From 2b35ce3c777c82e1cefc015f8209e9de9af435f3 Mon Sep 17 00:00:00 2001
From: Christophe Beyls <software@digitalia.be>
Date: Sun, 6 Feb 2022 17:37:49 +0100
Subject: [PATCH] simplify the implementation of createSimpleItemCallback()

---
 .../java/be/digitalia/fosdem/adapters/BookmarksAdapter.kt   | 5 ++---
 .../main/java/be/digitalia/fosdem/adapters/EventsAdapter.kt | 5 ++---
 .../java/be/digitalia/fosdem/adapters/SimpleItemCallback.kt | 6 +++---
 .../be/digitalia/fosdem/fragments/PersonsListFragment.kt    | 5 ++---
 4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/app/src/main/java/be/digitalia/fosdem/adapters/BookmarksAdapter.kt b/app/src/main/java/be/digitalia/fosdem/adapters/BookmarksAdapter.kt
index e520dec..318413e 100644
--- a/app/src/main/java/be/digitalia/fosdem/adapters/BookmarksAdapter.kt
+++ b/app/src/main/java/be/digitalia/fosdem/adapters/BookmarksAdapter.kt
@@ -15,6 +15,7 @@ import androidx.collection.SimpleArrayMap
 import androidx.core.content.ContextCompat
 import androidx.core.text.set
 import androidx.core.view.isGone
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
 import androidx.recyclerview.widget.RecyclerView.AdapterDataObserver
@@ -243,9 +244,7 @@ class BookmarksAdapter(context: Context, private val multiChoiceHelper: MultiCho
     }
 
     companion object {
-        private val DIFF_CALLBACK = createSimpleItemCallback<Event> { oldItem, newItem ->
-            oldItem.id == newItem.id
-        }
+        private val DIFF_CALLBACK: DiffUtil.ItemCallback<Event> = createSimpleItemCallback { it.id }
         private val DETAILS_PAYLOAD = Any()
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/digitalia/fosdem/adapters/EventsAdapter.kt b/app/src/main/java/be/digitalia/fosdem/adapters/EventsAdapter.kt
index 3596ec2..400218e 100644
--- a/app/src/main/java/be/digitalia/fosdem/adapters/EventsAdapter.kt
+++ b/app/src/main/java/be/digitalia/fosdem/adapters/EventsAdapter.kt
@@ -13,6 +13,7 @@ import androidx.core.content.ContextCompat
 import androidx.core.text.set
 import androidx.core.view.isGone
 import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import be.digitalia.fosdem.R
 import be.digitalia.fosdem.activities.EventDetailsActivity
@@ -150,9 +151,7 @@ class EventsAdapter constructor(context: Context, private val showDay: Boolean =
     }
 
     companion object {
-        val DIFF_CALLBACK = createSimpleItemCallback<StatusEvent> { oldItem, newItem ->
-            oldItem.event.id == newItem.event.id
-        }
+        val DIFF_CALLBACK: DiffUtil.ItemCallback<StatusEvent> = createSimpleItemCallback{ it.event.id }
         private val DETAILS_PAYLOAD = Any()
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/digitalia/fosdem/adapters/SimpleItemCallback.kt b/app/src/main/java/be/digitalia/fosdem/adapters/SimpleItemCallback.kt
index 12129a6..ccdd4f8 100644
--- a/app/src/main/java/be/digitalia/fosdem/adapters/SimpleItemCallback.kt
+++ b/app/src/main/java/be/digitalia/fosdem/adapters/SimpleItemCallback.kt
@@ -4,13 +4,13 @@ import android.annotation.SuppressLint
 import androidx.recyclerview.widget.DiffUtil
 
 /**
- * Creates a DiffUtil.ItemCallback instance using the provided lambda to determine
+ * Creates a DiffUtil.ItemCallback instance using the provided key selector to determine
  * if items are the same and using equals() to determine if item contents are the same.
  */
-inline fun <T : Any> createSimpleItemCallback(crossinline areItemsTheSame: (oldItem: T, newItem: T) -> Boolean): DiffUtil.ItemCallback<T> {
+inline fun <T : Any, K: Any?> createSimpleItemCallback(crossinline keySelector: (T) -> K): DiffUtil.ItemCallback<T> {
     return object : DiffUtil.ItemCallback<T>() {
         override fun areItemsTheSame(oldItem: T, newItem: T): Boolean {
-            return areItemsTheSame(oldItem, newItem)
+            return keySelector(oldItem) == keySelector(newItem)
         }
 
         @SuppressLint("DiffUtilEquals")
diff --git a/app/src/main/java/be/digitalia/fosdem/fragments/PersonsListFragment.kt b/app/src/main/java/be/digitalia/fosdem/fragments/PersonsListFragment.kt
index 1c7d2ae..0f15e69 100644
--- a/app/src/main/java/be/digitalia/fosdem/fragments/PersonsListFragment.kt
+++ b/app/src/main/java/be/digitalia/fosdem/fragments/PersonsListFragment.kt
@@ -11,6 +11,7 @@ import androidx.fragment.app.viewModels
 import androidx.lifecycle.lifecycleScope
 import androidx.paging.LoadState
 import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -73,9 +74,7 @@ class PersonsListFragment : Fragment(R.layout.recyclerview_fastscroll) {
         }
 
         companion object {
-            private val DIFF_CALLBACK = createSimpleItemCallback<Person> { oldItem, newItem ->
-                oldItem.id == newItem.id
-            }
+            private val DIFF_CALLBACK: DiffUtil.ItemCallback<Person> = createSimpleItemCallback { it.id }
         }
     }