Support for Golang GRPC (Experimental) (#4082)

* support for grpc golang

* refactored grpc go generator

* added grpc-go test and refactored

* refactored idl_gen_grpc.cpp

* fixed grpc generate method name

* refactored flatc and fixed line length issue

* added codec to go lib and fixed formatting issues

* fixed spacing issues

grpc/src/compiler/go_generator.h

@@ -0,0 +1,61 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_COMPILER_GO_GENERATOR_H
+#define GRPC_INTERNAL_COMPILER_GO_GENERATOR_H
+
+//go generator is used to generate GRPC code for serialization system, such as flatbuffers
+#include <memory>
+#include <vector>
+
+#include "src/compiler/schema_interface.h"
+
+namespace grpc_go_generator {
+
+struct Parameters {
+	//Defines the custom parameter types for methods
+	//eg: flatbuffers uses flatbuffers.Builder as input for the client and output for the server
+	grpc::string custom_method_io_type;
+
+	//Package name for the service
+	grpc::string package_name;
+};
+
+// Return the source of the generated service file.
+grpc::string GenerateServiceSource(grpc_generator::File *file,
+                                   const grpc_generator::Service *service,
+                                   grpc_go_generator::Parameters *parameters);
+
+}
+
+#endif  // GRPC_INTERNAL_COMPILER_GO_GENERATOR_H