Add a dev-tool subpackage

dev/format.sh

@@ -61,6 +61,7 @@ if "$lint"; then
     "${repo}/Tests" \
     "${repo}/Examples" \
     "${repo}/IntegrationTests/Benchmarks/Benchmarks/GRPCSwiftBenchmark" \
+    "${repo}/dev" \
     && SWIFT_FORMAT_RC=$? || SWIFT_FORMAT_RC=$?
 
   if [[ "${SWIFT_FORMAT_RC}" -ne 0 ]]; then
@@ -80,6 +81,7 @@ elif "$format"; then
     "${repo}/Tests" \
     "${repo}/Examples" \
     "${repo}/IntegrationTests/Benchmarks/Benchmarks/GRPCSwiftBenchmark" \
+    "${repo}/dev" \
     && SWIFT_FORMAT_RC=$? || SWIFT_FORMAT_RC=$?
 
   if [[ "${SWIFT_FORMAT_RC}" -ne 0 ]]; then

dev/grpc-dev-tool/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

dev/grpc-dev-tool/Package.swift

@@ -0,0 +1,36 @@
+// swift-tools-version:6.0
+/*
+ * Copyright 2025, gRPC 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 PackageDescription
+
+let package = Package(
+  name: "grpc-dev-tool",
+  platforms: [.macOS(.v15)],
+  dependencies: [
+    .package(path: "../.."),
+    .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0"),
+  ],
+  targets: [
+    .executableTarget(
+      name: "grpc-dev-tool",
+      dependencies: [
+        .product(name: "GRPCCodeGen", package: "grpc-swift"),
+        .product(name: "ArgumentParser", package: "swift-argument-parser"),
+      ]
+    )
+  ]
+)

dev/grpc-dev-tool/Sources/grpc-dev-tool/GRPCDevTool.swift

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2025, gRPC 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 ArgumentParser
+
+@main
+struct GRPCDevTool: AsyncParsableCommand {
+  static let configuration = CommandConfiguration(
+    commandName: "grpc-dev-tool",
+    subcommands: [GenerateJSON.self]
+  )
+}

dev/grpc-dev-tool/Sources/grpc-dev-tool/Subcommands/GenerateJSON/GRPCCodeGen+Conversions.swift

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2025, gRPC 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 GRPCCodeGen
+
+/// Creates a `ServiceDescriptor` from a JSON `ServiceSchema`.
+extension ServiceDescriptor {
+  init(_ service: ServiceSchema) {
+    self.init(
+      documentation: "",
+      name: .init(
+        identifyingName: service.name,
+        typeName: service.name,
+        propertyName: service.name
+      ),
+      methods: service.methods.map {
+        MethodDescriptor($0)
+      }
+    )
+  }
+}
+
+extension MethodDescriptor {
+  /// Creates a `MethodDescriptor` from a JSON `ServiceSchema.Method`.
+  init(_ method: ServiceSchema.Method) {
+    self.init(
+      documentation: "",
+      name: .init(
+        identifyingName: method.name,
+        typeName: method.name,
+        functionName: method.name
+      ),
+      isInputStreaming: method.kind.streamsInput,
+      isOutputStreaming: method.kind.streamsOutput,
+      inputType: method.input,
+      outputType: method.output
+    )
+  }
+}
+
+extension CodeGenerator.Config.AccessLevel {
+  init(_ level: GeneratorConfig.AccessLevel) {
+    switch level {
+    case .internal:
+      self = .internal
+    case .package:
+      self = .package
+    }
+  }
+}
+
+extension CodeGenerator.Config {
+  init(_ config: GeneratorConfig) {
+    self.init(
+      accessLevel: CodeGenerator.Config.AccessLevel(config.accessLevel),
+      accessLevelOnImports: config.accessLevelOnImports,
+      client: config.generateClient,
+      server: config.generateServer,
+      indentation: 2
+    )
+  }
+}

dev/grpc-dev-tool/Sources/grpc-dev-tool/Subcommands/GenerateJSON/GRPCDevUtils+GenerateJSON.swift

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2025, gRPC 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 ArgumentParser
+import Foundation
+
+struct GenerateJSON: ParsableCommand {
+  static let configuration = CommandConfiguration(
+    commandName: "generate-json",
+    subcommands: [Generate.self, DumpConfig.self],
+    defaultSubcommand: Generate.self
+  )
+}
+
+extension GenerateJSON {
+  struct Generate: ParsableCommand {
+    @Argument(help: "The path to a JSON input file.")
+    var input: String
+
+    func run() throws {
+      // Decode the input file.
+      let url = URL(filePath: self.input)
+      let data = try Data(contentsOf: url)
+      let json = JSONDecoder()
+      let config = try json.decode(JSONCodeGeneratorRequest.self, from: data)
+
+      // Generate the output and dump it to stdout.
+      let generator = JSONCodeGenerator()
+      let sourceFile = try generator.generate(request: config)
+      print(sourceFile.contents)
+    }
+  }
+}
+
+extension GenerateJSON {
+  struct DumpConfig: ParsableCommand {
+    func run() throws {
+      // Create a request for the code generator using all four RPC kinds.
+      var request = JSONCodeGeneratorRequest(
+        service: ServiceSchema(name: "Echo", methods: []),
+        config: .defaults
+      )
+
+      let methodNames = ["get", "collect", "expand", "update"]
+      let methodKinds: [ServiceSchema.Method.Kind] = [
+        .unary,
+        .clientStreaming,
+        .serverStreaming,
+        .bidiStreaming,
+      ]
+
+      for (name, kind) in zip(methodNames, methodKinds) {
+        let method = ServiceSchema.Method(
+          name: name,
+          input: "EchoRequest",
+          output: "EchoResponse",
+          kind: kind
+        )
+        request.service.methods.append(method)
+      }
+
+      // Encoding the config to JSON and dump it to stdout.
+      let encoder = JSONEncoder()
+      encoder.outputFormatting = [.prettyPrinted]
+      let data = try encoder.encode(request)
+      let json = String(decoding: data, as: UTF8.self)
+      print(json)
+    }
+  }
+}

dev/grpc-dev-tool/Sources/grpc-dev-tool/Subcommands/GenerateJSON/JSONCodeGenerator.swift

@@ -0,0 +1,119 @@
+/*
+ * Copyright 2025, gRPC 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 Foundation
+import GRPCCodeGen
+
+struct JSONCodeGenerator {
+  private static let currentYear: Int = {
+    let now = Date()
+    let year = Calendar.current.component(.year, from: Date())
+    return year
+  }()
+
+  private static let header = """
+    /*
+     * Copyright \(Self.currentYear), gRPC 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.
+     */
+    """
+
+  private static let jsonSerializers: String = """
+    fileprivate struct JSONSerializer<Message: Codable>: MessageSerializer {
+      fileprivate func serialize<Bytes: GRPCContiguousBytes>(
+        _ message: Message
+      ) throws -> Bytes {
+        do {
+          let jsonEncoder = JSONEncoder()
+          let data = try jsonEncoder.encode(message)
+          return Bytes(data)
+        } catch {
+          throw RPCError(
+            code: .internalError,
+            message: "Can't serialize message to JSON.",
+            cause: error
+          )
+        }
+      }
+    }
+
+    fileprivate struct JSONDeserializer<Message: Codable>: MessageDeserializer {
+      fileprivate func deserialize<Bytes: GRPCContiguousBytes>(
+        _ serializedMessageBytes: Bytes
+      ) throws -> Message {
+        do {
+          let jsonDecoder = JSONDecoder()
+          let data = serializedMessageBytes.withUnsafeBytes { Data($0) }
+          return try jsonDecoder.decode(Message.self, from: data)
+        } catch {
+          throw RPCError(
+            code: .internalError,
+            message: "Can't deserialize message from JSON.",
+            cause: error
+          )
+        }
+      }
+    }
+    """
+
+  func generate(request: JSONCodeGeneratorRequest) throws -> SourceFile {
+    let generator = CodeGenerator(config: CodeGenerator.Config(request.config))
+
+    let codeGenRequest = CodeGenerationRequest(
+      fileName: request.service.name + ".swift",
+      leadingTrivia: Self.header,
+      dependencies: [
+        Dependency(
+          item: Dependency.Item(kind: .struct, name: "Data"),
+          module: "Foundation",
+          accessLevel: .internal
+        ),
+        Dependency(
+          item: Dependency.Item(kind: .class, name: "JSONEncoder"),
+          module: "Foundation",
+          accessLevel: .internal
+        ),
+        Dependency(
+          item: Dependency.Item(kind: .class, name: "JSONDecoder"),
+          module: "Foundation",
+          accessLevel: .internal
+        ),
+      ],
+      services: [ServiceDescriptor(request.service)],
+      makeSerializerCodeSnippet: { type in "JSONSerializer<\(type)>()" },
+      makeDeserializerCodeSnippet: { type in "JSONDeserializer<\(type)>()" }
+    )
+
+    var sourceFile = try generator.generate(codeGenRequest)
+
+    // Insert a fileprivate serializer/deserializer for JSON at the bottom of each file.
+    sourceFile.contents += "\n\n"
+    sourceFile.contents += Self.jsonSerializers
+
+    return sourceFile
+  }
+}