HexEditor: Implement undo and redo actions

1 files changed, 82 insertions, 6 deletions

diff --git a/Userland/Applications/HexEditor/HexEditor.cpp b/Userland/Applications/HexEditor/HexEditor.cpp
index 701a461666..5aff8d3f5d 100644
--- a/Userland/Applications/HexEditor/HexEditor.cpp
+++ b/Userland/Applications/HexEditor/HexEditor.cpp
@@ -82,8 +82,22 @@ void HexEditor::fill_selection(u8 fill_byte)
     if (!has_selection())
         return;
 
-    for (size_t i = m_selection_start; i < m_selection_end; i++)
-        m_document->set(i, fill_byte);
+    ByteBuffer old_values;
+    ByteBuffer new_values;
+
+    size_t length = m_selection_end - m_selection_start;
+
+    new_values.resize(length);
+    old_values.resize(length);
+
+    for (size_t i = 0; i < length; i++) {
+        size_t position = m_selection_start + i;
+        old_values[i] = m_document->get(position).value;
+        new_values[i] = fill_byte;
+        m_document->set(position, fill_byte);
+    }
+
+    did_complete_action(m_selection_start, move(old_values), move(new_values));
 
     update();
     did_change();
@@ -465,6 +479,8 @@ void HexEditor::hex_mode_keydown_event(GUI::KeyEvent& event)
 
         VERIFY(m_position <= m_document->size());
 
+        auto old_value = m_document->get(m_position).value;
+
         // yes, this is terrible... but it works.
         auto value = (event.key() >= KeyCode::Key_0 && event.key() <= KeyCode::Key_9)
             ? event.key() - KeyCode::Key_0
@@ -472,11 +488,14 @@ void HexEditor::hex_mode_keydown_event(GUI::KeyEvent& event)
 
         if (!m_cursor_at_low_nibble) {
             u8 existing_change = m_document->get(m_position).value;
-            existing_change = value << 4 | (existing_change & 0xF); // shift new value left 4 bits, OR with existing last 4 bits
-            m_document->set(m_position, existing_change);
+            u8 new_value = value << 4 | (existing_change & 0xF); // shift new value left 4 bits, OR with existing last 4 bits
+            m_document->set(m_position, new_value);
+            did_complete_action(m_position, old_value, new_value);
             m_cursor_at_low_nibble = true;
         } else {
-            m_document->set(m_position, (m_document->get(m_position).value & 0xF0) | value); // save the first 4 bits, OR the new value in the last 4
+            u8 new_value = (m_document->get(m_position).value & 0xF0) | value; // save the first 4 bits, OR the new value in the last 4
+            m_document->set(m_position, new_value);
+            did_complete_action(m_position, old_value, new_value);
             if (m_position + 1 < m_document->size())
                 m_position++;
             m_cursor_at_low_nibble = false;
@@ -498,7 +517,11 @@ void HexEditor::text_mode_keydown_event(GUI::KeyEvent& event)
     if (event.code_point() == 0) // This is a control key
         return;
 
-    m_document->set(m_position, event.code_point());
+    auto old_value = m_document->get(m_position).value;
+    auto new_value = event.code_point();
+    m_document->set(m_position, new_value);
+    did_complete_action(m_position, old_value, new_value);
+
     if (m_position + 1 < m_document->size())
         m_position++;
     m_cursor_at_low_nibble = false;
@@ -797,3 +820,56 @@ void HexEditor::reset_cursor_blink_state()
     m_cursor_blink_active = true;
     m_blink_timer->restart();
 }
+
+void HexEditor::did_complete_action(size_t position, u8 old_value, u8 new_value)
+{
+    if (old_value == new_value)
+        return;
+
+    auto command = make<HexDocumentUndoCommand>(m_document->make_weak_ptr(), position);
+
+    // We know this won't allocate because the buffers start empty
+    MUST(command->try_add_changed_byte(old_value, new_value));
+    // FIXME: Handle errors
+    MUST(m_undo_stack.try_push(move(command)));
+}
+
+void HexEditor::did_complete_action(size_t position, ByteBuffer&& old_values, ByteBuffer&& new_values)
+{
+    auto command = make<HexDocumentUndoCommand>(m_document->make_weak_ptr(), position);
+
+    // FIXME: Handle errors
+    MUST(command->try_add_changed_bytes(move(old_values), move(new_values)));
+    MUST(m_undo_stack.try_push(move(command)));
+}
+
+bool HexEditor::undo()
+{
+    if (!m_undo_stack.can_undo())
+        return false;
+
+    m_undo_stack.undo();
+    reset_cursor_blink_state();
+    update();
+    update_status();
+    did_change();
+    return true;
+}
+
+bool HexEditor::redo()
+{
+    if (!m_undo_stack.can_redo())
+        return false;
+
+    m_undo_stack.redo();
+    reset_cursor_blink_state();
+    update();
+    update_status();
+    did_change();
+    return true;
+}
+
+GUI::UndoStack& HexEditor::undo_stack()
+{
+    return m_undo_stack;
+}