go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/grpc/cmd/svcdec/main.go (about)

     1  // Copyright 2016 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Command svcdec stands for 'service decorator'. It reads a service interface
    16  // XYZServer generated by protoc and generates DecoratedXYZ with this structure:
    17  //
    18  //	type DecoratedXYZ struct {
    19  //	  Service XYZServer
    20  //	  Prelude func(ctx context.Context, methodName string, req proto.Message) (context.Context, error)
    21  //	}
    22  //
    23  // DecoratedXYZ has the same methods as XYZServer: they call Prelude before
    24  // forwarding the call to the corresponding XYZServer method.
    25  //
    26  // svcdec is designed to be run through go generate:
    27  //
    28  //	//go:generate svcdec -type GreetServer
    29  package main
    30  
    31  import (
    32  	"context"
    33  	"os"
    34  	"strings"
    35  
    36  	"go.chromium.org/luci/grpc/internal/svctool"
    37  )
    38  
    39  func generate(ctx context.Context, a *svctool.GeneratorArgs) error {
    40  	args := templateArgs{
    41  		PackageName:  a.PackageName,
    42  		ExtraImports: a.ExtraImports,
    43  	}
    44  	for _, svc := range a.Services {
    45  		args.Services = append(args.Services, &service{
    46  			Service:    svc,
    47  			StructName: "Decorated" + strings.TrimSuffix(svc.TypeName, "Server"),
    48  		})
    49  	}
    50  
    51  	// Execute template.
    52  	return tmpl.Execute(a.Out, args)
    53  }
    54  
    55  func tool() *svctool.Tool {
    56  	return &svctool.Tool{Name: "svcdec", OutputFilenameSuffix: "dec"}
    57  }
    58  
    59  func main() {
    60  	tool().Main(os.Args[1:], generate)
    61  }