Brought CodeRenderer from OpenAPI Generator. (#1728)

Motivation:

Provides an API which takes Structured Swift Representation of a file and generates an object containing the generated code as a String.

Modifications:

- Brought over RendererProtocol and TextBasedRenderer.
- Brought over unit tests in Test_TextBasedRenderer.
- Fixed TypeName bugs that produced errors while building.

Result:

The CodeGenLib will have a code renderer that transforms `StructuredSwiftRepresentation` into `SourceFile`.

Author: stefanadranca

NOTICES.txt

@@ -61,7 +61,8 @@ This product uses derivations of swift-extras/swift-extras-base64 'Base64.swift'
 ---
 
 This product uses derivations of apple/swift-openapi-generator 'StructuredSwiftRepresentation.swift',
-'TypeName.swift', 'TypeUsage.swift' and 'Builtins.swift'.
+'TypeName.swift', 'TypeUsage.swift', 'Builtins.swift', 'RendererProtocol.swift', 'TextBasedProtocol',
+and 'Test_TextBasedRenderer'.
 
     * LICENSE (Apache License 2.0):
       * https://github.com/apple/swift-openapi-generator/blob/main/LICENSE.txt

Package.swift

@@ -216,7 +216,7 @@ extension Target {
       .nioEmbedded,
       .nioTransportServices,
       .logging,
-      .reflectionService,
+      .reflectionService
     ].appending(
       .nioSSL, if: includeNIOSSL
     ),
@@ -235,6 +235,13 @@ extension Target {
     ]
   )
 
+  static let grpcCodeGenTests: Target = .testTarget(
+    name: "GRPCCodeGenTests",
+    dependencies: [
+      .grpcCodeGen
+    ]
+  )
+  
   static let interopTestModels: Target = .target(
     name: "GRPCInteroperabilityTestModels",
     dependencies: [
@@ -559,9 +566,11 @@ let package = Package(
 
     // v2
     .grpcCore,
+    .grpcCodeGen,
 
     // v2 tests
     .grpcCoreTests,
+    .grpcCodeGenTests
   ]
 )
 

Sources/GRPCCodeGen/Internal/Renderer/RendererProtocol.swift

@@ -0,0 +1,44 @@
+/*
+ * 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.
+ */
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftOpenAPIGenerator open source project
+//
+// Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// An object that renders structured Swift representations
+/// into Swift files.
+///
+/// Rendering is the last phase of the generator pipeline.
+protocol RendererProtocol {
+
+  /// Renders the specified structured code into a raw Swift file.
+  /// - Parameters:
+  ///   - code: A structured representation of the Swift code.
+  ///   - config: The configuration of the generator.
+  ///   - diagnostics: The collector to which to emit diagnostics.
+  /// - Returns: A raw file with Swift contents.
+  /// - Throws: An error if an issue occurs during rendering.
+  func render(structured code: StructuredSwiftRepresentation) throws -> SourceFile
+}