Final backing sets

Author: spydon

lib/comparing_ordered_set.dart

@@ -16,8 +16,11 @@ class ComparingOrderedSet<E> extends OrderedSet<E>
   // If the default implementation of `Set` changes from `LinkedHashSet` to
   // something else that isn't ordered we'll have to change this to explicitly
   // be `LinkedHashSet` (or some other data structure that preserves order).
-  late SplayTreeSet<Set<E>> _backingSet;
-  late int _length;
+  late final SplayTreeSet<Set<E>> _backingSet = SplayTreeSet<LinkedHashSet<E>>(
+    _outerComparator,
+  );
+  final int Function(E e1, E e2) _comparator;
+  int _length = 0;
 
   bool _validReverseCache = true;
   Iterable<E> _reverseCache = const Iterable.empty();
@@ -45,22 +48,7 @@ class ComparingOrderedSet<E> extends OrderedSet<E>
   ComparingOrderedSet({
     int Function(E e1, E e2)? compare,
     this.strictMode = true,
-  }) {
-    final comparator = compare ?? _defaultCompare<E>();
-    _backingSet = SplayTreeSet<LinkedHashSet<E>>((Set<E> l1, Set<E> l2) {
-      if (l1.isEmpty) {
-        if (l2.isEmpty) {
-          return 0;
-        }
-        return -1;
-      }
-      if (l2.isEmpty) {
-        return 1;
-      }
-      return comparator(l1.first, l2.first);
-    });
-    _length = 0;
-  }
+  }) : _comparator = compare ?? _defaultCompare<E>();
 
   @override
   int get length => _length;
@@ -143,4 +131,17 @@ class ComparingOrderedSet<E> extends OrderedSet<E>
     _length = 0;
     onClear();
   }
+
+  int _outerComparator(Set<E> l1, Set<E> l2) {
+    if (l1.isEmpty) {
+      if (l2.isEmpty) {
+        return 0;
+      }
+      return -1;
+    }
+    if (l2.isEmpty) {
+      return 1;
+    }
+    return _comparator(l1.first, l2.first);
+  }
 }

lib/mapping_ordered_set.dart

@@ -14,21 +14,19 @@ import 'package:ordered_set/queryable_ordered_set_impl.dart';
 class MappingOrderedSet<K extends Comparable<K>, E> extends OrderedSet<E>
     with QueryableOrderedSetImpl<E> {
   final K Function(E a) _mappingFunction;
-  late SplayTreeMap<K, Set<E>> _backingSet;
-  late int _length;
+  final SplayTreeMap<K, Set<E>> _backingSet;
+  int _length = 0;
 
   bool _validReverseCache = true;
   Iterable<E> _reverseCache = const Iterable.empty();
 
   @override
   final bool strictMode;
 
-  MappingOrderedSet(this._mappingFunction, {this.strictMode = true}) {
-    _backingSet = SplayTreeMap((K k1, K k2) {
-      return k1.compareTo(k2);
-    });
-    _length = 0;
-  }
+  MappingOrderedSet(
+    this._mappingFunction, {
+    this.strictMode = true,
+  }) : _backingSet = SplayTreeMap((K k1, K k2) => k1.compareTo(k2));
 
   @override
   int get length => _length;