From 43d56b6f3a45dd2f92f4fd7b1cf7a8bdf0cb57ba Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Thu, 7 Mar 2019 16:49:04 +0100
Subject: [PATCH] GTextEditor: Support splitting lines at the cursor with the
 Return key.

---
 AK/Vector.h            | 20 +++++++++++++++-----
 LibGUI/GTextEditor.cpp | 15 ++++++++++++++-
 LibGUI/GTextEditor.h   |  1 +
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/AK/Vector.h b/AK/Vector.h
index 13ffb4df645..02f3997fd56 100644
--- a/AK/Vector.h
+++ b/AK/Vector.h
@@ -252,12 +252,22 @@ public:
 
     void resize(ssize_t new_size)
     {
-        ASSERT(new_size >= size());
-        if (!new_size)
+        if (new_size == size())
             return;
-        ensure_capacity(new_size);
-        for (ssize_t i = size(); i < new_size; ++i)
-            new (m_impl->slot(i)) T;
+
+        if (!new_size) {
+            clear();
+            return;
+        }
+
+        if (new_size > size()) {
+            ensure_capacity(new_size);
+            for (ssize_t i = size(); i < new_size; ++i)
+                new (m_impl->slot(i)) T;
+        } else {
+            for (int i = new_size; i < size(); ++i)
+                m_impl->at(i).~T();
+        }
         m_impl->m_size = new_size;
     }
 
diff --git a/LibGUI/GTextEditor.cpp b/LibGUI/GTextEditor.cpp
index 720277347b8..5e2b2f9dcb7 100644
--- a/LibGUI/GTextEditor.cpp
+++ b/LibGUI/GTextEditor.cpp
@@ -240,10 +240,17 @@ void GTextEditor::insert_at_cursor(char ch)
         if (at_tail || at_head) {
             m_lines.insert(m_cursor.line() + (at_tail ? 1 : 0), make<Line>());
             update_scrollbar_ranges();
-            set_cursor(m_cursor.line() + 1, 0);
             update();
+            set_cursor(m_cursor.line() + 1, 0);
             return;
         }
+        auto new_line = make<Line>();
+        new_line->append(current_line().characters() + m_cursor.column(), current_line().length() - m_cursor.column());
+        current_line().truncate(m_cursor.column());
+        m_lines.insert(m_cursor.line() + 1, move(new_line));
+        update_scrollbar_ranges();
+        update();
+        set_cursor(m_cursor.line() + 1, 0);
         return;
     }
     current_line().insert(m_cursor.column(), ch);
@@ -414,3 +421,9 @@ void GTextEditor::Line::remove(int index)
         m_text.remove(index);
     }
 }
+
+void GTextEditor::Line::truncate(int length)
+{
+    m_text.resize(length + 1);
+    m_text.last() = 0;
+}
diff --git a/LibGUI/GTextEditor.h b/LibGUI/GTextEditor.h
index 5964df624ba..1c905512b21 100644
--- a/LibGUI/GTextEditor.h
+++ b/LibGUI/GTextEditor.h
@@ -73,6 +73,7 @@ private:
         void insert(int index, char);
         void remove(int index);
         void append(const char*, int);
+        void truncate(int length);
 
     private:
         // NOTE: This vector is null terminated.