use ordered_float::OrderedFloat;use rope::{Point, Rope, TextSummary};use std::collections::{BTreeSet, HashMap};use std::{ cmp, fmt::{self, Debug}, ops::Range,}; struct Matrix { cells: Vec<f64>, rows: usize, cols: usize,} impl Matrix { fn new() -> Self { Self { cells: Vec::new(), rows: 0, cols: 0, } } fn resize(&mut self, rows: usize, cols: usize) { self.cells.resize(rows * cols, 0.); self.rows = rows; self.cols = cols; } fn swap_columns(&mut self, col1: usize, col2: usize) { if col1 == col2 { return; } if col1 >= self.cols { panic!("column out of bounds"); } if col2 >= self.cols { panic!("column out of bounds"); } unsafe { let ptr = self.cells.as_mut_ptr(); std::ptr::swap_nonoverlapping( ptr.add(col1 * self.rows), ptr.add(col2 * self.rows), self.rows, ); } } fn get(&self, row: usize, col: usize) -> f64 { if row >= self.rows { panic!("row out of bounds") } if col >= self.cols { panic!("column out of bounds") } self.cells[col * self.rows + row] } fn set(&mut self, row: usize, col: usize, value: f64) { if row >= self.rows { panic!("row out of bounds") } if col >= self.cols { panic!("column out of bounds") } self.cells[col * self.rows + row] = value; }} impl Debug for Matrix { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { writeln!(f)?; for i in 0..self.rows { for j in 0..self.cols { write!(f, "{:5}", self.get(i, j))?; } writeln!(f)?; } Ok(()) }} #[derive(Debug, Clone)]pub enum CharOperation { Insert { text: String }, Delete { bytes: usize }, Keep { bytes: usize },} pub struct StreamingDiff { old: Vec<char>, new: Vec<char>, scores: Matrix, old_text_ix: usize, new_text_ix: usize, equal_runs: HashMap<(usize, usize), u32>,} impl StreamingDiff { const INSERTION_SCORE: f64 = -1.; const DELETION_SCORE: f64 = -20.; const EQUALITY_BASE: f64 = 1.8; const MAX_EQUALITY_EXPONENT: i32 = 16; pub fn new(old: String) -> Self { let old = old.chars().collect::<Vec<_>>(); let mut scores = Matrix::new(); scores.resize(old.len() + 1, 1); for i in 0..=old.len() { scores.set(i, 0, i as f64 * Self::DELETION_SCORE); } Self { old, new: Vec::new(), scores, old_text_ix: 0, new_text_ix: 0, equal_runs: Default::default(), } } pub fn push_new(&mut self, text: &str) -> Vec<CharOperation> { self.new.extend(text.chars()); self.scores.swap_columns(0, self.scores.cols - 1); self.scores .resize(self.old.len() + 1, self.new.len() - self.new_text_ix + 1); self.equal_runs.retain(|(_i, j), _| *j == self.new_text_ix); for j in self.new_text_ix + 1..=self.new.len() { let relative_j = j - self.new_text_ix; self.scores .set(0, relative_j, j as f64 * Self::INSERTION_SCORE); for i in 1..=self.old.len() { let insertion_score = self.scores.get(i, relative_j - 1) + Self::INSERTION_SCORE; let deletion_score = self.scores.get(i - 1, relative_j) + Self::DELETION_SCORE; let equality_score = if self.old[i - 1] == self.new[j - 1] { let mut equal_run = self.equal_runs.get(&(i - 1, j - 1)).copied().unwrap_or(0); equal_run += 1; self.equal_runs.insert((i, j), equal_run); let exponent = cmp::min(equal_run as i32 / 4, Self::MAX_EQUALITY_EXPONENT); self.scores.get(i - 1, relative_j - 1) + Self::EQUALITY_BASE.powi(exponent) } else { f64::NEG_INFINITY }; let score = insertion_score.max(deletion_score).max(equality_score); self.scores.set(i, relative_j, score); } } let mut max_score = f64::NEG_INFINITY; let mut next_old_text_ix = self.old_text_ix; let next_new_text_ix = self.new.len(); for i in self.old_text_ix..=self.old.len() { let score = self.scores.get(i, next_new_text_ix - self.new_text_ix); if score > max_score { max_score = score; next_old_text_ix = i; } } let hunks = self.backtrack(next_old_text_ix, next_new_text_ix); self.old_text_ix = next_old_text_ix; self.new_text_ix = next_new_text_ix; hunks } fn backtrack(&self, old_text_ix: usize, new_text_ix: usize) -> Vec<CharOperation> { let mut pending_insert: Option<Range<usize>> = None; let mut hunks = Vec::new(); let mut i = old_text_ix; let mut j = new_text_ix; while (i, j) != (self.old_text_ix, self.new_text_ix) { let insertion_score = if j > self.new_text_ix { Some((i, j - 1)) } else { None }; let deletion_score = if i > self.old_text_ix { Some((i - 1, j)) } else { None }; let equality_score = if i > self.old_text_ix && j > self.new_text_ix { if self.old[i - 1] == self.new[j - 1] { Some((i - 1, j - 1)) } else { None } } else { None }; let (prev_i, prev_j) = [insertion_score, deletion_score, equality_score] .iter() .max_by_key(|cell| { cell.map(|(i, j)| OrderedFloat(self.scores.get(i, j - self.new_text_ix))) }) .unwrap() .unwrap(); if prev_i == i && prev_j == j - 1 { if let Some(pending_insert) = pending_insert.as_mut() { pending_insert.start = prev_j; } else { pending_insert = Some(prev_j..j); } } else { if let Some(range) = pending_insert.take() { hunks.push(CharOperation::Insert { text: self.new[range].iter().collect(), }); } let char_len = self.old[i - 1].len_utf8(); if prev_i == i - 1 && prev_j == j { if let Some(CharOperation::Delete { bytes: len }) = hunks.last_mut() { *len += char_len; } else { hunks.push(CharOperation::Delete { bytes: char_len }) } } else if let Some(CharOperation::Keep { bytes: len }) = hunks.last_mut() { *len += char_len; } else { hunks.push(CharOperation::Keep { bytes: char_len }) } } i = prev_i; j = prev_j; } if let Some(range) = pending_insert.take() { hunks.push(CharOperation::Insert { text: self.new[range].iter().collect(), }); } hunks.reverse(); hunks } pub fn finish(self) -> Vec<CharOperation> { self.backtrack(self.old.len(), self.new.len()) }} #[derive(Debug, Clone, PartialEq)]pub enum LineOperation { Insert { lines: u32 }, Delete { lines: u32 }, Keep { lines: u32 },} #[derive(Debug, Default)]pub struct LineDiff { inserted_newline_at_end: bool, /// The extent of kept and deleted text. old_end: Point, /// The extent of kept and inserted text. new_end: Point, /// Deleted rows, expressed in terms of the old text. deleted_rows: BTreeSet<u32>, /// Inserted rows, expressed in terms of the new text. inserted_rows: BTreeSet<u32>, buffered_insert: String, /// After deleting a newline, we buffer deletion until we keep or insert a character. buffered_delete: usize,} impl LineDiff { pub fn push_char_operations<'a>( &mut self, operations: impl IntoIterator<Item = &'a CharOperation>, old_text: &Rope, ) { for operation in operations { self.push_char_operation(operation, old_text); } } pub fn push_char_operation(&mut self, operation: &CharOperation, old_text: &Rope) { match operation { CharOperation::Insert { text } => { self.flush_delete(old_text); if is_line_start(self.old_end) { if let Some(newline_ix) = text.rfind('\n') { let (prefix, suffix) = text.split_at(newline_ix + 1); self.buffered_insert.push_str(prefix); self.flush_insert(old_text); self.buffered_insert.push_str(suffix); } else { self.buffered_insert.push_str(&text); } } else { self.buffered_insert.push_str(&text); if !text.ends_with('\n') { self.flush_insert(old_text); } } } CharOperation::Delete { bytes } => { self.buffered_delete += bytes; let common_suffix_len = self.trim_buffered_end(old_text); self.flush_insert(old_text); if common_suffix_len > 0 || !is_line_end(self.old_end, old_text) { self.flush_delete(old_text); self.keep(common_suffix_len, old_text); } } CharOperation::Keep { bytes } => { self.flush_delete(old_text); self.flush_insert(old_text); self.keep(*bytes, old_text); } } } fn flush_insert(&mut self, old_text: &Rope) { if self.buffered_insert.is_empty() { return; } let new_start = self.new_end; let lines = TextSummary::from(self.buffered_insert.as_str()).lines; self.new_end += lines; if is_line_start(self.old_end) { if self.new_end.column == 0 { self.inserted_rows.extend(new_start.row..self.new_end.row); } else { self.deleted_rows.insert(self.old_end.row); self.inserted_rows.extend(new_start.row..=self.new_end.row); } } else if is_line_end(self.old_end, old_text) { if self.buffered_insert.starts_with('\n') { self.inserted_rows .extend(new_start.row + 1..=self.new_end.row); self.inserted_newline_at_end = true; } else { if !self.inserted_newline_at_end { self.deleted_rows.insert(self.old_end.row); } self.inserted_rows.extend(new_start.row..=self.new_end.row); } } else { self.deleted_rows.insert(self.old_end.row); self.inserted_rows.extend(new_start.row..=self.new_end.row); } self.buffered_insert.clear(); } fn flush_delete(&mut self, old_text: &Rope) { if self.buffered_delete == 0 { return; } let old_start = self.old_end; self.old_end = old_text.offset_to_point(old_text.point_to_offset(self.old_end) + self.buffered_delete); if is_line_end(old_start, old_text) && is_line_end(self.old_end, old_text) { self.deleted_rows .extend(old_start.row + 1..=self.old_end.row); } else if is_line_start(old_start) && (is_line_start(self.old_end) && self.old_end < old_text.max_point()) && self.new_end.column == 0 { self.deleted_rows.extend(old_start.row..self.old_end.row); } else { self.inserted_rows.insert(self.new_end.row); self.deleted_rows.extend(old_start.row..=self.old_end.row); } self.inserted_newline_at_end = false; self.buffered_delete = 0; } fn keep(&mut self, bytes: usize, old_text: &Rope) { if bytes == 0 { return; } let lines = old_text.offset_to_point(old_text.point_to_offset(self.old_end) + bytes) - self.old_end; self.old_end += lines; self.new_end += lines; self.inserted_newline_at_end = false; } fn trim_buffered_end(&mut self, old_text: &Rope) -> usize { let old_start_offset = old_text.point_to_offset(self.old_end); let old_end_offset = old_start_offset + self.buffered_delete; let new_chars = self.buffered_insert.chars().rev(); let old_chars = old_text .chunks_in_range(old_start_offset..old_end_offset) .flat_map(|chunk| chunk.chars().rev()); let mut common_suffix_len = 0; for (new_ch, old_ch) in new_chars.zip(old_chars) { if new_ch == old_ch { common_suffix_len += new_ch.len_utf8(); } else { break; } } self.buffered_delete -= common_suffix_len; self.buffered_insert .truncate(self.buffered_insert.len() - common_suffix_len); common_suffix_len } pub fn finish(&mut self, old_text: &Rope) { self.flush_insert(old_text); self.flush_delete(old_text); let old_start = self.old_end; self.old_end = old_text.max_point(); self.new_end += self.old_end - old_start; } pub fn line_operations(&self) -> Vec<LineOperation> { let mut ops = Vec::new(); let mut deleted_rows = self.deleted_rows.iter().copied().peekable(); let mut inserted_rows = self.inserted_rows.iter().copied().peekable(); let mut old_row = 0; let mut new_row = 0; while deleted_rows.peek().is_some() || inserted_rows.peek().is_some() { // Check for a run of deleted lines at current old row. if Some(old_row) == deleted_rows.peek().copied() { if let Some(LineOperation::Delete { lines }) = ops.last_mut() { *lines += 1; } else { ops.push(LineOperation::Delete { lines: 1 }); } old_row += 1; deleted_rows.next(); } else if Some(new_row) == inserted_rows.peek().copied() { if let Some(LineOperation::Insert { lines }) = ops.last_mut() { *lines += 1; } else { ops.push(LineOperation::Insert { lines: 1 }); } new_row += 1; inserted_rows.next(); } else { // Keep lines until the next deletion, insertion, or the end of the old text. let lines_to_next_deletion = inserted_rows .peek() .copied() .unwrap_or(self.new_end.row + 1) - new_row; let lines_to_next_insertion = deleted_rows.peek().copied().unwrap_or(self.old_end.row + 1) - old_row; let kept_lines = cmp::max(1, cmp::min(lines_to_next_insertion, lines_to_next_deletion)); if kept_lines > 0 { ops.push(LineOperation::Keep { lines: kept_lines }); old_row += kept_lines; new_row += kept_lines; } } } if old_row < self.old_end.row + 1 { ops.push(LineOperation::Keep { lines: self.old_end.row + 1 - old_row, }); } ops }} fn is_line_start(point: Point) -> bool { point.column == 0} fn is_line_end(point: Point, text: &Rope) -> bool { text.line_len(point.row) == point.column} Lines 1–500 of 1102. 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use ordered_float::OrderedFloat; use rope::{Point, Rope, TextSummary}; use std::collections::{BTreeSet, HashMap}; use std::{ cmp, fmt::{self, Debug}, ops::Range, }; struct Matrix { cells: Vec<f64>, rows: usize, cols: usize, } impl Matrix { fn new() -> Self { Self { cells: Vec::new(), rows: 0, cols: 0, } } fn resize(&mut self, rows: usize, cols: usize) { self.cells.resize(rows * cols, 0.); self.rows = rows; self.cols = cols; } fn swap_columns(&mut self, col1: usize, col2: usize) { if col1 == col2 { return; } if col1 >= self.cols { panic!("column out of bounds"); } if col2 >= self.cols { panic!("column out of bounds"); } unsafe { let ptr = self.cells.as_mut_ptr(); std::ptr::swap_nonoverlapping( ptr.add(col1 * self.rows), ptr.add(col2 * self.rows), self.rows, ); } } fn get(&self, row: usize, col: usize) -> f64 { if row >= self.rows { panic!("row out of bounds") } if col >= self.cols { panic!("column out of bounds") } self.cells[col * self.rows + row] } fn set(&mut self, row: usize, col: usize, value: f64) { if row >= self.rows { panic!("row out of bounds") } if col >= self.cols { panic!("column out of bounds") } self.cells[col * self.rows + row] = value; } } impl Debug for Matrix { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { writeln!(f)?; for i in 0..self.rows { for j in 0..self.cols { write!(f, "{:5}", self.get(i, j))?; } writeln!(f)?; } Ok(()) } } #[derive(Debug, Clone)] pub enum CharOperation { Insert { text: String }, Delete { bytes: usize }, Keep { bytes: usize }, } pub struct StreamingDiff { old: Vec<char>, new: Vec<char>, scores: Matrix, old_text_ix: usize, new_text_ix: usize, equal_runs: HashMap<(usize, usize), u32>, } impl StreamingDiff { const INSERTION_SCORE: f64 = -1.; const DELETION_SCORE: f64 = -20.; const EQUALITY_BASE: f64 = 1.8; const MAX_EQUALITY_EXPONENT: i32 = 16; pub fn new(old: String) -> Self { let old = old.chars().collect::<Vec<_>>(); let mut scores = Matrix::new(); scores.resize(old.len() + 1, 1); for i in 0..=old.len() { scores.set(i, 0, i as f64 * Self::DELETION_SCORE); } Self { old, new: Vec::new(), scores, old_text_ix: 0, new_text_ix: 0, equal_runs: Default::default(), } } pub fn push_new(&mut self, text: &str) -> Vec<CharOperation> { self.new.extend(text.chars()); self.scores.swap_columns(0, self.scores.cols - 1); self.scores .resize(self.old.len() + 1, self.new.len() - self.new_text_ix + 1); self.equal_runs.retain(|(_i, j), _| *j == self.new_text_ix); for j in self.new_text_ix + 1..=self.new.len() { let relative_j = j - self.new_text_ix; self.scores .set(0, relative_j, j as f64 * Self::INSERTION_SCORE); for i in 1..=self.old.len() { let insertion_score = self.scores.get(i, relative_j - 1) + Self::INSERTION_SCORE; let deletion_score = self.scores.get(i - 1, relative_j) + Self::DELETION_SCORE; let equality_score = if self.old[i - 1] == self.new[j - 1] { let mut equal_run = self.equal_runs.get(&(i - 1, j - 1)).copied().unwrap_or(0); equal_run += 1; self.equal_runs.insert((i, j), equal_run); let exponent = cmp::min(equal_run as i32 / 4, Self::MAX_EQUALITY_EXPONENT); self.scores.get(i - 1, relative_j - 1) + Self::EQUALITY_BASE.powi(exponent) } else { f64::NEG_INFINITY }; let score = insertion_score.max(deletion_score).max(equality_score); self.scores.set(i, relative_j, score); } } let mut max_score = f64::NEG_INFINITY; let mut next_old_text_ix = self.old_text_ix; let next_new_text_ix = self.new.len(); for i in self.old_text_ix..=self.old.len() { let score = self.scores.get(i, next_new_text_ix - self.new_text_ix); if score > max_score { max_score = score; next_old_text_ix = i; } } let hunks = self.backtrack(next_old_text_ix, next_new_text_ix); self.old_text_ix = next_old_text_ix; self.new_text_ix = next_new_text_ix; hunks } fn backtrack(&self, old_text_ix: usize, new_text_ix: usize) -> Vec<CharOperation> { let mut pending_insert: Option<Range<usize>> = None; let mut hunks = Vec::new(); let mut i = old_text_ix; let mut j = new_text_ix; while (i, j) != (self.old_text_ix, self.new_text_ix) { let insertion_score = if j > self.new_text_ix { Some((i, j - 1)) } else { None }; let deletion_score = if i > self.old_text_ix { Some((i - 1, j)) } else { None }; let equality_score = if i > self.old_text_ix && j > self.new_text_ix { if self.old[i - 1] == self.new[j - 1] { Some((i - 1, j - 1)) } else { None } } else { None }; let (prev_i, prev_j) = [insertion_score, deletion_score, equality_score] .iter() .max_by_key(|cell| { cell.map(|(i, j)| OrderedFloat(self.scores.get(i, j - self.new_text_ix))) }) .unwrap() .unwrap(); if prev_i == i && prev_j == j - 1 { if let Some(pending_insert) = pending_insert.as_mut() { pending_insert.start = prev_j; } else { pending_insert = Some(prev_j..j); } } else { if let Some(range) = pending_insert.take() { hunks.push(CharOperation::Insert { text: self.new[range].iter().collect(), }); } let char_len = self.old[i - 1].len_utf8(); if prev_i == i - 1 && prev_j == j { if let Some(CharOperation::Delete { bytes: len }) = hunks.last_mut() { *len += char_len; } else { hunks.push(CharOperation::Delete { bytes: char_len }) } } else if let Some(CharOperation::Keep { bytes: len }) = hunks.last_mut() { *len += char_len; } else { hunks.push(CharOperation::Keep { bytes: char_len }) } } i = prev_i; j = prev_j; } if let Some(range) = pending_insert.take() { hunks.push(CharOperation::Insert { text: self.new[range].iter().collect(), }); } hunks.reverse(); hunks } pub fn finish(self) -> Vec<CharOperation> { self.backtrack(self.old.len(), self.new.len()) } } #[derive(Debug, Clone, PartialEq)] pub enum LineOperation { Insert { lines: u32 }, Delete { lines: u32 }, Keep { lines: u32 }, } #[derive(Debug, Default)] pub struct LineDiff { inserted_newline_at_end: bool, /// The extent of kept and deleted text. old_end: Point, /// The extent of kept and inserted text. new_end: Point, /// Deleted rows, expressed in terms of the old text. deleted_rows: BTreeSet<u32>, /// Inserted rows, expressed in terms of the new text. inserted_rows: BTreeSet<u32>, buffered_insert: String, /// After deleting a newline, we buffer deletion until we keep or insert a character. buffered_delete: usize, } impl LineDiff { pub fn push_char_operations<'a>( &mut self, operations: impl IntoIterator<Item = &'a CharOperation>, old_text: &Rope, ) { for operation in operations { self.push_char_operation(operation, old_text); } } pub fn push_char_operation(&mut self, operation: &CharOperation, old_text: &Rope) { match operation { CharOperation::Insert { text } => { self.flush_delete(old_text); if is_line_start(self.old_end) { if let Some(newline_ix) = text.rfind('\n') { let (prefix, suffix) = text.split_at(newline_ix + 1); self.buffered_insert.push_str(prefix); self.flush_insert(old_text); self.buffered_insert.push_str(suffix); } else { self.buffered_insert.push_str(&text); } } else { self.buffered_insert.push_str(&text); if !text.ends_with('\n') { self.flush_insert(old_text); } } } CharOperation::Delete { bytes } => { self.buffered_delete += bytes; let common_suffix_len = self.trim_buffered_end(old_text); self.flush_insert(old_text); if common_suffix_len > 0 || !is_line_end(self.old_end, old_text) { self.flush_delete(old_text); self.keep(common_suffix_len, old_text); } } CharOperation::Keep { bytes } => { self.flush_delete(old_text); self.flush_insert(old_text); self.keep(*bytes, old_text); } } } fn flush_insert(&mut self, old_text: &Rope) { if self.buffered_insert.is_empty() { return; } let new_start = self.new_end; let lines = TextSummary::from(self.buffered_insert.as_str()).lines; self.new_end += lines; if is_line_start(self.old_end) { if self.new_end.column == 0 { self.inserted_rows.extend(new_start.row..self.new_end.row); } else { self.deleted_rows.insert(self.old_end.row); self.inserted_rows.extend(new_start.row..=self.new_end.row); } } else if is_line_end(self.old_end, old_text) { if self.buffered_insert.starts_with('\n') { self.inserted_rows .extend(new_start.row + 1..=self.new_end.row); self.inserted_newline_at_end = true; } else { if !self.inserted_newline_at_end { self.deleted_rows.insert(self.old_end.row); } self.inserted_rows.extend(new_start.row..=self.new_end.row); } } else { self.deleted_rows.insert(self.old_end.row); self.inserted_rows.extend(new_start.row..=self.new_end.row); } self.buffered_insert.clear(); } fn flush_delete(&mut self, old_text: &Rope) { if self.buffered_delete == 0 { return; } let old_start = self.old_end; self.old_end = old_text.offset_to_point(old_text.point_to_offset(self.old_end) + self.buffered_delete); if is_line_end(old_start, old_text) && is_line_end(self.old_end, old_text) { self.deleted_rows .extend(old_start.row + 1..=self.old_end.row); } else if is_line_start(old_start) && (is_line_start(self.old_end) && self.old_end < old_text.max_point()) && self.new_end.column == 0 { self.deleted_rows.extend(old_start.row..self.old_end.row); } else { self.inserted_rows.insert(self.new_end.row); self.deleted_rows.extend(old_start.row..=self.old_end.row); } self.inserted_newline_at_end = false; self.buffered_delete = 0; } fn keep(&mut self, bytes: usize, old_text: &Rope) { if bytes == 0 { return; } let lines = old_text.offset_to_point(old_text.point_to_offset(self.old_end) + bytes) - self.old_end; self.old_end += lines; self.new_end += lines; self.inserted_newline_at_end = false; } fn trim_buffered_end(&mut self, old_text: &Rope) -> usize { let old_start_offset = old_text.point_to_offset(self.old_end); let old_end_offset = old_start_offset + self.buffered_delete; let new_chars = self.buffered_insert.chars().rev(); let old_chars = old_text .chunks_in_range(old_start_offset..old_end_offset) .flat_map(|chunk| chunk.chars().rev()); let mut common_suffix_len = 0; for (new_ch, old_ch) in new_chars.zip(old_chars) { if new_ch == old_ch { common_suffix_len += new_ch.len_utf8(); } else { break; } } self.buffered_delete -= common_suffix_len; self.buffered_insert .truncate(self.buffered_insert.len() - common_suffix_len); common_suffix_len } pub fn finish(&mut self, old_text: &Rope) { self.flush_insert(old_text); self.flush_delete(old_text); let old_start = self.old_end; self.old_end = old_text.max_point(); self.new_end += self.old_end - old_start; } pub fn line_operations(&self) -> Vec<LineOperation> { let mut ops = Vec::new(); let mut deleted_rows = self.deleted_rows.iter().copied().peekable(); let mut inserted_rows = self.inserted_rows.iter().copied().peekable(); let mut old_row = 0; let mut new_row = 0; while deleted_rows.peek().is_some() || inserted_rows.peek().is_some() { // Check for a run of deleted lines at current old row. if Some(old_row) == deleted_rows.peek().copied() { if let Some(LineOperation::Delete { lines }) = ops.last_mut() { *lines += 1; } else { ops.push(LineOperation::Delete { lines: 1 }); } old_row += 1; deleted_rows.next(); } else if Some(new_row) == inserted_rows.peek().copied() { if let Some(LineOperation::Insert { lines }) = ops.last_mut() { *lines += 1; } else { ops.push(LineOperation::Insert { lines: 1 }); } new_row += 1; inserted_rows.next(); } else { // Keep lines until the next deletion, insertion, or the end of the old text. let lines_to_next_deletion = inserted_rows .peek() .copied() .unwrap_or(self.new_end.row + 1) - new_row; let lines_to_next_insertion = deleted_rows.peek().copied().unwrap_or(self.old_end.row + 1) - old_row; let kept_lines = cmp::max(1, cmp::min(lines_to_next_insertion, lines_to_next_deletion)); if kept_lines > 0 { ops.push(LineOperation::Keep { lines: kept_lines }); old_row += kept_lines; new_row += kept_lines; } } } if old_row < self.old_end.row + 1 { ops.push(LineOperation::Keep { lines: self.old_end.row + 1 - old_row, }); } ops } } fn is_line_start(point: Point) -> bool { point.column == 0 } fn is_line_end(point: Point, text: &Rope) -> bool { text.line_len(point.row) == point.column }