VimEditingEngine: allow selection of the endline character

This patch fixes the visual selection of endline characters in the
VimEditingEngine. When the visual mode is disabled and the cursor
is located on the endline character, it is shifted back to the last
character of the line.

Userland/Libraries/LibGUI/VimEditingEngine.cpp

@@ -665,7 +665,7 @@ void VimMotion::calculate_find_range(VimCursor& cursor, int amount)
     m_find_mode = FindMode::None;
 }
 
-Optional<TextPosition> VimMotion::get_position(VimEditingEngine& engine)
+Optional<TextPosition> VimMotion::get_position(VimEditingEngine& engine, bool in_visual_mode)
 {
     auto range_optional = get_range(engine, true);
     if (!range_optional.has_value())
@@ -716,11 +716,13 @@ Optional<TextPosition> VimMotion::get_position(VimEditingEngine& engine)
             // above in get_range normalizes some values which shouldn't be
             // end-exclusive during normal operations.
             bool is_at_start = range.end().column() == 0;
-            size_t column = is_at_start ? 0 : range.end().column() - 1;
-            // Need to not go beyond the last character, as standard in vim.
             auto& line = editor.line(range.end().line());
 
-            return { TextPosition { range.end().line(), min(column, line.length() - 1) } };
+            size_t column = is_at_start ? 0 : range.end().column() - 1;
+            column = min(column, line.length() - (in_visual_mode ? 0 : 1));
+            // Need to not go beyond the last character, as standard in vim.
+
+            return { TextPosition { range.end().line(), column } };
         }
     }
     }
@@ -1012,7 +1014,7 @@ bool VimEditingEngine::on_key_in_visual_mode(const KeyEvent& event)
         m_motion.add_key_code(event.key(), event.ctrl(), event.shift(), event.alt());
         if (m_motion.is_complete()) {
             if (!m_motion.is_cancelled()) {
-                auto maybe_new_position = m_motion.get_position(*this);
+                auto maybe_new_position = m_motion.get_position(*this, true);
                 if (maybe_new_position.has_value()) {
                     auto new_position = maybe_new_position.value();
                     m_editor->set_cursor(new_position);
@@ -1114,7 +1116,7 @@ bool VimEditingEngine::on_key_in_visual_mode(const KeyEvent& event)
     m_motion.add_key_code(event.key(), event.ctrl(), event.shift(), event.alt());
     if (m_motion.is_complete()) {
         if (!m_motion.is_cancelled()) {
-            auto maybe_new_position = m_motion.get_position(*this);
+            auto maybe_new_position = m_motion.get_position(*this, true);
             if (maybe_new_position.has_value()) {
                 auto new_position = maybe_new_position.value();
                 m_editor->set_cursor(new_position);
@@ -1151,6 +1153,7 @@ void VimEditingEngine::switch_to_visual_mode()
     m_vim_mode = VimMode::Visual;
     m_editor->reset_cursor_blink();
     m_previous_key = {};
+    m_selection_start_position = m_editor->cursor();
     m_editor->selection()->set(m_editor->cursor(), { m_editor->cursor().line(), m_editor->cursor().column() + 1 });
     m_editor->did_update_selection();
     m_motion.reset();
@@ -1159,18 +1162,37 @@ void VimEditingEngine::switch_to_visual_mode()
 void VimEditingEngine::update_selection_on_cursor_move()
 {
     auto cursor = m_editor->cursor();
-    auto& line = m_editor->current_line();
+    auto start = m_selection_start_position < cursor ? m_selection_start_position : cursor;
-    cursor.set_column(min(cursor.column() + 1, line.length()));
+    auto end = m_selection_start_position < cursor ? cursor : m_selection_start_position;
-    m_editor->selection()->set_end(cursor);
+
+    if (end.column() >= m_editor->current_line().length()) {
+        if (end.line() != m_editor->line_count() - 1)
+            end = { end.line() + 1, 0 };
+    } else {
+        end.set_column(end.column() + 1);
+    }
+
+    m_editor->selection()->set(start, end);
     m_editor->did_update_selection();
 }
 
+void VimEditingEngine::clamp_cursor_position()
+{
+    auto cursor = m_editor->cursor();
+    if (cursor.column() >= m_editor->current_line().length()) {
+        cursor.set_column(m_editor->current_line().length() - 1);
+        m_editor->set_cursor(cursor);
+    }
+}
+
 void VimEditingEngine::clear_visual_mode_data()
 {
     if (m_editor->has_selection()) {
         m_editor->selection()->clear();
         m_editor->did_update_selection();
+        clamp_cursor_position();
     }
+    m_selection_start_position = {};
 }
 
 void VimEditingEngine::move_half_page_up()

Userland/Libraries/LibGUI/VimEditingEngine.h

@@ -101,7 +101,7 @@ public:
 
     void add_key_code(KeyCode key, bool ctrl, bool shift, bool alt);
     Optional<TextRange> get_range(class VimEditingEngine& engine, bool normalize_for_position = false);
-    Optional<TextPosition> get_position(VimEditingEngine& engine);
+    Optional<TextPosition> get_position(VimEditingEngine& engine, bool in_visual_mode = false);
     void reset();
 
     /// Returns whether the motion should consume the next character no matter what.
@@ -168,7 +168,9 @@ private:
     void yank(TextRange);
     void put();
 
+    TextPosition m_selection_start_position = {};
     void update_selection_on_cursor_move();
+    void clamp_cursor_position();
     void clear_visual_mode_data();
 
     KeyCode m_previous_key {};