Add helpers for Swift 6.2 compatibility (#260)

* Add helpers for Swift 6.2 compatibility

* Reformat

Author: simolus3

PowerSyncKotlin/src/appleMain/kotlin/com/powersync/Connector.kt

@@ -0,0 +1,20 @@
+package com.powersync
+
+import com.powersync.connectors.PowerSyncBackendConnector
+import com.powersync.connectors.PowerSyncCredentials
+
+public interface SwiftBackendConnector {
+    public suspend fun fetchCredentials(): PowerSyncResult
+
+    public suspend fun uploadData(): PowerSyncResult
+}
+
+public fun swiftBackendConnectorToPowerSyncConnector(connector: SwiftBackendConnector): PowerSyncBackendConnector =
+    object : PowerSyncBackendConnector() {
+        override suspend fun fetchCredentials(): PowerSyncCredentials? =
+            handleLockResult(connector.fetchCredentials()) as PowerSyncCredentials?
+
+        override suspend fun uploadData(database: PowerSyncDatabase) {
+            handleLockResult(connector.uploadData())
+        }
+    }

PowerSyncKotlin/src/appleMain/kotlin/com/powersync/Locks.kt

@@ -15,7 +15,7 @@ import com.powersync.db.internal.PowerSyncTransaction
  */
 public sealed class PowerSyncResult {
     public data class Success(
-        val value: Any,
+        val value: Any?,
     ) : PowerSyncResult()
 
     public data class Failure(
@@ -26,7 +26,7 @@ public sealed class PowerSyncResult {
 // Throws the [PowerSyncException] if the result is a failure, or returns the value if it is a success.
 // We throw the exception on behalf of the Swift SDK.
 @Throws(PowerSyncException::class)
-private fun handleLockResult(result: PowerSyncResult): Any {
+internal fun handleLockResult(result: PowerSyncResult): Any? {
     when (result) {
         is PowerSyncResult.Failure -> {
             throw result.exception
@@ -41,13 +41,13 @@ private fun handleLockResult(result: PowerSyncResult): Any {
 public class LockContextWrapper(
     private val handler: (context: ConnectionContext) -> PowerSyncResult,
 ) : ThrowableLockCallback<Any> {
-    override fun execute(context: ConnectionContext): Any = handleLockResult(handler(context))
+    override fun execute(context: ConnectionContext): Any = handleLockResult(handler(context))!!
 }
 
 public class TransactionContextWrapper(
     private val handler: (context: PowerSyncTransaction) -> PowerSyncResult,
 ) : ThrowableTransactionCallback<Any> {
-    override fun execute(transaction: PowerSyncTransaction): Any = handleLockResult(handler(transaction))
+    override fun execute(transaction: PowerSyncTransaction): Any = handleLockResult(handler(transaction))!!
 }
 
 public fun wrapContextHandler(handler: (context: ConnectionContext) -> PowerSyncResult): ThrowableLockCallback<Any> =

PowerSyncKotlin/src/appleMain/kotlin/com/powersync/SDK.kt

@@ -2,10 +2,14 @@
 
 package com.powersync
 
+import com.powersync.db.crud.CrudTransaction
 import com.powersync.sync.SyncClientConfiguration
 import com.powersync.sync.SyncOptions
 import io.ktor.client.plugins.logging.LogLevel
 import io.ktor.client.plugins.logging.Logging
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.map
 import io.ktor.client.plugins.logging.Logger as KtorLogger
 
 /**
@@ -88,3 +92,16 @@ public fun createSyncOptions(
         userAgent = userAgent,
         clientConfiguration = createExtendedSyncClientConfiguration(loggingConfig),
     )
+
+public fun errorHandledCrudTransactions(db: PowerSyncDatabase): Flow<PowerSyncResult> =
+    db
+        .getCrudTransactions()
+        .map<CrudTransaction, PowerSyncResult> {
+            PowerSyncResult.Success(it)
+        }.catch {
+            if (it is PowerSyncException) {
+                emit(PowerSyncResult.Failure(it))
+            } else {
+                throw it
+            }
+        }

core/src/commonMain/kotlin/com/powersync/PowerSyncDatabase.kt

@@ -173,8 +173,7 @@ public interface PowerSyncDatabase : Queries {
      *
      * If there is no local data to upload, returns an empty flow.
      */
-    @Throws(PowerSyncException::class, CancellationException::class)
-    public suspend fun getCrudTransactions(): Flow<CrudTransaction>
+    public fun getCrudTransactions(): Flow<CrudTransaction>
 
     /**
      * Convenience method to get the current version of PowerSync.

core/src/commonMain/kotlin/com/powersync/db/PowerSyncDatabaseImpl.kt

@@ -270,7 +270,7 @@ internal class PowerSyncDatabaseImpl(
         })
     }
 
-    override suspend fun getCrudTransactions(): Flow<CrudTransaction> =
+    override fun getCrudTransactions(): Flow<CrudTransaction> =
         flow {
             waitReady()
             var lastItemId = -1