docs: Add GtkStringFilter

docs/reference/gtk/gtk4-docs.xml

@@ -48,6 +48,7 @@
       <section>
         <xi:include href="xml/gtkfilter.xml" />
         <xi:include href="xml/gtkcustomfilter.xml" />
+        <xi:include href="xml/gtkstringfilter.xml" />
         <xi:include href="xml/gtkmultifilter.xml" />
         <xi:include href="xml/gtkexpression.xml" />
       </section>

docs/reference/gtk/gtk4-sections.txt

@@ -7781,3 +7781,21 @@ GTK_TYPE_EXPRESSION
 <SUBSECTION Private>
 gtk_expression_get_type
 </SECTION>
+
+<SECTION>
+<FILE>gtkstringfilter</FILE>
+GtkStringFilter
+GtkStringFilterMatchMode
+gtk_string_filter_new
+gtk_string_filter_get_search
+gtk_string_filter_set_search
+gtk_string_filter_get_expression
+gtk_string_filter_set_expression
+gtk_string_filter_get_ignore_case
+gtk_string_filter_set_ignore_case
+gtk_string_filter_get_match_mode
+gtk_string_filter_set_match_mode
+
+<SUBSECTION Private>
+gtk_string_filter_get_type
+</SECTION>

docs/reference/gtk/gtk4.types.in

@@ -194,6 +194,7 @@ gtk_stack_page_get_type
 gtk_stack_sidebar_get_type
 gtk_stack_switcher_get_type
 gtk_statusbar_get_type
+gtk_string_filter_get_type
 gtk_string_sorter_get_type
 gtk_switch_get_type
 gtk_level_bar_get_type

gtk/gtkstringfilter.c

@@ -24,6 +24,19 @@
 #include "gtkintl.h"
 #include "gtktypebuiltins.h"
 
+/**
+ * SECTION:gtkstringfilter
+ * @Title: GtkStringFilter
+ * @Short_description: Filtering by string
+ *
+ * GtkStringFilter determines whether to include items by looking
+ * at strings and comparing them to a fixed search term. The strings
+ * are obtained from the items by evaluating a #GtkExpression.
+ *
+ * GtkStringFilter has several different modes of comparison - it
+ * can match the whole string, just a prefix, or any substring.
+ */
+
 struct _GtkStringFilter
 {
   GtkFilter parent_instance;