LibGUI: Add up & down arrow hooks and input history to TextBox

This patch adds the ability to enable "input history" on a textbox,
allowing to navigate between the history with the arrow keys.

Also removes a custom TextBox subclass from HackStudio that added
the exact same hooks, and moves it to use the now standard ones.

DevTools/HackStudio/Locator.cpp

@@ -73,28 +73,6 @@ private:
     Vector<String> m_suggestions;
 };
 
-class LocatorTextBox final : public GUI::TextBox {
-    C_OBJECT(LocatorTextBox)
-public:
-    virtual ~LocatorTextBox() override {}
-
-    Function<void()> on_up;
-    Function<void()> on_down;
-
-    virtual void keydown_event(GUI::KeyEvent& event) override
-    {
-        if (event.key() == Key_Up)
-            on_up();
-        else if (event.key() == Key_Down)
-            on_down();
-
-        GUI::TextBox::keydown_event(event);
-    }
-
-private:
-    LocatorTextBox() {}
-};
-
 Locator::Locator()
 {
     if (!s_cplusplus_icon) {
@@ -106,14 +84,14 @@ Locator::Locator()
     set_layout<GUI::VerticalBoxLayout>();
     set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
     set_preferred_size(0, 20);
-    m_textbox = add<LocatorTextBox>();
+    m_textbox = add<GUI::TextBox>();
     m_textbox->on_change = [this] {
         update_suggestions();
     };
     m_textbox->on_escape_pressed = [this] {
         m_popup_window->hide();
     };
-    m_textbox->on_up = [this] {
+    m_textbox->on_up_pressed = [this] {
         GUI::ModelIndex new_index = m_suggestion_view->selection().first();
         if (new_index.is_valid())
             new_index = m_suggestion_view->model()->index(new_index.row() - 1);
@@ -125,7 +103,7 @@ Locator::Locator()
             m_suggestion_view->scroll_into_view(new_index, Orientation::Vertical);
         }
     };
-    m_textbox->on_down = [this] {
+    m_textbox->on_down_pressed = [this] {
         GUI::ModelIndex new_index = m_suggestion_view->selection().first();
         if (new_index.is_valid())
             new_index = m_suggestion_view->model()->index(new_index.row() + 1);

DevTools/HackStudio/Locator.h

@@ -28,8 +28,6 @@
 
 #include <LibGUI/Widget.h>
 
-class LocatorTextBox;
-
 class Locator final : public GUI::Widget {
     C_OBJECT(Locator)
 public:
@@ -44,7 +42,7 @@ private:
 
     Locator();
 
-    RefPtr<LocatorTextBox> m_textbox;
+    RefPtr<GUI::TextBox> m_textbox;
     RefPtr<GUI::Window> m_popup_window;
     RefPtr<GUI::TableView> m_suggestion_view;
 };

Libraries/LibGUI/TextBox.cpp

@@ -37,4 +37,55 @@ TextBox::~TextBox()
 {
 }
 
+void TextBox::keydown_event(GUI::KeyEvent& event)
+{
+    TextEditor::keydown_event(event);
+
+    if (event.key() == Key_Up) {
+        if (on_up_pressed)
+            on_up_pressed();
+
+        if (has_no_history() || !can_go_backwards_in_history())
+            return;
+
+        if (m_history_index >= static_cast<int>(m_history.size()))
+            m_saved_input = text();
+
+        m_history_index--;
+        set_text(m_history[m_history_index]);
+    } else if (event.key() == Key_Down) {
+        if (on_down_pressed)
+            on_down_pressed();
+
+        if (has_no_history())
+            return;
+
+        if (can_go_forwards_in_history()) {
+            m_history_index++;
+            set_text(m_history[m_history_index]);
+        } else if (m_history_index < static_cast<int>(m_history.size())) {
+            m_history_index++;
+            set_text(m_saved_input);
+        }
+    }
+}
+
+void TextBox::add_current_text_to_history()
+{
+    if (!m_history_enabled)
+        return;
+    
+    auto input = text();
+    if (m_history.is_empty() || m_history.last() != input)
+        add_input_to_history(input);
+    m_history_index = static_cast<int>(m_history.size());
+    m_saved_input = {};
+}
+
+void TextBox::add_input_to_history(String input)
+{
+    m_history.append(move(input));
+    m_history_index++;
+}
+
 }

Libraries/LibGUI/TextBox.h

@@ -35,6 +35,25 @@ class TextBox : public TextEditor {
 public:
     TextBox();
     virtual ~TextBox() override;
+
+    Function<void()> on_up_pressed;
+    Function<void()> on_down_pressed;
+
+    void set_history_enabled(bool enabled) { m_history_enabled = enabled; }
+    void add_current_text_to_history();
+
+private:
+    virtual void keydown_event(GUI::KeyEvent&) override;
+
+    bool has_no_history() const { return !m_history_enabled || m_history.is_empty(); }
+    bool can_go_backwards_in_history() const { return m_history_index > 0; }
+    bool can_go_forwards_in_history() const { return m_history_index < static_cast<int>(m_history.size()) - 1; }
+    void add_input_to_history(String);
+
+    bool m_history_enabled { false };
+    Vector<String> m_history;
+    int m_history_index { -1 };
+    String m_saved_input;
 };
 
 }