Make swift_grpc_library available to Bazel users.

RELNOTES: The `swift_grpc_library` rule has been added, which can be used to generate Swift code for gRPC clients/servers. Necessary dependencies (gRPC and gRPC-Swift) are automatically added to the workspace.

The `com_github_apple_swift_swift_protobuf` repository was incorrectly named; it should have been `com_github_apple_swift_protobuf` (note the duplicated "swift"). This version changes it to the correct name. If you have any explicit dependencies on `@com_github_apple_swift_swift_protobuf//:SwiftProtobuf`, you will need to change them to `@com_github_apple_swift_protobuf//:SwiftProtobuf`.

PiperOrigin-RevId: 241978971

examples/xplatform/grpc/BUILD

@@ -0,0 +1,73 @@
+# This example illustrates how to use `swift_grpc_library` along with
+# `swift_proto_library` to build Swift binaries for a gRPC server and
+# client.
+#
+# To explore this example:
+#
+# 1.  Build both the `:echo_server` and `:echo_client` targets in this package.
+# 2.  Run the `echo_server` binary in the background of a terminal. It should
+#     print a message indicating that the service has started.
+# 3.  Run the `echo_client` binary in the same terminal. It will send a request
+#     to this service and then print the response that it received.
+
+load(
+    "//swift:swift.bzl",
+    "swift_binary",
+    "swift_grpc_library",
+    "swift_proto_library",
+    "swift_test",
+)
+
+licenses(["notice"])
+
+proto_library(
+    name = "echo_proto",
+    srcs = ["echo.proto"],
+)
+
+swift_proto_library(
+    name = "echo_proto_swift",
+    deps = [":echo_proto"],
+)
+
+swift_grpc_library(
+    name = "echo_client_services_swift",
+    srcs = [":echo_proto"],
+    flavor = "client",
+    deps = [":echo_proto_swift"],
+)
+
+swift_grpc_library(
+    name = "echo_client_test_stubs_swift",
+    srcs = [":echo_proto"],
+    flavor = "client_stubs",
+    deps = [":echo_client_services_swift"],
+)
+
+swift_grpc_library(
+    name = "echo_server_services_swift",
+    srcs = [":echo_proto"],
+    flavor = "server",
+    deps = [":echo_proto_swift"],
+)
+
+swift_binary(
+    name = "echo_server",
+    srcs = ["server_main.swift"],
+    deps = [":echo_server_services_swift"],
+)
+
+swift_test(
+    name = "echo_client_unit_test",
+    srcs = ["client_unit_test.swift"],
+    deps = [
+        ":echo_client_services_swift",
+        ":echo_client_test_stubs_swift",
+    ],
+)
+
+swift_binary(
+    name = "echo_client",
+    srcs = ["client_main.swift"],
+    deps = [":echo_client_services_swift"],
+)

examples/xplatform/grpc/client_main.swift

@@ -0,0 +1,27 @@
+// Copyright 2019 The Bazel Authors. 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.
+
+import examples_xplatform_grpc_echo_proto
+import examples_xplatform_grpc_echo_client_services_swift
+
+// Initialize the client using the same address the server is started on.
+let client = EchoServiceServiceClient(address: "0.0.0.0:9000", secure: false)
+
+// Construct a request to the echo service.
+var request = EchoRequest()
+request.contents = "Hello, world!"
+
+// Make the remote method call and print the response we receive.
+let response = try client.echo(request)
+print(response.contents)

examples/xplatform/grpc/client_unit_test.swift

@@ -0,0 +1,34 @@
+// Copyright 2019 The Bazel Authors. 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.
+
+import XCTest
+import examples_xplatform_grpc_echo_client_services_swift
+import examples_xplatform_grpc_echo_proto
+
+@testable import examples_xplatform_grpc_echo_client_test_stubs_swift
+
+class ClientUnitTest {
+
+  func testSynchronousCall() throws {
+    let client: EchoServiceService = {
+      let stub = EchoServiceServiceTestStub()
+      stub.echoResponses.append(EchoResponse.with { response in
+        response.contents = "Hello"
+      })
+      return stub
+   }()
+   let response = try client.echo(EchoRequest())
+   XCTAssertEqual(response.contents, "Hello")
+  }
+}

examples/xplatform/grpc/echo.proto

@@ -0,0 +1,27 @@
+// Copyright 2019 The Bazel Authors. 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.
+
+syntax = "proto3";
+
+service EchoService {
+  rpc Echo(EchoRequest) returns (EchoResponse);
+}
+
+message EchoRequest {
+  string contents = 1;
+}
+
+message EchoResponse {
+  string contents = 1;
+}

examples/xplatform/grpc/server_main.swift

@@ -0,0 +1,44 @@
+// Copyright 2019 The Bazel Authors. 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.
+
+import Dispatch
+import SwiftGRPC
+import examples_xplatform_grpc_echo_proto
+import examples_xplatform_grpc_echo_server_services_swift
+
+/// Concrete implementation of the `EchoService` service definition.
+class EchoProvider: EchoServiceProvider {
+
+  /// Called when the server receives a request for the `EchoService.Echo` method.
+  ///
+  /// - Parameters:
+  ///   - request: The message containing the request parameters.
+  ///   - session: Information about the current session.
+  /// - Returns: The response that will be sent back to the client.
+  /// - Throws: If an error occurs while processing the request.
+  func echo(request: EchoRequest, session: EchoServiceEchoSession) throws -> EchoResponse {
+    var response = EchoResponse()
+    response.contents = "You sent: \(request.contents)"
+    return response
+  }
+}
+
+// Initialize and start the service.
+let address = "0.0.0.0:9000"
+let server = ServiceServer(address: address, serviceProviders: [EchoProvider()])
+print("Starting server in \(address)")
+server.start()
+
+// Park the main thread so that the server continues to run and listen for requests.
+dispatchMain()