Make extension accessors have same safety as other functions

bluetooth/src/commonMain/kotlin/Bluetooth.kt

@@ -628,6 +628,15 @@ fun Flow<RemoteCharacteristic?>.value(): Flow<ByteArray> = distinctUntilChanged(
     characteristic?.value() ?: emptyFlow()
 }
 
+/**
+ * Gets a ([Flow] of) the [ByteArray] value from a [Flow] of an [RemoteCharacteristic] or an empty [ByteArray] if data is unavailable
+ * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected
+ * @return the [Flow] of the [ByteArray] value of the [RemoteCharacteristic] in the given [Flow], or an empty [ByteArray] if data is unavailable
+ */
+fun Flow<RemoteCharacteristic?>.valueOrEmpty(): Flow<ByteArray> = distinctUntilChanged().flatMapLatest { characteristic ->
+    characteristic?.value() ?: flowOf(byteArrayOf())
+}
+
 /**
  * Gets a ([Flow] of) [T] value from a [Flow] of an [RemoteCharacteristic]
  * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected
@@ -641,6 +650,19 @@ fun <T> Flow<RemoteCharacteristic?>.value(deserializationStrategy: Deserializati
         characteristic?.value(deserializationStrategy, bluetoothFormat) ?: emptyFlow()
     }
 
+/**
+ * Gets a ([Flow] of) [T] value from a [Flow] of an [RemoteCharacteristic] or `null` if data is unavailable
+ * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected
+ * @param T the type of the data to receive
+ * @param deserializationStrategy the [DeserializationStrategy] to use to deserialize the [ByteArray] to [T]
+ * @param bluetoothFormat the [BluetoothFormat] to use to deserialize the [ByteArray] to [T]
+ * @return the [Flow] of the [T] value of the [RemoteCharacteristic] in the given [Flow] or `null` if data is unavailable
+ */
+fun <T> Flow<RemoteCharacteristic?>.valueOrNull(deserializationStrategy: DeserializationStrategy<T>, bluetoothFormat: BluetoothFormat = BluetoothFormat): Flow<T?> =
+    distinctUntilChanged().flatMapLatest { characteristic ->
+        characteristic?.value(deserializationStrategy, bluetoothFormat) ?: flowOf(null)
+    }
+
 /**
  * Gets a ([Flow] of) [T] value from a [Flow] of an [RemoteCharacteristic]
  * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected
@@ -651,6 +673,16 @@ fun <T> Flow<RemoteCharacteristic?>.value(deserializationStrategy: Deserializati
 inline fun <reified T> Flow<RemoteCharacteristic?>.value(bluetoothFormat: BluetoothFormat = BluetoothFormat): Flow<T> =
     value(bluetoothFormat.serializersModule.serializer(), bluetoothFormat)
 
+/**
+ * Gets a ([Flow] of) [T] value from a [Flow] of an [RemoteCharacteristic]
+ * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected
+ * @param T the type of the data to receive
+ * @param bluetoothFormat the [BluetoothFormat] to use to deserialize the [ByteArray] to [T]
+ * @return the [Flow] of the [T] value of the [RemoteCharacteristic] in the given [Flow]
+ */
+inline fun <reified T> Flow<RemoteCharacteristic?>.valueOrNull(bluetoothFormat: BluetoothFormat = BluetoothFormat): Flow<T?> =
+    valueOrNull(bluetoothFormat.serializersModule.serializer(), bluetoothFormat)
+
 /**
  * Gets a ([Flow] of) the [ByteArray] value from a [RemoteCharacteristic]
  * This method will automatically subscribe/unsubscribe to the [RemoteCharacteristic] when the [Flow] is collected

bluetooth/src/commonMain/kotlin/extensions/Accessors.kt

@@ -1,69 +1,194 @@
 package com.splendo.kaluga.bluetooth.extensions
 
-import com.splendo.kaluga.bluetooth.Characteristic
+import com.splendo.kaluga.bluetooth.RemoteCharacteristic
 import com.splendo.kaluga.bluetooth.RemoteDescriptor
+import com.splendo.kaluga.bluetooth.RemoteService
 import com.splendo.kaluga.bluetooth.UUIDException
 import com.splendo.kaluga.bluetooth.characteristics
 import com.splendo.kaluga.bluetooth.descriptors
 import com.splendo.kaluga.bluetooth.device.ConnectableDevice
+import com.splendo.kaluga.bluetooth.discoveredServices
+import com.splendo.kaluga.bluetooth.serialization.BluetoothFormat
 import com.splendo.kaluga.bluetooth.services
 import com.splendo.kaluga.bluetooth.value
+import com.splendo.kaluga.bluetooth.valueOrNull
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.filterNotNull
 import kotlinx.coroutines.flow.first
+import kotlinx.serialization.DeserializationStrategy
 
 /**
- * Provides access to device data flow by service, characteristic and descriptor string uuids.
+ * Provides access to a [RemoteService] [Flow] by service string uuids.
+ * Only emits after services have been discovered.
+ * @param serviceUUID string service uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] is not valid
+ * @return the [Flow] of the [com.splendo.kaluga.bluetooth.RemoteService] associated with [serviceUUID]. Flow throws [NoSuchElementException] if the service cannot be found after discovery.
+ */
+fun Flow<ConnectableDevice?>.serviceFlow(serviceUUID: String) = discoveredServices()[serviceUUID]
+
+/**
+ * Provides access to a [RemoteService] [Flow] by service string uuids.
+ * Emits `null` if the service cannot be found.
+ * @param serviceUUID string service uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] is not valid
+ * @return the [Flow] of the [RemoteService] associated with [serviceUUID] or `null` if the service is not available.
+ */
+fun Flow<ConnectableDevice?>.serviceOrNullFlow(serviceUUID: String) = services().getOrNull(serviceUUID)
+
+/**
+ * Provides access to [RemoteService] by service string uuids.
+ * The method will suspend until services have been discovered.
+ * @param serviceUUID string service uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] is not valid
+ * @throws NoSuchElementException if the service cannot be found after discovery.
+ * @return the [RemoteService] associated with [serviceUUID]
+ */
+suspend fun Flow<ConnectableDevice?>.service(serviceUUID: String) = serviceFlow(serviceUUID)
+    .first()
+
+/**
+ * Provides access to [RemoteService] by service and characteristic string uuids or `null` if not available.
  * @param serviceUUID string service uuid representation
- * @param characteristicUUID string characteristic uuid representation
  * @throws UUIDException.InvalidFormat
+ * @return the [RemoteService] associated with [serviceUUID] or `null` if not available
  */
-fun Flow<ConnectableDevice?>.dataFlow(serviceUUID: String, characteristicUUID: String) = characteristicsFlow(serviceUUID, characteristicUUID).value()
+suspend fun Flow<ConnectableDevice?>.serviceOrNull(serviceUUID: String) = serviceOrNullFlow(serviceUUID)
+    .first()
 
 /**
- * Provides access to characteristic's flow by service and characteristic string uuids.
+ * Provides access to [RemoteCharacteristic]'s flow by service and characteristic string uuids.
+ * Only emits after services have been discovered.
  * @param serviceUUID string service uuid representation
  * @param characteristicUUID string characteristic uuid representation
- * @throws UUIDException.InvalidFormat
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]. Flow throws [NoSuchElementException] if the characteristic cannot be found after discovery.
  */
-fun Flow<ConnectableDevice?>.characteristicsFlow(serviceUUID: String, characteristicUUID: String) = services().getOrNull(serviceUUID)
+fun Flow<ConnectableDevice?>.characteristicFlow(serviceUUID: String, characteristicUUID: String) = serviceFlow(serviceUUID)
     .characteristics()[characteristicUUID]
-    .filterNotNull()
 
 /**
- * Provides access to [Characteristic] by service and characteristic string uuids.
+ * Provides access to [RemoteCharacteristic]'s flow by service and characteristic string uuids.
+ * Emits `null` if the characteristic cannot be found.
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID] or `null` if the characteristic is not available.
+ */
+fun Flow<ConnectableDevice?>.characteristicOrNullFlow(serviceUUID: String, characteristicUUID: String) = serviceOrNullFlow(serviceUUID)
+    .characteristics().getOrNull(characteristicUUID)
+
+/**
+ * Provides access to [RemoteCharacteristic] by service and characteristic string uuids.
  * The method will suspend if characteristic is not available.
  * @param serviceUUID string service uuid representation
  * @param characteristicUUID string characteristic uuid representation
- * @throws UUIDException.InvalidFormat
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @throws NoSuchElementException if the characteristic cannot be found after discovery.
+ * @return the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]
  */
-suspend fun Flow<ConnectableDevice?>.characteristic(serviceUUID: String, characteristicUUID: String) = services().getOrNull(serviceUUID)
-    .characteristics()[characteristicUUID]
-    .filterNotNull()
+suspend fun Flow<ConnectableDevice?>.characteristic(serviceUUID: String, characteristicUUID: String) = characteristicFlow(serviceUUID, characteristicUUID)
     .first()
 
 /**
- * Provides access to descriptors's flow by service, characteristic and descriptor string uuids.
+ * Provides access to [RemoteCharacteristic] by service and characteristic string uuids or `null` if not available.
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID] or `null` if not available
+ */
+suspend fun Flow<ConnectableDevice?>.characteristicOrNull(serviceUUID: String, characteristicUUID: String) = characteristicOrNullFlow(serviceUUID, characteristicUUID)
+    .first()
+
+/**
+ * Provides access to [RemoteDescriptor]'s flow by service, characteristic, and descriptor string uuids.
+ * Only emits after services have been discovered.
  * @param serviceUUID string service uuid representation
  * @param characteristicUUID string characteristic uuid representation
  * @param descriptorUUID string descriptor uuid representation
- * @throws UUIDException.InvalidFormat
+ * @throws UUIDException.InvalidFormat if [serviceUUID], [characteristicUUID], or [descriptorUUID] is not valid
+ * @return the [Flow] of the [RemoteDescriptor] associated with [serviceUUID], [characteristicUUID], and [descriptorUUID]. Flow throws [NoSuchElementException] if the descriptor cannot be found after discovery.
  */
-fun Flow<ConnectableDevice?>.descriptorsFlow(serviceUUID: String, characteristicUUID: String, descriptorUUID: String) = services().getOrNull(serviceUUID)
-    .characteristics()[characteristicUUID]
+fun Flow<ConnectableDevice?>.descriptorFlow(serviceUUID: String, characteristicUUID: String, descriptorUUID: String) = characteristicFlow(serviceUUID, characteristicUUID)
     .descriptors()[descriptorUUID]
-    .filterNotNull()
+
+/**
+ * Provides access to [RemoteDescriptor]'s flow by service, characteristic, and descriptor string uuids.
+ * Emits `null` if the descriptor cannot be found.
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @param descriptorUUID string descriptor uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID], [characteristicUUID], or [descriptorUUID] is not valid
+ * @return the [Flow] of the [RemoteDescriptor] associated with [serviceUUID], [characteristicUUID], and [descriptorUUID] or `null` if the descriptor is not available.
+ */
+fun Flow<ConnectableDevice?>.descriptorOrNullFlow(serviceUUID: String, characteristicUUID: String, descriptorUUID: String) =
+    characteristicOrNullFlow(serviceUUID, characteristicUUID)
+        .descriptors().getOrNull(descriptorUUID)
 
 /**
  * Provides access to [RemoteDescriptor] by service, characteristic and descriptor string uuids.
  * The method will suspend if descriptor is not available.
  * @param serviceUUID string service uuid representation
  * @param characteristicUUID string characteristic uuid representation
  * @param descriptorUUID string descriptor uuid representation
- * @throws UUIDException.InvalidFormat
+ * @throws UUIDException.InvalidFormat if [serviceUUID], [characteristicUUID], or [descriptorUUID] is not valid
+ * @throws NoSuchElementException if the descriptor cannot be found after discovery.
+ * @return the [RemoteDescriptor] associated with [serviceUUID], [characteristicUUID], and [descriptorUUID]
  */
-suspend fun Flow<ConnectableDevice?>.descriptor(serviceUUID: String, characteristicUUID: String, descriptorUUID: String) = services().getOrNull(serviceUUID)
-    .characteristics()[characteristicUUID]
-    .descriptors()[descriptorUUID]
-    .filterNotNull()
-    .first()
+suspend fun Flow<ConnectableDevice?>.descriptor(serviceUUID: String, characteristicUUID: String, descriptorUUID: String) =
+    descriptorFlow(serviceUUID, characteristicUUID, descriptorUUID)
+        .first()
+
+/**
+ * Provides access to device data flow by service and characteristic string uuids.
+ * Only emits after services have been discovered.
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [ByteArray] value of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]. Flow throws [NoSuchElementException] if the characteristic cannot be found after discovery.
+ */
+fun Flow<ConnectableDevice?>.dataFlow(serviceUUID: String, characteristicUUID: String) = characteristicFlow(serviceUUID, characteristicUUID).value()
+
+/**
+ * Provides access to device data flow [T] by service and characteristic string uuids.
+ * Only emits after services have been discovered.
+ * @param T the type of the data to receive
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @param deserializationStrategy the [DeserializationStrategy] to use to deserialize the [ByteArray] to [T]
+ * @param bluetoothFormat the [BluetoothFormat] to use to deserialize the [ByteArray] to [T]
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [T] value of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]. Flow throws [NoSuchElementException] if the characteristic cannot be found after discovery.
+ */
+inline fun <reified T> Flow<ConnectableDevice?>.dataFlow(
+    serviceUUID: String,
+    characteristicUUID: String,
+    deserializationStrategy: DeserializationStrategy<T>,
+    bluetoothFormat: BluetoothFormat = BluetoothFormat,
+) = characteristicFlow(serviceUUID, characteristicUUID).value(deserializationStrategy, bluetoothFormat)
+
+/**
+ * Provides access to device data flow by service and characteristic string uuids.
+ * Emits and empty [ByteArray] if the service cannot be found.
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [ByteArray] value of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]. Emits an empty [ByteArray] if the characteristic is not available.
+ */
+fun Flow<ConnectableDevice?>.dataOrEmptyFlow(serviceUUID: String, characteristicUUID: String) = characteristicOrNullFlow(serviceUUID, characteristicUUID).value()
+
+/**
+ * Provides access to device data flow [T] by service and characteristic string uuids.
+ * Emits `null` if the descriptor cannot be found.
+ * @param T the type of the data to receive
+ * @param serviceUUID string service uuid representation
+ * @param characteristicUUID string characteristic uuid representation
+ * @param deserializationStrategy the [DeserializationStrategy] to use to deserialize the [ByteArray] to [T]
+ * @param bluetoothFormat the [BluetoothFormat] to use to deserialize the [ByteArray] to [T]
+ * @throws UUIDException.InvalidFormat if [serviceUUID] or [characteristicUUID] is not valid
+ * @return the [Flow] of the [T] value of the [RemoteCharacteristic] associated with [serviceUUID] and [characteristicUUID]. Emits `null` if the descriptor cannot be found.
+ */
+inline fun <reified T> Flow<ConnectableDevice?>.dataOrNullFlow(
+    serviceUUID: String,
+    characteristicUUID: String,
+    deserializationStrategy: DeserializationStrategy<T>,
+    bluetoothFormat: BluetoothFormat = BluetoothFormat,
+) = characteristicOrNullFlow(serviceUUID, characteristicUUID).valueOrNull(deserializationStrategy, bluetoothFormat)