[Swift] Adds GRPC to Swift (#5758)

* Adds the basic structure for required to add grpc support

Added the message implementation

Updated the code to confirm to the protocol flatbuffersobject

Adds an example for Swift flatbuffers GRPC

Started implementing the swift GRPC code Gen

Generator generates protocols now

Fixing ci issues

Migrated the logic to use grpc_generator::File instead of string

Refactored swift project

Implemented GRPC in swift

Finished implementing GRPC in swift

Fixes issues

Adds contiguousBytes initializer to swift

Adds documentation + fixes buffer nameing in tables + structs

Adds documentation + fixes buffer nameing in tables + structs

Updated tests

* Updated version

tests/FlatBuffers.GRPC.Swift/Sources/Model/greeter.fbs

@@ -0,0 +1,17 @@
+table HelloReply {
+  message:string;
+}
+
+table HelloRequest {
+  name:string;
+}
+
+table ManyHellosRequest {
+  name:string;
+  num_greetings:int;
+}
+
+rpc_service Greeter {
+  SayHello(HelloRequest):HelloReply;
+  SayManyHellos(ManyHellosRequest):HelloReply (streaming: "server");
+}

tests/FlatBuffers.GRPC.Swift/Sources/Model/greeter.grpc.swift

@@ -0,0 +1,73 @@
+// Generated GRPC code for FlatBuffers swift!
+/// The following code is generated by the Flatbuffers library which might not be in sync with grpc-swift
+/// in case of an issue please open github issue, though it would be maintained
+import Foundation
+import GRPC
+import NIO
+import NIOHTTP1
+import FlatBuffers
+
+public protocol GRPCFlatBufPayload: GRPCPayload, FlatBufferGRPCMessage {}
+public extension GRPCFlatBufPayload {
+    init(serializedByteBuffer: inout NIO.ByteBuffer) throws {
+        self.init(byteBuffer: FlatBuffers.ByteBuffer(contiguousBytes: serializedByteBuffer.readableBytesView, count: serializedByteBuffer.readableBytes))
+    }
+    func serialize(into buffer: inout NIO.ByteBuffer) throws {
+        let buf = UnsafeRawBufferPointer(start: self.rawPointer, count: Int(self.size))
+        buffer.writeBytes(buf)
+    }
+}
+extension Message: GRPCFlatBufPayload {}
+
+/// Usage: instantiate GreeterServiceClient, then call methods of this protocol to make API calls.
+public protocol GreeterService {
+	 func SayHello(_ request: Message<HelloRequest>, callOptions: CallOptions?) -> UnaryCall<Message<HelloRequest>,Message<HelloReply>>
+	 func SayManyHellos(_ request: Message<ManyHellosRequest>, callOptions: CallOptions?, handler: @escaping (Message<HelloReply>) -> Void) -> ServerStreamingCall<Message<ManyHellosRequest>, Message<HelloReply>>
+}
+
+public final class GreeterServiceClient: GRPCClient, GreeterService {
+	public let connection: ClientConnection
+	public var defaultCallOptions: CallOptions
+
+	public init(connection: ClientConnection, defaultCallOptions: CallOptions = CallOptions()) {
+		self.connection = connection
+		self.defaultCallOptions = defaultCallOptions
+	}
+
+	public func SayHello(_ request: Message<HelloRequest>, callOptions: CallOptions? = nil) -> UnaryCall<Message<HelloRequest>,Message<HelloReply>> {
+		return self.makeUnaryCall(path: "/Greeter/SayHello", request: request, callOptions: callOptions ?? self.defaultCallOptions)
+	}
+
+	public func SayManyHellos(_ request: Message<ManyHellosRequest>, callOptions: CallOptions? = nil, handler: @escaping (Message<HelloReply>) -> Void) -> ServerStreamingCall<Message<ManyHellosRequest>, Message<HelloReply>> {
+		return self.makeServerStreamingCall(path: "/Greeter/SayManyHellos", request: request, callOptions: callOptions ?? self.defaultCallOptions, handler: handler)
+	}
+}
+
+public protocol GreeterProvider: CallHandlerProvider {
+	func SayHello(_ request: Message<HelloRequest>, context: StatusOnlyCallContext) -> EventLoopFuture<Message<HelloReply>>
+	func SayManyHellos(request: Message<ManyHellosRequest>, context: StreamingResponseCallContext<Message<HelloReply>>) -> EventLoopFuture<GRPCStatus>
+}
+
+public extension GreeterProvider {
+	var serviceName: String { return "Greeter" }
+	func handleMethod(_ methodName: String, callHandlerContext: CallHandlerContext) -> GRPCCallHandler? {
+		switch methodName {
+		case "SayHello":
+		return UnaryCallHandler(callHandlerContext: callHandlerContext) { context in
+			return { request in
+				self.SayHello(request, context: context)
+			}
+		}
+		case "SayManyHellos":
+		return ServerStreamingCallHandler(callHandlerContext: callHandlerContext) { context in
+			return { request in
+				self.SayManyHellos(request: request, context: context)
+			}
+		}
+		default: return nil;
+		}
+	}
+
+}
+
+

tests/FlatBuffers.GRPC.Swift/Sources/Model/greeter_generated.swift

@@ -0,0 +1,80 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+import FlatBuffers
+
+public struct HelloReply: FlatBufferObject {
+
+	static func validateVersion() { FlatBuffersVersion_1_11_1() }
+	public var __buffer: ByteBuffer! { return _accessor.bb }
+
+	private var _accessor: Table
+	public static func getRootAsHelloReply(bb: ByteBuffer) -> HelloReply { return HelloReply(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
+
+	private init(_ t: Table) { _accessor = t }
+	public init(_ bb: ByteBuffer, o: Int32) { _accessor = Table(bb: bb, position: o) }
+
+	public var message: String? { let o = _accessor.offset(4); return o == 0 ? nil : _accessor.string(at: o) }
+	public var messageSegmentArray: [UInt8]? { return _accessor.getVector(at: 4) }
+	public static func startHelloReply(_ fbb: FlatBufferBuilder) -> UOffset { fbb.startTable(with: 1) }
+	public static func add(message: Offset<String>, _ fbb: FlatBufferBuilder) { fbb.add(offset: message, at: 0)  }
+	public static func endHelloReply(_ fbb: FlatBufferBuilder, start: UOffset) -> Offset<UOffset> { let end = Offset<UOffset>(offset: fbb.endTable(at: start)); return end }
+	public static func createHelloReply(_ fbb: FlatBufferBuilder,
+		offsetOfMessage message: Offset<String> = Offset()) -> Offset<UOffset> {
+		let __start = HelloReply.startHelloReply(fbb)
+		HelloReply.add(message: message, fbb)
+		return HelloReply.endHelloReply(fbb, start: __start)
+	}
+}
+
+public struct HelloRequest: FlatBufferObject {
+
+	static func validateVersion() { FlatBuffersVersion_1_11_1() }
+	public var __buffer: ByteBuffer! { return _accessor.bb }
+
+	private var _accessor: Table
+	public static func getRootAsHelloRequest(bb: ByteBuffer) -> HelloRequest { return HelloRequest(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
+
+	private init(_ t: Table) { _accessor = t }
+	public init(_ bb: ByteBuffer, o: Int32) { _accessor = Table(bb: bb, position: o) }
+
+	public var name: String? { let o = _accessor.offset(4); return o == 0 ? nil : _accessor.string(at: o) }
+	public var nameSegmentArray: [UInt8]? { return _accessor.getVector(at: 4) }
+	public static func startHelloRequest(_ fbb: FlatBufferBuilder) -> UOffset { fbb.startTable(with: 1) }
+	public static func add(name: Offset<String>, _ fbb: FlatBufferBuilder) { fbb.add(offset: name, at: 0)  }
+	public static func endHelloRequest(_ fbb: FlatBufferBuilder, start: UOffset) -> Offset<UOffset> { let end = Offset<UOffset>(offset: fbb.endTable(at: start)); return end }
+	public static func createHelloRequest(_ fbb: FlatBufferBuilder,
+		offsetOfName name: Offset<String> = Offset()) -> Offset<UOffset> {
+		let __start = HelloRequest.startHelloRequest(fbb)
+		HelloRequest.add(name: name, fbb)
+		return HelloRequest.endHelloRequest(fbb, start: __start)
+	}
+}
+
+public struct ManyHellosRequest: FlatBufferObject {
+
+	static func validateVersion() { FlatBuffersVersion_1_11_1() }
+	public var __buffer: ByteBuffer! { return _accessor.bb }
+
+	private var _accessor: Table
+	public static func getRootAsManyHellosRequest(bb: ByteBuffer) -> ManyHellosRequest { return ManyHellosRequest(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
+
+	private init(_ t: Table) { _accessor = t }
+	public init(_ bb: ByteBuffer, o: Int32) { _accessor = Table(bb: bb, position: o) }
+
+	public var name: String? { let o = _accessor.offset(4); return o == 0 ? nil : _accessor.string(at: o) }
+	public var nameSegmentArray: [UInt8]? { return _accessor.getVector(at: 4) }
+	public var numGreetings: Int32 { let o = _accessor.offset(6); return o == 0 ? 0 : _accessor.readBuffer(of: Int32.self, at: o) }
+	public static func startManyHellosRequest(_ fbb: FlatBufferBuilder) -> UOffset { fbb.startTable(with: 2) }
+	public static func add(name: Offset<String>, _ fbb: FlatBufferBuilder) { fbb.add(offset: name, at: 0)  }
+	public static func add(numGreetings: Int32, _ fbb: FlatBufferBuilder) { fbb.add(element: numGreetings, def: 0, at: 1) }
+	public static func endManyHellosRequest(_ fbb: FlatBufferBuilder, start: UOffset) -> Offset<UOffset> { let end = Offset<UOffset>(offset: fbb.endTable(at: start)); return end }
+	public static func createManyHellosRequest(_ fbb: FlatBufferBuilder,
+		offsetOfName name: Offset<String> = Offset(),
+		numGreetings: Int32 = 0) -> Offset<UOffset> {
+		let __start = ManyHellosRequest.startManyHellosRequest(fbb)
+		ManyHellosRequest.add(name: name, fbb)
+		ManyHellosRequest.add(numGreetings: numGreetings, fbb)
+		return ManyHellosRequest.endManyHellosRequest(fbb, start: __start)
+	}
+}
+