only keep selections invariant under replacement

Keeping selections unchanged if they are inside an exact replacement
is intuitive. However, for diagnostics this is not desirable as
helix would otherwise fail to remove diagnostics if replacing parts
of the document.

helix-core/src/history.rs

@@ -176,7 +176,7 @@ impl History {
  let pos = current_revision
  .transaction
  .changes()
- .map_pos(to, Assoc::After);
+ .map_pos(to, Assoc::After, true);
  Some(pos)
  }
 

helix-core/src/selection.rs

@@ -167,16 +167,16 @@ impl Range {
  use std::cmp::Ordering;
  let (anchor, head) = match self.anchor.cmp(&self.head) {
  Ordering::Equal => (
- changes.map_pos(self.anchor, Assoc::After),
- changes.map_pos(self.head, Assoc::After),
+ changes.map_pos(self.anchor, Assoc::After, true),
+ changes.map_pos(self.head, Assoc::After, true),
  ),
  Ordering::Less => (
- changes.map_pos(self.anchor, Assoc::After),
- changes.map_pos(self.head, Assoc::Before),
+ changes.map_pos(self.anchor, Assoc::After, true),
+ changes.map_pos(self.head, Assoc::Before, true),
  ),
  Ordering::Greater => (
- changes.map_pos(self.anchor, Assoc::Before),
- changes.map_pos(self.head, Assoc::After),
+ changes.map_pos(self.anchor, Assoc::Before, true),
+ changes.map_pos(self.head, Assoc::After, true),
  ),
  };
 

helix-core/src/transaction.rs

@@ -329,7 +329,10 @@ impl ChangeSet {
  /// position close to the character before, and will place it before insertions over that
  /// range, or at that point. `After` will move it forward, placing it at the end of such
  /// insertions.
- pub fn map_pos(&self, pos: usize, assoc: Assoc) -> usize {
+ ///
+ /// `sticky` indicates that `pos` should remain unchaged for exact replacements. This is
+ //// desirable for cursors but undesirable for other things like diagnostics
+ pub fn map_pos(&self, pos: usize, assoc: Assoc, sticky: bool) -> usize {
  use Operation::*;
  let mut old_pos = 0;
  let mut new_pos = 0;
@@ -368,7 +371,7 @@ impl ChangeSet {
  if old_end > pos {
  // if the deleted and inserted text have the exact same size
  // keep the relative offset into the new text
- if *len == ins {
+ if *len == ins && sticky {
  return new_pos + (pos - old_pos);
  }
  // at point or tracking before
@@ -659,21 +662,21 @@ mod test {
  len_after: 10,
  };
 
- assert_eq!(cs.map_pos(0, Assoc::Before), 0); // before insert region
- assert_eq!(cs.map_pos(4, Assoc::Before), 4); // at insert, track before
- assert_eq!(cs.map_pos(4, Assoc::After), 6); // at insert, track after
- assert_eq!(cs.map_pos(5, Assoc::Before), 7); // after insert region
+ assert_eq!(cs.map_pos(0, Assoc::Before, false), 0); // before insert region
+ assert_eq!(cs.map_pos(4, Assoc::Before, false), 4); // at insert, track before
+ assert_eq!(cs.map_pos(4, Assoc::After, false), 6); // at insert, track after
+ assert_eq!(cs.map_pos(5, Assoc::Before, false), 7); // after insert region
 
  // maps deletes
  let cs = ChangeSet {
  changes: vec![Retain(4), Delete(4), Retain(4)],
  len: 12,
  len_after: 8,
  };
- assert_eq!(cs.map_pos(0, Assoc::Before), 0); // at start
- assert_eq!(cs.map_pos(4, Assoc::Before), 4); // before a delete
- assert_eq!(cs.map_pos(5, Assoc::Before), 4); // inside a delete
- assert_eq!(cs.map_pos(5, Assoc::After), 4); // inside a delete
+ assert_eq!(cs.map_pos(0, Assoc::Before, false), 0); // at start
+ assert_eq!(cs.map_pos(4, Assoc::Before, false), 4); // before a delete
+ assert_eq!(cs.map_pos(5, Assoc::Before, false), 4); // inside a delete
+ assert_eq!(cs.map_pos(5, Assoc::After, false), 4); // inside a delete
 
  // TODO: delete tracking
 
@@ -688,8 +691,8 @@ mod test {
  len: 4,
  len_after: 4,
  };
- assert_eq!(cs.map_pos(2, Assoc::Before), 2);
- assert_eq!(cs.map_pos(2, Assoc::After), 2);
+ assert_eq!(cs.map_pos(2, Assoc::Before, false), 2);
+ assert_eq!(cs.map_pos(2, Assoc::After, false), 2);
  }
 
  #[test]

helix-view/src/document.rs

@@ -863,8 +863,9 @@ impl Document {
  for diagnostic in &mut self.diagnostics {
  use helix_core::Assoc;
  let changes = transaction.changes();
- diagnostic.range.start = changes.map_pos(diagnostic.range.start, Assoc::After);
- diagnostic.range.end = changes.map_pos(diagnostic.range.end, Assoc::After);
+ diagnostic.range.start =
+ changes.map_pos(diagnostic.range.start, Assoc::After, false);
+ diagnostic.range.end = changes.map_pos(diagnostic.range.end, Assoc::After, false);
  diagnostic.line = self.text.char_to_line(diagnostic.range.start);
  }
  self.diagnostics