1use crate::PointUtf16;
   2
   3use super::Point;
   4use arrayvec::ArrayString;
   5use smallvec::SmallVec;
   6use std::{cmp, fmt, io, mem, ops::Range, str};
   7use sum_tree::{Bias, Dimension, SumTree};
   8
   9#[cfg(test)]
  10const CHUNK_BASE: usize = 6;
  11
  12#[cfg(not(test))]
  13const CHUNK_BASE: usize = 16;
  14
  15#[derive(Clone, Default, Debug)]
  16pub struct Rope {
  17    chunks: SumTree<Chunk>,
  18}
  19
  20impl Rope {
  21    pub fn new() -> Self {
  22        Self::default()
  23    }
  24
  25    pub fn append(&mut self, rope: Rope) {
  26        let mut chunks = rope.chunks.cursor::<()>();
  27        chunks.next(&());
  28        if let Some(chunk) = chunks.item() {
  29            if self.chunks.last().map_or(false, |c| c.0.len() < CHUNK_BASE)
  30                || chunk.0.len() < CHUNK_BASE
  31            {
  32                self.push(&chunk.0);
  33                chunks.next(&());
  34            }
  35        }
  36
  37        self.chunks.push_tree(chunks.suffix(&()), &());
  38        self.check_invariants();
  39    }
  40
  41    pub fn replace(&mut self, range: Range<usize>, text: &str) {
  42        let mut new_rope = Rope::new();
  43        let mut cursor = self.cursor(0);
  44        new_rope.append(cursor.slice(range.start));
  45        cursor.seek_forward(range.end);
  46        new_rope.push(text);
  47        new_rope.append(cursor.suffix());
  48        *self = new_rope;
  49    }
  50
  51    pub fn push(&mut self, text: &str) {
  52        let mut new_chunks = SmallVec::<[_; 16]>::new();
  53        let mut new_chunk = ArrayString::new();
  54        for ch in text.chars() {
  55            if new_chunk.len() + ch.len_utf8() > 2 * CHUNK_BASE {
  56                new_chunks.push(Chunk(new_chunk));
  57                new_chunk = ArrayString::new();
  58            }
  59            new_chunk.push(ch);
  60        }
  61        if !new_chunk.is_empty() {
  62            new_chunks.push(Chunk(new_chunk));
  63        }
  64
  65        let mut new_chunks = new_chunks.into_iter();
  66        let mut first_new_chunk = new_chunks.next();
  67        self.chunks.update_last(
  68            |last_chunk| {
  69                if let Some(first_new_chunk_ref) = first_new_chunk.as_mut() {
  70                    if last_chunk.0.len() + first_new_chunk_ref.0.len() <= 2 * CHUNK_BASE {
  71                        last_chunk.0.push_str(&first_new_chunk.take().unwrap().0);
  72                    } else {
  73                        let mut text = ArrayString::<{ 4 * CHUNK_BASE }>::new();
  74                        text.push_str(&last_chunk.0);
  75                        text.push_str(&first_new_chunk_ref.0);
  76                        let (left, right) = text.split_at(find_split_ix(&text));
  77                        last_chunk.0.clear();
  78                        last_chunk.0.push_str(left);
  79                        first_new_chunk_ref.0.clear();
  80                        first_new_chunk_ref.0.push_str(right);
  81                    }
  82                }
  83            },
  84            &(),
  85        );
  86
  87        self.chunks
  88            .extend(first_new_chunk.into_iter().chain(new_chunks), &());
  89        self.check_invariants();
  90    }
  91
  92    pub fn push_front(&mut self, text: &str) {
  93        let suffix = mem::replace(self, Rope::from(text));
  94        self.append(suffix);
  95    }
  96
  97    fn check_invariants(&self) {
  98        #[cfg(test)]
  99        {
 100            // Ensure all chunks except maybe the last one are not underflowing.
 101            // Allow some wiggle room for multibyte characters at chunk boundaries.
 102            let mut chunks = self.chunks.cursor::<()>().peekable();
 103            while let Some(chunk) = chunks.next() {
 104                if chunks.peek().is_some() {
 105                    assert!(chunk.0.len() + 3 >= CHUNK_BASE);
 106                }
 107            }
 108        }
 109    }
 110
 111    pub fn summary(&self) -> TextSummary {
 112        self.chunks.summary()
 113    }
 114
 115    pub fn len(&self) -> usize {
 116        self.chunks.extent(&())
 117    }
 118
 119    pub fn max_point(&self) -> Point {
 120        self.chunks.extent(&())
 121    }
 122
 123    pub fn cursor(&self, offset: usize) -> Cursor {
 124        Cursor::new(self, offset)
 125    }
 126
 127    pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
 128        self.chars_at(0)
 129    }
 130
 131    pub fn chars_at(&self, start: usize) -> impl Iterator<Item = char> + '_ {
 132        self.chunks_in_range(start..self.len()).flat_map(str::chars)
 133    }
 134
 135    pub fn reversed_chars_at(&self, start: usize) -> impl Iterator<Item = char> + '_ {
 136        self.reversed_chunks_in_range(0..start)
 137            .flat_map(|chunk| chunk.chars().rev())
 138    }
 139
 140    pub fn bytes_in_range(&self, range: Range<usize>) -> Bytes {
 141        Bytes::new(self, range)
 142    }
 143
 144    pub fn chunks<'a>(&'a self) -> Chunks<'a> {
 145        self.chunks_in_range(0..self.len())
 146    }
 147
 148    pub fn chunks_in_range(&self, range: Range<usize>) -> Chunks {
 149        Chunks::new(self, range, false)
 150    }
 151
 152    pub fn reversed_chunks_in_range(&self, range: Range<usize>) -> Chunks {
 153        Chunks::new(self, range, true)
 154    }
 155
 156    pub fn offset_to_point(&self, offset: usize) -> Point {
 157        if offset >= self.summary().bytes {
 158            return self.summary().lines;
 159        }
 160        let mut cursor = self.chunks.cursor::<(usize, Point)>();
 161        cursor.seek(&offset, Bias::Left, &());
 162        let overshoot = offset - cursor.start().0;
 163        cursor.start().1
 164            + cursor
 165                .item()
 166                .map_or(Point::zero(), |chunk| chunk.offset_to_point(overshoot))
 167    }
 168
 169    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
 170        if offset >= self.summary().bytes {
 171            return self.summary().lines_utf16;
 172        }
 173        let mut cursor = self.chunks.cursor::<(usize, PointUtf16)>();
 174        cursor.seek(&offset, Bias::Left, &());
 175        let overshoot = offset - cursor.start().0;
 176        cursor.start().1
 177            + cursor.item().map_or(PointUtf16::zero(), |chunk| {
 178                chunk.offset_to_point_utf16(overshoot)
 179            })
 180    }
 181
 182    pub fn point_to_offset(&self, point: Point) -> usize {
 183        if point >= self.summary().lines {
 184            return self.summary().bytes;
 185        }
 186        let mut cursor = self.chunks.cursor::<(Point, usize)>();
 187        cursor.seek(&point, Bias::Left, &());
 188        let overshoot = point - cursor.start().0;
 189        cursor.start().1
 190            + cursor
 191                .item()
 192                .map_or(0, |chunk| chunk.point_to_offset(overshoot))
 193    }
 194
 195    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
 196        if point >= self.summary().lines_utf16 {
 197            return self.summary().bytes;
 198        }
 199        let mut cursor = self.chunks.cursor::<(PointUtf16, usize)>();
 200        cursor.seek(&point, Bias::Left, &());
 201        let overshoot = point - cursor.start().0;
 202        cursor.start().1
 203            + cursor
 204                .item()
 205                .map_or(0, |chunk| chunk.point_utf16_to_offset(overshoot))
 206    }
 207
 208    pub fn point_utf16_to_point(&self, point: PointUtf16) -> Point {
 209        if point >= self.summary().lines_utf16 {
 210            return self.summary().lines;
 211        }
 212        let mut cursor = self.chunks.cursor::<(PointUtf16, Point)>();
 213        cursor.seek(&point, Bias::Left, &());
 214        let overshoot = point - cursor.start().0;
 215        cursor.start().1
 216            + cursor
 217                .item()
 218                .map_or(Point::zero(), |chunk| chunk.point_utf16_to_point(overshoot))
 219    }
 220
 221    pub fn clip_offset(&self, mut offset: usize, bias: Bias) -> usize {
 222        let mut cursor = self.chunks.cursor::<usize>();
 223        cursor.seek(&offset, Bias::Left, &());
 224        if let Some(chunk) = cursor.item() {
 225            let mut ix = offset - cursor.start();
 226            while !chunk.0.is_char_boundary(ix) {
 227                match bias {
 228                    Bias::Left => {
 229                        ix -= 1;
 230                        offset -= 1;
 231                    }
 232                    Bias::Right => {
 233                        ix += 1;
 234                        offset += 1;
 235                    }
 236                }
 237            }
 238            offset
 239        } else {
 240            self.summary().bytes
 241        }
 242    }
 243
 244    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
 245        let mut cursor = self.chunks.cursor::<Point>();
 246        cursor.seek(&point, Bias::Right, &());
 247        if let Some(chunk) = cursor.item() {
 248            let overshoot = point - cursor.start();
 249            *cursor.start() + chunk.clip_point(overshoot, bias)
 250        } else {
 251            self.summary().lines
 252        }
 253    }
 254
 255    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
 256        let mut cursor = self.chunks.cursor::<PointUtf16>();
 257        cursor.seek(&point, Bias::Right, &());
 258        if let Some(chunk) = cursor.item() {
 259            let overshoot = point - cursor.start();
 260            *cursor.start() + chunk.clip_point_utf16(overshoot, bias)
 261        } else {
 262            self.summary().lines_utf16
 263        }
 264    }
 265
 266    pub fn line_len(&self, row: u32) -> u32 {
 267        self.clip_point(Point::new(row, u32::MAX), Bias::Left)
 268            .column
 269    }
 270}
 271
 272impl<'a> From<&'a str> for Rope {
 273    fn from(text: &'a str) -> Self {
 274        let mut rope = Self::new();
 275        rope.push(text);
 276        rope
 277    }
 278}
 279
 280impl fmt::Display for Rope {
 281    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 282        for chunk in self.chunks() {
 283            write!(f, "{}", chunk)?;
 284        }
 285        Ok(())
 286    }
 287}
 288
 289pub struct Cursor<'a> {
 290    rope: &'a Rope,
 291    chunks: sum_tree::Cursor<'a, Chunk, usize>,
 292    offset: usize,
 293}
 294
 295impl<'a> Cursor<'a> {
 296    pub fn new(rope: &'a Rope, offset: usize) -> Self {
 297        let mut chunks = rope.chunks.cursor();
 298        chunks.seek(&offset, Bias::Right, &());
 299        Self {
 300            rope,
 301            chunks,
 302            offset,
 303        }
 304    }
 305
 306    pub fn seek_forward(&mut self, end_offset: usize) {
 307        debug_assert!(end_offset >= self.offset);
 308
 309        self.chunks.seek_forward(&end_offset, Bias::Right, &());
 310        self.offset = end_offset;
 311    }
 312
 313    pub fn slice(&mut self, end_offset: usize) -> Rope {
 314        debug_assert!(
 315            end_offset >= self.offset,
 316            "cannot slice backwards from {} to {}",
 317            self.offset,
 318            end_offset
 319        );
 320
 321        let mut slice = Rope::new();
 322        if let Some(start_chunk) = self.chunks.item() {
 323            let start_ix = self.offset - self.chunks.start();
 324            let end_ix = cmp::min(end_offset, self.chunks.end(&())) - self.chunks.start();
 325            slice.push(&start_chunk.0[start_ix..end_ix]);
 326        }
 327
 328        if end_offset > self.chunks.end(&()) {
 329            self.chunks.next(&());
 330            slice.append(Rope {
 331                chunks: self.chunks.slice(&end_offset, Bias::Right, &()),
 332            });
 333            if let Some(end_chunk) = self.chunks.item() {
 334                let end_ix = end_offset - self.chunks.start();
 335                slice.push(&end_chunk.0[..end_ix]);
 336            }
 337        }
 338
 339        self.offset = end_offset;
 340        slice
 341    }
 342
 343    pub fn summary<D: TextDimension>(&mut self, end_offset: usize) -> D {
 344        debug_assert!(end_offset >= self.offset);
 345
 346        let mut summary = D::default();
 347        if let Some(start_chunk) = self.chunks.item() {
 348            let start_ix = self.offset - self.chunks.start();
 349            let end_ix = cmp::min(end_offset, self.chunks.end(&())) - self.chunks.start();
 350            summary.add_assign(&D::from_text_summary(&TextSummary::from(
 351                &start_chunk.0[start_ix..end_ix],
 352            )));
 353        }
 354
 355        if end_offset > self.chunks.end(&()) {
 356            self.chunks.next(&());
 357            summary.add_assign(&self.chunks.summary(&end_offset, Bias::Right, &()));
 358            if let Some(end_chunk) = self.chunks.item() {
 359                let end_ix = end_offset - self.chunks.start();
 360                summary.add_assign(&D::from_text_summary(&TextSummary::from(
 361                    &end_chunk.0[..end_ix],
 362                )));
 363            }
 364        }
 365
 366        self.offset = end_offset;
 367        summary
 368    }
 369
 370    pub fn suffix(mut self) -> Rope {
 371        self.slice(self.rope.chunks.extent(&()))
 372    }
 373
 374    pub fn offset(&self) -> usize {
 375        self.offset
 376    }
 377}
 378
 379pub struct Chunks<'a> {
 380    chunks: sum_tree::Cursor<'a, Chunk, usize>,
 381    range: Range<usize>,
 382    reversed: bool,
 383}
 384
 385impl<'a> Chunks<'a> {
 386    pub fn new(rope: &'a Rope, range: Range<usize>, reversed: bool) -> Self {
 387        let mut chunks = rope.chunks.cursor();
 388        if reversed {
 389            chunks.seek(&range.end, Bias::Left, &());
 390        } else {
 391            chunks.seek(&range.start, Bias::Right, &());
 392        }
 393        Self {
 394            chunks,
 395            range,
 396            reversed,
 397        }
 398    }
 399
 400    pub fn offset(&self) -> usize {
 401        if self.reversed {
 402            self.range.end.min(self.chunks.end(&()))
 403        } else {
 404            self.range.start.max(*self.chunks.start())
 405        }
 406    }
 407
 408    pub fn seek(&mut self, offset: usize) {
 409        let bias = if self.reversed {
 410            Bias::Left
 411        } else {
 412            Bias::Right
 413        };
 414
 415        if offset >= self.chunks.end(&()) {
 416            self.chunks.seek_forward(&offset, bias, &());
 417        } else {
 418            self.chunks.seek(&offset, bias, &());
 419        }
 420
 421        if self.reversed {
 422            self.range.end = offset;
 423        } else {
 424            self.range.start = offset;
 425        }
 426    }
 427
 428    pub fn peek(&self) -> Option<&'a str> {
 429        let chunk = self.chunks.item()?;
 430        if self.reversed && self.range.start >= self.chunks.end(&()) {
 431            return None;
 432        }
 433        let chunk_start = *self.chunks.start();
 434        if self.range.end <= chunk_start {
 435            return None;
 436        }
 437
 438        let start = self.range.start.saturating_sub(chunk_start);
 439        let end = self.range.end - chunk_start;
 440        Some(&chunk.0[start..chunk.0.len().min(end)])
 441    }
 442}
 443
 444impl<'a> Iterator for Chunks<'a> {
 445    type Item = &'a str;
 446
 447    fn next(&mut self) -> Option<Self::Item> {
 448        let result = self.peek();
 449        if result.is_some() {
 450            if self.reversed {
 451                self.chunks.prev(&());
 452            } else {
 453                self.chunks.next(&());
 454            }
 455        }
 456        result
 457    }
 458}
 459
 460pub struct Bytes<'a> {
 461    chunks: sum_tree::Cursor<'a, Chunk, usize>,
 462    range: Range<usize>,
 463}
 464
 465impl<'a> Bytes<'a> {
 466    pub fn new(rope: &'a Rope, range: Range<usize>) -> Self {
 467        let mut chunks = rope.chunks.cursor();
 468        chunks.seek(&range.start, Bias::Right, &());
 469        Self { chunks, range }
 470    }
 471
 472    pub fn peek(&self) -> Option<&'a [u8]> {
 473        let chunk = self.chunks.item()?;
 474        let chunk_start = *self.chunks.start();
 475        if self.range.end <= chunk_start {
 476            return None;
 477        }
 478
 479        let start = self.range.start.saturating_sub(chunk_start);
 480        let end = self.range.end - chunk_start;
 481        Some(&chunk.0.as_bytes()[start..chunk.0.len().min(end)])
 482    }
 483}
 484
 485impl<'a> Iterator for Bytes<'a> {
 486    type Item = &'a [u8];
 487
 488    fn next(&mut self) -> Option<Self::Item> {
 489        let result = self.peek();
 490        if result.is_some() {
 491            self.chunks.next(&());
 492        }
 493        result
 494    }
 495}
 496
 497impl<'a> io::Read for Bytes<'a> {
 498    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
 499        if let Some(chunk) = self.peek() {
 500            let len = cmp::min(buf.len(), chunk.len());
 501            buf[..len].copy_from_slice(&chunk[..len]);
 502            self.range.start += len;
 503            if len == chunk.len() {
 504                self.chunks.next(&());
 505            }
 506            Ok(len)
 507        } else {
 508            Ok(0)
 509        }
 510    }
 511}
 512
 513#[derive(Clone, Debug, Default)]
 514struct Chunk(ArrayString<{ 2 * CHUNK_BASE }>);
 515
 516impl Chunk {
 517    fn offset_to_point(&self, target: usize) -> Point {
 518        let mut offset = 0;
 519        let mut point = Point::new(0, 0);
 520        for ch in self.0.chars() {
 521            if offset >= target {
 522                break;
 523            }
 524
 525            if ch == '\n' {
 526                point.row += 1;
 527                point.column = 0;
 528            } else {
 529                point.column += ch.len_utf8() as u32;
 530            }
 531            offset += ch.len_utf8();
 532        }
 533        point
 534    }
 535
 536    fn offset_to_point_utf16(&self, target: usize) -> PointUtf16 {
 537        let mut offset = 0;
 538        let mut point = PointUtf16::new(0, 0);
 539        for ch in self.0.chars() {
 540            if offset >= target {
 541                break;
 542            }
 543
 544            if ch == '\n' {
 545                point.row += 1;
 546                point.column = 0;
 547            } else {
 548                point.column += ch.len_utf16() as u32;
 549            }
 550            offset += ch.len_utf8();
 551        }
 552        point
 553    }
 554
 555    fn point_to_offset(&self, target: Point) -> usize {
 556        let mut offset = 0;
 557        let mut point = Point::new(0, 0);
 558        for ch in self.0.chars() {
 559            if point >= target {
 560                if point > target {
 561                    panic!("point {:?} is inside of character {:?}", target, ch);
 562                }
 563                break;
 564            }
 565
 566            if ch == '\n' {
 567                point.row += 1;
 568                point.column = 0;
 569            } else {
 570                point.column += ch.len_utf8() as u32;
 571            }
 572            offset += ch.len_utf8();
 573        }
 574        offset
 575    }
 576
 577    fn point_utf16_to_offset(&self, target: PointUtf16) -> usize {
 578        let mut offset = 0;
 579        let mut point = PointUtf16::new(0, 0);
 580        for ch in self.0.chars() {
 581            if point >= target {
 582                if point > target {
 583                    panic!("point {:?} is inside of character {:?}", target, ch);
 584                }
 585                break;
 586            }
 587
 588            if ch == '\n' {
 589                point.row += 1;
 590                point.column = 0;
 591            } else {
 592                point.column += ch.len_utf16() as u32;
 593            }
 594            offset += ch.len_utf8();
 595        }
 596        offset
 597    }
 598
 599    fn point_utf16_to_point(&self, target: PointUtf16) -> Point {
 600        let mut point = Point::zero();
 601        let mut point_utf16 = PointUtf16::zero();
 602        for ch in self.0.chars() {
 603            if point_utf16 >= target {
 604                if point_utf16 > target {
 605                    panic!("point {:?} is inside of character {:?}", target, ch);
 606                }
 607                break;
 608            }
 609
 610            if ch == '\n' {
 611                point_utf16 += PointUtf16::new(1, 0);
 612                point += Point::new(1, 0);
 613            } else {
 614                point_utf16 += PointUtf16::new(0, ch.len_utf16() as u32);
 615                point += Point::new(0, ch.len_utf8() as u32);
 616            }
 617        }
 618        point
 619    }
 620
 621    fn clip_point(&self, target: Point, bias: Bias) -> Point {
 622        for (row, line) in self.0.split('\n').enumerate() {
 623            if row == target.row as usize {
 624                let mut column = target.column.min(line.len() as u32);
 625                while !line.is_char_boundary(column as usize) {
 626                    match bias {
 627                        Bias::Left => column -= 1,
 628                        Bias::Right => column += 1,
 629                    }
 630                }
 631                return Point::new(row as u32, column);
 632            }
 633        }
 634        unreachable!()
 635    }
 636
 637    fn clip_point_utf16(&self, target: PointUtf16, bias: Bias) -> PointUtf16 {
 638        for (row, line) in self.0.split('\n').enumerate() {
 639            if row == target.row as usize {
 640                let mut code_units = line.encode_utf16();
 641                let mut column = code_units.by_ref().take(target.column as usize).count();
 642                if char::decode_utf16(code_units).next().transpose().is_err() {
 643                    match bias {
 644                        Bias::Left => column -= 1,
 645                        Bias::Right => column += 1,
 646                    }
 647                }
 648                return PointUtf16::new(row as u32, column as u32);
 649            }
 650        }
 651        unreachable!()
 652    }
 653}
 654
 655impl sum_tree::Item for Chunk {
 656    type Summary = TextSummary;
 657
 658    fn summary(&self) -> Self::Summary {
 659        TextSummary::from(self.0.as_str())
 660    }
 661}
 662
 663#[derive(Clone, Debug, Default, Eq, PartialEq)]
 664pub struct TextSummary {
 665    pub bytes: usize,
 666    pub lines: Point,
 667    pub lines_utf16: PointUtf16,
 668    pub first_line_chars: u32,
 669    pub last_line_chars: u32,
 670    pub longest_row: u32,
 671    pub longest_row_chars: u32,
 672}
 673
 674impl<'a> From<&'a str> for TextSummary {
 675    fn from(text: &'a str) -> Self {
 676        let mut lines = Point::new(0, 0);
 677        let mut lines_utf16 = PointUtf16::new(0, 0);
 678        let mut first_line_chars = 0;
 679        let mut last_line_chars = 0;
 680        let mut longest_row = 0;
 681        let mut longest_row_chars = 0;
 682        for c in text.chars() {
 683            if c == '\n' {
 684                lines += Point::new(1, 0);
 685                lines_utf16 += PointUtf16::new(1, 0);
 686                last_line_chars = 0;
 687            } else {
 688                lines.column += c.len_utf8() as u32;
 689                lines_utf16.column += c.len_utf16() as u32;
 690                last_line_chars += 1;
 691            }
 692
 693            if lines.row == 0 {
 694                first_line_chars = last_line_chars;
 695            }
 696
 697            if last_line_chars > longest_row_chars {
 698                longest_row = lines.row;
 699                longest_row_chars = last_line_chars;
 700            }
 701        }
 702
 703        TextSummary {
 704            bytes: text.len(),
 705            lines,
 706            lines_utf16,
 707            first_line_chars,
 708            last_line_chars,
 709            longest_row,
 710            longest_row_chars,
 711        }
 712    }
 713}
 714
 715impl sum_tree::Summary for TextSummary {
 716    type Context = ();
 717
 718    fn add_summary(&mut self, summary: &Self, _: &Self::Context) {
 719        *self += summary;
 720    }
 721}
 722
 723impl<'a> std::ops::Add<Self> for TextSummary {
 724    type Output = Self;
 725
 726    fn add(mut self, rhs: Self) -> Self::Output {
 727        self.add_assign(&rhs);
 728        self
 729    }
 730}
 731
 732impl<'a> std::ops::AddAssign<&'a Self> for TextSummary {
 733    fn add_assign(&mut self, other: &'a Self) {
 734        let joined_chars = self.last_line_chars + other.first_line_chars;
 735        if joined_chars > self.longest_row_chars {
 736            self.longest_row = self.lines.row;
 737            self.longest_row_chars = joined_chars;
 738        }
 739        if other.longest_row_chars > self.longest_row_chars {
 740            self.longest_row = self.lines.row + other.longest_row;
 741            self.longest_row_chars = other.longest_row_chars;
 742        }
 743
 744        if self.lines.row == 0 {
 745            self.first_line_chars += other.first_line_chars;
 746        }
 747
 748        if other.lines.row == 0 {
 749            self.last_line_chars += other.first_line_chars;
 750        } else {
 751            self.last_line_chars = other.last_line_chars;
 752        }
 753
 754        self.bytes += other.bytes;
 755        self.lines += other.lines;
 756        self.lines_utf16 += other.lines_utf16;
 757    }
 758}
 759
 760impl std::ops::AddAssign<Self> for TextSummary {
 761    fn add_assign(&mut self, other: Self) {
 762        *self += &other;
 763    }
 764}
 765
 766pub trait TextDimension: 'static + for<'a> Dimension<'a, TextSummary> {
 767    fn from_text_summary(summary: &TextSummary) -> Self;
 768    fn add_assign(&mut self, other: &Self);
 769}
 770
 771impl<'a, D1: TextDimension, D2: TextDimension> TextDimension for (D1, D2) {
 772    fn from_text_summary(summary: &TextSummary) -> Self {
 773        (
 774            D1::from_text_summary(summary),
 775            D2::from_text_summary(summary),
 776        )
 777    }
 778
 779    fn add_assign(&mut self, other: &Self) {
 780        self.0.add_assign(&other.0);
 781        self.1.add_assign(&other.1);
 782    }
 783}
 784
 785impl TextDimension for TextSummary {
 786    fn from_text_summary(summary: &TextSummary) -> Self {
 787        summary.clone()
 788    }
 789
 790    fn add_assign(&mut self, other: &Self) {
 791        *self += other;
 792    }
 793}
 794
 795impl<'a> sum_tree::Dimension<'a, TextSummary> for usize {
 796    fn add_summary(&mut self, summary: &'a TextSummary, _: &()) {
 797        *self += summary.bytes;
 798    }
 799}
 800
 801impl TextDimension for usize {
 802    fn from_text_summary(summary: &TextSummary) -> Self {
 803        summary.bytes
 804    }
 805
 806    fn add_assign(&mut self, other: &Self) {
 807        *self += other;
 808    }
 809}
 810
 811impl<'a> sum_tree::Dimension<'a, TextSummary> for Point {
 812    fn add_summary(&mut self, summary: &'a TextSummary, _: &()) {
 813        *self += summary.lines;
 814    }
 815}
 816
 817impl TextDimension for Point {
 818    fn from_text_summary(summary: &TextSummary) -> Self {
 819        summary.lines
 820    }
 821
 822    fn add_assign(&mut self, other: &Self) {
 823        *self += other;
 824    }
 825}
 826
 827impl<'a> sum_tree::Dimension<'a, TextSummary> for PointUtf16 {
 828    fn add_summary(&mut self, summary: &'a TextSummary, _: &()) {
 829        *self += summary.lines_utf16;
 830    }
 831}
 832
 833impl TextDimension for PointUtf16 {
 834    fn from_text_summary(summary: &TextSummary) -> Self {
 835        summary.lines_utf16
 836    }
 837
 838    fn add_assign(&mut self, other: &Self) {
 839        *self += other;
 840    }
 841}
 842
 843fn find_split_ix(text: &str) -> usize {
 844    let mut ix = text.len() / 2;
 845    while !text.is_char_boundary(ix) {
 846        if ix < 2 * CHUNK_BASE {
 847            ix += 1;
 848        } else {
 849            ix = (text.len() / 2) - 1;
 850            break;
 851        }
 852    }
 853    while !text.is_char_boundary(ix) {
 854        ix -= 1;
 855    }
 856
 857    debug_assert!(ix <= 2 * CHUNK_BASE);
 858    debug_assert!(text.len() - ix <= 2 * CHUNK_BASE);
 859    ix
 860}
 861
 862#[cfg(test)]
 863mod tests {
 864    use super::*;
 865    use crate::random_char_iter::RandomCharIter;
 866    use rand::prelude::*;
 867    use std::{cmp::Ordering, env, io::Read};
 868    use Bias::{Left, Right};
 869
 870    #[test]
 871    fn test_all_4_byte_chars() {
 872        let mut rope = Rope::new();
 873        let text = "🏀".repeat(256);
 874        rope.push(&text);
 875        assert_eq!(rope.text(), text);
 876    }
 877
 878    #[test]
 879    fn test_clip() {
 880        let rope = Rope::from("🧘");
 881
 882        assert_eq!(rope.clip_offset(1, Bias::Left), 0);
 883        assert_eq!(rope.clip_offset(1, Bias::Right), 4);
 884        assert_eq!(rope.clip_offset(5, Bias::Right), 4);
 885
 886        assert_eq!(
 887            rope.clip_point(Point::new(0, 1), Bias::Left),
 888            Point::new(0, 0)
 889        );
 890        assert_eq!(
 891            rope.clip_point(Point::new(0, 1), Bias::Right),
 892            Point::new(0, 4)
 893        );
 894        assert_eq!(
 895            rope.clip_point(Point::new(0, 5), Bias::Right),
 896            Point::new(0, 4)
 897        );
 898
 899        assert_eq!(
 900            rope.clip_point_utf16(PointUtf16::new(0, 1), Bias::Left),
 901            PointUtf16::new(0, 0)
 902        );
 903        assert_eq!(
 904            rope.clip_point_utf16(PointUtf16::new(0, 1), Bias::Right),
 905            PointUtf16::new(0, 2)
 906        );
 907        assert_eq!(
 908            rope.clip_point_utf16(PointUtf16::new(0, 3), Bias::Right),
 909            PointUtf16::new(0, 2)
 910        );
 911    }
 912
 913    #[gpui::test(iterations = 100)]
 914    fn test_random_rope(mut rng: StdRng) {
 915        let operations = env::var("OPERATIONS")
 916            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
 917            .unwrap_or(10);
 918
 919        let mut expected = String::new();
 920        let mut actual = Rope::new();
 921        for _ in 0..operations {
 922            let end_ix = clip_offset(&expected, rng.gen_range(0..=expected.len()), Right);
 923            let start_ix = clip_offset(&expected, rng.gen_range(0..=end_ix), Left);
 924            let len = rng.gen_range(0..=64);
 925            let new_text: String = RandomCharIter::new(&mut rng).take(len).collect();
 926
 927            let mut new_actual = Rope::new();
 928            let mut cursor = actual.cursor(0);
 929            new_actual.append(cursor.slice(start_ix));
 930            new_actual.push(&new_text);
 931            cursor.seek_forward(end_ix);
 932            new_actual.append(cursor.suffix());
 933            actual = new_actual;
 934
 935            expected.replace_range(start_ix..end_ix, &new_text);
 936
 937            assert_eq!(actual.text(), expected);
 938            log::info!("text: {:?}", expected);
 939
 940            for _ in 0..5 {
 941                let end_ix = clip_offset(&expected, rng.gen_range(0..=expected.len()), Right);
 942                let start_ix = clip_offset(&expected, rng.gen_range(0..=end_ix), Left);
 943
 944                let actual_text = actual.chunks_in_range(start_ix..end_ix).collect::<String>();
 945                assert_eq!(actual_text, &expected[start_ix..end_ix]);
 946
 947                let mut actual_text = String::new();
 948                actual
 949                    .bytes_in_range(start_ix..end_ix)
 950                    .read_to_string(&mut actual_text)
 951                    .unwrap();
 952                assert_eq!(actual_text, &expected[start_ix..end_ix]);
 953
 954                assert_eq!(
 955                    actual
 956                        .reversed_chunks_in_range(start_ix..end_ix)
 957                        .collect::<Vec<&str>>()
 958                        .into_iter()
 959                        .rev()
 960                        .collect::<String>(),
 961                    &expected[start_ix..end_ix]
 962                );
 963            }
 964
 965            let mut point = Point::new(0, 0);
 966            let mut point_utf16 = PointUtf16::new(0, 0);
 967            for (ix, ch) in expected.char_indices().chain(Some((expected.len(), '\0'))) {
 968                assert_eq!(actual.offset_to_point(ix), point, "offset_to_point({})", ix);
 969                assert_eq!(
 970                    actual.offset_to_point_utf16(ix),
 971                    point_utf16,
 972                    "offset_to_point_utf16({})",
 973                    ix
 974                );
 975                assert_eq!(
 976                    actual.point_to_offset(point),
 977                    ix,
 978                    "point_to_offset({:?})",
 979                    point
 980                );
 981                assert_eq!(
 982                    actual.point_utf16_to_offset(point_utf16),
 983                    ix,
 984                    "point_utf16_to_offset({:?})",
 985                    point_utf16
 986                );
 987                if ch == '\n' {
 988                    point += Point::new(1, 0);
 989                    point_utf16 += PointUtf16::new(1, 0);
 990                } else {
 991                    point.column += ch.len_utf8() as u32;
 992                    point_utf16.column += ch.len_utf16() as u32;
 993                }
 994            }
 995
 996            let mut point_utf16 = PointUtf16::zero();
 997            for unit in expected.encode_utf16() {
 998                let left_point = actual.clip_point_utf16(point_utf16, Bias::Left);
 999                let right_point = actual.clip_point_utf16(point_utf16, Bias::Right);
1000                assert!(right_point >= left_point);
1001                // Ensure translating UTF-16 points to offsets doesn't panic.
1002                actual.point_utf16_to_offset(left_point);
1003                actual.point_utf16_to_offset(right_point);
1004
1005                if unit == b'\n' as u16 {
1006                    point_utf16 += PointUtf16::new(1, 0);
1007                } else {
1008                    point_utf16 += PointUtf16::new(0, 1);
1009                }
1010            }
1011
1012            for _ in 0..5 {
1013                let end_ix = clip_offset(&expected, rng.gen_range(0..=expected.len()), Right);
1014                let start_ix = clip_offset(&expected, rng.gen_range(0..=end_ix), Left);
1015                assert_eq!(
1016                    actual.cursor(start_ix).summary::<TextSummary>(end_ix),
1017                    TextSummary::from(&expected[start_ix..end_ix])
1018                );
1019            }
1020
1021            let mut expected_longest_rows = Vec::new();
1022            let mut longest_line_len = -1_isize;
1023            for (row, line) in expected.split('\n').enumerate() {
1024                let row = row as u32;
1025                assert_eq!(
1026                    actual.line_len(row),
1027                    line.len() as u32,
1028                    "invalid line len for row {}",
1029                    row
1030                );
1031
1032                let line_char_count = line.chars().count() as isize;
1033                match line_char_count.cmp(&longest_line_len) {
1034                    Ordering::Less => {}
1035                    Ordering::Equal => expected_longest_rows.push(row),
1036                    Ordering::Greater => {
1037                        longest_line_len = line_char_count;
1038                        expected_longest_rows.clear();
1039                        expected_longest_rows.push(row);
1040                    }
1041                }
1042            }
1043
1044            let longest_row = actual.summary().longest_row;
1045            assert!(
1046                expected_longest_rows.contains(&longest_row),
1047                "incorrect longest row {}. expected {:?} with length {}",
1048                longest_row,
1049                expected_longest_rows,
1050                longest_line_len,
1051            );
1052        }
1053    }
1054
1055    fn clip_offset(text: &str, mut offset: usize, bias: Bias) -> usize {
1056        while !text.is_char_boundary(offset) {
1057            match bias {
1058                Bias::Left => offset -= 1,
1059                Bias::Right => offset += 1,
1060            }
1061        }
1062        offset
1063    }
1064
1065    impl Rope {
1066        fn text(&self) -> String {
1067            let mut text = String::new();
1068            for chunk in self.chunks.cursor::<()>() {
1069                text.push_str(&chunk.0);
1070            }
1071            text
1072        }
1073    }
1074}