From 66f1fb0b5ea767b83a3ef6844145ac776ea3bfd3 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Tue, 13 Jan 2026 23:54:48 +0000
Subject: [PATCH] implement 'yk' motion (next: add tests for it)

---
 fcore/normal-mode/normal-mode.sml |  1 +
 fcore/normal-mode/normal-yank.sml | 55 +++++++++++++++++++++++++++++++
 temp.txt                          |  2 ++
 todo.md                           |  4 +--
 4 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/fcore/normal-mode/normal-mode.sml b/fcore/normal-mode/normal-mode.sml
index f2f6a75..7d6df17 100644
--- a/fcore/normal-mode/normal-mode.sml
+++ b/fcore/normal-mode/normal-mode.sml
@@ -462,6 +462,7 @@ struct
     fun parseYankTerminal (str, count, app, chrCmd, time) =
       case chrCmd of
         #"h" => NormalYank.yankLeft (app, count)
+      | #"k" => NormalYank.yankLineUp (app, count)
       | #"l" => NormalYank.yankRight (app, count)
       | #"y" => NormalYank.yankLine (app, count)
       | #"0" => NormalYank.yankToStartOfLine app
diff --git a/fcore/normal-mode/normal-yank.sml b/fcore/normal-mode/normal-yank.sml
index fd58e26..93815b4 100644
--- a/fcore/normal-mode/normal-yank.sml
+++ b/fcore/normal-mode/normal-yank.sml
@@ -44,6 +44,61 @@ struct
       finish (app, buffer, str)
     end
 
+  fun yankLineUp (app: app_type, count) =
+    let
+      val {buffer, cursorIdx, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+      val cursorLineNumber =
+        if Cursor.isNextChrEndOfLine (buffer, cursorIdx) then
+          LineGap.idxToLineNumber (cursorIdx + 1, buffer)
+        else
+          LineGap.idxToLineNumber (cursorIdx, buffer)
+      val newCursorLineNumber = Int.max (cursorLineNumber - count, 0)
+    in
+      if cursorLineNumber = 0 then
+        NormalFinish.clearMode app
+      else if newCursorLineNumber = 0 then
+        let
+          val endOfLine = Cursor.viDlr (buffer, cursorIdx, 1)
+          val buffer = LineGap.goToIdx (endOfLine, buffer)
+
+          val endOfLine =
+            if Cursor.isCursorAtStartOfLine (buffer, endOfLine) then
+              endOfLine + 1
+            else
+              endOfLine + 2
+
+          val buffer = LineGap.goToIdx (endOfLine, buffer)
+          val str = LineGap.substring (0, endOfLine, buffer)
+        in
+          finish (app, buffer, str)
+        end
+      else
+        let
+          val endOfLine = Cursor.viDlr (buffer, cursorIdx, 1)
+          val buffer = LineGap.goToIdx (endOfLine, buffer)
+          val endsOnNewline = Cursor.isCursorAtStartOfLine (buffer, endOfLine)
+
+          val endOfLine = if endsOnNewline then endOfLine else endOfLine + 1
+
+          val newCursorLineNumber =
+            if endsOnNewline andalso endOfLine = #textLength buffer - 1 then
+              newCursorLineNumber - 1
+            else
+              newCursorLineNumber
+          val buffer = LineGap.goToLine (newCursorLineNumber, buffer)
+
+          val lineIdx = LineGap.lineNumberToIdx (newCursorLineNumber, buffer)
+          val length = endOfLine - lineIdx
+
+          val buffer = LineGap.goToIdx (endOfLine, buffer)
+          val str = LineGap.substring (lineIdx, length, buffer)
+        in
+          finish (app, buffer, str)
+        end
+    end
+
   fun yankLine (app: app_type, count) =
     let
       val {buffer, cursorIdx, ...} = app
diff --git a/temp.txt b/temp.txt
index 3b18e51..bc52a2b 100644
--- a/temp.txt
+++ b/temp.txt
@@ -1 +1,3 @@
 hello world
+test line
+zzz
diff --git a/todo.md b/todo.md
index 92c3079..48fdb18 100644
--- a/todo.md
+++ b/todo.md
@@ -1,3 +1,3 @@
 # To-do list
-
-- Implement 'yj' and 'yk' and add tests for them
+- Add tests for 'yk' motion
+- Implement 'yj' motion and add tests for it