refactor: use list extension

lib/screens/gh_trending.dart

@@ -30,9 +30,7 @@ class GhTrendingScreen extends StatelessWidget {
       bodyBuilder: (payload, activeTab) {
         return Column(
           crossAxisAlignment: CrossAxisAlignment.stretch,
-          children: join(
-            CommonStyle.border,
-            activeTab == 0
+          children: (activeTab == 0
                   ? [
                       for (var v in payload.cast<GithubTrendingRepository>())
                         RepoItem.gh(
@@ -82,8 +80,8 @@ class GhTrendingScreen extends StatelessWidget {
                                   ),
                                 ),
                         )
-                  ],
-          ),
+                    ])
+              .withSeparator(CommonStyle.border),
         );
       },
     );

lib/utils/utils.dart

@@ -77,32 +77,17 @@ class GithubPalette {
 // final pageSize = 5;
 const kPageSize = 30;
 
-List<T> join<T>(T seperator, List<T> xs) {
+extension MyList on List {
+  List<T> withSeparator<T>(T separator) {
     final result = <T>[];
-  xs.asMap().forEach((index, x) {
-    if (x == null) return;
-
-    result.add(x);
-    if (index < xs.length - 1) {
-      result.add(seperator);
+    for (var i = 0; i < length; i++) {
+      if (i != 0) {
+        result.add(separator);
+      }
+      result.add(this[i]);
     }
-  });
-
     return result;
   }
-
-List<T> joinAll<T>(T seperator, List<List<T>> xss) {
-  final result = <T>[];
-  xss.asMap().forEach((index, x) {
-    if (x.isEmpty) return;
-
-    result.addAll(x);
-    if (index < xss.length - 1) {
-      result.add(seperator);
-    }
-  });
-
-  return result;
 }
 
 final numberFormat = NumberFormat();

lib/widgets/event_item.dart

@@ -56,7 +56,7 @@ class EventItem extends StatelessWidget {
               Expanded(
                 child: Column(
                   crossAxisAlignment: CrossAxisAlignment.start,
-                  children: join(const SizedBox(height: 6), [
+                  children: [
                     Text.rich(
                       TextSpan(
                         style: TextStyle(
@@ -81,7 +81,7 @@ class EventItem extends StatelessWidget {
                       ],
                     ),
                     if (card != null) card
-                  ]),
+                  ].withSeparator(const SizedBox(height: 6)),
                 ),
               ),
             ],
@@ -233,7 +233,7 @@ class EventItem extends StatelessWidget {
             borderRadius: const BorderRadius.all(Radius.circular(4))),
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
-          children: join(const SizedBox(height: 6), [
+          children: [
             Row(
               children: <Widget>[
                 IssueIcon(state, size: 20),
@@ -285,7 +285,7 @@ class EventItem extends StatelessWidget {
                 ]
               ],
             )
-          ]),
+          ].withSeparator(const SizedBox(height: 6)),
         ),
       ),
     );

lib/widgets/issue_item.dart

@@ -68,7 +68,7 @@ class IssueItem extends StatelessWidget {
           Expanded(
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
-              children: join(const SizedBox(height: 8), [
+              children: [
                 Text.rich(
                   TextSpan(
                     children: [
@@ -129,7 +129,7 @@ class IssueItem extends StatelessWidget {
                     ],
                   ),
                 )
-              ]),
+              ].withSeparator(const SizedBox(height: 8)),
             ),
           ),
           // Column(

lib/widgets/repo_header.dart

@@ -30,7 +30,7 @@ class RepoHeader extends StatelessWidget {
       padding: CommonStyle.padding,
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
-        children: join(const SizedBox(height: 12), [
+        children: [
           Row(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: <Widget>[
@@ -73,7 +73,7 @@ class RepoHeader extends StatelessWidget {
               ),
             ),
           if (trailings != null) ...trailings!
-        ]),
+        ].withSeparator(const SizedBox(height: 12)),
       ),
     );
   }