create more universal `SortableInfiniteList`

lib/widgets/sortable_infinite_list.dart

@@ -1,18 +1,25 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:lemmur/widgets/post.dart';
 import 'package:lemmy_api_client/lemmy_api_client.dart';
 
 import '../hooks/infinite_scroll.dart';
 import 'infinite_scroll.dart';
-import 'post.dart';
 import 'post_list_options.dart';
 
 /// Infinite list of posts
-class InfinitePostList extends HookWidget {
-  final Future<List<PostView>> Function(
-      int page, int batchSize, SortType sortType) fetcher;
+class SortableInfiniteList<T> extends HookWidget {
+  final Future<List<T>> Function(int page, int batchSize, SortType sortType)
+      fetcher;
+  final Widget Function(T) builder;
+  final Function onStyleChange;
 
-  InfinitePostList({@required this.fetcher}) : assert(fetcher != null);
+  SortableInfiniteList({
+    @required this.fetcher,
+    @required this.builder,
+    this.onStyleChange,
+  })  : assert(fetcher != null),
+        assert(builder != null);
 
   @override
   Widget build(BuildContext context) {
@@ -24,21 +31,37 @@ class InfinitePostList extends HookWidget {
       isc.clear();
     }
 
-    return InfiniteScroll<PostView>(
+    return InfiniteScroll<T>(
       prepend: PostListOptions(
         onChange: changeSorting,
         defaultSort: SortType.active,
+        styleButton: onStyleChange != null,
       ),
+      builder: builder,
+      padding: EdgeInsets.zero,
+      fetchMore: (page, batchSize) => fetcher(page, batchSize, sort.value),
+      controller: isc,
+      batchSize: 20,
+    );
+  }
+}
+
+class InfinitePostList extends StatelessWidget {
+  final Future<List<PostView>> Function(
+      int page, int batchSize, SortType sortType) fetcher;
+
+  InfinitePostList({this.fetcher});
+
+  Widget build(BuildContext context) {
+    return SortableInfiniteList<PostView>(
+      onStyleChange: () {},
       builder: (post) => Column(
         children: [
           Post(post),
           SizedBox(height: 20),
         ],
       ),
-      padding: EdgeInsets.zero,
-      fetchMore: (page, batchSize) => fetcher(page, batchSize, sort.value),
-      controller: isc,
-      // batchSize: 20,
+      fetcher: fetcher,
     );
   }
 }