[Swift] Migrate to swift 6.0 and Implements support gRPC v2 (#8983)

* Migrate to swift 6.0 & swift-gRPC 2.0

The following migrates to swift 6.0, and also
migrate to swift-grpc 2.0 that uses swift-nio
under the hood to provide nicer API and async await

Adds sendable to enum & update @_implementationOnly imports to use internal imports

* Address PR comments regarding misspelling & proper method naming.

swift/Sources/FlatBuffers/ByteBuffer.swift

@@ -20,7 +20,7 @@ import Foundation
 /// it allows users to write and read data directly from memory thus the use of its
 /// functions should be used
 @frozen
-public struct ByteBuffer {
+public struct ByteBuffer: @unchecked Sendable {
 
   /// Storage is a container that would hold the memory pointer to solve the issue of
   /// deallocating the memory that was held by (memory: UnsafeMutableRawPointer)
@@ -30,7 +30,7 @@ public struct ByteBuffer {
     enum Blob {
       #if !os(WASI)
       case data(Data)
-      case bytes(ContiguousBytes)
+      case bytes(any ContiguousBytes)
       #endif
 
       case byteBuffer(_InternalByteBuffer)

swift/Sources/FlatBuffers/Enum.swift

@@ -23,7 +23,7 @@ import Common
 /// Enum is a protocol that all flatbuffers enums should conform to
 /// Since it allows us to get the actual `ByteSize` and `Value` from
 /// a swift enum.
-public protocol Enum {
+public protocol Enum: Sendable {
   /// associatedtype that the type of the enum should conform to
   associatedtype T: Scalar & Verifiable
   /// Size of the current associatedtype in the enum

swift/Sources/FlatBuffers/FlatBufferBuilder.swift

@@ -45,7 +45,7 @@ public struct FlatBufferBuilder {
   /// Dictonary that stores a map of all the strings that were written to the buffer
   private var stringOffsetMap: [String: Offset] = [:]
   /// A check to see if finish(::) was ever called to retreive data object
-  private var finished = false
+  private(set) var finished = false
   /// A check to see if the buffer should serialize Default values
   private var serializeDefaults: Bool
 
@@ -488,7 +488,7 @@ public struct FlatBufferBuilder {
   ///
   /// - Parameter bytes: bytes to be written into the buffer
   /// - Returns: ``Offset`` of the vector
-  mutating public func createVector(bytes: ContiguousBytes) -> Offset {
+  mutating public func createVector(bytes: any ContiguousBytes) -> Offset {
     bytes.withUnsafeBytes {
       startVector($0.count, elementSize: MemoryLayout<UInt8>.size)
       _bb.push(bytes: $0)

swift/Sources/FlatBuffers/FlatBufferObject.swift

@@ -20,6 +20,8 @@ import Foundation
 /// since now we will be serializing native structs into the buffer.
 public protocol NativeStruct {}
 
+public protocol FlatBufferVerifiableNativeStruct: NativeStruct, Verifiable {}
+
 /// FlatbuffersInitializable is a protocol that allows any object to be
 /// Initialized from a ByteBuffer
 public protocol FlatbuffersInitializable {
@@ -35,6 +37,8 @@ public protocol FlatBufferTable: FlatbuffersInitializable,
   var __buffer: ByteBuffer! { get }
 }
 
+public protocol FlatBufferVerifiableTable: FlatBufferTable, Verifiable {}
+
 /// FlatbufferStruct structures all the Flatbuffers structs
 public protocol FlatBufferStruct: FlatbuffersInitializable,
   FlatbuffersVectorInitializable

swift/Sources/FlatBuffers/Message.swift

@@ -16,50 +16,52 @@
 
 import Foundation
 
-/// FlatBufferGRPCMessage protocol that should allow us to invoke
-/// initializers directly from the GRPC generated code
-public protocol FlatBufferGRPCMessage {
-  /// Size of readable bytes in the buffer
-  var size: Int { get }
-
-  init(byteBuffer: ByteBuffer)
-
-  @discardableResult
-  @inline(__always)
-  func withUnsafeReadableBytes<T>(
-    _ body: (UnsafeRawBufferPointer) throws
-      -> T) rethrows -> T
+enum FlatbuffersGRPCError: Error {
+  case finishedNotCalledOnBuilder
 }
 
-/// Message is a wrapper around Buffers to to able to send Flatbuffers `Buffers` through the
-/// GRPC library
-public struct Message<T: FlatBufferTable>: FlatBufferGRPCMessage {
-  internal var buffer: ByteBuffer
+public protocol GRPCVerifiableMessage<Message> {
+  associatedtype Message
 
-  /// Returns the an object of type T that would be  read from the buffer
-  public var object: T {
-    T.init(
-      buffer,
-      o: Int32(buffer.read(def: UOffset.self, position: buffer.reader)) &+
-        Int32(buffer.reader))
-  }
+  init(pointer: UnsafeRawBufferPointer)
+  init(byteBuffer: ByteBuffer)
+
+  func decode() throws -> Message
+  func withUnsafeReadableBytes<Data>(
+    _ body: (UnsafeRawBufferPointer) throws
+      -> Data) rethrows -> Data
+}
+
+public struct GRPCMessage<
+  Table: FlatBufferVerifiableTable
+>: Sendable, GRPCVerifiableMessage {
+  public typealias Message = Table
+
+  private let buffer: ByteBuffer
 
   public var size: Int { Int(buffer.size) }
 
-  /// Initializes the message with the type Flatbuffer.Bytebuffer that is transmitted over
-  /// GRPC
-  /// - Parameter byteBuffer: Flatbuffer ByteBuffer object
+  public init(pointer: UnsafeRawBufferPointer) {
+    buffer = ByteBuffer(
+      copyingMemoryBound: pointer.baseAddress!,
+      capacity: pointer.count)
+  }
+
+  public init(builder: inout FlatBufferBuilder) throws {
+    guard builder.finished else {
+      throw FlatbuffersGRPCError.finishedNotCalledOnBuilder
+    }
+
+    buffer = builder.sizedBuffer
+  }
+
   public init(byteBuffer: ByteBuffer) {
     buffer = byteBuffer
   }
 
-  /// Initializes the message by copying the buffer to the message to be sent.
-  /// from the builder
-  /// - Parameter builder: FlatbufferBuilder that has the bytes created in
-  /// - Note: Use  `builder.finish(offset)` before passing the builder without prefixing anything to it
-  public init(builder: inout FlatBufferBuilder) {
-    buffer = builder.sizedBuffer
-    builder.clear()
+  public func decode() throws -> Table {
+    var buf = buffer
+    return try getCheckedRoot(byteBuffer: &buf)
   }
 
   @discardableResult
@@ -73,3 +75,30 @@ public struct Message<T: FlatBufferTable>: FlatBufferGRPCMessage {
     }
   }
 }
+
+@available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *)
+public struct FlatBuffersMessageSerializer<
+  Message: GRPCVerifiableMessage
+>: Sendable {
+  public init() {}
+
+  public func serialize<Data>(
+    message: Message,
+    _ completion: (UnsafeRawBufferPointer) throws -> Data) throws -> Data
+  {
+    return try message.withUnsafeReadableBytes {
+      try completion($0)
+    }
+  }
+}
+
+@available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *)
+public struct FlatBuffersMessageDeserializer<
+  Message: GRPCVerifiableMessage
+>: Sendable {
+  public init() {}
+
+  public func deserialize(pointer: UnsafeRawBufferPointer) throws -> Message {
+    Message.init(pointer: pointer)
+  }
+}

swift/Sources/FlatBuffers/TableVerifier.swift

@@ -115,7 +115,7 @@ public struct TableVerifier {
     unionKeyName: String,
     fieldName: String,
     required: Bool,
-    completion: @escaping (inout Verifier, T, Int) throws -> Void) throws
+    completion: (inout Verifier, T, Int) throws -> Void) throws
     where T: UnionEnum
   {
     let keyPos = try dereference(key)

swift/Sources/FlatBuffers/Vectors/FlatbufferVector.swift

@@ -68,7 +68,7 @@ public struct FlatbufferVector<
 }
 
 extension FlatbufferVector: Encodable where Element: Encodable {
-  public func encode(to encoder: Encoder) throws {
+  public func encode(to encoder: any Encoder) throws {
     var container = encoder.unkeyedContainer()
     for element in self {
       try container.encode(element)

swift/Sources/FlatBuffers/Vectors/UnionFlatbufferVector.swift

@@ -49,8 +49,8 @@ public struct UnionFlatbufferVector {
 
   public subscript(
     position: Int,
-    Type: FlatbuffersVectorInitializable
-      .Type) -> FlatbuffersVectorInitializable
+    Type: any FlatbuffersVectorInitializable
+      .Type) -> any FlatbuffersVectorInitializable
   {
     guard position < count else {
       fatalError(

swift/Sources/FlatBuffers/_InternalByteBuffer.swift

@@ -146,7 +146,7 @@ struct _InternalByteBuffer {
   #if !os(WASI)
   @inline(__always)
   @usableFromInline
-  mutating func push(bytes: ContiguousBytes) {
+  mutating func push(bytes: any ContiguousBytes) {
     bytes.withUnsafeBytes { ptr in
       ensureSpace(size: ptr.count)
       memcpy(

swift/Sources/FlexBuffers/ByteBuffer.swift

@@ -30,7 +30,7 @@ public struct ByteBuffer {
     enum Blob {
       #if !os(WASI)
       case data(Data)
-      case bytes(ContiguousBytes)
+      case bytes(any ContiguousBytes)
       #endif
 
       case byteBuffer(_InternalByteBuffer)

swift/Sources/FlexBuffers/FlexBufferType.swift

@@ -16,7 +16,7 @@
 
 import Foundation
 
-public enum FlexBufferType: UInt64 {
+public enum FlexBufferType: UInt64, Sendable {
   case null = 0
   /// Variable width signed integer: `Int8, Int16, Int32, Int64`
   case int = 1

swift/Sources/FlexBuffers/Utils/BitWidth.swift

@@ -17,7 +17,7 @@
 import Foundation
 
 @usableFromInline
-enum BitWidth: UInt64, CaseIterable {
+enum BitWidth: UInt64, CaseIterable, Sendable {
   case w8 = 0
   case w16 = 1
   case w32 = 2

swift/Sources/FlexBuffers/Utils/Value.swift

@@ -20,10 +20,10 @@ import Foundation
 import Common
 #endif
 
-public struct Value: Equatable {
+public struct Value: Equatable, Sendable {
 
   @usableFromInline
-  enum Union: Equatable {
+  enum Union: Equatable, Sendable {
     case i(Int64)
     case u(UInt64)
     case f(Double)

swift/Sources/FlexBuffers/Writer/FlexBuffersWriter.swift

@@ -977,6 +977,9 @@ fileprivate struct Stack: RandomAccessCollection {
   mutating func removeAll(keepingCapacity keepCapacity: Bool = false) {
     count = 0
     if !keepCapacity {
+      let ptr = storage.memory
+      defer { ptr.deallocate() }
+
       capacity = Self.initialCapacity
       storage.memory = UnsafeMutableRawPointer.allocate(
         byteCount: capacity,