From 09fe611efbcdc9031d66d990fac55bb81777f09c Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Sun, 14 Sep 2025 15:48:26 +0100
Subject: [PATCH] fix tracking of textLength and lineLength fields, which were
 previously buggy in only one delete branch; the current commit fixes that
 branch and verifies the tests pass

---
 src/line_gap.sml | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/line_gap.sml b/src/line_gap.sml
index fe1e00c..d915924 100644
--- a/src/line_gap.sml
+++ b/src/line_gap.sml
@@ -1584,9 +1584,16 @@ struct
                     else
                       Vector.fromList []
 
-                  val newTextLength = String.size sub1 + String.size sub1
-                  val newLineLength =
+                  val newNodeTextLength = String.size sub1 + String.size sub2
+                  val textLengthDifference =
+                    oldNodeTextLength - newNodeTextLength
+                  val newTextLength = textLength - textLengthDifference
+
+                  val newNodeLineLength =
                     Vector.length sub1Lines + Vector.length sub2Lines
+                  val lineLengthDifference =
+                    oldNodeLineLength - newNodeLineLength
+                  val newLineLength = lineLength - lineLengthDifference
                 in
                   { idx = curIdx + String.size sub1
                   , textLength = newTextLength