frontend-utils: Add TableExt trait

This moves the logic previously found in BookmarkWriter's `with_underlying_table`
into a common trait to be reused by other writers.

desktop/src/preferences/write.rs

@@ -3,8 +3,9 @@ use crate::preferences::storage::StorageBackend;
 use crate::preferences::SavedGlobalPreferences;
 use ruffle_frontend_utils::bookmarks::{Bookmark, Bookmarks};
 use ruffle_frontend_utils::parse::DocumentHolder;
+use ruffle_frontend_utils::write::TableExt;
 use ruffle_render_wgpu::clap::{GraphicsBackend, PowerPreference};
-use toml_edit::{array, value, ArrayOfTables, DocumentMut, Table};
+use toml_edit::{value, ArrayOfTables, Table};
 use unic_langid::LanguageIdentifier;
 
 pub struct PreferencesWriter<'a>(&'a mut DocumentHolder<SavedGlobalPreferences>);
@@ -83,22 +84,8 @@ impl<'a> BookmarksWriter<'a> {
     }
 
     fn with_underlying_table(&mut self, fun: impl FnOnce(&mut Bookmarks, &mut ArrayOfTables)) {
-        fn find_table(toml_document: &mut DocumentMut) -> &mut ArrayOfTables {
-            if toml_document.contains_array_of_tables("bookmark") {
-                return toml_document["bookmark"]
-                    .as_array_of_tables_mut()
-                    .expect("type was just verified");
-            }
-
-            tracing::warn!("missing or invalid bookmark array, recreating..");
-            toml_document.insert("bookmark", array());
-            toml_document["bookmark"]
-                .as_array_of_tables_mut()
-                .expect("type was just created")
-        }
-
         self.0.edit(|values, toml_document| {
-            let table = find_table(toml_document);
+            let table = toml_document.get_or_create_array_of_tables("bookmark");
             fun(values, table)
         })
     }

frontend-utils/Cargo.toml

@@ -13,3 +13,4 @@ workspace = true
 [dependencies]
 toml_edit = { version = "0.22.9", features = ["parse"] }
 url = { workspace = true }
+tracing = { workspace = true }

frontend-utils/src/lib.rs

@@ -1,2 +1,3 @@
 pub mod bookmarks;
 pub mod parse;
+pub mod write;

frontend-utils/src/write.rs

@@ -0,0 +1,22 @@
+use toml_edit::{array, ArrayOfTables, Table};
+
+pub trait TableExt {
+    /// Gets an existing array of tables, or creates a new one if it does not exist or type is different.
+    fn get_or_create_array_of_tables(&mut self, key: &str) -> &mut ArrayOfTables;
+}
+
+impl TableExt for Table {
+    fn get_or_create_array_of_tables(&mut self, key: &str) -> &mut ArrayOfTables {
+        if self.contains_array_of_tables(key) {
+            return self[key]
+                .as_array_of_tables_mut()
+                .expect("type was just verified");
+        }
+
+        tracing::warn!("missing or invalid '{key}' array, recreating..");
+        self.insert(key, array());
+        self[key]
+            .as_array_of_tables_mut()
+            .expect("type was just created")
+    }
+}