add swift flatbuffers

flatbuffers/FlatBufferObject.swift

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2023 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if !os(WASI)
+import Foundation
+#else
+import SwiftOverlayShims
+#endif
+
+/// NativeStruct is a protocol that indicates if the struct is a native `swift` struct
+/// since now we will be serializing native structs into the buffer.
+public protocol NativeStruct {}
+
+/// FlatbuffersInitializable is a protocol that allows any object to be
+/// Initialized from a ByteBuffer
+public protocol FlatbuffersInitializable {
+  /// Any flatbuffers object that confirms to this protocol is going to be
+  /// initializable through this initializer
+  init(_ bb: ByteBuffer, o: Int32)
+}
+
+/// FlatbufferObject structures all the Flatbuffers objects
+public protocol FlatBufferObject: FlatbuffersInitializable {
+  var __buffer: ByteBuffer! { get }
+}
+
+/// ``ObjectAPIPacker`` is a protocol that allows object to pack and unpack from a
+/// ``NativeObject`` to a flatbuffers Object and vice versa.
+public protocol ObjectAPIPacker {
+  /// associatedtype to the object that should be unpacked.
+  associatedtype T
+
+  /// ``pack(_:obj:)-3ptws`` tries to pacs the variables of a native Object into the `ByteBuffer` by using
+  /// a FlatBufferBuilder
+  /// - Parameters:
+  ///   - builder: FlatBufferBuilder that will host incoming data
+  ///   - obj: Object of associatedtype to the current implementer
+  ///
+  /// ``pack(_:obj:)-3ptws`` can be called by passing through an already initialized ``FlatBufferBuilder``
+  /// or it can be called by using the public API that will create a new ``FlatBufferBuilder``
+  static func pack(_ builder: inout FlatBufferBuilder, obj: inout T?) -> Offset
+
+  /// ``pack(_:obj:)-20ipk`` packs the variables of a native Object into the `ByteBuffer` by using
+  /// the FlatBufferBuilder
+  /// - Parameters:
+  ///   - builder: FlatBufferBuilder that will host incoming data
+  ///   - obj: Object of associatedtype to the current implementer
+  ///
+  /// ``pack(_:obj:)-20ipk`` can be called by passing through an already initialized ``FlatBufferBuilder``
+  /// or it can be called by using the public API that will create a new ``FlatBufferBuilder``
+  static func pack(_ builder: inout FlatBufferBuilder, obj: inout T) -> Offset
+
+  /// ``unpack()`` unpacks a ``FlatBuffers`` object into a Native swift object.
+  mutating func unpack() -> T
+}