list: move instructions into recycler

Move the instructions enum (which is only concerned with recyclerview
semantics) into the list.recycler module instead of list.

app/src/main/java/org/oxycblt/auxio/detail/AlbumDetailFragment.kt

@@ -31,7 +31,7 @@ import org.oxycblt.auxio.databinding.FragmentDetailBinding
 import org.oxycblt.auxio.detail.recycler.AlbumDetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
@@ -260,7 +260,7 @@ class AlbumDetailFragment :
     }
 
     private fun updateList(items: List<Item>) {
-        detailAdapter.submitList(items, UpdateInstructions.DIFF)
+        detailAdapter.submitList(items, BasicInstructions.DIFF)
     }
 
     private fun updateSelection(selected: List<Music>) {

app/src/main/java/org/oxycblt/auxio/detail/ArtistDetailFragment.kt

@@ -31,7 +31,7 @@ import org.oxycblt.auxio.detail.recycler.ArtistDetailAdapter
 import org.oxycblt.auxio.detail.recycler.DetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
@@ -236,7 +236,7 @@ class ArtistDetailFragment :
     }
 
     private fun updateList(items: List<Item>) {
-        detailAdapter.submitList(items, UpdateInstructions.DIFF)
+        detailAdapter.submitList(items, BasicInstructions.DIFF)
     }
 
     private fun updateSelection(selected: List<Music>) {

app/src/main/java/org/oxycblt/auxio/detail/GenreDetailFragment.kt

@@ -31,7 +31,7 @@ import org.oxycblt.auxio.detail.recycler.DetailAdapter
 import org.oxycblt.auxio.detail.recycler.GenreDetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Genre
@@ -219,7 +219,7 @@ class GenreDetailFragment :
     }
 
     private fun updateList(items: List<Item>) {
-        detailAdapter.submitList(items, UpdateInstructions.DIFF)
+        detailAdapter.submitList(items, BasicInstructions.DIFF)
     }
 
     private fun updateSelection(selected: List<Music>) {

app/src/main/java/org/oxycblt/auxio/detail/recycler/DetailAdapter.kt

@@ -28,7 +28,7 @@ import org.oxycblt.auxio.detail.SortHeader
 import org.oxycblt.auxio.list.Header
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.SelectableListListener
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.list.recycler.*
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.util.context
@@ -45,7 +45,7 @@ abstract class DetailAdapter(
     private val listener: Listener<*>,
     diffCallback: DiffUtil.ItemCallback<Item>
 ) :
-    SelectionIndicatorAdapter<Item, UpdateInstructions, RecyclerView.ViewHolder>(
+    SelectionIndicatorAdapter<Item, BasicInstructions, RecyclerView.ViewHolder>(
         ListDiffer.Async(diffCallback)),
     AuxioRecyclerView.SpanSizeLookup {
 

app/src/main/java/org/oxycblt/auxio/home/HomeViewModel.kt

@@ -22,7 +22,7 @@ import androidx.lifecycle.AndroidViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.home.tabs.Tab
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.library.Library
@@ -46,7 +46,7 @@ class HomeViewModel(application: Application) :
     val songsList: StateFlow<List<Song>>
         get() = _songsList
     /** Specifies how to update [songsList] when it changes. */
-    var songsListInstructions: UpdateInstructions? = null
+    var songsListInstructions: BasicInstructions? = null
         private set
 
     private val _albumsLists = MutableStateFlow(listOf<Album>())
@@ -54,7 +54,7 @@ class HomeViewModel(application: Application) :
     val albumsList: StateFlow<List<Album>>
         get() = _albumsLists
     /** Specifies how to update [albumsList] when it changes. */
-    var albumsListInstructions: UpdateInstructions? = null
+    var albumsListInstructions: BasicInstructions? = null
         private set
 
     private val _artistsList = MutableStateFlow(listOf<Artist>())
@@ -66,7 +66,7 @@ class HomeViewModel(application: Application) :
     val artistsList: MutableStateFlow<List<Artist>>
         get() = _artistsList
     /** Specifies how to update [artistsList] when it changes. */
-    var artistsListInstructions: UpdateInstructions? = null
+    var artistsListInstructions: BasicInstructions? = null
         private set
 
     private val _genresList = MutableStateFlow(listOf<Genre>())
@@ -74,7 +74,7 @@ class HomeViewModel(application: Application) :
     val genresList: StateFlow<List<Genre>>
         get() = _genresList
     /** Specifies how to update [genresList] when it changes. */
-    var genresListInstructions: UpdateInstructions? = null
+    var genresListInstructions: BasicInstructions? = null
         private set
 
     /** The [MusicMode] to use when playing a [Song] from the UI. */
@@ -120,11 +120,11 @@ class HomeViewModel(application: Application) :
             logD("Library changed, refreshing library")
             // Get the each list of items in the library to use as our list data.
             // Applying the preferred sorting to them.
-            songsListInstructions = UpdateInstructions.DIFF
+            songsListInstructions = BasicInstructions.DIFF
             _songsList.value = musicSettings.songSort.songs(library.songs)
-            albumsListInstructions = UpdateInstructions.DIFF
+            albumsListInstructions = BasicInstructions.DIFF
             _albumsLists.value = musicSettings.albumSort.albums(library.albums)
-            artistsListInstructions = UpdateInstructions.DIFF
+            artistsListInstructions = BasicInstructions.DIFF
             _artistsList.value =
                 musicSettings.artistSort.artists(
                     if (homeSettings.shouldHideCollaborators) {
@@ -133,7 +133,7 @@ class HomeViewModel(application: Application) :
                     } else {
                         library.artists
                     })
-            genresListInstructions = UpdateInstructions.DIFF
+            genresListInstructions = BasicInstructions.DIFF
             _genresList.value = musicSettings.genreSort.genres(library.genres)
         }
     }
@@ -173,48 +173,48 @@ class HomeViewModel(application: Application) :
         when (_currentTabMode.value) {
             MusicMode.SONGS -> {
                 musicSettings.songSort = sort
-                songsListInstructions = UpdateInstructions.REPLACE
+                songsListInstructions = BasicInstructions.REPLACE
                 _songsList.value = sort.songs(_songsList.value)
             }
             MusicMode.ALBUMS -> {
                 musicSettings.albumSort = sort
-                albumsListInstructions = UpdateInstructions.REPLACE
+                albumsListInstructions = BasicInstructions.REPLACE
                 _albumsLists.value = sort.albums(_albumsLists.value)
             }
             MusicMode.ARTISTS -> {
                 musicSettings.artistSort = sort
-                artistsListInstructions = UpdateInstructions.REPLACE
+                artistsListInstructions = BasicInstructions.REPLACE
                 _artistsList.value = sort.artists(_artistsList.value)
             }
             MusicMode.GENRES -> {
                 musicSettings.genreSort = sort
-                genresListInstructions = UpdateInstructions.REPLACE
+                genresListInstructions = BasicInstructions.REPLACE
                 _genresList.value = sort.genres(_genresList.value)
             }
         }
     }
 
-    /** Signal that the specified [UpdateInstructions] in [songsListInstructions] were performed. */
+    /** Signal that the specified [BasicInstructions] in [songsListInstructions] were performed. */
     fun finishSongsListInstructions() {
         songsListInstructions = null
     }
 
     /**
-     * Signal that the specified [UpdateInstructions] in [albumsListInstructions] were performed.
+     * Signal that the specified [BasicInstructions] in [albumsListInstructions] were performed.
      */
     fun finishAlbumsListInstructions() {
         albumsListInstructions = null
     }
 
     /**
-     * Signal that the specified [UpdateInstructions] in [artistsListInstructions] were performed.
+     * Signal that the specified [BasicInstructions] in [artistsListInstructions] were performed.
      */
     fun finishArtistsListInstructions() {
         artistsListInstructions = null
     }
 
     /**
-     * Signal that the specified [UpdateInstructions] in [genresListInstructions] were performed.
+     * Signal that the specified [BasicInstructions] in [genresListInstructions] were performed.
      */
     fun finishGenresListInstructions() {
         genresListInstructions = null

app/src/main/java/org/oxycblt/auxio/home/list/AlbumListFragment.kt

@@ -33,6 +33,7 @@ import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.recycler.AlbumViewHolder
 import org.oxycblt.auxio.list.recycler.ListDiffer
 import org.oxycblt.auxio.list.recycler.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.library.Sort
 import org.oxycblt.auxio.playback.formatDurationMs
@@ -131,7 +132,7 @@ class AlbumListFragment :
     }
 
     private fun updateList(albums: List<Album>) {
-        albumAdapter.submitList(albums, homeModel.albumsListInstructions ?: UpdateInstructions.DIFF)
+        albumAdapter.submitList(albums, homeModel.albumsListInstructions ?: BasicInstructions.DIFF)
         homeModel.finishAlbumsListInstructions()
     }
 
@@ -149,7 +150,7 @@ class AlbumListFragment :
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     private class AlbumAdapter(private val listener: SelectableListListener<Album>) :
-        SelectionIndicatorAdapter<Album, UpdateInstructions, AlbumViewHolder>(
+        SelectionIndicatorAdapter<Album, BasicInstructions, AlbumViewHolder>(
             ListDiffer.Async(AlbumViewHolder.DIFF_CALLBACK)) {
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =

app/src/main/java/org/oxycblt/auxio/home/list/ArtistListFragment.kt

@@ -31,6 +31,7 @@ import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.recycler.ArtistViewHolder
 import org.oxycblt.auxio.list.recycler.ListDiffer
 import org.oxycblt.auxio.list.recycler.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
@@ -110,7 +111,7 @@ class ArtistListFragment :
 
     private fun updateList(artists: List<Artist>) {
         artistAdapter.submitList(
-            artists, homeModel.artistsListInstructions ?: UpdateInstructions.DIFF)
+            artists, homeModel.artistsListInstructions ?: BasicInstructions.DIFF)
         homeModel.finishArtistsListInstructions()
     }
 
@@ -128,7 +129,7 @@ class ArtistListFragment :
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     private class ArtistAdapter(private val listener: SelectableListListener<Artist>) :
-        SelectionIndicatorAdapter<Artist, UpdateInstructions, ArtistViewHolder>(
+        SelectionIndicatorAdapter<Artist, BasicInstructions, ArtistViewHolder>(
             ListDiffer.Async(ArtistViewHolder.DIFF_CALLBACK)) {
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =

app/src/main/java/org/oxycblt/auxio/home/list/GenreListFragment.kt

@@ -31,6 +31,7 @@ import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.recycler.GenreViewHolder
 import org.oxycblt.auxio.list.recycler.ListDiffer
 import org.oxycblt.auxio.list.recycler.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
@@ -109,7 +110,7 @@ class GenreListFragment :
 
     private fun updateList(artists: List<Genre>) {
         genreAdapter.submitList(
-            artists, homeModel.genresListInstructions ?: UpdateInstructions.DIFF)
+            artists, homeModel.genresListInstructions ?: BasicInstructions.DIFF)
         homeModel.finishGenresListInstructions()
     }
 
@@ -127,7 +128,7 @@ class GenreListFragment :
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     private class GenreAdapter(private val listener: SelectableListListener<Genre>) :
-        SelectionIndicatorAdapter<Genre, UpdateInstructions, GenreViewHolder>(
+        SelectionIndicatorAdapter<Genre, BasicInstructions, GenreViewHolder>(
             ListDiffer.Async(GenreViewHolder.DIFF_CALLBACK)) {
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
             GenreViewHolder.from(parent)

app/src/main/java/org/oxycblt/auxio/home/list/SongListFragment.kt

@@ -33,6 +33,7 @@ import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.recycler.ListDiffer
 import org.oxycblt.auxio.list.recycler.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.SongViewHolder
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
@@ -138,7 +139,7 @@ class SongListFragment :
     }
 
     private fun updateList(songs: List<Song>) {
-        songAdapter.submitList(songs, homeModel.songsListInstructions ?: UpdateInstructions.DIFF)
+        songAdapter.submitList(songs, homeModel.songsListInstructions ?: BasicInstructions.DIFF)
         homeModel.finishSongsListInstructions()
     }
 
@@ -160,7 +161,7 @@ class SongListFragment :
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     private class SongAdapter(private val listener: SelectableListListener<Song>) :
-        SelectionIndicatorAdapter<Song, UpdateInstructions, SongViewHolder>(
+        SelectionIndicatorAdapter<Song, BasicInstructions, SongViewHolder>(
             ListDiffer.Async(SongViewHolder.DIFF_CALLBACK)) {
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =

app/src/main/java/org/oxycblt/auxio/list/UpdateInstructions.kt

@@ -1,36 +0,0 @@
-/*
- * Copyright (c) 2023 Auxio Project
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.auxio.list
-
-/**
- * Represents the specific way to update a list of items.
- * @author Alexander Capehart (OxygenCobalt)
- */
-enum class UpdateInstructions {
-    /**
-     * (A)synchronously diff the list. This should be used for small diffs with little item
-     * movement.
-     */
-    DIFF,
-
-    /**
-     * Synchronously remove the current list and replace it with a new one. This should be used for
-     * large diffs with that would cause erratic scroll behavior or in-efficiency.
-     */
-    REPLACE
-}

app/src/main/java/org/oxycblt/auxio/list/recycler/ListDiffer.kt

@@ -24,7 +24,6 @@ import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListUpdateCallback
 import androidx.recyclerview.widget.RecyclerView
 import java.lang.reflect.Field
-import org.oxycblt.auxio.list.UpdateInstructions
 import org.oxycblt.auxio.util.lazyReflectedField
 import org.oxycblt.auxio.util.requireIs
 
@@ -39,7 +38,7 @@ interface ListDiffer<T, I> {
     /**
      * Dynamically determine how to update the list based on the given instructions.
      * @param newList The new list of [T] items to show.
-     * @param instructions The [UpdateInstructions] specifying how to update the list.
+     * @param instructions The [BasicInstructions] specifying how to update the list.
      * @param onDone Called when the update process is completed.
      */
     fun submitList(newList: List<T>, instructions: I, onDone: () -> Unit)
@@ -63,8 +62,8 @@ interface ListDiffer<T, I> {
      * internal list.
      */
     class Async<T>(private val diffCallback: DiffUtil.ItemCallback<T>) :
-        Factory<T, UpdateInstructions>() {
+        Factory<T, BasicInstructions>() {
-        override fun new(adapter: RecyclerView.Adapter<*>): ListDiffer<T, UpdateInstructions> =
+        override fun new(adapter: RecyclerView.Adapter<*>): ListDiffer<T, BasicInstructions> =
             RealAsyncListDiffer(AdapterListUpdateCallback(adapter), diffCallback)
     }
 
@@ -75,21 +74,39 @@ interface ListDiffer<T, I> {
      * internal list.
      */
     class Blocking<T>(private val diffCallback: DiffUtil.ItemCallback<T>) :
-        Factory<T, UpdateInstructions>() {
+        Factory<T, BasicInstructions>() {
-        override fun new(adapter: RecyclerView.Adapter<*>): ListDiffer<T, UpdateInstructions> =
+        override fun new(adapter: RecyclerView.Adapter<*>): ListDiffer<T, BasicInstructions> =
             RealBlockingListDiffer(AdapterListUpdateCallback(adapter), diffCallback)
     }
 }
 
-private abstract class RealListDiffer<T>() : ListDiffer<T, UpdateInstructions> {
+/**
+ * Represents the specific way to update a list of items.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+enum class BasicInstructions {
+    /**
+     * (A)synchronously diff the list. This should be used for small diffs with little item
+     * movement.
+     */
+    DIFF,
+
+    /**
+     * Synchronously remove the current list and replace it with a new one. This should be used for
+     * large diffs with that would cause erratic scroll behavior or in-efficiency.
+     */
+    REPLACE
+}
+
+private abstract class RealListDiffer<T>() : ListDiffer<T, BasicInstructions> {
     override fun submitList(
         newList: List<T>,
-        instructions: UpdateInstructions,
+        instructions: BasicInstructions,
         onDone: () -> Unit
     ) {
         when (instructions) {
-            UpdateInstructions.DIFF -> diffList(newList, onDone)
+            BasicInstructions.DIFF -> diffList(newList, onDone)
-            UpdateInstructions.REPLACE -> replaceList(newList, onDone)
+            BasicInstructions.REPLACE -> replaceList(newList, onDone)
         }
     }
 

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueAdapter.kt

@@ -27,7 +27,7 @@ import com.google.android.material.shape.MaterialShapeDrawable
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.ItemQueueSongBinding
 import org.oxycblt.auxio.list.EditableListListener
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.list.recycler.DiffAdapter
 import org.oxycblt.auxio.list.recycler.ListDiffer
 import org.oxycblt.auxio.list.recycler.PlayingIndicatorAdapter
@@ -41,7 +41,7 @@ import org.oxycblt.auxio.util.*
  * @author Alexander Capehart (OxygenCobalt)
  */
 class QueueAdapter(private val listener: EditableListListener<Song>) :
-    DiffAdapter<Song, UpdateInstructions, QueueSongViewHolder>(
+    DiffAdapter<Song, BasicInstructions, QueueSongViewHolder>(
         ListDiffer.Blocking(QueueSongViewHolder.DIFF_CALLBACK)) {
     // Since PlayingIndicator adapter relies on an item value, we cannot use it for this
     // adapter, as one item can appear at several points in the UI. Use a similar implementation

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueFragment.kt

@@ -27,7 +27,7 @@ import androidx.recyclerview.widget.RecyclerView
 import kotlin.math.min
 import org.oxycblt.auxio.databinding.FragmentQueueBinding
 import org.oxycblt.auxio.list.EditableListListener
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
@@ -101,7 +101,7 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), EditableListL
 
         // Replace or diff the queue depending on the type of change it is.
         val instructions = queueModel.instructions
-        queueAdapter.submitList(queue, instructions?.update ?: UpdateInstructions.DIFF)
+        queueAdapter.submitList(queue, instructions?.update ?: BasicInstructions.DIFF)
         // Update position in list (and thus past/future items)
         queueAdapter.setPosition(index, isPlaying)
 

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueViewModel.kt

@@ -20,7 +20,7 @@ package org.oxycblt.auxio.playback.queue
 import androidx.lifecycle.ViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
@@ -57,7 +57,7 @@ class QueueViewModel : ViewModel(), PlaybackStateManager.Listener {
 
     override fun onQueueChanged(queue: Queue, change: Queue.ChangeResult) {
         // Queue changed trivially due to item mo -> Diff queue, stay at current index.
-        instructions = Instructions(UpdateInstructions.DIFF, null)
+        instructions = Instructions(BasicInstructions.DIFF, null)
         _queue.value = queue.resolve()
         if (change != Queue.ChangeResult.MAPPING) {
             // Index changed, make sure it remains updated without actually scrolling to it.
@@ -67,14 +67,14 @@ class QueueViewModel : ViewModel(), PlaybackStateManager.Listener {
 
     override fun onQueueReordered(queue: Queue) {
         // Queue changed completely -> Replace queue, update index
-        instructions = Instructions(UpdateInstructions.REPLACE, queue.index)
+        instructions = Instructions(BasicInstructions.REPLACE, queue.index)
         _queue.value = queue.resolve()
         _index.value = queue.index
     }
 
     override fun onNewPlayback(queue: Queue, parent: MusicParent?) {
         // Entirely new queue -> Replace queue, update index
-        instructions = Instructions(UpdateInstructions.REPLACE, queue.index)
+        instructions = Instructions(BasicInstructions.REPLACE, queue.index)
         _queue.value = queue.resolve()
         _index.value = queue.index
     }
@@ -124,5 +124,5 @@ class QueueViewModel : ViewModel(), PlaybackStateManager.Listener {
         instructions = null
     }
 
-    class Instructions(val update: UpdateInstructions?, val scrollTo: Int?)
+    class Instructions(val update: BasicInstructions?, val scrollTo: Int?)
 }

app/src/main/java/org/oxycblt/auxio/search/SearchAdapter.kt

@@ -29,7 +29,7 @@ import org.oxycblt.auxio.music.*
  * @author Alexander Capehart (OxygenCobalt)
  */
 class SearchAdapter(private val listener: SelectableListListener<Music>) :
-    SelectionIndicatorAdapter<Item, UpdateInstructions, RecyclerView.ViewHolder>(
+    SelectionIndicatorAdapter<Item, BasicInstructions, RecyclerView.ViewHolder>(
         ListDiffer.Async(DIFF_CALLBACK)),
     AuxioRecyclerView.SpanSizeLookup {
 

app/src/main/java/org/oxycblt/auxio/search/SearchFragment.kt

@@ -31,7 +31,7 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentSearchBinding
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
-import org.oxycblt.auxio.list.UpdateInstructions
+import org.oxycblt.auxio.list.recycler.BasicInstructions
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Genre
@@ -154,7 +154,7 @@ class SearchFragment : ListFragment<Music, FragmentSearchBinding>() {
         // Don't show the RecyclerView (and it's stray overscroll effects) when there
         // are no results.
         binding.searchRecycler.isInvisible = results.isEmpty()
-        searchAdapter.submitList(results.toMutableList(), UpdateInstructions.DIFF) {
+        searchAdapter.submitList(results.toMutableList(), BasicInstructions.DIFF) {
             // I would make it so that the position is only scrolled back to the top when
             // the query actually changes instead of once every re-creation event, but sadly
             // that doesn't seem possible.

app/src/main/res/layout/item_header.xml

@@ -13,4 +13,10 @@
         android:layout_height="wrap_content"
         tools:text="Songs" />
 
+    <com.google.android.material.divider.MaterialDivider
+        android:id="@+id/header_divider"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent" />
+
 </LinearLayout>

app/src/main/res/layout/item_sort_header.xml

@@ -12,6 +12,7 @@
         android:layout_width="0dp"
         android:layout_height="wrap_content"
         android:layout_marginEnd="@dimen/spacing_mid_medium"
+        app:layout_constraintBottom_toTopOf="@id/header_divider"
         app:layout_constraintEnd_toStartOf="@+id/header_button"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
@@ -25,7 +26,14 @@
         android:layout_marginEnd="@dimen/spacing_mid_medium"
         android:contentDescription="@string/lbl_sort"
         app:icon="@drawable/ic_sort_24"
+        app:layout_constraintBottom_toTopOf="@id/header_divider"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <com.google.android.material.divider.MaterialDivider
+        android:id="@+id/header_divider"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>