movement.rs

   1//! Movement module contains helper functions for calculating intended position
   2//! in editor given a given motion (e.g. it handles converting a "move left" command into coordinates in editor). It is exposed mostly for use by vim crate.
   3
   4use super::{Bias, DisplayPoint, DisplaySnapshot, SelectionGoal, ToDisplayPoint};
   5use crate::{scroll::ScrollAnchor, CharKind, DisplayRow, EditorStyle, ToOffset, ToPoint};
   6use gpui::{Pixels, WindowTextSystem};
   7use language::Point;
   8use multi_buffer::{MultiBufferRow, MultiBufferSnapshot};
   9use serde::Deserialize;
  10use workspace::searchable::Direction;
  11
  12use std::{ops::Range, sync::Arc};
  13
  14/// Defines search strategy for items in `movement` module.
  15/// `FindRange::SingeLine` only looks for a match on a single line at a time, whereas
  16/// `FindRange::MultiLine` keeps going until the end of a string.
  17#[derive(Clone, Copy, Debug, PartialEq, Eq, Deserialize)]
  18pub enum FindRange {
  19    SingleLine,
  20    MultiLine,
  21}
  22
  23/// TextLayoutDetails encompasses everything we need to move vertically
  24/// taking into account variable width characters.
  25pub struct TextLayoutDetails {
  26    pub(crate) text_system: Arc<WindowTextSystem>,
  27    pub(crate) editor_style: EditorStyle,
  28    pub(crate) rem_size: Pixels,
  29    pub scroll_anchor: ScrollAnchor,
  30    pub visible_rows: Option<f32>,
  31    pub vertical_scroll_margin: f32,
  32}
  33
  34/// Returns a column to the left of the current point, wrapping
  35/// to the previous line if that point is at the start of line.
  36pub fn left(map: &DisplaySnapshot, mut point: DisplayPoint) -> DisplayPoint {
  37    if point.column() > 0 {
  38        *point.column_mut() -= 1;
  39    } else if point.row().0 > 0 {
  40        *point.row_mut() -= 1;
  41        *point.column_mut() = map.line_len(point.row());
  42    }
  43    map.clip_point(point, Bias::Left)
  44}
  45
  46/// Returns a column to the left of the current point, doing nothing if
  47/// that point is already at the start of line.
  48pub fn saturating_left(map: &DisplaySnapshot, mut point: DisplayPoint) -> DisplayPoint {
  49    if point.column() > 0 {
  50        *point.column_mut() -= 1;
  51    } else if point.column() == 0 {
  52        // If the current sofr_wrap mode is used, the column corresponding to the display is 0,
  53        //  which does not necessarily mean that the actual beginning of a paragraph
  54        if map.display_point_to_fold_point(point, Bias::Left).column() > 0 {
  55            return left(map, point);
  56        }
  57    }
  58    map.clip_point(point, Bias::Left)
  59}
  60
  61/// Returns a column to the right of the current point, doing nothing
  62// if that point is at the end of the line.
  63pub fn right(map: &DisplaySnapshot, mut point: DisplayPoint) -> DisplayPoint {
  64    if point.column() < map.line_len(point.row()) {
  65        *point.column_mut() += 1;
  66    } else if point.row() < map.max_point().row() {
  67        *point.row_mut() += 1;
  68        *point.column_mut() = 0;
  69    }
  70    map.clip_point(point, Bias::Right)
  71}
  72
  73/// Returns a column to the right of the current point, not performing any wrapping
  74/// if that point is already at the end of line.
  75pub fn saturating_right(map: &DisplaySnapshot, mut point: DisplayPoint) -> DisplayPoint {
  76    *point.column_mut() += 1;
  77    map.clip_point(point, Bias::Right)
  78}
  79
  80/// Returns a display point for the preceding displayed line (which might be a soft-wrapped line).
  81pub fn up(
  82    map: &DisplaySnapshot,
  83    start: DisplayPoint,
  84    goal: SelectionGoal,
  85    preserve_column_at_start: bool,
  86    text_layout_details: &TextLayoutDetails,
  87) -> (DisplayPoint, SelectionGoal) {
  88    up_by_rows(
  89        map,
  90        start,
  91        1,
  92        goal,
  93        preserve_column_at_start,
  94        text_layout_details,
  95    )
  96}
  97
  98/// Returns a display point for the next displayed line (which might be a soft-wrapped line).
  99pub fn down(
 100    map: &DisplaySnapshot,
 101    start: DisplayPoint,
 102    goal: SelectionGoal,
 103    preserve_column_at_end: bool,
 104    text_layout_details: &TextLayoutDetails,
 105) -> (DisplayPoint, SelectionGoal) {
 106    down_by_rows(
 107        map,
 108        start,
 109        1,
 110        goal,
 111        preserve_column_at_end,
 112        text_layout_details,
 113    )
 114}
 115
 116pub(crate) fn up_by_rows(
 117    map: &DisplaySnapshot,
 118    start: DisplayPoint,
 119    row_count: u32,
 120    goal: SelectionGoal,
 121    preserve_column_at_start: bool,
 122    text_layout_details: &TextLayoutDetails,
 123) -> (DisplayPoint, SelectionGoal) {
 124    let goal_x = match goal {
 125        SelectionGoal::HorizontalPosition(x) => x.into(),
 126        SelectionGoal::WrappedHorizontalPosition((_, x)) => x.into(),
 127        SelectionGoal::HorizontalRange { end, .. } => end.into(),
 128        _ => map.x_for_display_point(start, text_layout_details),
 129    };
 130
 131    let prev_row = DisplayRow(start.row().0.saturating_sub(row_count));
 132    let mut point = map.clip_point(
 133        DisplayPoint::new(prev_row, map.line_len(prev_row)),
 134        Bias::Left,
 135    );
 136    if point.row() < start.row() {
 137        *point.column_mut() = map.display_column_for_x(point.row(), goal_x, text_layout_details)
 138    } else if preserve_column_at_start {
 139        return (start, goal);
 140    } else {
 141        point = DisplayPoint::new(DisplayRow(0), 0);
 142    }
 143
 144    let mut clipped_point = map.clip_point(point, Bias::Left);
 145    if clipped_point.row() < point.row() {
 146        clipped_point = map.clip_point(point, Bias::Right);
 147    }
 148    (
 149        clipped_point,
 150        SelectionGoal::HorizontalPosition(goal_x.into()),
 151    )
 152}
 153
 154pub(crate) fn down_by_rows(
 155    map: &DisplaySnapshot,
 156    start: DisplayPoint,
 157    row_count: u32,
 158    goal: SelectionGoal,
 159    preserve_column_at_end: bool,
 160    text_layout_details: &TextLayoutDetails,
 161) -> (DisplayPoint, SelectionGoal) {
 162    let goal_x = match goal {
 163        SelectionGoal::HorizontalPosition(x) => x.into(),
 164        SelectionGoal::WrappedHorizontalPosition((_, x)) => x.into(),
 165        SelectionGoal::HorizontalRange { end, .. } => end.into(),
 166        _ => map.x_for_display_point(start, text_layout_details),
 167    };
 168
 169    let new_row = DisplayRow(start.row().0 + row_count);
 170    let mut point = map.clip_point(DisplayPoint::new(new_row, 0), Bias::Right);
 171    if point.row() > start.row() {
 172        *point.column_mut() = map.display_column_for_x(point.row(), goal_x, text_layout_details)
 173    } else if preserve_column_at_end {
 174        return (start, goal);
 175    } else {
 176        point = map.max_point();
 177    }
 178
 179    let mut clipped_point = map.clip_point(point, Bias::Right);
 180    if clipped_point.row() > point.row() {
 181        clipped_point = map.clip_point(point, Bias::Left);
 182    }
 183    (
 184        clipped_point,
 185        SelectionGoal::HorizontalPosition(goal_x.into()),
 186    )
 187}
 188
 189/// Returns a position of the start of line.
 190/// If `stop_at_soft_boundaries` is true, the returned position is that of the
 191/// displayed line (e.g. it could actually be in the middle of a text line if that line is soft-wrapped).
 192/// Otherwise it's always going to be the start of a logical line.
 193pub fn line_beginning(
 194    map: &DisplaySnapshot,
 195    display_point: DisplayPoint,
 196    stop_at_soft_boundaries: bool,
 197) -> DisplayPoint {
 198    let point = display_point.to_point(map);
 199    let soft_line_start = map.clip_point(DisplayPoint::new(display_point.row(), 0), Bias::Right);
 200    let line_start = map.prev_line_boundary(point).1;
 201
 202    if stop_at_soft_boundaries && display_point != soft_line_start {
 203        soft_line_start
 204    } else {
 205        line_start
 206    }
 207}
 208
 209/// Returns the last indented position on a given line.
 210/// If `stop_at_soft_boundaries` is true, the returned [`DisplayPoint`] is that of a
 211/// displayed line (e.g. if there's soft wrap it's gonna be returned),
 212/// otherwise it's always going to be a start of a logical line.
 213pub fn indented_line_beginning(
 214    map: &DisplaySnapshot,
 215    display_point: DisplayPoint,
 216    stop_at_soft_boundaries: bool,
 217    stop_at_indent: bool,
 218) -> DisplayPoint {
 219    let point = display_point.to_point(map);
 220    let soft_line_start = map.clip_point(DisplayPoint::new(display_point.row(), 0), Bias::Right);
 221    let indent_start = Point::new(
 222        point.row,
 223        map.buffer_snapshot
 224            .indent_size_for_line(MultiBufferRow(point.row))
 225            .len,
 226    )
 227    .to_display_point(map);
 228    let line_start = map.prev_line_boundary(point).1;
 229
 230    if stop_at_soft_boundaries && soft_line_start > indent_start && display_point != soft_line_start
 231    {
 232        soft_line_start
 233    } else if stop_at_indent && display_point != indent_start {
 234        indent_start
 235    } else {
 236        line_start
 237    }
 238}
 239
 240/// Returns a position of the end of line.
 241///
 242/// If `stop_at_soft_boundaries` is true, the returned position is that of the
 243/// displayed line (e.g. it could actually be in the middle of a text line if that line is soft-wrapped).
 244/// Otherwise it's always going to be the end of a logical line.
 245pub fn line_end(
 246    map: &DisplaySnapshot,
 247    display_point: DisplayPoint,
 248    stop_at_soft_boundaries: bool,
 249) -> DisplayPoint {
 250    let soft_line_end = map.clip_point(
 251        DisplayPoint::new(display_point.row(), map.line_len(display_point.row())),
 252        Bias::Left,
 253    );
 254    if stop_at_soft_boundaries && display_point != soft_line_end {
 255        soft_line_end
 256    } else {
 257        map.next_line_boundary(display_point.to_point(map)).1
 258    }
 259}
 260
 261/// Returns a position of the previous word boundary, where a word character is defined as either
 262/// uppercase letter, lowercase letter, '_' character or language-specific word character (like '-' in CSS).
 263pub fn previous_word_start(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 264    let raw_point = point.to_point(map);
 265    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 266
 267    find_preceding_boundary_display_point(map, point, FindRange::MultiLine, |left, right| {
 268        (classifier.kind(left) != classifier.kind(right) && !classifier.is_whitespace(right))
 269            || left == '\n'
 270    })
 271}
 272
 273/// Returns a position of the previous word boundary, where a word character is defined as either
 274/// uppercase letter, lowercase letter, '_' character, language-specific word character (like '-' in CSS) or newline.
 275pub fn previous_word_start_or_newline(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 276    let raw_point = point.to_point(map);
 277    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 278
 279    find_preceding_boundary_display_point(map, point, FindRange::MultiLine, |left, right| {
 280        (classifier.kind(left) != classifier.kind(right) && !right.is_whitespace())
 281            || left == '\n'
 282            || right == '\n'
 283    })
 284}
 285
 286/// Returns a position of the previous subword boundary, where a subword is defined as a run of
 287/// word characters of the same "subkind" - where subcharacter kinds are '_' character,
 288/// lowerspace characters and uppercase characters.
 289pub fn previous_subword_start(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 290    let raw_point = point.to_point(map);
 291    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 292
 293    find_preceding_boundary_display_point(map, point, FindRange::MultiLine, |left, right| {
 294        let is_word_start =
 295            classifier.kind(left) != classifier.kind(right) && !right.is_whitespace();
 296        let is_subword_start = classifier.is_word('-') && left == '-' && right != '-'
 297            || left == '_' && right != '_'
 298            || left.is_lowercase() && right.is_uppercase();
 299        is_word_start || is_subword_start || left == '\n'
 300    })
 301}
 302
 303/// Returns a position of the next word boundary, where a word character is defined as either
 304/// uppercase letter, lowercase letter, '_' character or language-specific word character (like '-' in CSS).
 305pub fn next_word_end(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 306    let raw_point = point.to_point(map);
 307    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 308
 309    find_boundary(map, point, FindRange::MultiLine, |left, right| {
 310        (classifier.kind(left) != classifier.kind(right) && !classifier.is_whitespace(left))
 311            || right == '\n'
 312    })
 313}
 314
 315/// Returns a position of the next word boundary, where a word character is defined as either
 316/// uppercase letter, lowercase letter, '_' character, language-specific word character (like '-' in CSS) or newline.
 317pub fn next_word_end_or_newline(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 318    let raw_point = point.to_point(map);
 319    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 320
 321    let mut on_starting_row = true;
 322    find_boundary(map, point, FindRange::MultiLine, |left, right| {
 323        if left == '\n' {
 324            on_starting_row = false;
 325        }
 326        (classifier.kind(left) != classifier.kind(right)
 327            && ((on_starting_row && !left.is_whitespace())
 328                || (!on_starting_row && !right.is_whitespace())))
 329            || right == '\n'
 330    })
 331}
 332
 333/// Returns a position of the next subword boundary, where a subword is defined as a run of
 334/// word characters of the same "subkind" - where subcharacter kinds are '_' character,
 335/// lowerspace characters and uppercase characters.
 336pub fn next_subword_end(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPoint {
 337    let raw_point = point.to_point(map);
 338    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 339
 340    find_boundary(map, point, FindRange::MultiLine, |left, right| {
 341        let is_word_end =
 342            (classifier.kind(left) != classifier.kind(right)) && !classifier.is_whitespace(left);
 343        let is_subword_end = classifier.is_word('-') && left != '-' && right == '-'
 344            || left != '_' && right == '_'
 345            || left.is_lowercase() && right.is_uppercase();
 346        is_word_end || is_subword_end || right == '\n'
 347    })
 348}
 349
 350/// Returns a position of the start of the current paragraph, where a paragraph
 351/// is defined as a run of non-blank lines.
 352pub fn start_of_paragraph(
 353    map: &DisplaySnapshot,
 354    display_point: DisplayPoint,
 355    mut count: usize,
 356) -> DisplayPoint {
 357    let point = display_point.to_point(map);
 358    if point.row == 0 {
 359        return DisplayPoint::zero();
 360    }
 361
 362    let mut found_non_blank_line = false;
 363    for row in (0..point.row + 1).rev() {
 364        let blank = map.buffer_snapshot.is_line_blank(MultiBufferRow(row));
 365        if found_non_blank_line && blank {
 366            if count <= 1 {
 367                return Point::new(row, 0).to_display_point(map);
 368            }
 369            count -= 1;
 370            found_non_blank_line = false;
 371        }
 372
 373        found_non_blank_line |= !blank;
 374    }
 375
 376    DisplayPoint::zero()
 377}
 378
 379/// Returns a position of the end of the current paragraph, where a paragraph
 380/// is defined as a run of non-blank lines.
 381pub fn end_of_paragraph(
 382    map: &DisplaySnapshot,
 383    display_point: DisplayPoint,
 384    mut count: usize,
 385) -> DisplayPoint {
 386    let point = display_point.to_point(map);
 387    if point.row == map.buffer_snapshot.max_row().0 {
 388        return map.max_point();
 389    }
 390
 391    let mut found_non_blank_line = false;
 392    for row in point.row..=map.buffer_snapshot.max_row().0 {
 393        let blank = map.buffer_snapshot.is_line_blank(MultiBufferRow(row));
 394        if found_non_blank_line && blank {
 395            if count <= 1 {
 396                return Point::new(row, 0).to_display_point(map);
 397            }
 398            count -= 1;
 399            found_non_blank_line = false;
 400        }
 401
 402        found_non_blank_line |= !blank;
 403    }
 404
 405    map.max_point()
 406}
 407
 408pub fn start_of_excerpt(
 409    map: &DisplaySnapshot,
 410    display_point: DisplayPoint,
 411    direction: Direction,
 412) -> DisplayPoint {
 413    let point = map.display_point_to_point(display_point, Bias::Left);
 414    let Some(excerpt) = map.buffer_snapshot.excerpt_containing(point..point) else {
 415        return display_point;
 416    };
 417    match direction {
 418        Direction::Prev => {
 419            let mut start = excerpt.start_anchor().to_display_point(&map);
 420            if start >= display_point && start.row() > DisplayRow(0) {
 421                let Some(excerpt) = map.buffer_snapshot.excerpt_before(excerpt.id()) else {
 422                    return display_point;
 423                };
 424                start = excerpt.start_anchor().to_display_point(&map);
 425            }
 426            start
 427        }
 428        Direction::Next => {
 429            let mut end = excerpt.end_anchor().to_display_point(&map);
 430            *end.row_mut() += 1;
 431            map.clip_point(end, Bias::Right)
 432        }
 433    }
 434}
 435
 436pub fn end_of_excerpt(
 437    map: &DisplaySnapshot,
 438    display_point: DisplayPoint,
 439    direction: Direction,
 440) -> DisplayPoint {
 441    let point = map.display_point_to_point(display_point, Bias::Left);
 442    let Some(excerpt) = map.buffer_snapshot.excerpt_containing(point..point) else {
 443        return display_point;
 444    };
 445    match direction {
 446        Direction::Prev => {
 447            let mut start = excerpt.start_anchor().to_display_point(&map);
 448            if start.row() > DisplayRow(0) {
 449                *start.row_mut() -= 1;
 450            }
 451            map.clip_point(start, Bias::Left)
 452        }
 453        Direction::Next => {
 454            let mut end = excerpt.end_anchor().to_display_point(&map);
 455            *end.column_mut() = 0;
 456            if end <= display_point {
 457                *end.row_mut() += 1;
 458                let point_end = map.display_point_to_point(end, Bias::Right);
 459                let Some(excerpt) = map.buffer_snapshot.excerpt_containing(point_end..point_end)
 460                else {
 461                    return display_point;
 462                };
 463                end = excerpt.end_anchor().to_display_point(&map);
 464                *end.column_mut() = 0;
 465            }
 466            end
 467        }
 468    }
 469}
 470
 471/// Scans for a boundary preceding the given start point `from` until a boundary is found,
 472/// indicated by the given predicate returning true.
 473/// The predicate is called with the character to the left and right of the candidate boundary location.
 474/// If FindRange::SingleLine is specified and no boundary is found before the start of the current line, the start of the current line will be returned.
 475pub fn find_preceding_boundary_point(
 476    buffer_snapshot: &MultiBufferSnapshot,
 477    from: Point,
 478    find_range: FindRange,
 479    mut is_boundary: impl FnMut(char, char) -> bool,
 480) -> Point {
 481    let mut prev_ch = None;
 482    let mut offset = from.to_offset(buffer_snapshot);
 483
 484    for ch in buffer_snapshot.reversed_chars_at(offset) {
 485        if find_range == FindRange::SingleLine && ch == '\n' {
 486            break;
 487        }
 488        if let Some(prev_ch) = prev_ch {
 489            if is_boundary(ch, prev_ch) {
 490                break;
 491            }
 492        }
 493
 494        offset -= ch.len_utf8();
 495        prev_ch = Some(ch);
 496    }
 497
 498    offset.to_point(buffer_snapshot)
 499}
 500
 501/// Scans for a boundary preceding the given start point `from` until a boundary is found,
 502/// indicated by the given predicate returning true.
 503/// The predicate is called with the character to the left and right of the candidate boundary location.
 504/// If FindRange::SingleLine is specified and no boundary is found before the start of the current line, the start of the current line will be returned.
 505pub fn find_preceding_boundary_display_point(
 506    map: &DisplaySnapshot,
 507    from: DisplayPoint,
 508    find_range: FindRange,
 509    is_boundary: impl FnMut(char, char) -> bool,
 510) -> DisplayPoint {
 511    let result = find_preceding_boundary_point(
 512        &map.buffer_snapshot,
 513        from.to_point(map),
 514        find_range,
 515        is_boundary,
 516    );
 517    map.clip_point(result.to_display_point(map), Bias::Left)
 518}
 519
 520/// Scans for a boundary following the given start point until a boundary is found, indicated by the
 521/// given predicate returning true. The predicate is called with the character to the left and right
 522/// of the candidate boundary location, and will be called with `\n` characters indicating the start
 523/// or end of a line. The function supports optionally returning the point just before the boundary
 524/// is found via return_point_before_boundary.
 525pub fn find_boundary_point(
 526    map: &DisplaySnapshot,
 527    from: DisplayPoint,
 528    find_range: FindRange,
 529    mut is_boundary: impl FnMut(char, char) -> bool,
 530    return_point_before_boundary: bool,
 531) -> DisplayPoint {
 532    let mut offset = from.to_offset(map, Bias::Right);
 533    let mut prev_offset = offset;
 534    let mut prev_ch = None;
 535
 536    for ch in map.buffer_snapshot.chars_at(offset) {
 537        if find_range == FindRange::SingleLine && ch == '\n' {
 538            break;
 539        }
 540        if let Some(prev_ch) = prev_ch {
 541            if is_boundary(prev_ch, ch) {
 542                if return_point_before_boundary {
 543                    return map.clip_point(prev_offset.to_display_point(map), Bias::Right);
 544                } else {
 545                    break;
 546                }
 547            }
 548        }
 549        prev_offset = offset;
 550        offset += ch.len_utf8();
 551        prev_ch = Some(ch);
 552    }
 553    map.clip_point(offset.to_display_point(map), Bias::Right)
 554}
 555
 556pub fn find_preceding_boundary_trail(
 557    map: &DisplaySnapshot,
 558    head: DisplayPoint,
 559    mut is_boundary: impl FnMut(char, char) -> bool,
 560) -> (Option<DisplayPoint>, DisplayPoint) {
 561    let mut offset = head.to_offset(map, Bias::Left);
 562    let mut trail_offset = None;
 563
 564    let mut prev_ch = map.buffer_snapshot.chars_at(offset).next();
 565    let mut forward = map.buffer_snapshot.reversed_chars_at(offset).peekable();
 566
 567    // Skip newlines
 568    while let Some(&ch) = forward.peek() {
 569        if ch == '\n' {
 570            prev_ch = forward.next();
 571            offset -= ch.len_utf8();
 572            trail_offset = Some(offset);
 573        } else {
 574            break;
 575        }
 576    }
 577
 578    // Find the boundary
 579    let start_offset = offset;
 580    for ch in forward {
 581        if let Some(prev_ch) = prev_ch {
 582            if is_boundary(prev_ch, ch) {
 583                if start_offset == offset {
 584                    trail_offset = Some(offset);
 585                } else {
 586                    break;
 587                }
 588            }
 589        }
 590        offset -= ch.len_utf8();
 591        prev_ch = Some(ch);
 592    }
 593
 594    let trail = trail_offset
 595        .map(|trail_offset: usize| map.clip_point(trail_offset.to_display_point(map), Bias::Left));
 596
 597    (
 598        trail,
 599        map.clip_point(offset.to_display_point(map), Bias::Left),
 600    )
 601}
 602
 603/// Finds the location of a boundary
 604pub fn find_boundary_trail(
 605    map: &DisplaySnapshot,
 606    head: DisplayPoint,
 607    mut is_boundary: impl FnMut(char, char) -> bool,
 608) -> (Option<DisplayPoint>, DisplayPoint) {
 609    let mut offset = head.to_offset(map, Bias::Right);
 610    let mut trail_offset = None;
 611
 612    let mut prev_ch = map.buffer_snapshot.reversed_chars_at(offset).next();
 613    let mut forward = map.buffer_snapshot.chars_at(offset).peekable();
 614
 615    // Skip newlines
 616    while let Some(&ch) = forward.peek() {
 617        if ch == '\n' {
 618            prev_ch = forward.next();
 619            offset += ch.len_utf8();
 620            trail_offset = Some(offset);
 621        } else {
 622            break;
 623        }
 624    }
 625
 626    // Find the boundary
 627    let start_offset = offset;
 628    for ch in forward {
 629        if let Some(prev_ch) = prev_ch {
 630            if is_boundary(prev_ch, ch) {
 631                if start_offset == offset {
 632                    trail_offset = Some(offset);
 633                } else {
 634                    break;
 635                }
 636            }
 637        }
 638        offset += ch.len_utf8();
 639        prev_ch = Some(ch);
 640    }
 641
 642    let trail = trail_offset
 643        .map(|trail_offset: usize| map.clip_point(trail_offset.to_display_point(map), Bias::Right));
 644
 645    (
 646        trail,
 647        map.clip_point(offset.to_display_point(map), Bias::Right),
 648    )
 649}
 650
 651pub fn find_boundary(
 652    map: &DisplaySnapshot,
 653    from: DisplayPoint,
 654    find_range: FindRange,
 655    is_boundary: impl FnMut(char, char) -> bool,
 656) -> DisplayPoint {
 657    find_boundary_point(map, from, find_range, is_boundary, false)
 658}
 659
 660pub fn find_boundary_exclusive(
 661    map: &DisplaySnapshot,
 662    from: DisplayPoint,
 663    find_range: FindRange,
 664    is_boundary: impl FnMut(char, char) -> bool,
 665) -> DisplayPoint {
 666    find_boundary_point(map, from, find_range, is_boundary, true)
 667}
 668
 669/// Returns an iterator over the characters following a given offset in the [`DisplaySnapshot`].
 670/// The returned value also contains a range of the start/end of a returned character in
 671/// the [`DisplaySnapshot`]. The offsets are relative to the start of a buffer.
 672pub fn chars_after(
 673    map: &DisplaySnapshot,
 674    mut offset: usize,
 675) -> impl Iterator<Item = (char, Range<usize>)> + '_ {
 676    map.buffer_snapshot.chars_at(offset).map(move |ch| {
 677        let before = offset;
 678        offset += ch.len_utf8();
 679        (ch, before..offset)
 680    })
 681}
 682
 683/// Returns a reverse iterator over the characters following a given offset in the [`DisplaySnapshot`].
 684/// The returned value also contains a range of the start/end of a returned character in
 685/// the [`DisplaySnapshot`]. The offsets are relative to the start of a buffer.
 686pub fn chars_before(
 687    map: &DisplaySnapshot,
 688    mut offset: usize,
 689) -> impl Iterator<Item = (char, Range<usize>)> + '_ {
 690    map.buffer_snapshot
 691        .reversed_chars_at(offset)
 692        .map(move |ch| {
 693            let after = offset;
 694            offset -= ch.len_utf8();
 695            (ch, offset..after)
 696        })
 697}
 698
 699pub(crate) fn is_inside_word(map: &DisplaySnapshot, point: DisplayPoint) -> bool {
 700    let raw_point = point.to_point(map);
 701    let classifier = map.buffer_snapshot.char_classifier_at(raw_point);
 702    let ix = map.clip_point(point, Bias::Left).to_offset(map, Bias::Left);
 703    let text = &map.buffer_snapshot;
 704    let next_char_kind = text.chars_at(ix).next().map(|c| classifier.kind(c));
 705    let prev_char_kind = text
 706        .reversed_chars_at(ix)
 707        .next()
 708        .map(|c| classifier.kind(c));
 709    prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
 710}
 711
 712pub(crate) fn surrounding_word(
 713    map: &DisplaySnapshot,
 714    position: DisplayPoint,
 715) -> Range<DisplayPoint> {
 716    let position = map
 717        .clip_point(position, Bias::Left)
 718        .to_offset(map, Bias::Left);
 719    let (range, _) = map.buffer_snapshot.surrounding_word(position, false);
 720    let start = range
 721        .start
 722        .to_point(&map.buffer_snapshot)
 723        .to_display_point(map);
 724    let end = range
 725        .end
 726        .to_point(&map.buffer_snapshot)
 727        .to_display_point(map);
 728    start..end
 729}
 730
 731/// Returns a list of lines (represented as a [`DisplayPoint`] range) contained
 732/// within a passed range.
 733///
 734/// The line ranges are **always* going to be in bounds of a requested range, which means that
 735/// the first and the last lines might not necessarily represent the
 736/// full range of a logical line (as their `.start`/`.end` values are clipped to those of a passed in range).
 737pub fn split_display_range_by_lines(
 738    map: &DisplaySnapshot,
 739    range: Range<DisplayPoint>,
 740) -> Vec<Range<DisplayPoint>> {
 741    let mut result = Vec::new();
 742
 743    let mut start = range.start;
 744    // Loop over all the covered rows until the one containing the range end
 745    for row in range.start.row().0..range.end.row().0 {
 746        let row_end_column = map.line_len(DisplayRow(row));
 747        let end = map.clip_point(
 748            DisplayPoint::new(DisplayRow(row), row_end_column),
 749            Bias::Left,
 750        );
 751        if start != end {
 752            result.push(start..end);
 753        }
 754        start = map.clip_point(DisplayPoint::new(DisplayRow(row + 1), 0), Bias::Left);
 755    }
 756
 757    // Add the final range from the start of the last end to the original range end.
 758    result.push(start..range.end);
 759
 760    result
 761}
 762
 763#[cfg(test)]
 764mod tests {
 765    use super::*;
 766    use crate::{
 767        display_map::Inlay,
 768        test::{editor_test_context::EditorTestContext, marked_display_snapshot},
 769        Buffer, DisplayMap, DisplayRow, ExcerptRange, FoldPlaceholder, InlayId, MultiBuffer,
 770    };
 771    use gpui::{font, px, AppContext as _};
 772    use language::Capability;
 773    use project::Project;
 774    use settings::SettingsStore;
 775    use util::post_inc;
 776
 777    #[gpui::test]
 778    fn test_previous_word_start(cx: &mut gpui::App) {
 779        init_test(cx);
 780
 781        fn assert(marked_text: &str, cx: &mut gpui::App) {
 782            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
 783            assert_eq!(
 784                previous_word_start(&snapshot, display_points[1]),
 785                display_points[0]
 786            );
 787        }
 788
 789        assert("\nˇ   ˇlorem", cx);
 790        assert("ˇ\nˇ   lorem", cx);
 791        assert("    ˇloremˇ", cx);
 792        assert("ˇ    ˇlorem", cx);
 793        assert("    ˇlorˇem", cx);
 794        assert("\nlorem\nˇ   ˇipsum", cx);
 795        assert("\n\nˇ\nˇ", cx);
 796        assert("    ˇlorem  ˇipsum", cx);
 797        assert("loremˇ-ˇipsum", cx);
 798        assert("loremˇ-#$@ˇipsum", cx);
 799        assert("ˇlorem_ˇipsum", cx);
 800        assert(" ˇdefγˇ", cx);
 801        assert(" ˇbcΔˇ", cx);
 802        assert(" abˇ——ˇcd", cx);
 803    }
 804
 805    #[gpui::test]
 806    fn test_previous_subword_start(cx: &mut gpui::App) {
 807        init_test(cx);
 808
 809        fn assert(marked_text: &str, cx: &mut gpui::App) {
 810            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
 811            assert_eq!(
 812                previous_subword_start(&snapshot, display_points[1]),
 813                display_points[0]
 814            );
 815        }
 816
 817        // Subword boundaries are respected
 818        assert("lorem_ˇipˇsum", cx);
 819        assert("lorem_ˇipsumˇ", cx);
 820        assert("ˇlorem_ˇipsum", cx);
 821        assert("lorem_ˇipsum_ˇdolor", cx);
 822        assert("loremˇIpˇsum", cx);
 823        assert("loremˇIpsumˇ", cx);
 824
 825        // Word boundaries are still respected
 826        assert("\nˇ   ˇlorem", cx);
 827        assert("    ˇloremˇ", cx);
 828        assert("    ˇlorˇem", cx);
 829        assert("\nlorem\nˇ   ˇipsum", cx);
 830        assert("\n\nˇ\nˇ", cx);
 831        assert("    ˇlorem  ˇipsum", cx);
 832        assert("loremˇ-ˇipsum", cx);
 833        assert("loremˇ-#$@ˇipsum", cx);
 834        assert(" ˇdefγˇ", cx);
 835        assert(" bcˇΔˇ", cx);
 836        assert(" ˇbcδˇ", cx);
 837        assert(" abˇ——ˇcd", cx);
 838    }
 839
 840    #[gpui::test]
 841    fn test_find_preceding_boundary(cx: &mut gpui::App) {
 842        init_test(cx);
 843
 844        fn assert(
 845            marked_text: &str,
 846            cx: &mut gpui::App,
 847            is_boundary: impl FnMut(char, char) -> bool,
 848        ) {
 849            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
 850            assert_eq!(
 851                find_preceding_boundary_display_point(
 852                    &snapshot,
 853                    display_points[1],
 854                    FindRange::MultiLine,
 855                    is_boundary
 856                ),
 857                display_points[0]
 858            );
 859        }
 860
 861        assert("abcˇdef\ngh\nijˇk", cx, |left, right| {
 862            left == 'c' && right == 'd'
 863        });
 864        assert("abcdef\nˇgh\nijˇk", cx, |left, right| {
 865            left == '\n' && right == 'g'
 866        });
 867        let mut line_count = 0;
 868        assert("abcdef\nˇgh\nijˇk", cx, |left, _| {
 869            if left == '\n' {
 870                line_count += 1;
 871                line_count == 2
 872            } else {
 873                false
 874            }
 875        });
 876    }
 877
 878    #[gpui::test]
 879    fn test_find_preceding_boundary_with_inlays(cx: &mut gpui::App) {
 880        init_test(cx);
 881
 882        let input_text = "abcdefghijklmnopqrstuvwxys";
 883        let font = font("Helvetica");
 884        let font_size = px(14.0);
 885        let buffer = MultiBuffer::build_simple(input_text, cx);
 886        let buffer_snapshot = buffer.read(cx).snapshot(cx);
 887
 888        let display_map = cx.new(|cx| {
 889            DisplayMap::new(
 890                buffer,
 891                font,
 892                font_size,
 893                None,
 894                true,
 895                1,
 896                1,
 897                1,
 898                FoldPlaceholder::test(),
 899                cx,
 900            )
 901        });
 902
 903        // add all kinds of inlays between two word boundaries: we should be able to cross them all, when looking for another boundary
 904        let mut id = 0;
 905        let inlays = (0..buffer_snapshot.len())
 906            .flat_map(|offset| {
 907                [
 908                    Inlay {
 909                        id: InlayId::InlineCompletion(post_inc(&mut id)),
 910                        position: buffer_snapshot.anchor_at(offset, Bias::Left),
 911                        text: "test".into(),
 912                    },
 913                    Inlay {
 914                        id: InlayId::InlineCompletion(post_inc(&mut id)),
 915                        position: buffer_snapshot.anchor_at(offset, Bias::Right),
 916                        text: "test".into(),
 917                    },
 918                    Inlay {
 919                        id: InlayId::Hint(post_inc(&mut id)),
 920                        position: buffer_snapshot.anchor_at(offset, Bias::Left),
 921                        text: "test".into(),
 922                    },
 923                    Inlay {
 924                        id: InlayId::Hint(post_inc(&mut id)),
 925                        position: buffer_snapshot.anchor_at(offset, Bias::Right),
 926                        text: "test".into(),
 927                    },
 928                ]
 929            })
 930            .collect();
 931        let snapshot = display_map.update(cx, |map, cx| {
 932            map.splice_inlays(&[], inlays, cx);
 933            map.snapshot(cx)
 934        });
 935
 936        assert_eq!(
 937            find_preceding_boundary_display_point(
 938                &snapshot,
 939                buffer_snapshot.len().to_display_point(&snapshot),
 940                FindRange::MultiLine,
 941                |left, _| left == 'e',
 942            ),
 943            snapshot
 944                .buffer_snapshot
 945                .offset_to_point(5)
 946                .to_display_point(&snapshot),
 947            "Should not stop at inlays when looking for boundaries"
 948        );
 949    }
 950
 951    #[gpui::test]
 952    fn test_next_word_end(cx: &mut gpui::App) {
 953        init_test(cx);
 954
 955        fn assert(marked_text: &str, cx: &mut gpui::App) {
 956            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
 957            assert_eq!(
 958                next_word_end(&snapshot, display_points[0]),
 959                display_points[1]
 960            );
 961        }
 962
 963        assert("\nˇ   loremˇ", cx);
 964        assert("    ˇloremˇ", cx);
 965        assert("    lorˇemˇ", cx);
 966        assert("    loremˇ    ˇ\nipsum\n", cx);
 967        assert("\nˇ\nˇ\n\n", cx);
 968        assert("loremˇ    ipsumˇ   ", cx);
 969        assert("loremˇ-ˇipsum", cx);
 970        assert("loremˇ#$@-ˇipsum", cx);
 971        assert("loremˇ_ipsumˇ", cx);
 972        assert(" ˇbcΔˇ", cx);
 973        assert(" abˇ——ˇcd", cx);
 974    }
 975
 976    #[gpui::test]
 977    fn test_next_subword_end(cx: &mut gpui::App) {
 978        init_test(cx);
 979
 980        fn assert(marked_text: &str, cx: &mut gpui::App) {
 981            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
 982            assert_eq!(
 983                next_subword_end(&snapshot, display_points[0]),
 984                display_points[1]
 985            );
 986        }
 987
 988        // Subword boundaries are respected
 989        assert("loˇremˇ_ipsum", cx);
 990        assert("ˇloremˇ_ipsum", cx);
 991        assert("loremˇ_ipsumˇ", cx);
 992        assert("loremˇ_ipsumˇ_dolor", cx);
 993        assert("loˇremˇIpsum", cx);
 994        assert("loremˇIpsumˇDolor", cx);
 995
 996        // Word boundaries are still respected
 997        assert("\nˇ   loremˇ", cx);
 998        assert("    ˇloremˇ", cx);
 999        assert("    lorˇemˇ", cx);
1000        assert("    loremˇ    ˇ\nipsum\n", cx);
1001        assert("\nˇ\nˇ\n\n", cx);
1002        assert("loremˇ    ipsumˇ   ", cx);
1003        assert("loremˇ-ˇipsum", cx);
1004        assert("loremˇ#$@-ˇipsum", cx);
1005        assert("loremˇ_ipsumˇ", cx);
1006        assert(" ˇbcˇΔ", cx);
1007        assert(" abˇ——ˇcd", cx);
1008    }
1009
1010    #[gpui::test]
1011    fn test_find_boundary(cx: &mut gpui::App) {
1012        init_test(cx);
1013
1014        fn assert(
1015            marked_text: &str,
1016            cx: &mut gpui::App,
1017            is_boundary: impl FnMut(char, char) -> bool,
1018        ) {
1019            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
1020            assert_eq!(
1021                find_boundary(
1022                    &snapshot,
1023                    display_points[0],
1024                    FindRange::MultiLine,
1025                    is_boundary,
1026                ),
1027                display_points[1]
1028            );
1029        }
1030
1031        assert("abcˇdef\ngh\nijˇk", cx, |left, right| {
1032            left == 'j' && right == 'k'
1033        });
1034        assert("abˇcdef\ngh\nˇijk", cx, |left, right| {
1035            left == '\n' && right == 'i'
1036        });
1037        let mut line_count = 0;
1038        assert("abcˇdef\ngh\nˇijk", cx, |left, _| {
1039            if left == '\n' {
1040                line_count += 1;
1041                line_count == 2
1042            } else {
1043                false
1044            }
1045        });
1046    }
1047
1048    #[gpui::test]
1049    fn test_surrounding_word(cx: &mut gpui::App) {
1050        init_test(cx);
1051
1052        fn assert(marked_text: &str, cx: &mut gpui::App) {
1053            let (snapshot, display_points) = marked_display_snapshot(marked_text, cx);
1054            assert_eq!(
1055                surrounding_word(&snapshot, display_points[1]),
1056                display_points[0]..display_points[2],
1057                "{}",
1058                marked_text
1059            );
1060        }
1061
1062        assert("ˇˇloremˇ  ipsum", cx);
1063        assert("ˇloˇremˇ  ipsum", cx);
1064        assert("ˇloremˇˇ  ipsum", cx);
1065        assert("loremˇ ˇ  ˇipsum", cx);
1066        assert("lorem\nˇˇˇ\nipsum", cx);
1067        assert("lorem\nˇˇipsumˇ", cx);
1068        assert("loremˇ,ˇˇ ipsum", cx);
1069        assert("ˇloremˇˇ, ipsum", cx);
1070    }
1071
1072    #[gpui::test]
1073    async fn test_move_up_and_down_with_excerpts(cx: &mut gpui::TestAppContext) {
1074        cx.update(|cx| {
1075            init_test(cx);
1076        });
1077
1078        let mut cx = EditorTestContext::new(cx).await;
1079        let editor = cx.editor.clone();
1080        let window = cx.window;
1081        _ = cx.update_window(window, |_, window, cx| {
1082            let text_layout_details = editor.read(cx).text_layout_details(window);
1083
1084            let font = font("Helvetica");
1085
1086            let buffer = cx.new(|cx| Buffer::local("abc\ndefg\nhijkl\nmn", cx));
1087            let multibuffer = cx.new(|cx| {
1088                let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
1089                multibuffer.push_excerpts(
1090                    buffer.clone(),
1091                    [
1092                        ExcerptRange {
1093                            context: Point::new(0, 0)..Point::new(1, 4),
1094                            primary: None,
1095                        },
1096                        ExcerptRange {
1097                            context: Point::new(2, 0)..Point::new(3, 2),
1098                            primary: None,
1099                        },
1100                    ],
1101                    cx,
1102                );
1103                multibuffer
1104            });
1105            let display_map = cx.new(|cx| {
1106                DisplayMap::new(
1107                    multibuffer,
1108                    font,
1109                    px(14.0),
1110                    None,
1111                    true,
1112                    0,
1113                    2,
1114                    0,
1115                    FoldPlaceholder::test(),
1116                    cx,
1117                )
1118            });
1119            let snapshot = display_map.update(cx, |map, cx| map.snapshot(cx));
1120
1121            assert_eq!(snapshot.text(), "\n\nabc\ndefg\n\n\nhijkl\nmn");
1122
1123            let col_2_x = snapshot
1124                .x_for_display_point(DisplayPoint::new(DisplayRow(2), 2), &text_layout_details);
1125
1126            // Can't move up into the first excerpt's header
1127            assert_eq!(
1128                up(
1129                    &snapshot,
1130                    DisplayPoint::new(DisplayRow(2), 2),
1131                    SelectionGoal::HorizontalPosition(col_2_x.0),
1132                    false,
1133                    &text_layout_details
1134                ),
1135                (
1136                    DisplayPoint::new(DisplayRow(2), 0),
1137                    SelectionGoal::HorizontalPosition(col_2_x.0),
1138                ),
1139            );
1140            assert_eq!(
1141                up(
1142                    &snapshot,
1143                    DisplayPoint::new(DisplayRow(2), 0),
1144                    SelectionGoal::None,
1145                    false,
1146                    &text_layout_details
1147                ),
1148                (
1149                    DisplayPoint::new(DisplayRow(2), 0),
1150                    SelectionGoal::HorizontalPosition(0.0),
1151                ),
1152            );
1153
1154            let col_4_x = snapshot
1155                .x_for_display_point(DisplayPoint::new(DisplayRow(3), 4), &text_layout_details);
1156
1157            // Move up and down within first excerpt
1158            assert_eq!(
1159                up(
1160                    &snapshot,
1161                    DisplayPoint::new(DisplayRow(3), 4),
1162                    SelectionGoal::HorizontalPosition(col_4_x.0),
1163                    false,
1164                    &text_layout_details
1165                ),
1166                (
1167                    DisplayPoint::new(DisplayRow(2), 3),
1168                    SelectionGoal::HorizontalPosition(col_4_x.0)
1169                ),
1170            );
1171            assert_eq!(
1172                down(
1173                    &snapshot,
1174                    DisplayPoint::new(DisplayRow(2), 3),
1175                    SelectionGoal::HorizontalPosition(col_4_x.0),
1176                    false,
1177                    &text_layout_details
1178                ),
1179                (
1180                    DisplayPoint::new(DisplayRow(3), 4),
1181                    SelectionGoal::HorizontalPosition(col_4_x.0)
1182                ),
1183            );
1184
1185            let col_5_x = snapshot
1186                .x_for_display_point(DisplayPoint::new(DisplayRow(6), 5), &text_layout_details);
1187
1188            // Move up and down across second excerpt's header
1189            assert_eq!(
1190                up(
1191                    &snapshot,
1192                    DisplayPoint::new(DisplayRow(6), 5),
1193                    SelectionGoal::HorizontalPosition(col_5_x.0),
1194                    false,
1195                    &text_layout_details
1196                ),
1197                (
1198                    DisplayPoint::new(DisplayRow(3), 4),
1199                    SelectionGoal::HorizontalPosition(col_5_x.0)
1200                ),
1201            );
1202            assert_eq!(
1203                down(
1204                    &snapshot,
1205                    DisplayPoint::new(DisplayRow(3), 4),
1206                    SelectionGoal::HorizontalPosition(col_5_x.0),
1207                    false,
1208                    &text_layout_details
1209                ),
1210                (
1211                    DisplayPoint::new(DisplayRow(6), 5),
1212                    SelectionGoal::HorizontalPosition(col_5_x.0)
1213                ),
1214            );
1215
1216            let max_point_x = snapshot
1217                .x_for_display_point(DisplayPoint::new(DisplayRow(7), 2), &text_layout_details);
1218
1219            // Can't move down off the end, and attempting to do so leaves the selection goal unchanged
1220            assert_eq!(
1221                down(
1222                    &snapshot,
1223                    DisplayPoint::new(DisplayRow(7), 0),
1224                    SelectionGoal::HorizontalPosition(0.0),
1225                    false,
1226                    &text_layout_details
1227                ),
1228                (
1229                    DisplayPoint::new(DisplayRow(7), 2),
1230                    SelectionGoal::HorizontalPosition(0.0)
1231                ),
1232            );
1233            assert_eq!(
1234                down(
1235                    &snapshot,
1236                    DisplayPoint::new(DisplayRow(7), 2),
1237                    SelectionGoal::HorizontalPosition(max_point_x.0),
1238                    false,
1239                    &text_layout_details
1240                ),
1241                (
1242                    DisplayPoint::new(DisplayRow(7), 2),
1243                    SelectionGoal::HorizontalPosition(max_point_x.0)
1244                ),
1245            );
1246        });
1247    }
1248
1249    fn init_test(cx: &mut gpui::App) {
1250        let settings_store = SettingsStore::test(cx);
1251        cx.set_global(settings_store);
1252        workspace::init_settings(cx);
1253        theme::init(theme::LoadThemes::JustBase, cx);
1254        language::init(cx);
1255        crate::init(cx);
1256        Project::init_settings(cx);
1257    }
1258}