LibVT+Everywhere: Introduce 'automarks' and 'clear previous command'

Automarks are similar to bookmarks placed by the terminal, allowing the
user to selectively remove a single command and its output from the
terminal scrollback.
This commit implements a single way to add marks: automatically placing
them when the shell becomes interactive.

To make sure the shell behaves correctly after its expected prompt
position changes, the terminal layer forces a resize event to be passed
to the shell on such (possibly) partial clears; this also has the nice
side effect of fixing the disappearing prompt on the preexisting "clear
including history" action: Fixes #4192.

Userland/Applications/Terminal/main.cpp

@@ -284,6 +284,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->set_obey_widget_min_size(false);
 
     auto terminal = window->set_main_widget<VT::TerminalWidget>(ptm_fd, true);
+    terminal->set_startup_process_id(shell_pid);
+
     terminal->on_command_exit = [&] {
         app->quit(0);
     };
@@ -309,6 +311,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         terminal->set_bell_mode(VT::TerminalWidget::BellMode::Visible);
     }
 
+    auto automark = Config::read_string("Terminal"sv, "Terminal"sv, "AutoMark"sv, "MarkInteractiveShellPrompt"sv);
+    if (automark == "MarkNothing") {
+        terminal->set_auto_mark_mode(VT::TerminalWidget::AutoMarkMode::MarkNothing);
+    } else {
+        terminal->set_auto_mark_mode(VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt);
+    }
+
     auto cursor_shape = VT::TerminalWidget::parse_cursor_shape(Config::read_string("Terminal"sv, "Cursor"sv, "Shape"sv, "Block"sv)).value_or(VT::CursorShape::Block);
     terminal->set_cursor_shape(cursor_shape);
 
@@ -399,6 +408,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         window->set_fullscreen(!window->is_fullscreen());
     }));
     view_menu->add_action(terminal->clear_including_history_action());
+    view_menu->add_action(terminal->clear_to_previous_mark_action());
 
     auto adjust_font_size = [&](float adjustment, Gfx::Font::AllowInexactSizeMatch preference) {
         auto& font = terminal->font();

Userland/Applications/TerminalSettings/MainWidget.cpp

@@ -40,10 +40,15 @@ ErrorOr<void> MainWidget::setup()
     auto& beep_bell_radio = *find_descendant_of_type_named<GUI::RadioButton>("beep_bell_radio");
     auto& visual_bell_radio = *find_descendant_of_type_named<GUI::RadioButton>("visual_bell_radio");
     auto& no_bell_radio = *find_descendant_of_type_named<GUI::RadioButton>("no_bell_radio");
+    auto& automark_off_radio = *find_descendant_of_type_named<GUI::RadioButton>("automark_of");
+    auto& automark_on_interactive_prompt_radio = *find_descendant_of_type_named<GUI::RadioButton>("automark_on_interactive_prompt");
 
     m_bell_mode = parse_bell(Config::read_string("Terminal"sv, "Window"sv, "Bell"sv));
     m_original_bell_mode = m_bell_mode;
 
+    m_automark_mode = parse_automark_mode(Config::read_string("Terminal"sv, "Terminal"sv, "AutoMark"sv));
+    m_original_automark_mode = m_automark_mode;
+
     switch (m_bell_mode) {
     case VT::TerminalWidget::BellMode::Visible:
         visual_bell_radio.set_checked(true, GUI::AllowCallback::No);
@@ -72,6 +77,26 @@ ErrorOr<void> MainWidget::setup()
         set_modified(true);
     };
 
+    switch (m_automark_mode) {
+    case VT::TerminalWidget::AutoMarkMode::MarkNothing:
+        automark_off_radio.set_checked(true, GUI::AllowCallback::No);
+        break;
+    case VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt:
+        automark_on_interactive_prompt_radio.set_checked(true, GUI::AllowCallback::No);
+        break;
+    }
+
+    automark_off_radio.on_checked = [this](bool) {
+        m_automark_mode = VT::TerminalWidget::AutoMarkMode::MarkNothing;
+        Config::write_string("Terminal"sv, "Terminal"sv, "AutoMark"sv, stringify_automark_mode(m_automark_mode));
+        set_modified(true);
+    };
+    automark_on_interactive_prompt_radio.on_checked = [this](bool) {
+        m_automark_mode = VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt;
+        Config::write_string("Terminal"sv, "Terminal"sv, "AutoMark"sv, stringify_automark_mode(m_automark_mode));
+        set_modified(true);
+    };
+
     m_confirm_close = Config::read_bool("Terminal"sv, "Terminal"sv, "ConfirmClose"sv, true);
     m_orignal_confirm_close = m_confirm_close;
     auto& confirm_close_checkbox = *find_descendant_of_type_named<GUI::CheckBox>("terminal_confirm_close");
@@ -106,6 +131,24 @@ ByteString MainWidget::stringify_bell(VT::TerminalWidget::BellMode bell_mode)
     VERIFY_NOT_REACHED();
 }
 
+VT::TerminalWidget::AutoMarkMode MainWidget::parse_automark_mode(StringView automark_mode)
+{
+    if (automark_mode == "MarkNothing")
+        return VT::TerminalWidget::AutoMarkMode::MarkNothing;
+    if (automark_mode == "MarkInteractiveShellPrompt")
+        return VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt;
+    VERIFY_NOT_REACHED();
+}
+
+ByteString MainWidget::stringify_automark_mode(VT::TerminalWidget::AutoMarkMode automark_mode)
+{
+    if (automark_mode == VT::TerminalWidget::AutoMarkMode::MarkNothing)
+        return "MarkNothing";
+    if (automark_mode == VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt)
+        return "MarkInteractiveShellPrompt";
+    VERIFY_NOT_REACHED();
+}
+
 void MainWidget::apply_settings()
 {
     m_original_bell_mode = m_bell_mode;

Userland/Applications/TerminalSettings/MainWidget.h

@@ -29,12 +29,16 @@ private:
     void write_back_settings() const;
 
     static VT::TerminalWidget::BellMode parse_bell(StringView bell_string);
+    static VT::TerminalWidget::AutoMarkMode parse_automark_mode(StringView automark_mode);
     static ByteString stringify_bell(VT::TerminalWidget::BellMode bell_mode);
+    static ByteString stringify_automark_mode(VT::TerminalWidget::AutoMarkMode automark_mode);
 
     VT::TerminalWidget::BellMode m_bell_mode { VT::TerminalWidget::BellMode::Disabled };
+    VT::TerminalWidget::AutoMarkMode m_automark_mode { VT::TerminalWidget::AutoMarkMode::MarkInteractiveShellPrompt };
     bool m_confirm_close { true };
 
     VT::TerminalWidget::BellMode m_original_bell_mode;
+    VT::TerminalWidget::AutoMarkMode m_original_automark_mode;
     bool m_orignal_confirm_close { true };
 };
 }

Userland/Applications/TerminalSettings/TerminalSettingsMain.gml

@@ -48,4 +48,22 @@
             text: "Confirm exit when process is active"
         }
     }
+
+    @GUI::GroupBox {
+        title: "Auto-mark behavior"
+        preferred_height: "fit"
+        layout: @GUI::VerticalBoxLayout {
+            margins: [8]
+        }
+
+        @GUI::RadioButton {
+            name: "automark_off"
+            text: "Do not auto-mark"
+        }
+
+        @GUI::RadioButton {
+            name: "automark_on_interactive_prompt"
+            text: "Auto-mark on interactive shell prompts"
+        }
+    }
 }