diff options
author | Pascal Kuthe | 2023-06-28 14:35:31 +0000 |
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committer | GitHub | 2023-06-28 14:35:31 +0000 |
commit | 4a2337d828c6c2fa7c0e46052e4c8a62dbd4737d (patch) | |
tree | 6d99233c1411fb6d4fcbcd87f0161071d4faac76 /helix-core/src/transaction.rs | |
parent | d8f9b901ddb1d91bf3ade66cf091e93b5cab6e49 (diff) |
correctly map unsorted positions (#7471)
* correctly map unsorted positions
* Fix typo
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
---------
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
Diffstat (limited to 'helix-core/src/transaction.rs')
-rw-r--r-- | helix-core/src/transaction.rs | 130 |
1 files changed, 94 insertions, 36 deletions
diff --git a/helix-core/src/transaction.rs b/helix-core/src/transaction.rs index 53e53c23..9d2a3e5c 100644 --- a/helix-core/src/transaction.rs +++ b/helix-core/src/transaction.rs @@ -326,7 +326,7 @@ impl ChangeSet { self.changes.is_empty() || self.changes == [Operation::Retain(self.len)] } - /// Map a *sorted* list of positions through the changes. + /// Map a (mostly) *sorted* list of positions through the changes. /// /// This is equivalent to updating each position with `map_pos`: /// @@ -335,27 +335,63 @@ impl ChangeSet { /// *pos = changes.map_pos(*pos, assoc); /// } /// ``` - /// However this function is significantly faster running in `O(N+M)` instead of `O(NM)` + /// However this function is significantly faster for sorted lists running + /// in `O(N+M)` instead of `O(NM)`. This function also handles unsorted/ + /// partially sorted lists. However, in that case worst case complexity is + /// again `O(MN)`. For lists that are often/mostly sorted (like the end of diagnostic ranges) + /// performance is usally close to `O(N + M)` pub fn update_positions<'a>(&self, positions: impl Iterator<Item = (&'a mut usize, Assoc)>) { use Operation::*; let mut positions = positions.peekable(); - macro_rules! map { - ($map: expr) => { - loop { - let Some((pos, assoc)) = positions.peek_mut() else { return; }; - let Some(new_pos) = $map(**pos, *assoc) else { break; }; - **pos = new_pos; - positions.next(); - } - }; - } let mut old_pos = 0; let mut new_pos = 0; - let mut iter = self.changes.iter().peekable(); + let mut iter = self.changes.iter().enumerate().peekable(); + + 'outer: loop { + macro_rules! map { + ($map: expr, $i: expr) => { + loop { + let Some((pos, assoc)) = positions.peek_mut() else { return; }; + if **pos < old_pos { + // Positions are not sorted, revert to the last Operation that + // contains this position and continue iterating from there. + // We can unwrap here since `pos` can not be negative + // (unsigned integer) and iterating backwards to the start + // should always move us back to the start + for (i, change) in self.changes[..$i].iter().enumerate().rev() { + match change { + Retain(i) => { + old_pos -= i; + new_pos -= i; + } + Delete(i) => { + old_pos -= i; + } + Insert(ins) => { + new_pos -= ins.chars().count(); + } + } + if old_pos <= **pos { + iter = self.changes[i..].iter().enumerate().peekable(); + } + } + debug_assert!(old_pos <= **pos, "Reverse Iter across changeset works"); + continue 'outer; + } + let Some(new_pos) = $map(**pos, *assoc) else { break; }; + **pos = new_pos; + positions.next(); + } + }; + } + + let Some((i, change)) = iter.next() else { + map!(|pos, _| (old_pos == pos).then_some(new_pos), self.changes.len()); + break; + }; - while let Some(change) = iter.next() { let len = match change { Delete(i) | Retain(i) => *i, Insert(_) => 0, @@ -364,42 +400,51 @@ impl ChangeSet { match change { Retain(_) => { - map!(|pos, _| (old_end > pos).then_some(new_pos + (pos - old_pos))); + map!( + |pos, _| (old_end > pos).then_some(new_pos + (pos - old_pos)), + i + ); new_pos += len; } Delete(_) => { // in range - map!(|pos, _| (old_end > pos).then_some(new_pos)); + map!(|pos, _| (old_end > pos).then_some(new_pos), i); } Insert(s) => { let ins = s.chars().count(); // a subsequent delete means a replace, consume it - if let Some(Delete(len)) = iter.peek() { + if let Some((_, Delete(len))) = iter.peek() { iter.next(); old_end = old_pos + len; // in range of replaced text - map!(|pos, assoc| (old_end > pos).then(|| { - // at point or tracking before - if pos == old_pos || assoc == Assoc::Before { - new_pos - } else { - // place to end of insert - new_pos + ins - } - })); + map!( + |pos, assoc| (old_end > pos).then(|| { + // at point or tracking before + if pos == old_pos || assoc == Assoc::Before { + new_pos + } else { + // place to end of insert + new_pos + ins + } + }), + i + ); } else { // at insert point - map!(|pos, assoc| (old_pos == pos).then(|| { - // return position before inserted text - if assoc == Assoc::Before { - new_pos - } else { - // after text - new_pos + ins - } - })); + map!( + |pos, assoc| (old_pos == pos).then(|| { + // return position before inserted text + if assoc == Assoc::Before { + new_pos + } else { + // after text + new_pos + ins + } + }), + i + ); } new_pos += ins; @@ -407,7 +452,6 @@ impl ChangeSet { } old_pos = old_end; } - map!(|pos, _| (old_pos == pos).then_some(new_pos)); let out_of_bounds: Vec<_> = positions.collect(); panic!("Positions {out_of_bounds:?} are out of range for changeset len {old_pos}!",) @@ -822,6 +866,20 @@ mod test { }; assert_eq!(cs.map_pos(2, Assoc::Before), 2); assert_eq!(cs.map_pos(2, Assoc::After), 2); + // unsorted selection + let cs = ChangeSet { + changes: vec![ + Insert("ab".into()), + Delete(2), + Insert("cd".into()), + Delete(2), + ], + len: 4, + len_after: 4, + }; + let mut positions = [4, 2]; + cs.update_positions(positions.iter_mut().map(|pos| (pos, Assoc::After))); + assert_eq!(positions, [4, 2]); } #[test] |