Support for C++ files generated by protobuf/grpc (#3640)

* Support for C++ files generated by protobuf/grpc

This changeset includes a sample generated file.

[grpc](http://grpc.io) is a high performance, open-source universal
RPC framework.

* Account for older gRPC protobuf plugin message

lib/linguist/generated.rb

@@ -81,7 +81,8 @@ module Linguist
       generated_grammarkit? ||
       generated_roxygen2? ||
       generated_jison? ||
-      generated_yarn_lock?
+      generated_yarn_lock? ||
+      generated_grpc_cpp?
     end
 
     # Internal: Is the blob an Xcode file?
@@ -489,5 +490,18 @@ module Linguist
       return false unless lines.count > 0
       return lines[0].include?("# THIS IS AN AUTOGENERATED FILE")
     end
+
+    # Internal: Is this a protobuf/grpc-generated C++ file?
+    #
+    # A generated file contains:
+    # // Generated by the gRPC C++ plugin.
+    # on the first line.
+    #
+    # Return true or false
+    def generated_grpc_cpp?
+      return false unless %w{.cpp .hpp .h .cc}.include? extname
+      return false unless lines.count > 1
+      return lines[0].start_with?("// Generated by the gRPC")
+    end
   end
 end

samples/C++/grpc.pb.cc

@@ -0,0 +1,2 @@
+// Generated by the gRPC protobuf plugin.
+// If you make any local change, they will be lost.

samples/C++/hello.grpc.pb.h

@@ -0,0 +1,125 @@
+// Generated by the gRPC C++ plugin.
+// If you make any local change, they will be lost.
+// source: hello.proto
+#ifndef GRPC_hello_2eproto__INCLUDED
+#define GRPC_hello_2eproto__INCLUDED
+
+#include "hello.pb.h"
+
+#include <grpc++/impl/codegen/async_stream.h>
+#include <grpc++/impl/codegen/async_unary_call.h>
+#include <grpc++/impl/codegen/method_handler_impl.h>
+#include <grpc++/impl/codegen/proto_utils.h>
+#include <grpc++/impl/codegen/rpc_method.h>
+#include <grpc++/impl/codegen/service_type.h>
+#include <grpc++/impl/codegen/status.h>
+#include <grpc++/impl/codegen/stub_options.h>
+#include <grpc++/impl/codegen/sync_stream.h>
+
+namespace grpc {
+class CompletionQueue;
+class Channel;
+class RpcService;
+class ServerCompletionQueue;
+class ServerContext;
+}  // namespace grpc
+
+class HelloService final {
+ public:
+  class StubInterface {
+   public:
+    virtual ~StubInterface() {}
+    virtual ::grpc::Status SayHello(::grpc::ClientContext* context, const ::HelloRequest& request, ::HelloResponse* response) = 0;
+    std::unique_ptr< ::grpc::ClientAsyncResponseReaderInterface< ::HelloResponse>> AsyncSayHello(::grpc::ClientContext* context, const ::HelloRequest& request, ::grpc::CompletionQueue* cq) {
+      return std::unique_ptr< ::grpc::ClientAsyncResponseReaderInterface< ::HelloResponse>>(AsyncSayHelloRaw(context, request, cq));
+    }
+  private:
+    virtual ::grpc::ClientAsyncResponseReaderInterface< ::HelloResponse>* AsyncSayHelloRaw(::grpc::ClientContext* context, const ::HelloRequest& request, ::grpc::CompletionQueue* cq) = 0;
+  };
+  class Stub final : public StubInterface {
+   public:
+    Stub(const std::shared_ptr< ::grpc::ChannelInterface>& channel);
+    ::grpc::Status SayHello(::grpc::ClientContext* context, const ::HelloRequest& request, ::HelloResponse* response) override;
+    std::unique_ptr< ::grpc::ClientAsyncResponseReader< ::HelloResponse>> AsyncSayHello(::grpc::ClientContext* context, const ::HelloRequest& request, ::grpc::CompletionQueue* cq) {
+      return std::unique_ptr< ::grpc::ClientAsyncResponseReader< ::HelloResponse>>(AsyncSayHelloRaw(context, request, cq));
+    }
+
+   private:
+    std::shared_ptr< ::grpc::ChannelInterface> channel_;
+    ::grpc::ClientAsyncResponseReader< ::HelloResponse>* AsyncSayHelloRaw(::grpc::ClientContext* context, const ::HelloRequest& request, ::grpc::CompletionQueue* cq) override;
+    const ::grpc::RpcMethod rpcmethod_SayHello_;
+  };
+  static std::unique_ptr<Stub> NewStub(const std::shared_ptr< ::grpc::ChannelInterface>& channel, const ::grpc::StubOptions& options = ::grpc::StubOptions());
+
+  class Service : public ::grpc::Service {
+   public:
+    Service();
+    virtual ~Service();
+    virtual ::grpc::Status SayHello(::grpc::ServerContext* context, const ::HelloRequest* request, ::HelloResponse* response);
+  };
+  template <class BaseClass>
+  class WithAsyncMethod_SayHello : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithAsyncMethod_SayHello() {
+      ::grpc::Service::MarkMethodAsync(0);
+    }
+    ~WithAsyncMethod_SayHello() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status SayHello(::grpc::ServerContext* context, const ::HelloRequest* request, ::HelloResponse* response) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    void RequestSayHello(::grpc::ServerContext* context, ::HelloRequest* request, ::grpc::ServerAsyncResponseWriter< ::HelloResponse>* response, ::grpc::CompletionQueue* new_call_cq, ::grpc::ServerCompletionQueue* notification_cq, void *tag) {
+      ::grpc::Service::RequestAsyncUnary(0, context, request, response, new_call_cq, notification_cq, tag);
+    }
+  };
+  typedef WithAsyncMethod_SayHello<Service > AsyncService;
+  template <class BaseClass>
+  class WithGenericMethod_SayHello : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithGenericMethod_SayHello() {
+      ::grpc::Service::MarkMethodGeneric(0);
+    }
+    ~WithGenericMethod_SayHello() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable synchronous version of this method
+    ::grpc::Status SayHello(::grpc::ServerContext* context, const ::HelloRequest* request, ::HelloResponse* response) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+  };
+  template <class BaseClass>
+  class WithStreamedUnaryMethod_SayHello : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithStreamedUnaryMethod_SayHello() {
+      ::grpc::Service::MarkMethodStreamed(0,
+        new ::grpc::StreamedUnaryHandler< ::HelloRequest, ::HelloResponse>(std::bind(&WithStreamedUnaryMethod_SayHello<BaseClass>::StreamedSayHello, this, std::placeholders::_1, std::placeholders::_2)));
+    }
+    ~WithStreamedUnaryMethod_SayHello() override {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable regular version of this method
+    ::grpc::Status SayHello(::grpc::ServerContext* context, const ::HelloRequest* request, ::HelloResponse* response) final override {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    // replace default version of method with streamed unary
+    virtual ::grpc::Status StreamedSayHello(::grpc::ServerContext* context, ::grpc::ServerUnaryStreamer< ::HelloRequest,::HelloResponse>* server_unary_streamer) = 0;
+  };
+  typedef WithStreamedUnaryMethod_SayHello<Service > StreamedUnaryService;
+  typedef Service SplitStreamedService;
+  typedef WithStreamedUnaryMethod_SayHello<Service > StreamedService;
+};
+
+
+#endif  // GRPC_hello_2eproto__INCLUDED
+

test/test_blob.rb

@@ -235,6 +235,10 @@ class TestBlob < Minitest::Test
 
     # Racc-generated Ruby
     assert sample_blob_memory("Ruby/racc.rb").generated?
+
+    # protobuf/grpc-plugin C++
+    assert sample_blob_memory("C++/hello.grpc.pb.h").generated?
+    assert sample_blob_memory("C++/grpc.pb.cc").generated?
   end
 
   def test_vendored