Help: TRY() all the things in serenity_main() :^)

This patch makes use of all the new fallible APIs in LibGUI together
with TRY() to catch and propagate errors. The main error getting caught
is allocation failures while trying to construct the Help UI.

It's quite interesting to see how the code changes as more and more
fallible calls get branded as such by wrapping them in TRY().

There's a lot of repetitive "TRY(try_foo())" going on right now. Once
this becomes the dominant programming pattern, we can drop the "try_"
prefix everywhere. :^)

Userland/Applications/Help/main.cpp

@@ -32,10 +32,6 @@
 #include <LibMain/Main.h>
 #include <LibMarkdown/Document.h>
 #include <LibWeb/OutOfProcessWebView.h>
-#include <libgen.h>
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
@@ -61,45 +57,45 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->set_title("Help");
     window->resize(570, 500);
 
-    auto& widget = window->set_main_widget<GUI::Widget>();
-    widget.set_layout<GUI::VerticalBoxLayout>();
-    widget.set_fill_with_background_color(true);
-    widget.layout()->set_spacing(2);
-
-    auto& toolbar_container = widget.add<GUI::ToolbarContainer>();
-    auto& toolbar = toolbar_container.add<GUI::Toolbar>();
-
-    auto& splitter = widget.add<GUI::HorizontalSplitter>();
-    splitter.layout()->set_spacing(5);
-
-    auto model = ManualModel::create();
-
-    auto& left_tab_bar = splitter.add<GUI::TabWidget>();
-    auto& tree_view_container = left_tab_bar.add_tab<GUI::Widget>("Browse");
-    tree_view_container.set_layout<GUI::VerticalBoxLayout>();
-    tree_view_container.layout()->set_margins(4);
-    auto& tree_view = tree_view_container.add<GUI::TreeView>();
-    auto& search_view = left_tab_bar.add_tab<GUI::Widget>("Search");
-    search_view.set_layout<GUI::VerticalBoxLayout>();
-    search_view.layout()->set_margins(4);
-    auto& search_box = search_view.add<GUI::TextBox>();
-    auto& search_list_view = search_view.add<GUI::ListView>();
-    search_box.set_fixed_height(20);
-    search_box.set_placeholder("Search...");
-    search_box.on_change = [&] {
-        if (auto model = search_list_view.model()) {
+    auto widget = TRY(window->try_set_main_widget<GUI::Widget>());
+    TRY(widget->try_set_layout<GUI::VerticalBoxLayout>());
+    widget->set_fill_with_background_color(true);
+    widget->layout()->set_spacing(2);
+
+    auto toolbar_container = TRY(widget->try_add<GUI::ToolbarContainer>());
+    auto toolbar = TRY(toolbar_container->try_add<GUI::Toolbar>());
+
+    auto splitter = TRY(widget->try_add<GUI::HorizontalSplitter>());
+    splitter->layout()->set_spacing(5);
+
+    auto manual_model = ManualModel::create();
+
+    auto left_tab_bar = TRY(splitter->try_add<GUI::TabWidget>());
+    auto tree_view_container = TRY(left_tab_bar->try_add_tab<GUI::Widget>("Browse"));
+    TRY(tree_view_container->try_set_layout<GUI::VerticalBoxLayout>());
+    tree_view_container->layout()->set_margins(4);
+    auto tree_view = TRY(tree_view_container->try_add<GUI::TreeView>());
+    auto search_view = TRY(left_tab_bar->try_add_tab<GUI::Widget>("Search"));
+    TRY(search_view->try_set_layout<GUI::VerticalBoxLayout>());
+    search_view->layout()->set_margins(4);
+    auto search_box = TRY(search_view->try_add<GUI::TextBox>());
+    auto search_list_view = TRY(search_view->try_add<GUI::ListView>());
+    search_box->set_fixed_height(20);
+    search_box->set_placeholder("Search...");
+    search_box->on_change = [&] {
+        if (auto* model = search_list_view->model()) {
             auto& search_model = *static_cast<GUI::FilteringProxyModel*>(model);
-            search_model.set_filter_term(search_box.text());
+            search_model.set_filter_term(search_box->text());
             search_model.invalidate();
         }
     };
-    search_list_view.set_model(GUI::FilteringProxyModel::construct(model));
-    search_list_view.model()->invalidate();
+    search_list_view->set_model(GUI::FilteringProxyModel::construct(manual_model));
+    search_list_view->model()->invalidate();
 
-    tree_view.set_model(model);
-    left_tab_bar.set_fixed_width(200);
+    tree_view->set_model(manual_model);
+    left_tab_bar->set_fixed_width(200);
 
-    auto& page_view = splitter.add<Web::OutOfProcessWebView>();
+    auto page_view = TRY(splitter->try_add<Web::OutOfProcessWebView>());
 
     History history;
 
@@ -114,11 +110,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto open_page = [&](const String& path) {
         if (path.is_null()) {
             window->set_title("Help");
-            page_view.load_empty_document();
+            page_view->load_empty_document();
             return;
         }
 
-        auto source_result = model->page_view(path);
+        auto source_result = manual_model->page_view(path);
         if (source_result.is_error()) {
             GUI::MessageBox::show(window, String::formatted("{}", source_result.error()), "Failed to open man page", GUI::MessageBox::Type::Error);
             return;
@@ -133,15 +129,15 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
 
         auto url = URL::create_with_file_protocol(path);
-        page_view.load_html(html, url);
+        page_view->load_html(html, url);
 
         app->deferred_invoke([&, path] {
-            auto tree_view_index = model->index_from_path(path);
+            auto tree_view_index = manual_model->index_from_path(path);
             if (tree_view_index.has_value()) {
-                tree_view.expand_tree(tree_view_index.value().parent());
-                tree_view.selection().set(tree_view_index.value());
+                tree_view->expand_tree(tree_view_index.value().parent());
+                tree_view->selection().set(tree_view_index.value());
 
-                String page_and_section = model->page_and_section(tree_view_index.value());
+                String page_and_section = manual_model->page_and_section(tree_view_index.value());
                 window->set_title(String::formatted("{} - Help", page_and_section));
             } else {
                 window->set_title("Help");
@@ -149,8 +145,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         });
     };
 
-    tree_view.on_selection_change = [&] {
-        String path = model->page_path(tree_view.selection().first());
+    tree_view->on_selection_change = [&] {
+        String path = manual_model->page_path(tree_view->selection().first());
         if (path.is_null())
             return;
 
@@ -159,8 +155,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         open_page(path);
     };
 
-    tree_view.on_toggle = [&](const GUI::ModelIndex& index, const bool open) {
-        model->update_section_node_on_toggle(index, open);
+    tree_view->on_toggle = [&](GUI::ModelIndex const& index, bool open) {
+        manual_model->update_section_node_on_toggle(index, open);
     };
 
     auto open_external = [&](auto& url) {
@@ -171,31 +167,31 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 GUI::MessageBox::Type::Error);
         }
     };
-    search_list_view.on_selection_change = [&] {
-        const auto& index = search_list_view.selection().first();
+    search_list_view->on_selection_change = [&] {
+        auto const& index = search_list_view->selection().first();
         if (!index.is_valid())
             return;
 
-        auto view_model = search_list_view.model();
+        auto* view_model = search_list_view->model();
         if (!view_model) {
-            page_view.load_empty_document();
+            page_view->load_empty_document();
             return;
         }
         auto& search_model = *static_cast<GUI::FilteringProxyModel*>(view_model);
         const auto& mapped_index = search_model.map(index);
-        String path = model->page_path(mapped_index);
+        String path = manual_model->page_path(mapped_index);
         if (path.is_null()) {
-            page_view.load_empty_document();
+            page_view->load_empty_document();
             return;
         }
-        tree_view.selection().clear();
-        tree_view.selection().add(mapped_index);
+        tree_view->selection().clear();
+        tree_view->selection().add(mapped_index);
         history.push(path);
         update_actions();
         open_page(path);
     };
 
-    page_view.on_link_click = [&](auto& url, auto&, unsigned) {
+    page_view->on_link_click = [&](auto& url, auto&, unsigned) {
         if (url.protocol() != "file") {
             open_external(url);
             return;
@@ -205,10 +201,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             open_external(url);
             return;
         }
-        auto tree_view_index = model->index_from_path(path);
+        auto tree_view_index = manual_model->index_from_path(path);
         if (tree_view_index.has_value()) {
-            dbgln("Found path _{}_ in model at index {}", path, tree_view_index.value());
-            tree_view.selection().set(tree_view_index.value());
+            dbgln("Found path _{}_ in manual_model at index {}", path, tree_view_index.value());
+            tree_view->selection().set(tree_view_index.value());
             return;
         }
         history.push(path);
@@ -238,43 +234,43 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         open_page(path);
     });
 
-    toolbar.add_action(*go_back_action);
-    toolbar.add_action(*go_forward_action);
-    toolbar.add_action(*go_home_action);
+    TRY(toolbar->try_add_action(*go_back_action));
+    TRY(toolbar->try_add_action(*go_forward_action));
+    TRY(toolbar->try_add_action(*go_home_action));
 
-    auto& file_menu = window->add_menu("&File");
-    file_menu.add_action(GUI::CommonActions::make_quit_action([](auto&) {
+    auto file_menu = TRY(window->try_add_menu("&File"));
+    TRY(file_menu->try_add_action(GUI::CommonActions::make_quit_action([](auto&) {
         GUI::Application::the()->quit();
-    }));
+    })));
 
-    auto& go_menu = window->add_menu("&Go");
-    go_menu.add_action(*go_back_action);
-    go_menu.add_action(*go_forward_action);
-    go_menu.add_action(*go_home_action);
+    auto go_menu = TRY(window->try_add_menu("&Go"));
+    TRY(go_menu->try_add_action(*go_back_action));
+    TRY(go_menu->try_add_action(*go_forward_action));
+    TRY(go_menu->try_add_action(*go_home_action));
 
-    auto& help_menu = window->add_menu("&Help");
-    help_menu.add_action(GUI::CommonActions::make_about_action("Help", app_icon, window));
+    auto help_menu = TRY(window->try_add_menu("&Help"));
+    TRY(help_menu->try_add_action(GUI::CommonActions::make_about_action("Help", app_icon, window)));
 
     auto context_menu = TRY(GUI::Menu::try_create());
-    context_menu->add_action(*go_back_action);
-    context_menu->add_action(*go_forward_action);
-    context_menu->add_action(*go_home_action);
-    context_menu->add_separator();
+    TRY(context_menu->try_add_action(*go_back_action));
+    TRY(context_menu->try_add_action(*go_forward_action));
+    TRY(context_menu->try_add_action(*go_home_action));
+    TRY(context_menu->try_add_separator());
 
     RefPtr<GUI::Action> copy_action = GUI::CommonActions::make_copy_action([&](auto&) {
-        auto selected_text = page_view.selected_text();
+        auto selected_text = page_view->selected_text();
         if (!selected_text.is_empty())
             GUI::Clipboard::the().set_plain_text(selected_text);
     });
-    context_menu->add_action(*copy_action);
+    TRY(context_menu->try_add_action(*copy_action));
 
     RefPtr<GUI::Action> select_all_function = GUI::CommonActions::make_select_all_action([&](auto&) {
-        page_view.select_all();
+        page_view->select_all();
     });
-    context_menu->add_action(*select_all_function);
+    TRY(context_menu->try_add_action(*select_all_function));
 
-    page_view.on_context_menu_request = [&](auto& screen_position) {
-        copy_action->set_enabled(!page_view.selected_text().is_empty());
+    page_view->on_context_menu_request = [&](auto& screen_position) {
+        copy_action->set_enabled(!page_view->selected_text().is_empty());
         context_menu->popup(screen_position);
     };
 
@@ -285,33 +281,33 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             update_actions();
             open_page(url.path());
         } else {
-            left_tab_bar.set_active_widget(&search_view);
-            search_box.set_text(start_page);
-            if (auto model = search_list_view.model()) {
+            left_tab_bar->set_active_widget(search_view);
+            search_box->set_text(start_page);
+            if (auto* model = search_list_view->model()) {
                 auto& search_model = *static_cast<GUI::FilteringProxyModel*>(model);
-                search_model.set_filter_term(search_box.text());
+                search_model.set_filter_term(search_box->text());
             }
         }
     } else {
         go_home_action->activate();
     }
 
-    auto& statusbar = widget.add<GUI::Statusbar>();
+    auto statusbar = TRY(widget->try_add<GUI::Statusbar>());
     app->on_action_enter = [&statusbar](GUI::Action const& action) {
-        statusbar.set_override_text(action.status_tip());
+        statusbar->set_override_text(action.status_tip());
     };
     app->on_action_leave = [&statusbar](GUI::Action const&) {
-        statusbar.set_override_text({});
+        statusbar->set_override_text({});
     };
 
-    page_view.on_link_hover = [&](URL const& url) {
+    page_view->on_link_hover = [&](URL const& url) {
         if (url.is_valid())
-            statusbar.set_text(url.to_string());
+            statusbar->set_text(url.to_string());
         else
-            statusbar.set_text({});
+            statusbar->set_text({});
     };
 
-    window->set_focused_widget(&left_tab_bar);
+    window->set_focused_widget(left_tab_bar);
     window->show();
 
     return app->exec();