Add code gen config for the module name (#2201)

Modifications:

- Add config to the code generator allowing a different module name to
be specified.
- Remove unused code

Result:

The grpc module name can be specified in generated code

Author: glbrntt

Diff for: Sources/GRPCCodeGen/CodeGenerator.swift

@@ -40,6 +40,8 @@ public struct CodeGenerator: Sendable {
     public var client: Bool
     /// Whether or not server code should be generated.
     public var server: Bool
+    /// The name of the core gRPC module.
+    public var grpcCoreModuleName: String
 
     /// Creates a new configuration.
     ///
@@ -61,6 +63,7 @@ public struct CodeGenerator: Sendable {
       self.indentation = indentation
       self.client = client
       self.server = server
+      self.grpcCoreModuleName = "GRPCCore"
     }
 
     /// The possible access levels for the generated code.
@@ -96,7 +99,8 @@ public struct CodeGenerator: Sendable {
       accessLevel: self.config.accessLevel,
       accessLevelOnImports: self.config.accessLevelOnImports,
       client: self.config.client,
-      server: self.config.server
+      server: self.config.server,
+      grpcCoreModuleName: self.config.grpcCoreModuleName
     )
 
     let sourceFile = try textRenderer.render(structured: structuredSwiftRepresentation)

Diff for: Sources/GRPCCodeGen/Internal/Namer.swift

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2024, 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.
+ */
+
+package struct Namer: Sendable, Hashable {
+  let grpcCore: String
+
+  package init(grpcCore: String = "GRPCCore") {
+    self.grpcCore = grpcCore
+  }
+
+  private func grpcCore(_ typeName: String) -> ExistingTypeDescription {
+    return .member([self.grpcCore, typeName])
+  }
+
+  private func requestResponse(
+    for type: String?,
+    isRequest: Bool,
+    isStreaming: Bool,
+    isClient: Bool
+  ) -> ExistingTypeDescription {
+    let prefix = isStreaming ? "Streaming" : ""
+    let peer = isClient ? "Client" : "Server"
+    let kind = isRequest ? "Request" : "Response"
+    let baseType = self.grpcCore(prefix + peer + kind)
+
+    if let type = type {
+      return .generic(wrapper: baseType, wrapped: .member(type))
+    } else {
+      return baseType
+    }
+  }
+
+  func literalNamespacedType(_ type: String) -> String {
+    return self.grpcCore + "." + type
+  }
+
+  func serverRequest(forType type: String?, isStreaming: Bool) -> ExistingTypeDescription {
+    return self.requestResponse(
+      for: type,
+      isRequest: true,
+      isStreaming: isStreaming,
+      isClient: false
+    )
+  }
+
+  func serverResponse(forType type: String?, isStreaming: Bool) -> ExistingTypeDescription {
+    return self.requestResponse(
+      for: type,
+      isRequest: false,
+      isStreaming: isStreaming,
+      isClient: false
+    )
+  }
+
+  func clientRequest(forType type: String?, isStreaming: Bool) -> ExistingTypeDescription {
+    return self.requestResponse(
+      for: type,
+      isRequest: true,
+      isStreaming: isStreaming,
+      isClient: true
+    )
+  }
+
+  func clientResponse(forType type: String?, isStreaming: Bool) -> ExistingTypeDescription {
+    return self.requestResponse(
+      for: type,
+      isRequest: false,
+      isStreaming: isStreaming,
+      isClient: true
+    )
+  }
+
+  var serverContext: ExistingTypeDescription {
+    self.grpcCore("ServerContext")
+  }
+
+  func rpcRouter(genericOver type: String) -> ExistingTypeDescription {
+    .generic(wrapper: self.grpcCore("RPCRouter"), wrapped: .member(type))
+  }
+
+  var serviceDescriptor: ExistingTypeDescription {
+    self.grpcCore("ServiceDescriptor")
+  }
+
+  var methodDescriptor: ExistingTypeDescription {
+    self.grpcCore("MethodDescriptor")
+  }
+
+  func serializer(forType type: String) -> ExistingTypeDescription {
+    .generic(wrapper: self.grpcCore("MessageSerializer"), wrapped: .member(type))
+  }
+
+  func deserializer(forType type: String) -> ExistingTypeDescription {
+    .generic(wrapper: self.grpcCore("MessageDeserializer"), wrapped: .member(type))
+  }
+
+  func rpcWriter(forType type: String) -> ExistingTypeDescription {
+    .generic(wrapper: self.grpcCore("RPCWriter"), wrapped: .member(type))
+  }
+
+  func rpcAsyncSequence(forType type: String) -> ExistingTypeDescription {
+    .generic(
+      wrapper: self.grpcCore("RPCAsyncSequence"),
+      wrapped: .member(type),
+      .any(.member(["Swift", "Error"]))
+    )
+  }
+
+  var callOptions: ExistingTypeDescription {
+    self.grpcCore("CallOptions")
+  }
+
+  var metadata: ExistingTypeDescription {
+    self.grpcCore("Metadata")
+  }
+
+  func grpcClient(genericOver transport: String) -> ExistingTypeDescription {
+    .generic(wrapper: self.grpcCore("GRPCClient"), wrapped: [.member(transport)])
+  }
+}