[tepl] LanguageChooserWidget: add Plain Text as first item (NULL language)

[Sébastien Wilmet <swilmet src gnome org>]

commit 76e9ae0cc5289ebe741ddb72dbda4690d4015242
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Nov 2 18:44:30 2020 +0100

    LanguageChooserWidget: add Plain Text as first item (NULL language)

 tepl/tepl-language-chooser-widget.c  | 115 ++++++++++++++++++++++++-----------
 tests/test-language-chooser-widget.c |   9 ++-
 2 files changed, 89 insertions(+), 35 deletions(-)
---
diff --git a/tepl/tepl-language-chooser-widget.c b/tepl/tepl-language-chooser-widget.c
index dbc89f7..8c64de5 100644
--- a/tepl/tepl-language-chooser-widget.c
+++ b/tepl/tepl-language-chooser-widget.c
@@ -31,6 +31,17 @@ G_DEFINE_TYPE_WITH_CODE (TeplLanguageChooserWidget,
                         G_IMPLEMENT_INTERFACE (TEPL_TYPE_LANGUAGE_CHOOSER,
                                                tepl_language_chooser_interface_init))
 
+static const gchar *
+get_language_name (GtkSourceLanguage *language)
+{
+       if (language == NULL)
+       {
+               return _("Plain Text");
+       }
+
+       return gtk_source_language_get_name (language);
+}
+
 static void
 list_box_row_set_language (GtkListBoxRow     *list_box_row,
                           GtkSourceLanguage *language)
@@ -83,6 +94,43 @@ tepl_language_chooser_interface_init (gpointer g_iface,
        interface->select_language = tepl_language_chooser_widget_select_language;
 }
 
+static GtkListBoxRow *
+create_list_box_row (const gchar *label_text)
+{
+       GtkWidget *label;
+       GtkListBoxRow *list_box_row;
+
+       label = gtk_label_new (label_text);
+       gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+
+       list_box_row = GTK_LIST_BOX_ROW (gtk_list_box_row_new ());
+       gtk_container_add (GTK_CONTAINER (list_box_row), label);
+
+       return list_box_row;
+}
+
+static void
+append_plain_text_item_to_list_box (TeplLanguageChooserWidget *chooser_widget)
+{
+       /* NULL GtkSourceLanguage. */
+       gtk_container_add (GTK_CONTAINER (chooser_widget->priv->list_box),
+                          GTK_WIDGET (create_list_box_row (get_language_name (NULL))));
+}
+
+static void
+append_language_to_list_box (TeplLanguageChooserWidget *chooser_widget,
+                            GtkSourceLanguage         *language)
+{
+       GtkListBoxRow *list_box_row;
+
+       g_return_if_fail (GTK_SOURCE_IS_LANGUAGE (language));
+
+       list_box_row = create_list_box_row (gtk_source_language_get_name (language));
+       list_box_row_set_language (list_box_row, language);
+       gtk_container_add (GTK_CONTAINER (chooser_widget->priv->list_box),
+                          GTK_WIDGET (list_box_row));
+}
+
 static void
 populate_list_box (TeplLanguageChooserWidget *chooser_widget)
 {
@@ -90,6 +138,9 @@ populate_list_box (TeplLanguageChooserWidget *chooser_widget)
        const gchar * const *language_ids;
        gint i;
 
+       // First item
+       append_plain_text_item_to_list_box (chooser_widget);
+
        language_manager = gtk_source_language_manager_get_default ();
        language_ids = gtk_source_language_manager_get_language_ids (language_manager);
 
@@ -102,22 +153,12 @@ populate_list_box (TeplLanguageChooserWidget *chooser_widget)
        {
                const gchar *cur_language_id = language_ids[i];
                GtkSourceLanguage *language;
-               GtkLabel *label;
-               GtkListBoxRow *list_box_row;
 
                language = gtk_source_language_manager_get_language (language_manager, cur_language_id);
-               if (gtk_source_language_get_hidden (language))
+               if (!gtk_source_language_get_hidden (language))
                {
-                       continue;
+                       append_language_to_list_box (chooser_widget, language);
                }
-
-               label = GTK_LABEL (gtk_label_new (gtk_source_language_get_name (language)));
-               gtk_label_set_xalign (label, 0.0);
-
-               list_box_row = GTK_LIST_BOX_ROW (gtk_list_box_row_new ());
-               list_box_row_set_language (list_box_row, language);
-               gtk_container_add (GTK_CONTAINER (list_box_row), GTK_WIDGET (label));
-               gtk_container_add (GTK_CONTAINER (chooser_widget->priv->list_box), GTK_WIDGET (list_box_row));
        }
 }
 
@@ -128,12 +169,12 @@ filter_cb (GtkListBoxRow *list_box_row,
        TeplLanguageChooserWidget *chooser_widget = user_data;
        const gchar *search_text;
        GtkSourceLanguage *language;
-       const gchar *language_name;
-       gchar *language_name_normalized;
-       gchar *language_name_casefolded;
+       const gchar *item_name;
+       gchar *item_name_normalized;
+       gchar *item_name_casefolded;
        gchar *search_text_normalized;
        gchar *search_text_casefolded;
-       gboolean visible;
+       gboolean visible = FALSE;
 
        search_text = gtk_entry_get_text (GTK_ENTRY (chooser_widget->priv->search_entry));
        if (search_text == NULL || search_text[0] == '\0')
@@ -142,24 +183,20 @@ filter_cb (GtkListBoxRow *list_box_row,
        }
 
        language = list_box_row_get_language (list_box_row);
-       g_return_val_if_fail (language != NULL, FALSE);
+       item_name = get_language_name (language);
+       g_return_val_if_fail (item_name != NULL, FALSE);
 
-       language_name = gtk_source_language_get_name (language);
-       g_return_val_if_fail (language_name != NULL, FALSE);
-
-       /* search_text is guaranteed to be UTF-8 (it comes from a GTK widget).
-        * language_name is not really, it can come from foreign input (*.lang
-        * file), so it's safer to check.
-        */
-       g_return_val_if_fail (g_utf8_validate (language_name, -1, NULL), FALSE);
+       /* Safer to check... (item_name can come from a *.lang file). */
+       g_return_val_if_fail (g_utf8_validate (search_text, -1, NULL), FALSE);
+       g_return_val_if_fail (g_utf8_validate (item_name, -1, NULL), FALSE);
 
-       language_name_normalized = g_utf8_normalize (language_name, -1, G_NORMALIZE_ALL);
-       language_name_casefolded = g_utf8_casefold (language_name_normalized, -1);
-       g_free (language_name_normalized);
+       item_name_normalized = g_utf8_normalize (item_name, -1, G_NORMALIZE_ALL);
+       item_name_casefolded = g_utf8_casefold (item_name_normalized, -1);
+       g_free (item_name_normalized);
 
        /* Note: we do not apply g_strstrip() on the search text, because a
         * trailing space (or - to a less extent - a leading space) can
-        * differentiate several GtkSourceLanguages, for example:
+        * differentiate several items, for example:
         * - "ERB"
         * - "ERB (HTML)"
         * - "ERB (JavaScript)"
@@ -168,9 +205,12 @@ filter_cb (GtkListBoxRow *list_box_row,
        search_text_casefolded = g_utf8_casefold (search_text_normalized, -1);
        g_free (search_text_normalized);
 
-       visible = strstr (language_name_casefolded, search_text_casefolded) != NULL;
+       if (item_name_casefolded != NULL && search_text_casefolded != NULL)
+       {
+               visible = strstr (item_name_casefolded, search_text_casefolded) != NULL;
+       }
 
-       g_free (language_name_casefolded);
+       g_free (item_name_casefolded);
        g_free (search_text_casefolded);
        return visible;
 }
@@ -190,11 +230,18 @@ list_box_row_activated_cb (GtkListBox                *list_box,
        GtkSourceLanguage *language;
 
        language = list_box_row_get_language (list_box_row);
-       g_return_if_fail (language != NULL);
 
-       g_object_ref (language);
+       if (language != NULL)
+       {
+               g_object_ref (language);
+       }
+
        g_signal_emit_by_name (chooser_widget, "language-activated", language);
-       g_object_unref (language);
+
+       if (language != NULL)
+       {
+               g_object_unref (language);
+       }
 }
 
 static void
diff --git a/tests/test-language-chooser-widget.c b/tests/test-language-chooser-widget.c
index 54301b5..2196d25 100644
--- a/tests/test-language-chooser-widget.c
+++ b/tests/test-language-chooser-widget.c
@@ -10,7 +10,14 @@ language_activated_cb (TeplLanguageChooser *chooser,
                       GtkSourceLanguage   *language,
                       gpointer             user_data)
 {
-       g_message ("Language activated: %s", gtk_source_language_get_id (language));
+       if (language != NULL)
+       {
+               g_message ("Language activated: %s", gtk_source_language_get_id (language));
+       }
+       else
+       {
+               g_message ("Plain Text activated.");
+       }
 }
 
 int