From 7eb009e259a3879a3c7016cc373477bba7a4ed65 Mon Sep 17 00:00:00 2001
From: Conrad Irwin <conrad.irwin@gmail.com>
Date: Thu, 12 Mar 2026 23:16:02 -0600
Subject: [PATCH] editor: Make underscores and newlines subword boundaries
 (#50552)

Updates #21054

Authored-By: @ngauder

Release Notes:

- Added _ and newline to subword boundaries

---------

Co-authored-by: Nikolas Gauder <nikolas.gauder@tum.de>
---
 crates/editor/src/movement.rs | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/crates/editor/src/movement.rs b/crates/editor/src/movement.rs
index 01f7d0064e6f5ecd0d4d9c1760386102e9ce16e0..6bf6449506f1c1eb2a71270546ad3b063f7e9022 100644
--- a/crates/editor/src/movement.rs
+++ b/crates/editor/src/movement.rs
@@ -408,7 +408,7 @@ pub fn previous_subword_start(map: &DisplaySnapshot, point: DisplayPoint) -> Dis
     let classifier = map.buffer_snapshot().char_classifier_at(raw_point);
 
     find_preceding_boundary_display_point(map, point, FindRange::MultiLine, &mut |left, right| {
-        is_subword_start(left, right, &classifier) || left == '\n'
+        is_subword_start(left, right, &classifier) || left == '\n' || right == '\n'
     })
 }
 
@@ -431,6 +431,7 @@ pub fn is_subword_start(left: char, right: char, classifier: &CharClassifier) ->
     let is_word_start = classifier.kind(left) != classifier.kind(right) && !right.is_whitespace();
     let is_subword_start = classifier.is_word('-') && left == '-' && right != '-'
         || left == '_' && right != '_'
+        || left != '_' && right == '_'
         || left.is_lowercase() && right.is_uppercase();
     is_word_start || is_subword_start
 }
@@ -484,7 +485,7 @@ pub fn next_subword_end(map: &DisplaySnapshot, point: DisplayPoint) -> DisplayPo
     let classifier = map.buffer_snapshot().char_classifier_at(raw_point);
 
     find_boundary(map, point, FindRange::MultiLine, &mut |left, right| {
-        is_subword_end(left, right, &classifier) || right == '\n'
+        is_subword_end(left, right, &classifier) || left == '\n' || right == '\n'
     })
 }
 
@@ -519,6 +520,7 @@ pub fn is_subword_end(left: char, right: char, classifier: &CharClassifier) -> b
 fn is_subword_boundary_end(left: char, right: char, classifier: &CharClassifier) -> bool {
     classifier.is_word('-') && left != '-' && right == '-'
         || left != '_' && right == '_'
+        || left == '_' && right != '_'
         || left.is_lowercase() && right.is_uppercase()
 }
 
@@ -973,10 +975,10 @@ mod tests {
         }
 
         // Subword boundaries are respected
-        assert("lorem_ˇipˇsum", cx);
+        assert("loremˇ_ˇipsum", cx);
         assert("lorem_ˇipsumˇ", cx);
-        assert("ˇlorem_ˇipsum", cx);
-        assert("lorem_ˇipsum_ˇdolor", cx);
+        assert("ˇloremˇ_ipsum", cx);
+        assert("lorem_ˇipsumˇ_dolor", cx);
         assert("loremˇIpˇsum", cx);
         assert("loremˇIpsumˇ", cx);
 
@@ -1156,10 +1158,10 @@ mod tests {
         }
 
         // Subword boundaries are respected
-        assert("loˇremˇ_ipsum", cx);
+        assert("loremˇ_ˇipsum", cx);
         assert("ˇloremˇ_ipsum", cx);
-        assert("loremˇ_ipsumˇ", cx);
-        assert("loremˇ_ipsumˇ_dolor", cx);
+        assert("loremˇ_ˇipsum", cx);
+        assert("lorem_ˇipsumˇ_dolor", cx);
         assert("loˇremˇIpsum", cx);
         assert("loremˇIpsumˇDolor", cx);
 
@@ -1172,7 +1174,7 @@ mod tests {
         assert("loremˇ    ipsumˇ   ", cx);
         assert("loremˇ-ˇipsum", cx);
         assert("loremˇ#$@-ˇipsum", cx);
-        assert("loremˇ_ipsumˇ", cx);
+        assert("loremˇ_ˇipsum", cx);
         assert(" ˇbcˇΔ", cx);
         assert(" abˇ——ˇcd", cx);
     }