refactor: use Context receivers to remove this within withCol [Experimental API] (#15254)

* chore: enable context receivers (experimental)

Allows removal of usages of `this` in `withCol`/`undoableOp` calls

Context receivers allow `this` as an implicit parameter to a method
 if `this` is in scope (typically due to a `with` call)

This means that:
* methods are only usable if `Collection` is scoped
  * you can't easily call these methods outside `withCol`
* methods can effectively accept two context receivers
  * in the below, both `Card` and `Collection` are scoped to `this`

Example

```kotlin
context(Collection)
fun Card.note() = this.note(this@Collection)
```

allows the transformation

```diff
- val note = withCol { card.note(this) }
+ val note = withCol { card.note() }
```

Which is much more readable, as `this` was confusingly named

https://github.com/Kotlin/KEEP/blob/master/proposals/context-receivers.md
https://blog.rockthejvm.com/kotlin-context-receivers/

* chore: context receiver for Card.renderOutput()

Once refactoring is complete, the `context` should be moved to the
 instance method, and the extension should be removed

* chore: context receiver for Card.note()

Once refactoring is complete, the `context` should be moved to the
 instance method, and the extension should be removed

* chore: context receiver for AnswerTimer.resume()
* chore: context receiver for CardTemplateNotetype.saveToDatabase
* chore: context receiver for Sequence<CardId>.toCardCache
* chore: context receiver for BackupManager.repairCollection()
* chore: context receiver for CollectionOperations.deleteMedia
* chore: context receiver for CollectionOperations.updateValuesFromDeck
* chore: context receiver for CollectionOperations.saveModel
* modifies saveToDatabase, as this always required the context
* chore: remove completed comment in CollectionOperations
* chore: context receiver for CardsOrNotes.fromCollection
* chore: context receiver for CardService.selectedNoteIds
+ accept CardId
* chore: context receiver for CardsOrNotes.saveToCollection
* chore: context receiver for BackupManager.deleteBackups()
* chore: context receiver for CardSoundConfig.create()
* add context receiver
* inline suspend fun create
  * make the `col` usage explicit
* review request: import 'Collection'

AnkiDroid/src/main/java/com/ichi2/anki/AbstractFlashcardViewer.kt

@@ -432,7 +432,7 @@ abstract class AbstractFlashcardViewer :
         val card = editorCard!!
         withProgress {
             undoableOp {
-                updateNote(card.note(this))
+                updateNote(card.note())
             }
         }
         onCardUpdated(card)
@@ -477,7 +477,7 @@ abstract class AbstractFlashcardViewer :
         // despite that making no sense outside of Reviewer.kt
         currentCard = withCol {
             sched.card?.apply {
-                renderOutput(this@withCol)
+                renderOutput()
             }
         }
     }

AnkiDroid/src/main/java/com/ichi2/anki/BackupManager.kt

@@ -262,15 +262,15 @@ open class BackupManager {
          * Run the sqlite3 command-line-tool (if it exists) on the collection to dump to a text file
          * and reload as a new database. Recently this command line tool isn't available on many devices
          *
-         * @param col Collection
          * @return whether the repair was successful
          */
-        fun repairCollection(col: Collection): Boolean {
+        context (Collection)
-            val colPath = col.path
+        fun repairCollection(): Boolean {
+            val colPath = this@Collection.path
             val colFile = File(colPath)
             val time = TimeManager.time
             Timber.i("BackupManager - RepairCollection - Closing Collection")
-            col.close()
+            this@Collection.close()
 
             // repair file
             val execString = "sqlite3 $colPath .dump | sqlite3 $colPath.tmp"
@@ -457,9 +457,10 @@ open class BackupManager {
          *
          * @return Whether all specified backups were successfully deleted.
          */
+        context (Collection)
         @Throws(IllegalArgumentException::class)
-        fun deleteBackups(collection: Collection, backupsToDelete: List<File>): Boolean {
+        fun deleteBackups(backupsToDelete: List<File>): Boolean {
-            val allBackups = getBackups(File(collection.path))
+            val allBackups = getBackups(File(this@Collection.path))
             val invalidBackupsToDelete = backupsToDelete.toSet() - allBackups.toSet()
 
             if (invalidBackupsToDelete.isNotEmpty()) {

AnkiDroid/src/main/java/com/ichi2/anki/CardBrowser.kt

@@ -89,6 +89,7 @@ import com.ichi2.anki.widgets.DeckDropDownAdapter.SubtitleListener
 import com.ichi2.annotations.NeedsTest
 import com.ichi2.async.*
 import com.ichi2.libanki.*
+import com.ichi2.libanki.Collection
 import com.ichi2.ui.CardBrowserSearchView
 import com.ichi2.ui.FixedTextView
 import com.ichi2.utils.*
@@ -515,7 +516,7 @@ open class CardBrowser :
     }
 
     // Finish initializing the activity after the collection has been correctly loaded
-    override fun onCollectionLoaded(col: com.ichi2.libanki.Collection) {
+    override fun onCollectionLoaded(col: Collection) {
         super.onCollectionLoaded(col)
         Timber.d("onCollectionLoaded()")
         registerExternalStorageListener()
@@ -1523,7 +1524,7 @@ open class CardBrowser :
     private suspend fun editSelectedCardsTags(selectedTags: List<String>, indeterminateTags: List<String>) = withProgress {
         undoableOp {
             val selectedNotes = selectedCardIds
-                .map { cardId -> getCard(cardId).note(this) }
+                .map { cardId -> getCard(cardId).note() }
                 .distinct()
                 .onEach { note ->
                     val previousTags: List<String> = note.tags
@@ -1563,7 +1564,7 @@ open class CardBrowser :
         val card = cardBrowserCard!!
         withProgress {
             undoableOp {
-                updateNote(card.note(this))
+                updateNote(card.note())
             }
         }
         updateCardInList(card)
@@ -1573,7 +1574,7 @@ open class CardBrowser :
      * Removes cards from view. Doesn't delete them in model (database).
      * @param reorderCards Whether to rearrange the positions of checked items (DEFECT: Currently deselects all)
      */
-    private fun removeNotesView(cardsIds: Collection<Long>, reorderCards: Boolean) {
+    private fun removeNotesView(cardsIds: List<Long>, reorderCards: Boolean) {
         val idToPos = viewModel.cardIdToPositionMap
         val idToRemove = cardsIds.filter { cId -> idToPos.containsKey(cId) }
         mReloadRequired = mReloadRequired || cardsIds.contains(reviewerCardId)
@@ -1940,7 +1941,7 @@ open class CardBrowser :
         override var position: Int
 
         private val inCardMode: Boolean
-        constructor(id: Long, col: com.ichi2.libanki.Collection, position: Int, cardsOrNotes: CardsOrNotes) : super(col, id) {
+        constructor(id: Long, col: Collection, position: Int, cardsOrNotes: CardsOrNotes) : super(col, id) {
             this.position = position
             this.inCardMode = cardsOrNotes == CARDS
         }
@@ -2259,13 +2260,14 @@ suspend fun searchForCards(
 ): MutableList<CardBrowser.CardCache> {
     return withCol {
         (if (cardsOrNotes == CARDS) findCards(query, order) else findOneCardByNote(query, order)).asSequence()
-            .toCardCache(this, cardsOrNotes)
+            .toCardCache(cardsOrNotes)
             .toMutableList()
     }
 }
 
-private fun Sequence<CardId>.toCardCache(col: com.ichi2.libanki.Collection, isInCardMode: CardsOrNotes): Sequence<CardBrowser.CardCache> {
+context (Collection)
-    return this.mapIndexed { idx, cid -> CardBrowser.CardCache(cid, col, idx, isInCardMode) }
+private fun Sequence<CardId>.toCardCache(isInCardMode: CardsOrNotes): Sequence<CardBrowser.CardCache> {
+    return this.mapIndexed { idx, cid -> CardBrowser.CardCache(cid, this@Collection, idx, isInCardMode) }
 }
 
 class Previewer2Destination(val currentIndex: Int, val selectedCardIds: LongArray)

AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateEditor.kt

@@ -547,9 +547,7 @@ open class CardTemplateEditor : AnkiActivity(), DeckSelectionListener {
                                     }
                                     launchCatchingTask(resources.getString(R.string.card_template_editor_save_error)) {
                                         requireActivity().withProgress(resources.getString(R.string.saving_model)) {
-                                            withCol {
+                                            withCol { tempModel!!.saveToDatabase() }
-                                                tempModel!!.saveToDatabase(this)
-                                            }
                                         }
                                         onModelSaved()
                                     }

AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateNotetype.kt

@@ -22,6 +22,7 @@ import androidx.core.os.bundleOf
 import com.ichi2.async.saveModel
 import com.ichi2.compat.CompatHelper.Companion.compat
 import com.ichi2.compat.CompatHelper.Companion.getSerializableCompat
+import com.ichi2.libanki.Collection
 import com.ichi2.libanki.NoteTypeId
 import com.ichi2.libanki.NotetypeJson
 import com.ichi2.utils.KotlinCleanup
@@ -87,11 +88,12 @@ class CardTemplateNotetype(val notetype: NotetypeJson) {
         addTemplateChange(ChangeType.DELETE, ord)
     }
 
-    fun saveToDatabase(collection: com.ichi2.libanki.Collection) {
+    context(Collection)
+    fun saveToDatabase() {
         Timber.d("saveToDatabase() called")
         dumpChanges()
         clearTempModelFiles()
-        return saveModel(collection, notetype, adjustedTemplateChanges)
+        return saveModel(notetype, adjustedTemplateChanges)
     }
 
     /**

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -1559,7 +1559,7 @@ open class DeckPicker :
                 withCol {
                     Timber.i("RepairCollection: Closing collection")
                     close()
-                    BackupManager.repairCollection(this)
+                    BackupManager.repairCollection()
                 }
             }
             if (!result) {
@@ -1618,7 +1618,7 @@ open class DeckPicker :
         launchCatchingTask {
             // Number of deleted files
             val noOfDeletedFiles = withProgress(resources.getString(R.string.delete_media_message)) {
-                withCol { deleteMedia(this, unused) }
+                withCol { deleteMedia(unused) }
             }
             showSimpleMessageDialog(
                 title = resources.getString(R.string.delete_media_result_title),
@@ -2127,7 +2127,7 @@ open class DeckPicker :
                     Timber.d("rebuildFiltered: doInBackground - RebuildCram")
                     decks.select(did)
                     sched.rebuildDyn(decks.selected())
-                    updateValuesFromDeck(this)
+                    updateValuesFromDeck()
                 }
             }
             updateDeckList()
@@ -2142,7 +2142,7 @@ open class DeckPicker :
                 withCol {
                     Timber.d("doInBackgroundEmptyCram")
                     sched.emptyDyn(decks.selected())
-                    updateValuesFromDeck(this)
+                    updateValuesFromDeck()
                 }
             }
             updateDeckList()

AnkiDroid/src/main/java/com/ichi2/anki/Reviewer.kt

@@ -202,7 +202,7 @@ open class Reviewer :
     override fun onResume() {
         when {
             stopTimerOnAnswer && isDisplayingAnswer -> {}
-            else -> launchCatchingTask { withCol { answerTimer.resume(this) } }
+            else -> launchCatchingTask { withCol { answerTimer.resume() } }
         }
         super.onResume()
         if (typeAnswer?.autoFocusEditText() == true) {
@@ -1015,7 +1015,7 @@ open class Reviewer :
     override suspend fun updateCurrentCard() {
         val state = withCol {
             sched.currentQueueState()?.apply {
-                topCard.renderOutput(this@withCol, true)
+                topCard.renderOutput(true)
             }
         }
         state?.timeboxReached?.let { dealWithTimeBox(it) }

AnkiDroid/src/main/java/com/ichi2/anki/StudyOptionsFragment.kt

@@ -283,7 +283,7 @@ class StudyOptionsFragment : Fragment(), Toolbar.OnMenuItemClickListener {
             withCol {
                 Timber.d("doInBackground - RebuildCram")
                 sched.rebuildDyn(decks.selected())
-                updateValuesFromDeck(this)
+                updateValuesFromDeck()
             }
         }
         rebuildUi(result, true)
@@ -295,7 +295,7 @@ class StudyOptionsFragment : Fragment(), Toolbar.OnMenuItemClickListener {
             withCol {
                 Timber.d("doInBackgroundEmptyCram")
                 sched.emptyDyn(decks.selected())
-                updateValuesFromDeck(this)
+                updateValuesFromDeck()
             }
         }
         rebuildUi(result, true)
@@ -446,7 +446,7 @@ class StudyOptionsFragment : Fragment(), Toolbar.OnMenuItemClickListener {
         // Load the deck counts for the deck from Collection asynchronously
         updateValuesFromDeckJob = launchCatchingTask {
             if (CollectionManager.isOpenUnsafe()) {
-                val result = withCol { updateValuesFromDeck(this) }
+                val result = withCol { updateValuesFromDeck() }
                 rebuildUi(result, resetDecklist)
             }
         }

AnkiDroid/src/main/java/com/ichi2/anki/browser/CardBrowserViewModel.kt

@@ -209,7 +209,7 @@ class CardBrowserViewModel(
         viewModelScope.launch {
             // PERF: slightly inefficient if the source was lastDeckId
             setDeckId(getInitialDeck())
-            val cardsOrNotes = withCol { CardsOrNotes.fromCollection(this) }
+            val cardsOrNotes = withCol { CardsOrNotes.fromCollection() }
             cardsOrNotesFlow.update { cardsOrNotes }
 
             withCol {
@@ -260,7 +260,7 @@ class CardBrowserViewModel(
     fun setCardsOrNotes(newValue: CardsOrNotes) = viewModelScope.launch {
         withCol {
             // Change this to only change the preference on a state change
-            newValue.saveToCollection(this)
+            newValue.saveToCollection()
         }
         cardsOrNotesFlow.update { newValue }
     }
@@ -363,7 +363,7 @@ class CardBrowserViewModel(
             CARDS -> Pair(ExportDialogFragment.ExportType.Cards, selectedCardIds)
             NOTES -> Pair(
                 ExportDialogFragment.ExportType.Notes,
-                withCol { CardService.selectedNoteIds(selectedCardIds, this) }
+                withCol { CardService.selectedNoteIds(selectedCardIds) }
             )
         }
     }

AnkiDroid/src/main/java/com/ichi2/anki/cardviewer/CardSoundConfig.kt

@@ -18,7 +18,6 @@ package com.ichi2.anki.cardviewer
 
 import androidx.annotation.CheckResult
 import com.ichi2.anki.CardUtils
-import com.ichi2.anki.CollectionManager.withCol
 import com.ichi2.libanki.Card
 import com.ichi2.libanki.Collection
 import com.ichi2.libanki.DeckId
@@ -38,10 +37,11 @@ class CardSoundConfig(val replayQuestion: Boolean, val autoplay: Boolean, val de
     fun appliesTo(card: Card): Boolean = CardUtils.getDeckIdForCard(card) == deckId
 
     companion object {
+        context(Collection)
         @CheckResult
-        fun create(collection: Collection, card: Card): CardSoundConfig {
+        fun create(card: Card): CardSoundConfig {
             Timber.v("start loading SoundConfig")
-            val deckConfig = collection.decks.confForDid(CardUtils.getDeckIdForCard(card))
+            val deckConfig = this@Collection.decks.confForDid(CardUtils.getDeckIdForCard(card))
 
             val autoPlay = deckConfig.optBoolean("autoplay", false)
 
@@ -51,8 +51,5 @@ class CardSoundConfig(val replayQuestion: Boolean, val autoplay: Boolean, val de
                 Timber.d("loaded SoundConfig: %s", this)
             }
         }
-
-        @CheckResult
-        suspend fun create(card: Card): CardSoundConfig = withCol { create(this, card) }
     }
 }

AnkiDroid/src/main/java/com/ichi2/anki/cardviewer/SoundPlayer.kt

@@ -30,6 +30,7 @@ import com.ichi2.anki.AbstractFlashcardViewer
 import com.ichi2.anki.AndroidTtsError
 import com.ichi2.anki.AndroidTtsError.TtsErrorCode
 import com.ichi2.anki.AndroidTtsPlayer
+import com.ichi2.anki.CollectionManager.withCol
 import com.ichi2.anki.cardviewer.SoundErrorBehavior.CONTINUE_AUDIO
 import com.ichi2.anki.cardviewer.SoundErrorBehavior.RETRY_AUDIO
 import com.ichi2.anki.cardviewer.SoundErrorBehavior.STOP_AUDIO
@@ -122,7 +123,7 @@ class SoundPlayer(
         this.side = side
 
         if (!this::config.isInitialized || !config.appliesTo(card)) {
-            config = CardSoundConfig.create(card)
+            config = withCol { CardSoundConfig.create(card) }
         }
     }
 

AnkiDroid/src/main/java/com/ichi2/anki/dialogs/customstudy/CreateCustomStudySessionListener.kt

@@ -42,7 +42,7 @@ suspend fun rebuildCram(listener: CreateCustomStudySessionListener) {
     CollectionManager.withCol {
         Timber.d("doInBackground - rebuildCram()")
         sched.rebuildDyn(decks.selected())
-        updateValuesFromDeck(this)
+        updateValuesFromDeck()
     }
     listener.onPostExecute()
 }

AnkiDroid/src/main/java/com/ichi2/anki/model/CardsOrNotes.kt

@@ -28,13 +28,15 @@ enum class CardsOrNotes {
     CARDS,
     NOTES;
 
-    fun saveToCollection(collection: Collection) {
+    context (Collection)
-        collection.config.setBool(ConfigKey.Bool.BROWSER_TABLE_SHOW_NOTES_MODE, this == NOTES)
+    fun saveToCollection() {
+        this@Collection.config.setBool(ConfigKey.Bool.BROWSER_TABLE_SHOW_NOTES_MODE, this == NOTES)
     }
 
     companion object {
-        fun fromCollection(col: Collection): CardsOrNotes =
+        context (Collection)
-            when (col.config.getBool(ConfigKey.Bool.BROWSER_TABLE_SHOW_NOTES_MODE)) {
+        fun fromCollection(): CardsOrNotes =
+            when (this@Collection.config.getBool(ConfigKey.Bool.BROWSER_TABLE_SHOW_NOTES_MODE)) {
                 true -> NOTES
                 false -> CARDS
             }

AnkiDroid/src/main/java/com/ichi2/anki/previewer/PreviewerViewModel.kt

@@ -31,6 +31,7 @@ import com.ichi2.anki.servicelayer.MARKED_TAG
 import com.ichi2.anki.servicelayer.NoteService
 import com.ichi2.libanki.Card
 import com.ichi2.libanki.Sound.addPlayButtons
+import com.ichi2.libanki.note
 import com.ichi2.themes.Themes
 import com.ichi2.utils.toRGBHex
 import kotlinx.coroutines.flow.MutableSharedFlow
@@ -90,8 +91,7 @@ class PreviewerViewModel(private val selectedCardIds: LongArray, firstIndex: Int
 
     fun toggleMark() {
         launchCatching {
-            // TODO: Consider a context receiver
+            val note = withCol { currentCard.note() }
-            val note = withCol { currentCard.note(this) }
             NoteService.toggleMark(note)
             isMarked.emit(NoteService.isMarked(note))
         }
@@ -132,7 +132,7 @@ class PreviewerViewModel(private val selectedCardIds: LongArray, firstIndex: Int
     }
 
     private suspend fun updateMarkIcon() {
-        val note = withCol { currentCard.note(this) }
+        val note = withCol { currentCard.note() }
         isMarked.emit(note.hasTag(MARKED_TAG))
     }
 
@@ -328,7 +328,7 @@ class PreviewerViewModel(private val selectedCardIds: LongArray, firstIndex: Int
 
         private suspend fun getExpectedTypeInAnswer(card: Card, field: JSONObject): String? {
             val fieldName = field.getString("name")
-            val expected = withCol { card.note(this).getItem(fieldName) }
+            val expected = withCol { card.note().getItem(fieldName) }
             return if (fieldName.startsWith("cloze:")) {
                 val clozeIdx = card.ord + 1
                 withCol {

AnkiDroid/src/main/java/com/ichi2/anki/reviewer/AnswerTimer.kt

@@ -135,3 +135,9 @@ class AnswerTimer(private val cardTimer: Chronometer) {
     private val elapsedRealTime
         get() = SystemClock.elapsedRealtime()
 }
+
+/** @see AnswerTimer.resume */
+context (Collection)
+fun AnswerTimer.resume() {
+    this@AnswerTimer.resume(this@Collection)
+}

AnkiDroid/src/main/java/com/ichi2/anki/servicelayer/CardService.kt

@@ -17,6 +17,7 @@
 package com.ichi2.anki.servicelayer
 
 import com.ichi2.anki.CardUtils
+import com.ichi2.libanki.CardId
 import com.ichi2.libanki.Collection
 
 object CardService {
@@ -24,11 +25,11 @@ object CardService {
      * get unique note ids from a list of card ids
      * @param selectedCardIds list of card ids
      * can do better with performance here
-     * TODO: blocks the UI, should be fixed
      */
-    fun selectedNoteIds(selectedCardIds: List<Long>, col: Collection) =
+    context (Collection)
+    fun selectedNoteIds(selectedCardIds: List<CardId>) =
         CardUtils.getNotes(
-            col,
+            this@Collection,
-            selectedCardIds.map { col.getCard(it) }
+            selectedCardIds.map { this@Collection.getCard(it) }
         ).map { it.id }
 }

AnkiDroid/src/main/java/com/ichi2/anki/ui/windows/managespace/ManageSpaceFragment.kt

@@ -84,9 +84,9 @@ class ManageSpaceViewModel(val app: Application) : AndroidViewModel(app), Collec
         }
     }
 
-    suspend fun deleteMedia(filesNamesToDelete: List<String>) {
+    suspend fun deleteMediaFiles(filesNamesToDelete: List<String>) {
         try {
-            withCol { deleteMedia(this, filesNamesToDelete) }
+            withCol { deleteMedia(filesNamesToDelete) }
         } finally {
             launchCalculationOfSizeOfEverything()
             launchCalculationOfCollectionSize()
@@ -108,7 +108,7 @@ class ManageSpaceViewModel(val app: Application) : AndroidViewModel(app), Collec
 
     suspend fun deleteBackups(backupsToDelete: List<File>) {
         try {
-            withCol { BackupManager.deleteBackups(this, backupsToDelete) }
+            withCol { BackupManager.deleteBackups(backupsToDelete) }
         } finally {
             launchCalculationOfBackupsSize()
             launchCalculationOfCollectionSize()
@@ -225,7 +225,7 @@ class ManageSpaceFragment : SettingsFragment() {
                 val filesNamesToDelete = unusedFileNames.filterIndexed { index, _ -> checkedItems[index] }
 
                 withProgress(R.string.delete_media_message) {
-                    viewModel.deleteMedia(filesNamesToDelete)
+                    viewModel.deleteMediaFiles(filesNamesToDelete)
                 }
             }
         } else {

AnkiDroid/src/main/java/com/ichi2/async/CollectionOperations.kt

@@ -27,33 +27,23 @@ import timber.log.Timber
 import java.util.*
 
 /**
- * This file contains functions that have been migrated from [CollectionTask]
+ * Takes a list of media file names and removes them from the [Collection]
- * Remove this comment when migration has been completed
- * TODO: All functions associated to Collection can be converted to extension function to avoid redundant parameter [col] in each.
- */
-
-/**
- * Takes a list of media file names and removes them from the Collection
- * @param col Collection from which media is to be deleted
  * @param unused List of media names to be deleted
  */
-fun deleteMedia(
+context (Collection)
-    col: Collection,
+fun deleteMedia(unused: List<String>): Int {
-    unused: List<String>
-): Int {
     // FIXME: this provides progress info that is not currently used
-    col.media.removeFiles(unused)
+    this@Collection.media.removeFiles(unused)
     return unused.size
 }
 
 // TODO: Once [com.ichi2.async.CollectionTask.RebuildCram] and [com.ichi2.async.CollectionTask.EmptyCram]
 // are migrated to Coroutines, move this function to [com.ichi2.anki.StudyOptionsFragment]
-fun updateValuesFromDeck(
+context (Collection)
-    col: Collection
+fun updateValuesFromDeck(): StudyOptionsFragment.DeckStudyData? {
-): StudyOptionsFragment.DeckStudyData? {
     Timber.d("doInBackgroundUpdateValuesFromDeck")
     return try {
-        val sched = col.sched
+        val sched = this@Collection.sched
         val counts = sched.counts()
         val totalNewCount = sched.totalNewForCurrentDeck()
         val totalCount = sched.cardCount()
@@ -125,13 +115,13 @@ suspend fun renderBrowserQA(
  * Handles everything for a model change at once - template add / deletes as well as content updates
  * @return Pair<Boolean, String> : (true, null) when success, (false, exceptionMessage) when failure
  */
+context (Collection)
 fun saveModel(
-    col: Collection,
     notetype: NotetypeJson,
     templateChanges: ArrayList<Array<Any>>
 ) {
     Timber.d("doInBackgroundSaveModel")
-    val oldModel = col.notetypes.get(notetype.getLong("id"))
+    val oldModel = this@Collection.notetypes.get(notetype.getLong("id"))
 
     // TODO: make undoable
     val newTemplates = notetype.getJSONArray("tmpls")
@@ -140,11 +130,11 @@ fun saveModel(
         when (change[1] as CardTemplateNotetype.ChangeType) {
             CardTemplateNotetype.ChangeType.ADD -> {
                 Timber.d("doInBackgroundSaveModel() adding template %s", change[0])
-                col.notetypes.addTemplate(oldModel, newTemplates.getJSONObject(change[0] as Int))
+                this@Collection.notetypes.addTemplate(oldModel, newTemplates.getJSONObject(change[0] as Int))
             }
             CardTemplateNotetype.ChangeType.DELETE -> {
                 Timber.d("doInBackgroundSaveModel() deleting template currently at ordinal %s", change[0])
-                col.notetypes.remTemplate(oldModel, oldTemplates.getJSONObject(change[0] as Int))
+                this@Collection.notetypes.remTemplate(oldModel, oldTemplates.getJSONObject(change[0] as Int))
             }
         }
     }
@@ -152,6 +142,6 @@ fun saveModel(
     // required for Rust: the modified time can't go backwards, and we updated the model by adding fields
     // This could be done better
     notetype.put("mod", oldModel!!.getLong("mod"))
-    col.notetypes.save(notetype)
+    this@Collection.notetypes.save(notetype)
-    col.notetypes.update(notetype)
+    this@Collection.notetypes.update(notetype)
 }

AnkiDroid/src/main/java/com/ichi2/libanki/Card.kt

@@ -531,3 +531,13 @@ open class Card : Cloneable {
         }
     }
 }
+
+/** @see Card.renderOutput */
+context (Collection)
+fun Card.renderOutput(reload: Boolean = false, browser: Boolean = false) =
+    this@Card.renderOutput(this@Collection, reload, browser)
+
+/** @see Card.note */
+context (Collection)
+fun Card.note() =
+    this@Card.note(this@Collection)

AnkiDroid/src/test/java/com/ichi2/anki/cardviewer/CardSoundConfigTest.kt

@@ -17,8 +17,9 @@
 package com.ichi2.anki.cardviewer
 
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.ichi2.anki.CollectionManager.withCol
+import com.ichi2.libanki.Card
 import com.ichi2.testutils.JvmTest
-import kotlinx.coroutines.test.runTest
 import org.hamcrest.MatcherAssert.assertThat
 import org.hamcrest.Matchers.equalTo
 import org.junit.Ignore
@@ -34,7 +35,7 @@ class CardSoundConfigTest : JvmTest() {
         // defaults as-of Anki Desktop 23.10 (51a10f09)
         val note = addNoteUsingBasicModel()
         val card = note.firstCard()
-        CardSoundConfig.create(card).run {
+        createCardSoundConfig(card).run {
             assertThat("deckId", deckId, equalTo(card.did))
             // Anki Desktop: "Skip question when replaying answer" -> false
             // our variable is reversed, so true
@@ -49,7 +50,7 @@ class CardSoundConfigTest : JvmTest() {
     fun `cards from the same note are equal`() = runTest {
         val note = addNoteUsingBasicAndReversedModel()
         val (card1, card2) = note.cards()
-        CardSoundConfig.create(card1).run {
+        createCardSoundConfig(card1).run {
             assertThat("same note", this.appliesTo(card2))
         }
     }
@@ -57,7 +58,7 @@ class CardSoundConfigTest : JvmTest() {
     @Test
     fun `cards from the same deck are equal`() = runTest {
         val (note1, note2) = addNotes(count = 2)
-        CardSoundConfig.create(note1.firstCard()).run {
+        createCardSoundConfig(note1.firstCard()).run {
             assertThat("same note", this.appliesTo(note2.firstCard()))
         }
     }
@@ -66,4 +67,6 @@ class CardSoundConfigTest : JvmTest() {
     @Test
     fun `cards with the same deck options are equal`() {
     }
+
+    private suspend fun createCardSoundConfig(card: Card) = withCol { CardSoundConfig.create(card) }
 }

build.gradle

@@ -96,7 +96,7 @@ subprojects {
         tasks.withType(KotlinCompile).configureEach {
             compilerOptions {
                 allWarningsAsErrors = fatalWarnings
-                def compilerArgs = ['-Xjvm-default=all']
+                def compilerArgs = ['-Xjvm-default=all', '-Xcontext-receivers']
                 if (project.name != "api") {
                     compilerArgs += ['-opt-in=kotlinx.coroutines.ExperimentalCoroutinesApi']
                 }