                    intersection.insertion_offset += fragment_start - old_fragments.start().visible;
 940                    intersection.id =
 941                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
 942                    intersection.deletions.insert(timestamp);
 943                    intersection.visible = false;
 944                }
 945                if intersection.len > 0 {
 946                    if fragment.visible && !intersection.visible {
 947                        let new_start = new_fragments.summary().text.visible;
 948                        edits_patch.push(Edit {
 949                            old: fragment_start..intersection_end,
 950                            new: new_start..new_start,
 951                        });
 952                        insertion_slices
 953                            .push(InsertionSlice::from_fragment(timestamp, &intersection));
 954                    }
 955                    new_insertions.push(InsertionFragment::insert_new(&intersection));
 956                    new_ropes.push_fragment(&intersection, fragment.visible);
 957                    new_fragments.push(intersection, &None);
 958                    fragment_start = intersection_end;
 959                }
 960                if fragment_end <= range.end {
 961                    old_fragments.next();
 962                }
 963            }
 964
 965            let full_range_end = FullOffset(range.end + old_fragments.start().deleted);
 966            edit_op.ranges.push(full_range_start..full_range_end);
 967            edit_op.new_text.push(new_text);
 968        }
 969
 970        // If the current fragment has been partially consumed, then consume the rest of it
 971        // and advance to the next fragment before slicing.
 972        if fragment_start > old_fragments.start().visible {
 973            let fragment_end = old_fragments.end().visible;
 974            if fragment_end > fragment_start {
 975                let mut suffix = old_fragments.item().unwrap().clone();
 976                suffix.len = fragment_end - fragment_start;
 977                suffix.insertion_offset += fragment_start - old_fragments.start().visible;
 978                new_insertions.push(InsertionFragment::insert_new(&suffix));
 979                new_ropes.push_fragment(&suffix, suffix.visible);
 980                new_fragments.push(suffix, &None);
 981            }
 982            old_fragments.next();
 983        }
 984
 985        let suffix = old_fragments.suffix();
 986        new_ropes.append(suffix.summary().text);
 987        new_fragments.append(suffix, &None);
 988        let (visible_text, deleted_text) = new_ropes.finish();
 989        drop(old_fragments);
 990
 991        self.snapshot.fragments = new_fragments;
 992        self.snapshot.insertions.edit(new_insertions, ());
 993        self.snapshot.visible_text = visible_text;
 994        self.snapshot.deleted_text = deleted_text;
 995        self.subscriptions.publish_mut(&edits_patch);
 996        self.snapshot.insertion_slices.extend(insertion_slices);
 997        edit_op
 998    }
 999
1000    pub fn set_line_ending(&mut self, line_ending: LineEnding) {
1001        self.snapshot.line_ending = line_ending;
1002    }
1003
1004    pub fn apply_ops<I: IntoIterator<Item = Operation>>(&mut self, ops: I) {
1005        let mut deferred_ops = Vec::new();
1006        for op in ops {
1007            self.history.push(op.clone());
1008            if self.can_apply_op(&op) {
1009                self.apply_op(op);
1010            } else {
1011                self.deferred_replicas.insert(op.replica_id());
1012                deferred_ops.push(op);
1013            }
1014        }
1015        self.deferred_ops.insert(deferred_ops);
1016        self.flush_deferred_ops();
1017    }
1018
1019    fn apply_op(&mut self, op: Operation) {
1020        match op {
1021            Operation::Edit(edit) => {
1022                if !self.version.observed(edit.timestamp) {
1023                    self.apply_remote_edit(
1024                        &edit.version,
1025                        &edit.ranges,
1026                        &edit.new_text,
1027                        edit.timestamp,
1028                    );
1029                    self.snapshot.version.observe(edit.timestamp);
1030                    self.lamport_clock.observe(edit.timestamp);
1031                    self.resolve_edit(edit.timestamp);
1032                }
1033            }
1034            Operation::Undo(undo) => {
1035                if !self.version.observed(undo.timestamp) {
1036                    self.apply_undo(&undo);
1037                    self.snapshot.version.observe(undo.timestamp);
1038                    self.lamport_clock.observe(undo.timestamp);
1039                }
1040            }
1041        }
1042        self.wait_for_version_txs.retain_mut(|(version, tx)| {
1043            if self.snapshot.version().observed_all(version) {
1044                tx.try_send(()).ok();
1045                false
1046            } else {
1047                true
1048            }
1049        });
1050    }
1051
1052    fn apply_remote_edit(
1053        &mut self,
1054        version: &clock::Global,
1055        ranges: &[Range<FullOffset>],
1056        new_text: &[Arc<str>],
1057        timestamp: clock::Lamport,
1058    ) {
1059        if ranges.is_empty() {
1060            return;
1061        }
1062
1063        let edits = ranges.iter().zip(new_text.iter());
1064        let mut edits_patch = Patch::default();
1065        let mut insertion_slices = Vec::new();
1066        let cx = Some(version.clone());
1067        let mut new_insertions = Vec::new();
1068        let mut insertion_offset = 0;
1069        let mut new_ropes =
1070            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
1071        let mut old_fragments = self
1072            .fragments
1073            .cursor::<Dimensions<VersionedFullOffset, usize>>(&cx);
1074        let mut new_fragments =
1075            old_fragments.slice(&VersionedFullOffset::Offset(ranges[0].start), Bias::Left);
1076        new_ropes.append(new_fragments.summary().text);
1077
1078        let mut fragment_start = old_fragments.start().0.full_offset();
1079        for (range, new_text) in edits {
1080            let fragment_end = old_fragments.end().0.full_offset();
1081
1082            // If the current fragment ends before this range, then jump ahead to the first fragment
1083            // that extends past the start of this range, reusing any intervening fragments.
1084            if fragment_end < range.start {
1085                // If the current fragment has been partially consumed, then consume the rest of it
1086                // and advance to the next fragment before slicing.
1087                if fragment_start > old_fragments.start().0.full_offset() {
1088                    if fragment_end > fragment_start {
1089                        let mut suffix = old_fragments.item().unwrap().clone();
1090                        suffix.len = fragment_end.0 - fragment_start.0;
1091                        suffix.insertion_offset +=
1092                            fragment_start - old_fragments.start().0.full_offset();
1093                        new_insertions.push(InsertionFragment::insert_new(&suffix));
1094                        new_ropes.push_fragment(&suffix, suffix.visible);
1095                        new_fragments.push(suffix, &None);
1096                    }
1097                    old_fragments.next();
1098                }
1099
1100                let slice =
1101                    old_fragments.slice(&VersionedFullOffset::Offset(range.start), Bias::Left);
1102                new_ropes.append(slice.summary().text);
1103                new_fragments.append(slice, &None);
1104                fragment_start = old_fragments.start().0.full_offset();
1105            }
1106
1107            // If we are at the end of a non-concurrent fragment, advance to the next one.
1108            let fragment_end = old_fragments.end().0.full_offset();
1109            if fragment_end == range.start && fragment_end > fragment_start {
1110                let mut fragment = old_fragments.item().unwrap().clone();
1111                fragment.len = fragment_end.0 - fragment_start.0;
1112                fragment.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1113                new_insertions.push(InsertionFragment::insert_new(&fragment));
1114                new_ropes.push_fragment(&fragment, fragment.visible);
1115                new_fragments.push(fragment, &None);
1116                old_fragments.next();
1117                fragment_start = old_fragments.start().0.full_offset();
1118            }
1119
1120            // Skip over insertions that are concurrent to this edit, but have a lower lamport
1121            // timestamp.
1122            while let Some(fragment) = old_fragments.item() {
1123                if fragment_start == range.start && fragment.timestamp > timestamp {
1124                    new_ropes.push_fragment(fragment, fragment.visible);
1125                    new_fragments.push(fragment.clone(), &None);
1126                    old_fragments.next();
1127                    debug_assert_eq!(fragment_start, range.start);
1128                } else {
1129                    break;
1130                }
1131            }
1132            debug_assert!(fragment_start <= range.start);
1133
1134            // Preserve any portion of the current fragment that precedes this range.
1135            if fragment_start < range.start {
1136                let mut prefix = old_fragments.item().unwrap().clone();
1137                prefix.len = range.start.0 - fragment_start.0;
1138                prefix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1139                prefix.id = Locator::between(&new_fragments.summary().max_id, &prefix.id);
1140                new_insertions.push(InsertionFragment::insert_new(&prefix));
1141                fragment_start = range.start;
1142                new_ropes.push_fragment(&prefix, prefix.visible);
1143                new_fragments.push(prefix, &None);
1144            }
1145
1146            // Insert the new text before any existing fragments within the range.
1147            if !new_text.is_empty() {
1148                let mut old_start = old_fragments.start().1;
1149                if old_fragments.item().is_some_and(|f| f.visible) {
1150                    old_start += fragment_start.0 - old_fragments.start().0.full_offset().0;
1151                }
1152                let new_start = new_fragments.summary().text.visible;
1153                let fragment = Fragment {
1154                    id: Locator::between(
1155                        &new_fragments.summary().max_id,
1156                        old_fragments
1157                            .item()
1158                            .map_or(&Locator::max(), |old_fragment| &old_fragment.id),
1159                    ),
1160                    timestamp,
1161                    insertion_offset,
1162                    len: new_text.len(),
1163                    deletions: Default::default(),
1164                    max_undos: Default::default(),
1165                    visible: true,
1166                };
1167                edits_patch.push(Edit {
1168                    old: old_start..old_start,
1169                    new: new_start..new_start + new_text.len(),
1170                });
1171                insertion_slices.push(InsertionSlice::from_fragment(timestamp, &fragment));
1172                new_insertions.push(InsertionFragment::insert_new(&fragment));
1173                new_ropes.push_str(new_text);
1174                new_fragments.push(fragment, &None);
1175                insertion_offset += new_text.len();
1176            }
1177
1178            // Advance through every fragment that intersects this range, marking the intersecting
1179            // portions as deleted.
1180            while fragment_start < range.end {
1181                let fragment = old_fragments.item().unwrap();
1182                let fragment_end = old_fragments.end().0.full_offset();
1183                let mut intersection = fragment.clone();
1184                let intersection_end = cmp::min(range.end, fragment_end);
1185                if fragment.was_visible(version, &self.undo_map) {
1186                    intersection.len = intersection_end.0 - fragment_start.0;
1187                    intersection.insertion_offset +=
1188                        fragment_start - old_fragments.start().0.full_offset();
1189                    intersection.id =
1190                        Locator::between(&new_fragments.summary().max_id, &intersection.id);
1191                    intersection.deletions.insert(timestamp);
1192                    intersection.visible = false;
1193                    insertion_slices.push(InsertionSlice::from_fragment(timestamp, &intersection));
1194                }
1195                if intersection.len > 0 {
1196                    if fragment.visible && !intersection.visible {
1197                        let old_start = old_fragments.start().1
1198                            + (fragment_start.0 - old_fragments.start().0.full_offset().0);
1199                        let new_start = new_fragments.summary().text.visible;
1200                        edits_patch.push(Edit {
1201                            old: old_start..old_start + intersection.len,
1202                            new: new_start..new_start,
1203                        });
1204                    }
1205                    new_insertions.push(InsertionFragment::insert_new(&intersection));
1206                    new_ropes.push_fragment(&intersection, fragment.visible);
1207                    new_fragments.push(intersection, &None);
1208                    fragment_start = intersection_end;
1209                }
1210                if fragment_end <= range.end {
1211                    old_fragments.next();
1212                }
1213            }
1214        }
1215
1216        // If the current fragment has been partially consumed, then consume the rest of it
1217        // and advance to the next fragment before slicing.
1218        if fragment_start > old_fragments.start().0.full_offset() {
1219            let fragment_end = old_fragments.end().0.full_offset();
1220            if fragment_end > fragment_start {
1221                let mut suffix = old_fragments.item().unwrap().clone();
1222                suffix.len = fragment_end.0 - fragment_start.0;
1223                suffix.insertion_offset += fragment_start - old_fragments.start().0.full_offset();
1224                new_insertions.push(InsertionFragment::insert_new(&suffix));
1225                new_ropes.push_fragment(&suffix, suffix.visible);
1226                new_fragments.push(suffix, &None);
1227            }
1228            old_fragments.next();
1229        }
1230
1231        let suffix = old_fragments.suffix();
1232        new_ropes.append(suffix.summary().text);
1233        new_fragments.append(suffix, &None);
1234        let (visible_text, deleted_text) = new_ropes.finish();
1235        drop(old_fragments);
1236
1237        self.snapshot.fragments = new_fragments;
1238        self.snapshot.visible_text = visible_text;
1239        self.snapshot.deleted_text = deleted_text;
1240        self.snapshot.insertions.edit(new_insertions, ());
1241        self.snapshot.insertion_slices.extend(insertion_slices);
1242        self.subscriptions.publish_mut(&edits_patch)
1243    }
1244
1245    fn fragment_ids_for_edits<'a>(
1246        &'a self,
1247        edit_ids: impl Iterator<Item = &'a clock::Lamport>,
1248    ) -> Vec<&'a Locator> {
1249        // Get all of the insertion slices changed by the given edits.
1250        let mut insertion_slices = Vec::new();
1251        for edit_id in edit_ids {
1252            let insertion_slice = InsertionSlice {
1253                edit_id: *edit_id,
1254                insertion_id: clock::Lamport::MIN,
1255                range: 0..0,
1256            };
1257            let slices = self
1258                .snapshot
1259                .insertion_slices
1260                .iter_from(&insertion_slice)
1261                .take_while(|slice| slice.edit_id == *edit_id);
1262            insertion_slices.extend(slices)
1263        }
1264        insertion_slices
1265            .sort_unstable_by_key(|s| (s.insertion_id, s.range.start, Reverse(s.range.end)));
1266
1267        // Get all of the fragments corresponding to these insertion slices.
1268        let mut fragment_ids = Vec::new();
1269        let mut insertions_cursor = self.insertions.cursor::<InsertionFragmentKey>(());
1270        for insertion_slice in &insertion_slices {
1271            if insertion_slice.insertion_id != insertions_cursor.start().timestamp
1272                || insertion_slice.range.start > insertions_cursor.start().split_offset
1273            {
1274                insertions_cursor.seek_forward(
1275                    &InsertionFragmentKey {
1276                        timestamp: insertion_slice.insertion_id,
1277                        split_offset: insertion_slice.range.start,
1278                    },
1279                    Bias::Left,
1280                );
1281            }
1282            while let Some(item) = insertions_cursor.item() {
1283                if item.timestamp != insertion_slice.insertion_id
1284                    || item.split_offset >= insertion_slice.range.end
1285                {
1286                    break;
1287                }
1288                fragment_ids.push(&item.fragment_id);
1289                insertions_cursor.next();
1290            }
1291        }
1292        fragment_ids.sort_unstable();
1293        fragment_ids
1294    }
1295
1296    fn apply_undo(&mut self, undo: &UndoOperation) {
1297        self.snapshot.undo_map.insert(undo);
1298
1299        let mut edits = Patch::default();
1300        let mut old_fragments = self
1301            .fragments
1302            .cursor::<Dimensions<Option<&Locator>, usize>>(&None);
1303        let mut new_fragments = SumTree::new(&None);
1304        let mut new_ropes =
1305            RopeBuilder::new(self.visible_text.cursor(0), self.deleted_text.cursor(0));
1306
1307        for fragment_id in self.fragment_ids_for_edits(undo.counts.keys()) {
1308            let preceding_fragments = old_fragments.slice(&Some(fragment_id), Bias::Left);
1309            new_ropes.append(preceding_fragments.summary().text);
1310            new_fragments.append(preceding_fragments, &None);
1311
1312            if let Some(fragment) = old_fragments.item() {
1313                let mut fragment = fragment.clone();
1314                let fragment_was_visible = fragment.visible;
1315
1316                fragment.visible = fragment.is_visible(&self.undo_map);
1317                fragment.max_undos.observe(undo.timestamp);
1318
1319                let old_start = old_fragments.start().1;
1320                let new_start = new_fragments.summary().text.visible;
1321                if fragment_was_visible && !fragment.visible {
1322                    edits.push(Edit {
1323                        old: old_start..old_start + fragment.len,
1324                        new: new_start..new_start,
1325                    });
1326                } else if !fragment_was_visible && fragment.visible {
1327                    edits.push(Edit {
1328                        old: old_start..old_start,
1329                        new: new_start..new_start + fragment.len,
1330                    });
1331                }
1332                new_ropes.push_fragment(&fragment, fragment_was_visible);
1333                new_fragments.push(fragment, &None);
1334
1335                old_fragments.next();
1336            }
1337        }
1338
1339        let suffix = old_fragments.suffix();
1340        new_ropes.append(suffix.summary().text);
1341        new_fragments.append(suffix, &None);
1342
1343        drop(old_fragments);
1344        let (visible_text, deleted_text) = new_ropes.finish();
1345        self.snapshot.fragments = new_fragments;
1346        self.snapshot.visible_text = visible_text;
1347        self.snapshot.deleted_text = deleted_text;
1348        self.subscriptions.publish_mut(&edits);
1349    }
1350
1351    fn flush_deferred_ops(&mut self) {
1352        self.deferred_replicas.clear();
1353        let mut deferred_ops = Vec::new();
1354        for op in self.deferred_ops.drain().iter().cloned() {
1355            if self.can_apply_op(&op) {
1356                self.apply_op(op);
1357            } else {
1358                self.deferred_replicas.insert(op.replica_id());
1359                deferred_ops.push(op);
1360            }
1361        }
1362        self.deferred_ops.insert(deferred_ops);
1363    }
1364
1365    fn can_apply_op(&self, op: &Operation) -> bool {
1366        if self.deferred_replicas.contains(&op.replica_id()) {
1367            false
1368        } else {
1369            self.version.observed_all(match op {
1370                Operation::Edit(edit) => &edit.version,
1371                Operation::Undo(undo) => &undo.version,
1372            })
1373        }
1374    }
1375
1376    pub fn has_deferred_ops(&self) -> bool {
1377        !self.deferred_ops.is_empty()
1378    }
1379
1380    pub fn peek_undo_stack(&self) -> Option<&HistoryEntry> {
1381        self.history.undo_stack.last()
1382    }
1383
1384    pub fn peek_redo_stack(&self) -> Option<&HistoryEntry> {
1385        self.history.redo_stack.last()
1386    }
1387
1388    pub fn start_transaction(&mut self) -> Option<TransactionId> {
1389        self.start_transaction_at(Instant::now())
1390    }
1391
1392    pub fn start_transaction_at(&mut self, now: Instant) -> Option<TransactionId> {
1393        self.history
1394            .start_transaction(self.version.clone(), now, &mut self.lamport_clock)
1395    }
1396
1397    pub fn end_transaction(&mut self) -> Option<(TransactionId, clock::Global)> {
1398        self.end_transaction_at(Instant::now())
1399    }
1400
1401    pub fn end_transaction_at(&mut self, now: Instant) -> Option<(TransactionId, clock::Global)> {
1402        if let Some(entry) = self.history.end_transaction(now) {
1403            let since = entry.transaction.start.clone();
1404            let id = self.history.group().unwrap();
1405            Some((id, since))
1406        } else {
1407            None
1408        }
1409    }
1410
1411    pub fn finalize_last_transaction(&mut self) -> Option<&Transaction> {
1412        self.history.finalize_last_transaction()
1413    }
1414
1415    pub fn group_until_transaction(&mut self, transaction_id: TransactionId) {
1416        self.history.group_until(transaction_id);
1417    }
1418
1419    pub fn base_text(&self) -> &Rope {
1420        &self.history.base_text
1421    }
1422
1423    pub fn operations(&self) -> &TreeMap<clock::Lamport, Operation> {
1424        &self.history.operations
1425    }
1426
1427    pub fn undo(&mut self) -> Option<(TransactionId, Operation)> {
1428        if let Some(entry) = self.history.pop_undo() {
1429            let transaction = entry.transaction.clone();
1430            let transaction_id = transaction.id;
1431            let op = self.undo_or_redo(transaction);
1432            Some((transaction_id, op))
1433        } else {
1434            None
1435        }
1436    }
1437
1438    pub fn undo_transaction(&mut self, transaction_id: TransactionId) -> Option<Operation> {
1439        let transaction = self
1440            .history
1441            .remove_from_undo(transaction_id)?
1442            .transaction
1443            .clone();
1444        Some(self.undo_or_redo(transaction))
1445    }
1446
1447    pub fn undo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1448        let transactions = self
1449            .history
1450            .remove_from_undo_until(transaction_id)
1451            .iter()
1452            .map(|entry| entry.transaction.clone())
1453            .collect::<Vec<_>>();
1454
1455        transactions
1456            .into_iter()
1457            .map(|transaction| self.undo_or_redo(transaction))
1458            .collect()
1459    }
1460
1461    pub fn forget_transaction(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
1462        self.history.forget(transaction_id)
1463    }
1464
1465    pub fn get_transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
1466        self.history.transaction(transaction_id)
1467    }
1468
1469    pub fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
1470        self.history.merge_transactions(transaction, destination);
1471    }
1472
1473    pub fn redo(&mut self) -> Option<(TransactionId, Operation)> {
1474        if let Some(entry) = self.history.pop_redo() {
1475            let transaction = entry.transaction.clone();
1476            let transaction_id = transaction.id;
1477            let op = self.undo_or_redo(transaction);
1478            Some((transaction_id, op))
1479        } else {
1480            None
1481        }
1482    }
1483
1484    pub fn redo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
1485        let transactions = self
1486            .history
1487            .remove_from_redo(transaction_id)
1488            .iter()
1489            .map(|entry| entry.transaction.clone())
1490            .collect::<Vec<_>>();
1491
1492        transactions
1493            .into_iter()
1494            .map(|transaction| self.undo_or_redo(transaction))
1495            .collect()
1496    }
1497
1498    fn undo_or_redo(&mut self, transaction: Transaction) -> Operation {
1499        let mut counts = HashMap::default();
1500        for edit_id in transaction.edit_ids {
1501            counts.insert(edit_id, self.undo_map.undo_count(edit_id).saturating_add(1));
1502        }
1503
1504        let operation = self.undo_operations(counts);
1505        self.history.push(operation.clone());
1506        operation
1507    }
1508
1509    pub fn undo_operations(&mut self, counts: HashMap<clock::Lamport, u32>) -> Operation {
1510        let timestamp = self.lamport_clock.tick();
1511        let version = self.version();
1512        self.snapshot.version.observe(timestamp);
1513        let undo = UndoOperation {
1514            timestamp,
1515            version,
1516            counts,
1517        };
1518        self.apply_undo(&undo);
1519        Operation::Undo(undo)
1520    }
1521
1522    pub fn push_transaction(&mut self, transaction: Transaction, now: Instant) {
1523        self.history.push_transaction(transaction, now);
1524    }
1525
1526    /// Differs from `push_transaction` in that it does not clear the redo stack.
1527    /// The caller responsible for
1528    /// Differs from `push_transaction` in that it does not clear the redo
1529    /// stack. Intended to be used to create a parent transaction to merge
1530    /// potential child transactions into.
1531    ///
1532    /// The caller is responsible for removing it from the undo history using
1533    /// `forget_transaction` if no edits are merged into it. Otherwise, if edits
1534    /// are merged into this transaction, the caller is responsible for ensuring
1535    /// the redo stack is cleared. The easiest way to ensure the redo stack is
1536    /// cleared is to create transactions with the usual `start_transaction` and
1537    /// `end_transaction` methods and merging the resulting transactions into
1538    /// the transaction created by this method
1539    pub fn push_empty_transaction(&mut self, now: Instant) -> TransactionId {
1540        self.history
1541            .push_empty_transaction(self.version.clone(), now, &mut self.lamport_clock)
1542    }
1543
1544    pub fn edited_ranges_for_transaction_id<D>(
1545        &self,
1546        transaction_id: TransactionId,
1547    ) -> impl '_ + Iterator<Item = Range<D>>
1548    where
1549        D: TextDimension,
1550    {
1551        self.history
1552            .transaction(transaction_id)
1553            .into_iter()
1554            .flat_map(|transaction| self.edited_ranges_for_transaction(transaction))
1555    }
1556
1557    pub fn edited_ranges_for_edit_ids<'a, D>(
1558        &'a self,
1559        edit_ids: impl IntoIterator<Item = &'a clock::Lamport>,
1560    ) -> impl 'a + Iterator<Item = Range<D>>
1561    where
1562        D: TextDimension,
1563    {
1564        // get fragment ranges
1565        let mut cursor = self
1566            .fragments
1567            .cursor::<Dimensions<Option<&Locator>, usize>>(&None);
1568        let offset_ranges = self
1569            .fragment_ids_for_edits(edit_ids.into_iter())
1570            .into_iter()
1571            .filter_map(move |fragment_id| {
1572                cursor.seek_forward(&Some(fragment_id), Bias::Left);
1573                let fragment = cursor.item()?;
1574                let start_offset = cursor.start().1;
1575                let end_offset = start_offset + if fragment.visible { fragment.len } else { 0 };
1576                Some(start_offset..end_offset)
1577            });
1578
1579        // combine adjacent ranges
1580        let mut prev_range: Option<Range<usize>> = None;
1581        let disjoint_ranges = offset_ranges
1582            .map(Some)
1583            .chain([None])
1584            .filter_map(move |range| {
1585                if let Some((range, prev_range)) = range.as_ref().zip(prev_range.as_mut())
1586                    && prev_range.end == range.start
1587                {
1588                    prev_range.end = range.end;
1589                    return None;
1590                }
1591                let result = prev_range.clone();
1592                prev_range = range;
1593                result
1594            });
1595
1596        // convert to the desired text dimension.
1597        let mut position = D::zero(());
1598        let mut rope_cursor = self.visible_text.cursor(0);
1599        disjoint_ranges.map(move |range| {
1600            position.add_assign(&rope_cursor.summary(range.start));
1601            let start = position;
1602            position.add_assign(&rope_cursor.summary(range.end));
1603            let end = position;
1604            start..end
1605        })
1606    }
1607
1608    pub fn edited_ranges_for_transaction<'a, D>(
1609        &'a self,
1610        transaction: &'a Transaction,
1611    ) -> impl 'a + Iterator<Item = Range<D>>
1612    where
1613        D: TextDimension,
1614    {
1615        self.edited_ranges_for_edit_ids(&transaction.edit_ids)
1616    }
1617
1618    pub fn subscribe(&mut self) -> Subscription {
1619        self.subscriptions.subscribe()
1620    }
1621
1622    pub fn wait_for_edits<It: IntoIterator<Item = clock::Lamport>>(
1623        &mut self,
1624        edit_ids: It,
1625    ) -> impl 'static + Future<Output = Result<()>> + use<It> {
1626        let mut futures = Vec::new();
1627        for edit_id in edit_ids {
1628            if !self.version.observed(edit_id) {
1629                let (tx, rx) = oneshot::channel();
1630                self.edit_id_resolvers.entry(edit_id).or_default().push(tx);
1631                futures.push(rx);
1632            }
1633        }
1634
1635        async move {
1636            for mut future in futures {
1637                if future.recv().await.is_none() {
1638                    anyhow::bail!("gave up waiting for edits");
1639                }
1640            }
1641            Ok(())
1642        }
1643    }
1644
1645    pub fn wait_for_anchors<It: IntoIterator<Item = Anchor>>(
1646        &mut self,
1647        anchors: It,
1648    ) -> impl 'static + Future<Output = Result<()>> + use<It> {
1649        let mut futures = Vec::new();
1650        for anchor in anchors {
1651            if !self.version.observed(anchor.timestamp)
1652                && anchor != Anchor::MAX
1653                && anchor != Anchor::MIN
1654            {
1655                let (tx, rx) = oneshot::channel();
1656                self.edit_id_resolvers
1657                    .entry(anchor.timestamp)
1658                    .or_default()
1659                    .push(tx);
1660                futures.push(rx);
1661            }
1662        }
1663
1664        async move {
1665            for mut future in futures {
1666                if future.recv().await.is_none() {
1667                    anyhow::bail!("gave up waiting for anchors");
1668                }
1669            }
1670            Ok(())
1671        }
1672    }
1673
1674    pub fn wait_for_version(
1675        &mut self,
1676        version: clock::Global,
1677    ) -> impl Future<Output = Result<()>> + use<> {
1678        let mut rx = None;
1679        if !self.snapshot.version.observed_all(&version) {
1680            let channel = oneshot::channel();
1681            self.wait_for_version_txs.push((version, channel.0));
1682            rx = Some(channel.1);
1683        }
1684        async move {
1685            if let Some(mut rx) = rx
1686                && rx.recv().await.is_none()
1687            {
1688                anyhow::bail!("gave up waiting for version");
1689            }
1690            Ok(())
1691        }
1692    }
1693
1694    pub fn give_up_waiting(&mut self) {
1695        self.edit_id_resolvers.clear();
1696        self.wait_for_version_txs.clear();
1697    }
1698
1699    fn resolve_edit(&mut self, edit_id: clock::Lamport) {
1700        for mut tx in self
1701            .edit_id_resolvers
1702            .remove(&edit_id)
1703            .into_iter()
1704            .flatten()
1705        {
1706            tx.try_send(()).ok();
1707        }
1708    }
1709}
1710
1711#[cfg(any(test, feature = "test-support"))]
1712impl Buffer {
1713    #[track_caller]
1714    pub fn edit_via_marked_text(&mut self, marked_string: &str) {
1715        let edits = self.edits_for_marked_text(marked_string);
1716        self.edit(edits);
1717    }
1718
1719    #[track_caller]
1720    pub fn edits_for_marked_text(&self, marked_string: &str) -> Vec<(Range<usize>, String)> {
1721        let old_text = self.text();
1722        let (new_text, mut ranges) = util::test::marked_text_ranges(marked_string, false);
1723        if ranges.is_empty() {
1724            ranges.push(0..new_text.len());
1725        }
1726
1727        assert_eq!(
1728            old_text[..ranges[0].start],
1729            new_text[..ranges[0].start],
1730            "invalid edit"
1731        );
1732
1733        let mut delta = 0;
1734        let mut edits = Vec::new();
1735        let mut ranges = ranges.into_iter().peekable();
1736
1737        while let Some(inserted_range) = ranges.next() {
1738            let new_start = inserted_range.start;
1739            let old_start = (new_start as isize - delta) as usize;
1740
1741            let following_text = if let Some(next_range) = ranges.peek() {
1742                &new_text[inserted_range.end..next_range.start]
1743            } else {
1744                &new_text[inserted_range.end..]
1745            };
1746
1747            let inserted_len = inserted_range.len();
1748            let deleted_len = old_text[old_start..]
1749                .find(following_text)
1750                .expect("invalid edit");
1751
1752            let old_range = old_start..old_start + deleted_len;
1753            edits.push((old_range, new_text[inserted_range].to_string()));
1754            delta += inserted_len as isize - deleted_len as isize;
1755        }
1756
1757        assert_eq!(
1758            old_text.len() as isize + delta,
1759            new_text.len() as isize,
1760            "invalid edit"
1761        );
1762
1763        edits
1764    }
1765
1766    pub fn check_invariants(&self) {
1767        // Ensure every fragment is ordered by locator in the fragment tree and corresponds
1768        // to an insertion fragment in the insertions tree.
1769        let mut prev_fragment_id = Locator::min();
1770        for fragment in self.snapshot.fragments.items(&None) {
1771            assert!(fragment.id > prev_fragment_id);
1772            prev_fragment_id = fragment.id.clone();
1773
1774            let insertion_fragment = self
1775                .snapshot
1776                .insertions
1777                .get(
1778                    &InsertionFragmentKey {
1779                        timestamp: fragment.timestamp,
1780                        split_offset: fragment.insertion_offset,
1781                    },
1782                    (),
1783                )
1784                .unwrap();
1785            assert_eq!(
1786                insertion_fragment.fragment_id, fragment.id,
1787                "fragment: {:?}\ninsertion: {:?}",
1788                fragment, insertion_fragment
1789            );
1790        }
1791
1792        let mut cursor = self.snapshot.fragments.cursor::<Option<&Locator>>(&None);
1793        for insertion_fragment in self.snapshot.insertions.cursor::<()>(()) {
1794            cursor.seek(&Some(&insertion_fragment.fragment_id), Bias::Left);
1795            let fragment = cursor.item().unwrap();
1796            assert_eq!(insertion_fragment.fragment_id, fragment.id);
1797            assert_eq!(insertion_fragment.split_offset, fragment.insertion_offset);
1798        }
1799
1800        let fragment_summary = self.snapshot.fragments.summary();
1801        assert_eq!(
1802            fragment_summary.text.visible,
1803            self.snapshot.visible_text.len()
1804        );
1805        assert_eq!(
1806            fragment_summary.text.deleted,
1807            self.snapshot.deleted_text.len()
1808        );
1809
1810        assert!(!self.text().contains("\r\n"));
1811    }
1812
1813    pub fn set_group_interval(&mut self, group_interval: Duration) {
1814        self.history.group_interval = group_interval;
1815    }
1816
1817    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
1818        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
1819        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
1820        start..end
1821    }
1822
1823    pub fn get_random_edits<T>(
1824        &self,
1825        rng: &mut T,
1826        edit_count: usize,
1827    ) -> Vec<(Range<usize>, Arc<str>)>
1828    where
1829        T: rand::Rng,
1830    {
1831        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1832        let mut last_end = None;
1833        for _ in 0..edit_count {
1834            if last_end.is_some_and(|last_end| last_end >= self.len()) {
1835                break;
1836            }
1837            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1838            let range = self.random_byte_range(new_start, rng);
1839            last_end = Some(range.end);
1840
1841            let new_text_len = rng.random_range(0..10);
1842            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1843
1844            edits.push((range, new_text.into()));
1845        }
1846        edits
1847    }
1848
1849    pub fn randomly_edit<T>(
1850        &mut self,
1851        rng: &mut T,
1852        edit_count: usize,
1853    ) -> (Vec<(Range<usize>, Arc<str>)>, Operation)
1854    where
1855        T: rand::Rng,
1856    {
1857        let mut edits = self.get_random_edits(rng, edit_count);
1858        log::info!("mutating buffer {:?} with {:?}", self.replica_id, edits);
1859
1860        let op = self.edit(edits.iter().cloned());
1861        if let Operation::Edit(edit) = &op {
1862            assert_eq!(edits.len(), edit.new_text.len());
1863            for (edit, new_text) in edits.iter_mut().zip(&edit.new_text) {
1864                edit.1 = new_text.clone();
1865            }
1866        } else {
1867            unreachable!()
1868        }
1869
1870        (edits, op)
1871    }
1872
1873    pub fn randomly_undo_redo(&mut self, rng: &mut impl rand::Rng) -> Vec<Operation> {
1874        use rand::prelude::*;
1875
1876        let mut ops = Vec::new();
1877        for _ in 0..rng.random_range(1..=5) {
1878            if let Some(entry) = self.history.undo_stack.choose(rng) {
1879                let transaction = entry.transaction.clone();
1880                log::info!(
1881                    "undoing buffer {:?} transaction {:?}",
1882                    self.replica_id,
1883                    transaction
1884                );
1885                ops.push(self.undo_or_redo(transaction));
1886            }
1887        }
1888        ops
1889    }
1890}
1891
1892impl Deref for Buffer {
1893    type Target = BufferSnapshot;
1894
1895    fn deref(&self) -> &Self::Target {
1896        &self.snapshot
1897    }
1898}
1899
1900impl BufferSnapshot {
1901    pub fn as_rope(&self) -> &Rope {
1902        &self.visible_text
1903    }
1904
1905    pub fn rope_for_version(&self, version: &clock::Global) -> Rope {
1906        let mut rope = Rope::new();
1907
1908        let mut cursor = self
1909            .fragments
1910            .filter::<_, FragmentTextSummary>(&None, move |summary| {
1911                !version.observed_all(&summary.max_version)
1912            });
1913        cursor.next();
1914
1915        let mut visible_cursor = self.visible_text.cursor(0);
1916        let mut deleted_cursor = self.deleted_text.cursor(0);
1917
1918        while let Some(fragment) = cursor.item() {
1919            if cursor.start().visible > visible_cursor.offset() {
1920                let text = visible_cursor.slice(cursor.start().visible);
1921                rope.append(text);
1922            }
1923
1924            if fragment.was_visible(version, &self.undo_map) {
1925                if fragment.visible {
1926                    let text = visible_cursor.slice(cursor.end().visible);
1927                    rope.append(text);
1928                } else {
1929                    deleted_cursor.seek_forward(cursor.start().deleted);
1930                    let text = deleted_cursor.slice(cursor.end().deleted);
1931                    rope.append(text);
1932                }
1933            } else if fragment.visible {
1934                visible_cursor.seek_forward(cursor.end().visible);
1935            }
1936
1937            cursor.next();
1938        }
1939
1940        if cursor.start().visible > visible_cursor.offset() {
1941            let text = visible_cursor.slice(cursor.start().visible);
1942            rope.append(text);
1943        }
1944
1945        rope
1946    }
1947
1948    pub fn remote_id(&self) -> BufferId {
1949        self.remote_id
1950    }
1951
1952    pub fn replica_id(&self) -> ReplicaId {
1953        self.replica_id
1954    }
1955
1956    pub fn row_count(&self) -> u32 {
1957        self.max_point().row + 1
1958    }
1959
1960    pub fn len(&self) -> usize {
1961        self.visible_text.len()
1962    }
1963
1964    pub fn is_empty(&self) -> bool {
1965        self.len() == 0
1966    }
1967
1968    pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
1969        self.chars_at(0)
1970    }
1971
1972    pub fn chars_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = char> + '_ {
1973        self.text_for_range(range).flat_map(str::chars)
1974    }
1975
1976    pub fn reversed_chars_for_range<T: ToOffset>(
1977        &self,
1978        range: Range<T>,
1979    ) -> impl Iterator<Item = char> + '_ {
1980        self.reversed_chunks_in_range(range)
1981            .flat_map(|chunk| chunk.chars().rev())
1982    }
1983
1984    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1985    where
1986        T: ToOffset,
1987    {
1988        let position = position.to_offset(self);
1989        position == self.clip_offset(position, Bias::Left)
1990            && self
1991                .bytes_in_range(position..self.len())
1992                .flatten()
1993                .copied()
1994                .take(needle.len())
1995                .eq(needle.bytes())
1996    }
1997
1998    pub fn common_prefix_at<T>(&self, position: T, needle: &str) -> Range<T>
1999    where
2000        T: ToOffset + TextDimension,
2001    {
2002        let offset = position.to_offset(self);
2003        let common_prefix_len = needle
2004            .char_indices()
2005            .map(|(index, _)| index)
2006            .chain([needle.len()])
2007            .take_while(|&len| len <= offset)
2008            .filter(|&len| {
2009                let left = self
2010                    .chars_for_range(offset - len..offset)
2011                    .flat_map(char::to_lowercase);
2012                let right = needle[..len].chars().flat_map(char::to_lowercase);
2013                left.eq(right)
2014            })
2015            .last()
2016            .unwrap_or(0);
2017        let start_offset = offset - common_prefix_len;
2018        let start = self.text_summary_for_range(0..start_offset);
2019        start..position
2020    }
2021
2022    pub fn text(&self) -> String {
2023        self.visible_text.to_string()
2024    }
2025
2026    pub fn line_ending(&self) -> LineEnding {
2027        self.line_ending
2028    }
2029
2030    pub fn deleted_text(&self) -> String {
2031        self.deleted_text.to_string()
2032    }
2033
2034    pub fn fragments(&self) -> impl Iterator<Item = &Fragment> {
2035        self.fragments.iter()
2036    }
2037
2038    pub fn text_summary(&self) -> TextSummary {
2039        self.visible_text.summary()
2040    }
2041
2042    pub fn max_point(&self) -> Point {
2043        self.visible_text.max_point()
2044    }
2045
2046    pub fn max_point_utf16(&self) -> PointUtf16 {
2047        self.visible_text.max_point_utf16()
2048    }
2049
2050    pub fn point_to_offset(&self, point: Point) -> usize {
2051        self.visible_text.point_to_offset(point)
2052    }
2053
2054    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2055        self.visible_text.point_utf16_to_offset(point)
2056    }
2057
2058    pub fn unclipped_point_utf16_to_offset(&self, point: Unclipped<PointUtf16>) -> usize {
2059        self.visible_text.unclipped_point_utf16_to_offset(point)
2060    }
2061
2062    pub fn unclipped_point_utf16_to_point(&self, point: Unclipped<PointUtf16>) -> Point {
2063        self.visible_text.unclipped_point_utf16_to_point(point)
2064    }
2065
2066    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
2067        self.visible_text.offset_utf16_to_offset(offset)
2068    }
2069
2070    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2071        self.visible_text.offset_to_offset_utf16(offset)
2072    }
2073
2074    pub fn offset_to_point(&self, offset: usize) -> Point {
2075        self.visible_text.offset_to_point(offset)
2076    }
2077
2078    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2079        self.visible_text.offset_to_point_utf16(offset)
2080    }
2081
2082    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2083        self.visible_text.point_to_point_utf16(point)
2084    }
2085
2086    pub fn version(&self) -> &clock::Global {
2087        &self.version
2088    }
2089
2090    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2091        let offset = position.to_offset(self);
2092        self.visible_text.chars_at(offset)
2093    }
2094
2095    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2096        let offset = position.to_offset(self);
2097        self.visible_text.reversed_chars_at(offset)
2098    }
2099
2100    pub fn reversed_chunks_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Chunks<'_> {
2101        let range = range.start.to_offset(self)..range.end.to_offset(self);
2102        self.visible_text.reversed_chunks_in_range(range)
2103    }
2104
2105    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
2106        let start = range.start.to_offset(self);
2107        let end = range.end.to_offset(self);
2108        self.visible_text.bytes_in_range(start..end)
2109    }
2110
2111    pub fn reversed_bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> rope::Bytes<'_> {
2112        let start = range.start.to_offset(self);
2113        let end = range.end.to_offset(self);
2114        self.visible_text.reversed_bytes_in_range(start..end)
2115    }
2116
2117    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> Chunks<'_> {
2118        let start = range.start.to_offset(self);
2119        let end = range.end.to_offset(self);
2120        self.visible_text.chunks_in_range(start..end)
2121    }
2122
2123    pub fn line_len(&self, row: u32) -> u32 {
2124        let row_start_offset = Point::new(row, 0).to_offset(self);
2125        let row_end_offset = if row >= self.max_point().row {
2126            self.len()
2127        } else {
2128            Point::new(row + 1, 0).to_previous_offset(self)
2129        };
2130        (row_end_offset - row_start_offset) as u32
2131    }
2132
2133    pub fn line_indents_in_row_range(
2134        &self,
2135        row_range: Range<u32>,
2136    ) -> impl Iterator<Item = (u32, LineIndent)> + '_ {
2137        let start = Point::new(row_range.start, 0).to_offset(self);
2138        let end = Point::new(row_range.end, self.line_len(row_range.end)).to_offset(self);
2139
2140        let mut chunks = self.as_rope().chunks_in_range(start..end);
2141        let mut row = row_range.start;
2142        let mut done = false;
2143        std::iter::from_fn(move || {
2144            if done {
2145                None
2146            } else {
2147                let indent = (row, LineIndent::from_chunks(&mut chunks));
2148                done = !chunks.next_line();
2149                row += 1;
2150                Some(indent)
2151            }
2152        })
2153    }
2154
2155    /// Returns the line indents in the given row range, exclusive of end row, in reversed order.
2156    pub fn reversed_line_indents_in_row_range(
2157        &self,
2158        row_range: Range<u32>,
2159    ) -> impl Iterator<Item = (u32, LineIndent)> + '_ {
2160        let start = Point::new(row_range.start, 0).to_offset(self);
2161
2162        let end_point;
2163        let end;
2164        if row_range.end > row_range.start {
2165            end_point = Point::new(row_range.end - 1, self.line_len(row_range.end - 1));
2166            end = end_point.to_offset(self);
2167        } else {
2168            end_point = Point::new(row_range.start, 0);
2169            end = start;
2170        };
2171
2172        let mut chunks = self.as_rope().chunks_in_range(start..end);
2173        // Move the cursor to the start of the last line if it's not empty.
2174        chunks.seek(end);
2175        if end_point.column > 0 {
2176            chunks.prev_line();
2177        }
2178
2179        let mut row = end_point.row;
2180        let mut done = false;
2181        std::iter::from_fn(move || {
2182            if done {
2183                None
2184            } else {
2185                let initial_offset = chunks.offset();
2186                let indent = (row, LineIndent::from_chunks(&mut chunks));
2187                if chunks.offset() > initial_offset {
2188                    chunks.prev_line();
2189                }
2190                done = !chunks.prev_line();
2191                if !done {
2192                    row -= 1;
2193                }
2194
2195                Some(indent)
2196            }
2197        })
2198    }
2199
2200    pub fn line_indent_for_row(&self, row: u32) -> LineIndent {
2201        LineIndent::from_iter(self.chars_at(Point::new(row, 0)))
2202    }
2203
2204    pub fn is_line_blank(&self, row: u32) -> bool {
2205        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
2206            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
2207    }
2208
2209    pub fn text_summary_for_range<D, O: ToOffset>(&self, range: Range<O>) -> D
2210    where
2211        D: TextDimension,
2212    {
2213        self.visible_text
2214            .cursor(range.start.to_offset(self))
2215            .summary(range.end.to_offset(self))
2216    }
2217
2218    pub fn summaries_for_anchors<'a, D, A>(&'a self, anchors: A) -> impl 'a + Iterator<Item = D>
2219    where
2220        D: 'a + TextDimension,
2221        A: 'a + IntoIterator<Item = &'a Anchor>,
2222    {
2223        let anchors = anchors.into_iter();
2224        self.summaries_for_anchors_with_payload::<D, _, ()>(anchors.map(|a| (a, ())))
2225            .map(|d| d.0)
2226    }
2227
2228    pub fn summaries_for_anchors_with_payload<'a, D, A, T>(
2229        &'a self,
2230        anchors: A,
2231    ) -> impl 'a + Iterator<Item = (D, T)>
2232    where
2233        D: 'a + TextDimension,
2234        A: 'a + IntoIterator<Item = (&'a Anchor, T)>,
2235    {
2236        let anchors = anchors.into_iter();
2237        let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(());
2238        let mut fragment_cursor = self
2239            .fragments
2240            .cursor::<Dimensions<Option<&Locator>, usize>>(&None);
2241        let mut text_cursor = self.visible_text.cursor(0);
2242        let mut position = D::zero(());
2243
2244        anchors.map(move |(anchor, payload)| {
2245            if *anchor == Anchor::MIN {
2246                return (D::zero(()), payload);
2247            } else if *anchor == Anchor::MAX {
2248                return (D::from_text_summary(&self.visible_text.summary()), payload);
2249            }
2250
2251            let anchor_key = InsertionFragmentKey {
2252                timestamp: anchor.timestamp,
2253                split_offset: anchor.offset,
2254            };
2255            insertion_cursor.seek(&anchor_key, anchor.bias);
2256            if let Some(insertion) = insertion_cursor.item() {
2257                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2258                if comparison == Ordering::Greater
2259                    || (anchor.bias == Bias::Left
2260                        && comparison == Ordering::Equal
2261                        && anchor.offset > 0)
2262                {
2263                    insertion_cursor.prev();
2264                }
2265            } else {
2266                insertion_cursor.prev();
2267            }
2268            let insertion = insertion_cursor.item().expect("invalid insertion");
2269            assert_eq!(insertion.timestamp, anchor.timestamp, "invalid insertion");
2270
2271            fragment_cursor.seek_forward(&Some(&insertion.fragment_id), Bias::Left);
2272            let fragment = fragment_cursor.item().unwrap();
2273            let mut fragment_offset = fragment_cursor.start().1;
2274            if fragment.visible {
2275                fragment_offset += anchor.offset - insertion.split_offset;
2276            }
2277
2278            position.add_assign(&text_cursor.summary(fragment_offset));
2279            (position, payload)
2280        })
2281    }
2282
2283    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2284    where
2285        D: TextDimension,
2286    {
2287        self.text_summary_for_range(0..self.offset_for_anchor(anchor))
2288    }
2289
2290    pub fn offset_for_anchor(&self, anchor: &Anchor) -> usize {
2291        if *anchor == Anchor::MIN {
2292            0
2293        } else if *anchor == Anchor::MAX {
2294            self.visible_text.len()
2295        } else {
2296            debug_assert!(anchor.buffer_id == Some(self.remote_id));
2297            let anchor_key = InsertionFragmentKey {
2298                timestamp: anchor.timestamp,
2299                split_offset: anchor.offset,
2300            };
2301            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(());
2302            insertion_cursor.seek(&anchor_key, anchor.bias);
2303            if let Some(insertion) = insertion_cursor.item() {
2304                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2305                if comparison == Ordering::Greater
2306                    || (anchor.bias == Bias::Left
2307                        && comparison == Ordering::Equal
2308                        && anchor.offset > 0)
2309                {
2310                    insertion_cursor.prev();
2311                }
2312            } else {
2313                insertion_cursor.prev();
2314            }
2315
2316            let Some(insertion) = insertion_cursor
2317                .item()
2318                .filter(|insertion| insertion.timestamp == anchor.timestamp)
2319            else {
2320                panic!(
2321                    "invalid anchor {:?}. buffer id: {}, version: {:?}",
2322                    anchor, self.remote_id, self.version
2323                );
2324            };
2325
2326            let (start, _, item) = self
2327                .fragments
2328                .find::<Dimensions<Option<&Locator>, usize>, _>(
2329                    &None,
2330                    &Some(&insertion.fragment_id),
2331                    Bias::Left,
2332                );
2333            let fragment = item.unwrap();
2334            let mut fragment_offset = start.1;
2335            if fragment.visible {
2336                fragment_offset += anchor.offset - insertion.split_offset;
2337            }
2338            fragment_offset
2339        }
2340    }
2341
2342    fn fragment_id_for_anchor(&self, anchor: &Anchor) -> &Locator {
2343        self.try_fragment_id_for_anchor(anchor).unwrap_or_else(|| {
2344            panic!(
2345                "invalid anchor {:?}. buffer id: {}, version: {:?}",
2346                anchor, self.remote_id, self.version,
2347            )
2348        })
2349    }
2350
2351    fn try_fragment_id_for_anchor(&self, anchor: &Anchor) -> Option<&Locator> {
2352        if *anchor == Anchor::MIN {
2353            Some(Locator::min_ref())
2354        } else if *anchor == Anchor::MAX {
2355            Some(Locator::max_ref())
2356        } else {
2357            let anchor_key = InsertionFragmentKey {
2358                timestamp: anchor.timestamp,
2359                split_offset: anchor.offset,
2360            };
2361            let mut insertion_cursor = self.insertions.cursor::<InsertionFragmentKey>(());
2362            insertion_cursor.seek(&anchor_key, anchor.bias);
2363            if let Some(insertion) = insertion_cursor.item() {
2364                let comparison = sum_tree::KeyedItem::key(insertion).cmp(&anchor_key);
2365                if comparison == Ordering::Greater
2366                    || (anchor.bias == Bias::Left
2367                        && comparison == Ordering::Equal
2368                        && anchor.offset > 0)
2369                {
2370                    insertion_cursor.prev();
2371                }
2372            } else {
2373                insertion_cursor.prev();
2374            }
2375
2376            insertion_cursor
2377                .item()
2378                .filter(|insertion| {
2379                    !cfg!(debug_assertions) || insertion.timestamp == anchor.timestamp
2380                })
2381                .map(|insertion| &insertion.fragment_id)
2382        }
2383    }
2384
2385    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2386        self.anchor_at(position, Bias::Left)
2387    }
2388
2389    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2390        self.anchor_at(position, Bias::Right)
2391    }
2392
2393    pub fn anchor_at<T: ToOffset>(&self, position: T, bias: Bias) -> Anchor {
2394        self.anchor_at_offset(position.to_offset(self), bias)
2395    }
2396
2397    fn anchor_at_offset(&self, offset: usize, bias: Bias) -> Anchor {
2398        if bias == Bias::Left && offset == 0 {
2399            Anchor::MIN
2400        } else if bias == Bias::Right && offset == self.len() {
2401            Anchor::MAX
2402        } else {
2403            if offset > self.visible_text.len() {
2404                panic!("offset {} is out of bounds", offset)
2405            } else if !self.visible_text.is_char_boundary(offset) {
2406                // find the character
2407                let char_start = self.visible_text.floor_char_boundary(offset);
2408                // `char_start` must be less than len and a char boundary
2409                let ch = self.visible_text.chars_at(char_start).next().unwrap();
2410                let char_range = char_start..char_start + ch.len_utf8();
2411                panic!(
2412                    "byte index {} is not a char boundary; it is inside {:?} (bytes {:?})",
2413                    offset, ch, char_range,
2414                );
2415            }
2416            let (start, _, item) = self.fragments.find::<usize, _>(&None, &offset, bias);
2417            let fragment = item.unwrap();
2418            let overshoot = offset - start;
2419            Anchor {
2420                timestamp: fragment.timestamp,
2421                offset: fragment.insertion_offset + overshoot,
2422                bias,
2423                buffer_id: Some(self.remote_id),
2424            }
2425        }
2426    }
2427
2428    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2429        *anchor == Anchor::MIN
2430            || *anchor == Anchor::MAX
2431            || (Some(self.remote_id) == anchor.buffer_id && self.version.observed(anchor.timestamp))
2432    }
2433
2434    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2435        self.visible_text.clip_offset(offset, bias)
2436    }
2437
2438    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2439        self.visible_text.clip_point(point, bias)
2440    }
2441
2442    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2443        self.visible_text.clip_offset_utf16(offset, bias)
2444    }
2445
2446    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2447        self.visible_text.clip_point_utf16(point, bias)
2448    }
2449
2450    pub fn edits_since<'a, D>(
2451        &'a self,
2452        since: &'a clock::Global,
2453    ) -> impl 'a + Iterator<Item = Edit<D>>
2454    where
2455        D: TextDimension + Ord,
2456    {
2457        self.edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2458    }
2459
2460    pub fn anchored_edits_since<'a, D>(
2461        &'a self,
2462        since: &'a clock::Global,
2463    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2464    where
2465        D: TextDimension + Ord,
2466    {
2467        self.anchored_edits_since_in_range(since, Anchor::MIN..Anchor::MAX)
2468    }
2469
2470    pub fn edits_since_in_range<'a, D>(
2471        &'a self,
2472        since: &'a clock::Global,
2473        range: Range<Anchor>,
2474    ) -> impl 'a + Iterator<Item = Edit<D>>
2475    where
2476        D: TextDimension + Ord,
2477    {
2478        self.anchored_edits_since_in_range(since, range)
2479            .map(|item| item.0)
2480    }
2481
2482    pub fn anchored_edits_since_in_range<'a, D>(
2483        &'a self,
2484        since: &'a clock::Global,
2485        range: Range<Anchor>,
2486    ) -> impl 'a + Iterator<Item = (Edit<D>, Range<Anchor>)>
2487    where
2488        D: TextDimension + Ord,
2489    {
2490        let fragments_cursor = if *since == self.version {
2491            None
2492        } else {
2493            let mut cursor = self.fragments.filter(&None, move |summary| {
2494                !since.observed_all(&summary.max_version)
2495            });
2496            cursor.next();
2497            Some(cursor)
2498        };
2499        let start_fragment_id = self.fragment_id_for_anchor(&range.start);
2500        let (start, _, item) = self
2501            .fragments
2502            .find::<Dimensions<Option<&Locator>, FragmentTextSummary>, _>(
2503                &None,
2504                &Some(start_fragment_id),
2505                Bias::Left,
2506            );
2507        let mut visible_start = start.1.visible;
2508        let mut deleted_start = start.1.deleted;
2509        if let Some(fragment) = item {
2510            let overshoot = range.start.offset - fragment.insertion_offset;
2511            if fragment.visible {
2512                visible_start += overshoot;
2513            } else {
2514                deleted_start += overshoot;
2515            }
2516        }
2517        let end_fragment_id = self.fragment_id_for_anchor(&range.end);
2518
2519        Edits {
2520            visible_cursor: self.visible_text.cursor(visible_start),
2521            deleted_cursor: self.deleted_text.cursor(deleted_start),
2522            fragments_cursor,
2523            undos: &self.undo_map,
2524            since,
2525            old_end: D::zero(()),
2526            new_end: D::zero(()),
2527            range: (start_fragment_id, range.start.offset)..(end_fragment_id, range.end.offset),
2528            buffer_id: self.remote_id,
2529        }
2530    }
2531
2532    pub fn has_edits_since_in_range(&self, since: &clock::Global, range: Range<Anchor>) -> bool {
2533        if *since != self.version {
2534            let start_fragment_id = self.fragment_id_for_anchor(&range.start);
2535            let end_fragment_id = self.fragment_id_for_anchor(&range.end);
2536            let mut cursor = self.fragments.filter::<_, usize>(&None, move |summary| {
2537                !since.observed_all(&summary.max_version)
2538            });
2539            cursor.next();
2540            while let Some(fragment) = cursor.item() {
2541                if fragment.id > *end_fragment_id {
2542                    break;
2543                }
2544                if fragment.id > *start_fragment_id {
2545                    let was_visible = fragment.was_visible(since, &self.undo_map);
2546                    let is_visible = fragment.visible;
2547                    if was_visible != is_visible {
2548                        return true;
2549                    }
2550                }
2551                cursor.next();
2552            }
2553        }
2554        false
2555    }
2556
2557    pub fn has_edits_since(&self, since: &clock::Global) -> bool {
2558        if *since != self.version {
2559            let mut cursor = self.fragments.filter::<_, usize>(&None, move |summary| {
2560                !since.observed_all(&summary.max_version)
2561            });
2562            cursor.next();
2563            while let Some(fragment) = cursor.item() {
2564                let was_visible = fragment.was_visible(since, &self.undo_map);
2565                let is_visible = fragment.visible;
2566                if was_visible != is_visible {
2567                    return true;
2568                }
2569                cursor.next();
2570            }
2571        }
2572        false
2573    }
2574
2575    pub fn range_to_version(&self, range: Range<usize>, version: &clock::Global) -> Range<usize> {
2576        let mut offsets = self.offsets_to_version([range.start, range.end], version);
2577        offsets.next().unwrap()..offsets.next().unwrap()
2578    }
2579
2580    /// Converts the given sequence of offsets into their corresponding offsets
2581    /// at a prior version of this buffer.
2582    pub fn offsets_to_version<'a>(
2583        &'a self,
2584        offsets: impl 'a + IntoIterator<Item = usize>,
2585        version: &'a clock::Global,
2586    ) -> impl 'a + Iterator<Item = usize> {
2587        let mut edits = self.edits_since(version).peekable();
2588        let mut last_old_end = 0;
2589        let mut last_new_end = 0;
2590        offsets.into_iter().map(move |new_offset| {
2591            while let Some(edit) = edits.peek() {
2592                if edit.new.start > new_offset {
2593                    break;
2594                }
2595
2596                if edit.new.end <= new_offset {
2597                    last_new_end = edit.new.end;
2598                    last_old_end = edit.old.end;
2599                    edits.next();
2600                    continue;
2601                }
2602
2603                let overshoot = new_offset - edit.new.start;
2604                return (edit.old.start + overshoot).min(edit.old.end);
2605            }
2606
2607            last_old_end + new_offset.saturating_sub(last_new_end)
2608        })
2609    }
2610
2611    /// Visually annotates a position or range with the `Debug` representation of a value. The
2612    /// callsite of this function is used as a key - previous annotations will be removed.
2613    #[cfg(debug_assertions)]
2614    #[track_caller]
2615    pub fn debug<R, V>(&self, ranges: &R, value: V)
2616    where
2617        R: debug::ToDebugRanges,
2618        V: std::fmt::Debug,
2619    {
2620        self.debug_with_key(std::panic::Location::caller(), ranges, value);
2621    }
2622
2623    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
2624    /// debug annotations with the same key will be removed. The key is also used to determine the
2625    /// annotation's color.
2626    #[cfg(debug_assertions)]
2627    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
2628    where
2629        K: std::hash::Hash + 'static,
2630        R: debug::ToDebugRanges,
2631        V: std::fmt::Debug,
2632    {
2633        let ranges = ranges
2634            .to_debug_ranges(self)
2635            .into_iter()
2636            .map(|range| self.anchor_after(range.start)..self.anchor_before(range.end))
2637            .collect();
2638        debug::GlobalDebugRanges::with_locked(|debug_ranges| {
2639            debug_ranges.insert(key, ranges, format!("{value:?}").into());
2640        });
2641    }
2642}
2643
2644struct RopeBuilder<'a> {
2645    old_visible_cursor: rope::Cursor<'a>,
2646    old_deleted_cursor: rope::Cursor<'a>,
2647    new_visible: Rope,
2648    new_deleted: Rope,
2649}
2650
2651impl<'a> RopeBuilder<'a> {
2652    fn new(old_visible_cursor: rope::Cursor<'a>, old_deleted_cursor: rope::Cursor<'a>) -> Self {
2653        Self {
2654            old_visible_cursor,
2655            old_deleted_cursor,
2656            new_visible: Rope::new(),
2657            new_deleted: Rope::new(),
2658        }
2659    }
2660
2661    fn append(&mut self, len: FragmentTextSummary) {
2662        self.push(len.visible, true, true);
2663        self.push(len.deleted, false, false);
2664    }
2665
2666    fn push_fragment(&mut self, fragment: &Fragment, was_visible: bool) {
2667        debug_assert!(fragment.len > 0);
2668        self.push(fragment.len, was_visible, fragment.visible)
2669    }
2670
2671    fn push(&mut self, len: usize, was_visible: bool, is_visible: bool) {
2672        let text = if was_visible {
2673            self.old_visible_cursor
2674                .slice(self.old_visible_cursor.offset() + len)
2675        } else {
2676            self.old_deleted_cursor
2677                .slice(self.old_deleted_cursor.offset() + len)
2678        };
2679        if is_visible {
2680            self.new_visible.append(text);
2681        } else {
2682            self.new_deleted.append(text);
2683        }
2684    }
2685
2686    fn push_str(&mut self, text: &str) {
2687        self.new_visible.push(text);
2688    }
2689
2690    fn finish(mut self) -> (Rope, Rope) {
2691        self.new_visible.append(self.old_visible_cursor.suffix());
2692        self.new_deleted.append(self.old_deleted_cursor.suffix());
2693        (self.new_visible, self.new_deleted)
2694    }
2695}
2696
2697impl<D: TextDimension + Ord, F: FnMut(&FragmentSummary) -> bool> Iterator for Edits<'_, D, F> {
2698    type Item = (Edit<D>, Range<Anchor>);
2699
2700    fn next(&mut self) -> Option<Self::Item> {
2701        let mut pending_edit: Option<Self::Item> = None;
2702        let cursor = self.fragments_cursor.as_mut()?;
2703
2704        while let Some(fragment) = cursor.item() {
2705            if fragment.id < *self.range.start.0 {
2706                cursor.next();
2707                continue;
2708            } else if fragment.id > *self.range.end.0 {
2709                break;
2710            }
2711
2712            if cursor.start().visible > self.visible_cursor.offset() {
2713                let summary = self.visible_cursor.summary(cursor.start().visible);
2714                self.old_end.add_assign(&summary);
2715                self.new_end.add_assign(&summary);
2716            }
2717
2718            if pending_edit
2719                .as_ref()
2720                .is_some_and(|(change, _)| change.new.end < self.new_end)
2721            {
2722                break;
2723            }
2724
2725            let start_anchor = Anchor {
2726                timestamp: fragment.timestamp,
2727                offset: fragment.insertion_offset,
2728                bias: Bias::Right,
2729                buffer_id: Some(self.buffer_id),
2730            };
2731            let end_anchor = Anchor {
2732                timestamp: fragment.timestamp,
2733                offset: fragment.insertion_offset + fragment.len,
2734                bias: Bias::Left,
2735                buffer_id: Some(self.buffer_id),
2736            };
2737
2738            if !fragment.was_visible(self.since, self.undos) && fragment.visible {
2739                let mut visible_end = cursor.end().visible;
2740                if fragment.id == *self.range.end.0 {
2741                    visible_end = cmp::min(
2742                        visible_end,
2743                        cursor.start().visible + (self.range.end.1 - fragment.insertion_offset),
2744                    );
2745                }
2746
2747                let fragment_summary = self.visible_cursor.summary(visible_end);
2748                let mut new_end = self.new_end;
2749                new_end.add_assign(&fragment_summary);
2750                if let Some((edit, range)) = pending_edit.as_mut() {
2751                    edit.new.end = new_end;
2752                    range.end = end_anchor;
2753                } else {
2754                    pending_edit = Some((
2755                        Edit {
2756                            old: self.old_end..self.old_end,
2757                            new: self.new_end..new_end,
2758                        },
2759                        start_anchor..end_anchor,
2760                    ));
2761                }
2762
2763                self.new_end = new_end;
2764            } else if fragment.was_visible(self.since, self.undos) && !fragment.visible {
2765                let mut deleted_end = cursor.end().deleted;
2766                if fragment.id == *self.range.end.0 {
2767                    deleted_end = cmp::min(
2768                        deleted_end,
2769                        cursor.start().deleted + (self.range.end.1 - fragment.insertion_offset),
2770                    );
2771                }
2772
2773                if cursor.start().deleted > self.deleted_cursor.offset() {
2774                    self.deleted_cursor.seek_forward(cursor.start().deleted);
2775                }
2776                let fragment_summary = self.deleted_cursor.summary(deleted_end);
2777                let mut old_end = self.old_end;
2778                old_end.add_assign(&fragment_summary);
2779                if let Some((edit, range)) = pending_edit.as_mut() {
2780                    edit.old.end = old_end;
2781                    range.end = end_anchor;
2782                } else {
2783                    pending_edit = Some((
2784                        Edit {
2785                            old: self.old_end..old_end,
2786                            new: self.new_end..self.new_end,
2787                        },
2788                        start_anchor..end_anchor,
2789                    ));
2790                }
2791
2792                self.old_end = old_end;
2793            }
2794
2795            cursor.next();
2796        }
2797
2798        pending_edit
2799    }
2800}
2801
2802impl Fragment {
2803    fn is_visible(&self, undos: &UndoMap) -> bool {
2804        !undos.is_undone(self.timestamp) && self.deletions.iter().all(|d| undos.is_undone(*d))
2805    }
2806
2807    fn was_visible(&self, version: &clock::Global, undos: &UndoMap) -> bool {
2808        (version.observed(self.timestamp) && !undos.was_undone(self.timestamp, version))
2809            && self
2810                .deletions
2811                .iter()
2812                .all(|d| !version.observed(*d) || undos.was_undone(*d, version))
2813    }
2814}
2815
2816impl sum_tree::Item for Fragment {
2817    type Summary = FragmentSummary;
2818
2819    fn summary(&self, _cx: &Option<clock::Global>) -> Self::Summary {
2820        let mut max_version = clock::Global::new();
2821        max_version.observe(self.timestamp);
2822        for deletion in &self.deletions {
2823            max_version.observe(*deletion);
2824        }
2825        max_version.join(&self.max_undos);
2826
2827        let mut min_insertion_version = clock::Global::new();
2828        min_insertion_version.observe(self.timestamp);
2829        let max_insertion_version = min_insertion_version.clone();
2830        if self.visible {
2831            FragmentSummary {
2832                max_id: self.id.clone(),
2833                text: FragmentTextSummary {
2834                    visible: self.len,
2835                    deleted: 0,
2836                },
2837                max_version,
2838                min_insertion_version,
2839                max_insertion_version,
2840            }
2841        } else {
2842            FragmentSummary {
2843                max_id: self.id.clone(),
2844                text: FragmentTextSummary {
2845                    visible: 0,
2846                    deleted: self.len,
2847                },
2848                max_version,
2849                min_insertion_version,
2850                max_insertion_version,
2851            }
2852        }
2853    }
2854}
2855
2856impl sum_tree::Summary for FragmentSummary {
2857    type Context<'a> = &'a Option<clock::Global>;
2858
2859    fn zero(_cx: Self::Context<'_>) -> Self {
2860        Default::default()
2861    }
2862
2863    fn add_summary(&mut self, other: &Self, _: Self::Context<'_>) {
2864        self.max_id.assign(&other.max_id);
2865        self.text.visible += &other.text.visible;
2866        self.text.deleted += &other.text.deleted;
2867        self.max_version.join(&other.max_version);
2868        self.min_insertion_version
2869            .meet(&other.min_insertion_version);
2870        self.max_insertion_version
2871            .join(&other.max_insertion_version);
2872    }
2873}
2874
2875impl Default for FragmentSummary {
2876    fn default() -> Self {
2877        FragmentSummary {
2878            max_id: Locator::min(),
2879            text: FragmentTextSummary::default(),
2880            max_version: clock::Global::new(),
2881            min_insertion_version: clock::Global::new(),
2882            max_insertion_version: clock::Global::new(),
2883        }
2884    }
2885}
2886
2887impl sum_tree::Item for InsertionFragment {
2888    type Summary = InsertionFragmentKey;
2889
2890    fn summary(&self, _cx: ()) -> Self::Summary {
2891        InsertionFragmentKey {
2892            timestamp: self.timestamp,
2893            split_offset: self.split_offset,
2894        }
2895    }
2896}
2897
2898impl sum_tree::KeyedItem for InsertionFragment {
2899    type Key = InsertionFragmentKey;
2900
2901    fn key(&self) -> Self::Key {
2902        sum_tree::Item::summary(self, ())
2903    }
2904}
2905
2906impl InsertionFragment {
2907    fn new(fragment: &Fragment) -> Self {
2908        Self {
2909            timestamp: fragment.timestamp,
2910            split_offset: fragment.insertion_offset,
2911            fragment_id: fragment.id.clone(),
2912        }
2913    }
2914
2915    fn insert_new(fragment: &Fragment) -> sum_tree::Edit<Self> {
2916        sum_tree::Edit::Insert(Self::new(fragment))
2917    }
2918}
2919
2920impl sum_tree::ContextLessSummary for InsertionFragmentKey {
2921    fn zero() -> Self {
2922        InsertionFragmentKey {
2923            timestamp: Lamport::MIN,
2924            split_offset: 0,
2925        }
2926    }
2927
2928    fn add_summary(&mut self, summary: &Self) {
2929        *self = *summary;
2930    }
2931}
2932
2933#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
2934pub struct FullOffset(pub usize);
2935
2936impl ops::AddAssign<usize> for FullOffset {
2937    fn add_assign(&mut self, rhs: usize) {
2938        self.0 += rhs;
2939    }
2940}
2941
2942impl ops::Add<usize> for FullOffset {
2943    type Output = Self;
2944
2945    fn add(mut self, rhs: usize) -> Self::Output {
2946        self += rhs;
2947        self
2948    }
2949}
2950
2951impl ops::Sub for FullOffset {
2952    type Output = usize;
2953
2954    fn sub(self, rhs: Self) -> Self::Output {
2955        self.0 - rhs.0
2956    }
2957}
2958
2959impl sum_tree::Dimension<'_, FragmentSummary> for usize {
2960    fn zero(_: &Option<clock::Global>) -> Self {
2961        Default::default()
2962    }
2963
2964    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2965        *self += summary.text.visible;
2966    }
2967}
2968
2969impl sum_tree::Dimension<'_, FragmentSummary> for FullOffset {
2970    fn zero(_: &Option<clock::Global>) -> Self {
2971        Default::default()
2972    }
2973
2974    fn add_summary(&mut self, summary: &FragmentSummary, _: &Option<clock::Global>) {
2975        self.0 += summary.text.visible + summary.text.deleted;
2976    }
2977}
2978
2979impl<'a> sum_tree::Dimension<'a, FragmentSummary> for Option<&'a Locator> {
2980    fn zero(_: &Option<clock::Global>) -> Self {
2981        Default::default()
2982    }
2983
2984    fn add_summary(&mut self, summary: &'a FragmentSummary, _: &Option<clock::Global>) {
2985        *self = Some(&summary.max_id);
2986    }
2987}
2988
2989impl sum_tree::SeekTarget<'_, FragmentSummary, FragmentTextSummary> for usize {
2990    fn cmp(
2991        &self,
2992        cursor_location: &FragmentTextSummary,
2993        _: &Option<clock::Global>,
2994    ) -> cmp::Ordering {
2995        Ord::cmp(self, &cursor_location.visible)
2996    }
2997}
2998
2999#[derive(Copy, Clone, Debug, Eq, PartialEq)]
3000enum VersionedFullOffset {
3001    Offset(FullOffset),
3002    Invalid,
3003}
3004
3005impl VersionedFullOffset {
3006    fn full_offset(&self) -> FullOffset {
3007        if let Self::Offset(position) = self {
3008            *position
3009        } else {
3010            panic!("invalid version")
3011        }
3012    }
3013}
3014
3015impl Default for VersionedFullOffset {
3016    fn default() -> Self {
3017        Self::Offset(Default::default())
3018    }
3019}
3020
3021impl<'a> sum_tree::Dimension<'a, FragmentSummary> for VersionedFullOffset {
3022    fn zero(_cx: &Option<clock::Global>) -> Self {
3023        Default::default()
3024    }
3025
3026    fn add_summary(&mut self, summary: &'a FragmentSummary, cx: &Option<clock::Global>) {
3027        if let Self::Offset(offset) = self {
3028            let version = cx.as_ref().unwrap();
3029            if version.observed_all(&summary.max_insertion_version) {
3030                *offset += summary.text.visible + summary.text.deleted;
3031            } else if version.observed_any(&summary.min_insertion_version) {
3032                *self = Self::Invalid;
3033            }
3034        }
3035    }
3036}
3037
3038impl sum_tree::SeekTarget<'_, FragmentSummary, Self> for VersionedFullOffset {
3039    fn cmp(&self, cursor_position: &Self, _: &Option<clock::Global>) -> cmp::Ordering {
3040        match (self, cursor_position) {
3041            (Self::Offset(a), Self::Offset(b)) => Ord::cmp(a, b),
3042            (Self::Offset(_), Self::Invalid) => cmp::Ordering::Less,
3043            (Self::Invalid, _) => unreachable!(),
3044        }
3045    }
3046}
3047
3048impl Operation {
3049    fn replica_id(&self) -> ReplicaId {
3050        operation_queue::Operation::lamport_timestamp(self).replica_id
3051    }
3052
3053    pub fn timestamp(&self) -> clock::Lamport {
3054        match self {
3055            Operation::Edit(edit) => edit.timestamp,
3056            Operation::Undo(undo) => undo.timestamp,
3057        }
3058    }
3059
3060    pub fn as_edit(&self) -> Option<&EditOperation> {
3061        match self {
3062            Operation::Edit(edit) => Some(edit),
3063            _ => None,
3064        }
3065    }
3066
3067    pub fn is_edit(&self) -> bool {
3068        matches!(self, Operation::Edit { .. })
3069    }
3070}
3071
3072impl operation_queue::Operation for Operation {
3073    fn lamport_timestamp(&self) -> clock::Lamport {
3074        match self {
3075            Operation::Edit(edit) => edit.timestamp,
3076            Operation::Undo(undo) => undo.timestamp,
3077        }
3078    }
3079}
3080
3081pub trait ToOffset {
3082    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize;
3083    /// Turns this point into the next offset in the buffer that comes after this, respecting utf8 boundaries.
3084    fn to_next_offset(&self, snapshot: &BufferSnapshot) -> usize {
3085        snapshot
3086            .visible_text
3087            .ceil_char_boundary(self.to_offset(snapshot) + 1)
3088    }
3089    /// Turns this point into the previous offset in the buffer that comes before this, respecting utf8 boundaries.
3090    fn to_previous_offset(&self, snapshot: &BufferSnapshot) -> usize {
3091        snapshot
3092            .visible_text
3093            .floor_char_boundary(self.to_offset(snapshot).saturating_sub(1))
3094    }
3095}
3096
3097impl ToOffset for Point {
3098    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3099        snapshot.point_to_offset(*self)
3100    }
3101}
3102
3103impl ToOffset for usize {
3104    #[track_caller]
3105    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3106        assert!(
3107            *self <= snapshot.len(),
3108            "offset {} is out of range, snapshot length is {}",
3109            self,
3110            snapshot.len()
3111        );
3112        *self
3113    }
3114}
3115
3116impl ToOffset for Anchor {
3117    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3118        snapshot.summary_for_anchor(self)
3119    }
3120}
3121
3122impl<T: ToOffset> ToOffset for &T {
3123    fn to_offset(&self, content: &BufferSnapshot) -> usize {
3124        (*self).to_offset(content)
3125    }
3126}
3127
3128impl ToOffset for PointUtf16 {
3129    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3130        snapshot.point_utf16_to_offset(*self)
3131    }
3132}
3133
3134impl ToOffset for Unclipped<PointUtf16> {
3135    fn to_offset(&self, snapshot: &BufferSnapshot) -> usize {
3136        snapshot.unclipped_point_utf16_to_offset(*self)
3137    }
3138}
3139
3140pub trait ToPoint {
3141    fn to_point(&self, snapshot: &BufferSnapshot) -> Point;
3142}
3143
3144impl ToPoint for Anchor {
3145    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3146        snapshot.summary_for_anchor(self)
3147    }
3148}
3149
3150impl ToPoint for usize {
3151    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3152        snapshot.offset_to_point(*self)
3153    }
3154}
3155
3156impl ToPoint for Point {
3157    fn to_point(&self, _: &BufferSnapshot) -> Point {
3158        *self
3159    }
3160}
3161
3162impl ToPoint for Unclipped<PointUtf16> {
3163    fn to_point(&self, snapshot: &BufferSnapshot) -> Point {
3164        snapshot.unclipped_point_utf16_to_point(*self)
3165    }
3166}
3167
3168pub trait ToPointUtf16 {
3169    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16;
3170}
3171
3172impl ToPointUtf16 for Anchor {
3173    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3174        snapshot.summary_for_anchor(self)
3175    }
3176}
3177
3178impl ToPointUtf16 for usize {
3179    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3180        snapshot.offset_to_point_utf16(*self)
3181    }
3182}
3183
3184impl ToPointUtf16 for PointUtf16 {
3185    fn to_point_utf16(&self, _: &BufferSnapshot) -> PointUtf16 {
3186        *self
3187    }
3188}
3189
3190impl ToPointUtf16 for Point {
3191    fn to_point_utf16(&self, snapshot: &BufferSnapshot) -> PointUtf16 {
3192        snapshot.point_to_point_utf16(*self)
3193    }
3194}
3195
3196pub trait ToOffsetUtf16 {
3197    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16;
3198}
3199
3200impl ToOffsetUtf16 for Anchor {
3201    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
3202        snapshot.summary_for_anchor(self)
3203    }
3204}
3205
3206impl ToOffsetUtf16 for usize {
3207    fn to_offset_utf16(&self, snapshot: &BufferSnapshot) -> OffsetUtf16 {
3208        snapshot.offset_to_offset_utf16(*self)
3209    }
3210}
3211
3212impl ToOffsetUtf16 for OffsetUtf16 {
3213    fn to_offset_utf16(&self, _snapshot: &BufferSnapshot) -> OffsetUtf16 {
3214        *self
3215    }
3216}
3217
3218pub trait FromAnchor {
3219    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self;
3220}
3221
3222impl FromAnchor for Anchor {
3223    fn from_anchor(anchor: &Anchor, _snapshot: &BufferSnapshot) -> Self {
3224        *anchor
3225    }
3226}
3227
3228impl FromAnchor for Point {
3229    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3230        snapshot.summary_for_anchor(anchor)
3231    }
3232}
3233
3234impl FromAnchor for PointUtf16 {
3235    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3236        snapshot.summary_for_anchor(anchor)
3237    }
3238}
3239
3240impl FromAnchor for usize {
3241    fn from_anchor(anchor: &Anchor, snapshot: &BufferSnapshot) -> Self {
3242        snapshot.summary_for_anchor(anchor)
3243    }
3244}
3245
3246#[derive(Clone, Copy, Debug, PartialEq)]
3247pub enum LineEnding {
3248    Unix,
3249    Windows,
3250}
3251
3252impl Default for LineEnding {
3253    fn default() -> Self {
3254        #[cfg(unix)]
3255        return Self::Unix;
3256
3257        #[cfg(not(unix))]
3258        return Self::Windows;
3259    }
3260}
3261
3262impl LineEnding {
3263    pub fn as_str(&self) -> &'static str {
3264        match self {
3265            LineEnding::Unix => "\n",
3266            LineEnding::Windows => "\r\n",
3267        }
3268    }
3269
3270    pub fn label(&self) -> &'static str {
3271        match self {
3272            LineEnding::Unix => "LF",
3273            LineEnding::Windows => "CRLF",
3274        }
3275    }
3276
3277    pub fn detect(text: &str) -> Self {
3278        let mut max_ix = cmp::min(text.len(), 1000);
3279        while !text.is_char_boundary(max_ix) {
3280            max_ix -= 1;
3281        }
3282
3283        if let Some(ix) = text[..max_ix].find(['\n']) {
3284            if ix > 0 && text.as_bytes()[ix - 1] == b'\r' {
3285                Self::Windows
3286            } else {
3287                Self::Unix
3288            }
3289        } else {
3290            Self::default()
3291        }
3292    }
3293
3294    pub fn normalize(text: &mut String) {
3295        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(text, "\n") {
3296            *text = replaced;
3297        }
3298    }
3299
3300    pub fn normalize_arc(text: Arc<str>) -> Arc<str> {
3301        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(&text, "\n") {
3302            replaced.into()
3303        } else {
3304            text
3305        }
3306    }
3307
3308    pub fn normalize_cow(text: Cow<str>) -> Cow<str> {
3309        if let Cow::Owned(replaced) = LINE_SEPARATORS_REGEX.replace_all(&text, "\n") {
3310            replaced.into()
3311        } else {
3312            text
3313        }
3314    }
3315}
3316
3317#[cfg(debug_assertions)]
3318pub mod debug {
3319    use super::*;
3320    use parking_lot::Mutex;
3321    use std::any::TypeId;
3322    use std::hash::{Hash, Hasher};
3323
3324    static GLOBAL_DEBUG_RANGES: Mutex<Option<GlobalDebugRanges>> = Mutex::new(None);
3325
3326    pub struct GlobalDebugRanges {
3327        pub ranges: Vec<DebugRange>,
3328        key_to_occurrence_index: HashMap<Key, usize>,
3329        next_occurrence_index: usize,
3330    }
3331
3332    pub struct DebugRange {
3333        key: Key,
3334        pub ranges: Vec<Range<Anchor>>,
3335        pub value: Arc<str>,
3336        pub occurrence_index: usize,
3337    }
3338
3339    #[derive(Debug, Clone, PartialEq, Eq, Hash)]
3340    struct Key {
3341        type_id: TypeId,
3342        hash: u64,
3343    }
3344
3345    impl GlobalDebugRanges {
3346        pub fn with_locked<R>(f: impl FnOnce(&mut Self) -> R) -> R {
3347            let mut state = GLOBAL_DEBUG_RANGES.lock();
3348            if state.is_none() {
3349                *state = Some(GlobalDebugRanges {
3350                    ranges: Vec::new(),
3351                    key_to_occurrence_index: HashMap::default(),
3352                    next_occurrence_index: 0,
3353                });
3354            }
3355            if let Some(global_debug_ranges) = state.as_mut() {
3356                f(global_debug_ranges)
3357            } else {
3358                unreachable!()
3359            }
3360        }
3361
3362        pub fn insert<K: Hash + 'static>(
3363            &mut self,
3364            key: &K,
3365            ranges: Vec<Range<Anchor>>,
3366            value: Arc<str>,
3367        ) {
3368            let occurrence_index = *self
3369                .key_to_occurrence_index
3370                .entry(Key::new(key))
3371                .or_insert_with(|| {
3372                    let occurrence_index = self.next_occurrence_index;
3373                    self.next_occurrence_index += 1;
3374                    occurrence_index
3375                });
3376            let key = Key::new(key);
3377            let existing = self
3378                .ranges
3379                .iter()
3380                .enumerate()
3381                .rfind(|(_, existing)| existing.key == key);
3382            if let Some((existing_ix, _)) = existing {
3383                self.ranges.remove(existing_ix);
3384            }
3385            self.ranges.push(DebugRange {
3386                ranges,
3387                key,
3388                value,
3389                occurrence_index,
3390            });
3391        }
3392
3393        pub fn remove<K: Hash + 'static>(&mut self, key: &K) {
3394            self.remove_impl(&Key::new(key));
3395        }
3396
3397        fn remove_impl(&mut self, key: &Key) {
3398            let existing = self
3399                .ranges
3400                .iter()
3401                .enumerate()
3402                .rfind(|(_, existing)| &existing.key == key);
3403            if let Some((existing_ix, _)) = existing {
3404                self.ranges.remove(existing_ix);
3405            }
3406        }
3407
3408        pub fn remove_all_with_key_type<K: 'static>(&mut self) {
3409            self.ranges
3410                .retain(|item| item.key.type_id != TypeId::of::<K>());
3411        }
3412    }
3413
3414    impl Key {
3415        fn new<K: Hash + 'static>(key: &K) -> Self {
3416            let type_id = TypeId::of::<K>();
3417            let mut hasher = collections::FxHasher::default();
3418            key.hash(&mut hasher);
3419            Key {
3420                type_id,
3421                hash: hasher.finish(),
3422            }
3423        }
3424    }
3425
3426    pub trait ToDebugRanges {
3427        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>>;
3428    }
3429
3430    impl<T: ToOffset> ToDebugRanges for T {
3431        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3432            [self.to_offset(snapshot)].to_debug_ranges(snapshot)
3433        }
3434    }
3435
3436    impl<T: ToOffset + Clone> ToDebugRanges for Range<T> {
3437        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3438            [self.clone()].to_debug_ranges(snapshot)
3439        }
3440    }
3441
3442    impl<T: ToOffset> ToDebugRanges for Vec<T> {
3443        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3444            self.as_slice().to_debug_ranges(snapshot)
3445        }
3446    }
3447
3448    impl<T: ToOffset> ToDebugRanges for Vec<Range<T>> {
3449        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3450            self.as_slice().to_debug_ranges(snapshot)
3451        }
3452    }
3453
3454    impl<T: ToOffset> ToDebugRanges for [T] {
3455        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3456            self.iter()
3457                .map(|item| {
3458                    let offset = item.to_offset(snapshot);
3459                    offset..offset
3460                })
3461                .collect()
3462        }
3463    }
3464
3465    impl<T: ToOffset> ToDebugRanges for [Range<T>] {
3466        fn to_debug_ranges(&self, snapshot: &BufferSnapshot) -> Vec<Range<usize>> {
3467            self.iter()
3468                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
3469                .collect()
3470        }
3471    }
3472}