Created the CodeGenerationRequest

Package.swift

@@ -87,6 +87,7 @@ extension Target.Dependency {
   static let grpc: Self = .target(name: grpcTargetName)
   static let cgrpcZlib: Self = .target(name: cgrpcZlibTargetName)
   static let protocGenGRPCSwift: Self = .target(name: "protoc-gen-grpc-swift")
+  static let grpcCodeGen: Self = .target(name: "GRPCCodeGen")
 
   // Target dependencies; internal
   static let grpcSampleData: Self = .target(name: "GRPCSampleData")
@@ -477,6 +478,11 @@ extension Target {
       .copy("Generated")
     ]
   )
+
+  static let grpcCodeGen: Target = .target(
+    name: "GRPCCodeGen",
+    path: "Sources/GRPCCodeGen"
+  )
 }
 
 // MARK: - Products

Sources/GRPCCodeGen/CodeGenerationRequest.swift

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2023, 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.
+ */
+
+/// Describes the services, dependencies and trivia from an IDL file,
+/// and the IDL itself through its specific serializer and deserializer.
+public struct CodeGenerationRequest {
+  /// The name of the source file containing the IDL. It contains the file's extension.
+  var fileName: String
+
+  /// The Swift imports that the generated file should depend on.
+  ///
+  /// - SeeAlso: ``Dependency``.
+  var dependencies: [Dependency] = []
+
+  /// Any comments at the top of the file including documentation and copyright headers.
+  var leadingTrivia: String
+
+  /// An array of service descriptors.
+  ///
+  /// - SeeAlso: ``ServiceDescriptor``.
+  var services: [ServiceDescriptor] = []
+
+  /// Closure that receives the message type and returns a string representation of the
+  /// serializer call for that message type. The result is inserted in the string representing
+  /// the generated code, where clients or servers serialize their output.
+  ///
+  /// For example: `lookupSerializer: {"ProtobufSerializer<\($0)>()"}`.
+  var lookupSerializer: (String) -> String
+
+  /// Closure that receives the message type and returns a string representation of the
+  /// deserializer call for that message type. The result is inserted in the string representing
+  /// the generated code, where clients or servers deserialize their input.
+  ///
+  /// For example: `lookupDeserializer: {"ProtobufDeserializer<\($0)>()"}`.
+  var lookupDeserializer: (String) -> String
+
+  /// Represents an import: a module or a specific item from a module.
+  public struct Dependency {
+    /// If the dependency is an item, the property's value is the item representation.
+    /// If the dependency is a module, this property is nil.
+    var item: Item? = nil
+
+    /// The name of the imported module or of the module an item is imported from.
+    var module: String
+
+    /// Represents an item imported from a module.
+    public struct Item {
+      /// The keyword that specifies the item's kind (e.g.  `func`, `struct`).
+      var kind: Kind
+
+      /// The imported item's symbol / name.
+      var name: String
+
+      /// Represents the imported item's kind.
+      public struct Kind {
+        /// One of the possible keywords associated to the imported item's kind.
+        var keyword: Keyword
+
+        public init(_ keyword: Keyword) {
+          self.keyword = keyword
+        }
+
+        internal enum Keyword {
+          case `typealias`
+          case `struct`
+          case `class`
+          case `enum`
+          case `protocol`
+          case `let`
+          case `var`
+          case `func`
+        }
+      }
+    }
+  }
+
+  /// Represents a service described in an IDL file.
+  struct ServiceDescriptor {
+    /// Documentation from comments above the IDL service description.
+    var documentation: String
+
+    /// Service name.
+    var name: String
+
+    /// Array of descriptors for the methods of a service.
+    ///
+    /// - SeeAlso: ``MethodDescriptor``.
+    var methods: [MethodDescriptor] = []
+
+    /// Represents a method described in an IDL file.
+    struct MethodDescriptor {
+      /// Documentation from comments above the IDL method description.
+      var documentation: String
+
+      /// Method name.
+      var name: String
+
+      /// Identifies if the method is input streaming.
+      var isInputStreaming: Bool
+
+      /// Identifies if the method is output streaming.
+      var isOutputStreaming: Bool
+
+      /// The generated input type for the described method.
+      var inputType: String
+
+      /// The generated output type for the described method.
+      var ouputType: String
+    }
+  }
+}