#161 Add DataConvertible conformance to ATTReadByGroupTypeRequest

Sources/BluetoothGATT/ATTReadByGroupTypeRequest.swift

@@ -6,16 +6,14 @@
 //  Copyright © 2018 PureSwift. All rights reserved.
 //
 
-import Foundation
-
 /// Read by Group Type Request
 ///
 /// The *Read By Group Type Request* is used to obtain the values of attributes where the attribute type is known,
 /// the type of a grouping attribute as defined by a higher layer specification, but the handle is not known.
 @frozen
-public struct ATTReadByGroupTypeRequest: ATTProtocolDataUnit, Equatable {
+public struct ATTReadByGroupTypeRequest: ATTProtocolDataUnit, Equatable, Hashable, Sendable {
 
-    public static var attributeOpcode: ATTOpcode { return .readByGroupTypeRequest }
+    public static var attributeOpcode: ATTOpcode { .readByGroupTypeRequest }
 
     /// First requested handle number.
     public var startHandle: UInt16
@@ -28,24 +26,26 @@ public struct ATTReadByGroupTypeRequest: ATTProtocolDataUnit, Equatable {
     /// 2 or 16 octet UUID
     public var type: BluetoothUUID
 
-    public init(startHandle: UInt16,
-                endHandle: UInt16,
-                type: BluetoothUUID) {
-
-        assert(type.length != .bit32)
-
+    public init(
+        startHandle: UInt16,
+        endHandle: UInt16,
+        type: BluetoothUUID
+    ) {
+        assert(type.dataLength != 4, "Cannot use 32-bit UUID")
         self.startHandle = startHandle
         self.endHandle = endHandle
         self.type = type
     }
 }
 
-public extension ATTReadByGroupTypeRequest {
+// MARK: - DataConvertible
+
+extension ATTReadByGroupTypeRequest: DataConvertible {
 
-    init?(data: Data) {
+    public init?<Data: DataContainer>(data: Data) {
 
         guard let length = Length(rawValue: data.count),
-            Swift.type(of: self).validateOpcode(data)
+            Self.validateOpcode(data)
             else { return nil }
 
         self.startHandle = UInt16(littleEndian: UInt16(bytes: (data[1], data[2])))
@@ -56,37 +56,25 @@ public extension ATTReadByGroupTypeRequest {
             let value = UInt16(littleEndian: UInt16(bytes: (data[5], data[6])))
             self.type = .bit16(value)
         case .uuid128:
-            self.type = BluetoothUUID(littleEndian: BluetoothUUID(data: data.subdataNoCopy(in: 5 ..< 21))!)
+            self.type = BluetoothUUID(littleEndian: BluetoothUUID(data: data.subdata(in: 5 ..< 21))!)
         }
     }
 
-    var data: Data {
-
-        return Data(self)
-    }
-}
-
-// MARK: - DataConvertible
-
-extension ATTReadByGroupTypeRequest: DataConvertible {
-
-    var dataLength: Int {
-
+    public var dataLength: Int {
         return length.rawValue
     }
 
-    static func += <T: DataContainer> (data: inout T, value: ATTReadByGroupTypeRequest) {
-
-        data += attributeOpcode.rawValue
-        data += value.startHandle.littleEndian
-        data += value.endHandle.littleEndian
-        data += value.type.littleEndian
+    public func append<Data>(to data: inout Data) where Data : DataContainer {
+        data += Self.attributeOpcode.rawValue
+        data += self.startHandle.littleEndian
+        data += self.endHandle.littleEndian
+        data += self.type.littleEndian
     }
 }
 
 // MARK: - Supporting Types
 
-private extension ATTReadByGroupTypeRequest {
+fileprivate extension ATTReadByGroupTypeRequest {
 
     enum Length: Int {
 
@@ -97,9 +85,13 @@ private extension ATTReadByGroupTypeRequest {
     var length: Length {
 
         switch type {
-        case .bit16: return .uuid16
-        case .bit128: return .uuid128
-        case .bit32: fatalError()
+        case .bit16:
+            return .uuid16
+        case .bit128:
+            return .uuid128
+        case .bit32:
+            assertionFailure("")
+            return .uuid128
         }
     }
 }