Support multiple generators

config.go

@@ -27,10 +27,19 @@ import (
 const configVersion = "unstable"
 
 type config struct {
-	Version   string
+	Version    string
+	Generators []string
+
+	// Generator is a code generator which is used from protoc.
+	// Deprecated: Use Generators instead.
 	Generator string
-	Plugins   []string
-	Includes  struct {
+
+	// Plugins will be deprecated. It has to be per-Generator setting,
+	// but neither protoc-gen-go nor protoc-gen-go-grpc support plugins.
+	// So the refactoring is not worth to do.
+	Plugins []string
+
+	Includes struct {
 		Before   []string
 		Vendored []string
 		Packages []string
@@ -40,9 +49,12 @@ type config struct {
 	Packages map[string]string
 
 	Overrides []struct {
-		Prefixes  []string
-		Generator string
-		Plugins   *[]string
+		Prefixes []string
+		// Generator is a code generator which is used from protoc.
+		// Deprecated: Use Generators instead.
+		Generator  string
+		Generators []string
+		Plugins    *[]string
 
 		// TODO(stevvooe): We could probably support overriding of includes and
 		// package maps, but they don't seem to be as useful. Likely,
@@ -59,7 +71,6 @@ type config struct {
 
 func newDefaultConfig() config {
 	return config{
-		Generator: "go",
 		Includes: struct {
 			Before   []string
 			Vendored []string
@@ -77,6 +88,10 @@ func readConfig(path string) (config, error) {
 	if err != nil {
 		log.Fatalln(err)
 	}
+	return readConfigFrom(p)
+}
+
+func readConfigFrom(p []byte) (config, error) {
 	c := newDefaultConfig()
 	if err := toml.Unmarshal(p, &c); err != nil {
 		log.Fatalln(err)
@@ -86,5 +101,33 @@ func readConfig(path string) (config, error) {
 		return config{}, fmt.Errorf("unknown file version %v; please upgrade to %v", c.Version, configVersion)
 	}
 
+	if c.Generator != "" {
+		if len(c.Generators) > 0 {
+			return config{}, fmt.Errorf(
+				`specify either "generators = %v" or "generator = %v", not both`,
+				c.Generators, c.Generator,
+			)
+		}
+		c.Generators = []string{c.Generator}
+		c.Generator = ""
+	}
+
+	for i, o := range c.Overrides {
+		if o.Generator != "" {
+			if len(o.Generators) > 0 {
+				return config{}, fmt.Errorf(
+					`specify either "overrides[%d].generators" or "overrides[%d].generator", not both`,
+					i, i,
+				)
+			}
+			c.Overrides[i].Generators = []string{o.Generator}
+			c.Overrides[i].Generator = ""
+		}
+	}
+
+	if len(c.Generators) == 0 {
+		c.Generators = []string{"go"}
+	}
+
 	return c, nil
 }

config_test.go

@@ -0,0 +1,60 @@
+/*
+   Copyright The containerd Authors.
+
+   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 main
+
+import "testing"
+
+func TestReadConfigFrom(t *testing.T) {
+	testcases := []struct {
+		name string
+		toml string
+	}{
+		{
+			name: "empty",
+			toml: `version="unstable"`,
+		},
+		{
+			name: "generator",
+			toml: `
+version="unstable"
+generator="go"
+`,
+		},
+		{
+			name: "generators",
+			toml: `
+version="unstable"
+generators=["go"]
+`,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			c, err := readConfigFrom([]byte(tc.toml))
+			if err != nil {
+				t.Fatalf("err must be nil, but got %v", err)
+			}
+			if c.Generator == "go" {
+				t.Fatalf("Generator must be cleared, but got %v", c.Generator)
+			}
+			if len(c.Generators) != 1 || c.Generators[0] != "go" {
+				t.Fatalf("Generators must be [go], but got %v", c.Generators)
+			}
+		})
+	}
+}

main.go

@@ -77,9 +77,10 @@ func main() {
 
 	// Index overrides by target import path
 	overrides := map[string]struct {
-		Prefixes  []string
-		Generator string
-		Plugins   *[]string
+		Prefixes   []string
+		Generator  string
+		Generators []string
+		Plugins    *[]string
 	}{}
 	for _, override := range c.Overrides {
 		for _, prefix := range override.Prefixes {
@@ -166,7 +167,7 @@ func main() {
 		includes = append(includes, c.Includes.After...)
 
 		protoc := protocCmd{
-			Name:       c.Generator,
+			Names:      c.Generators,
 			ImportPath: pkg.GoImportPath,
 			PackageMap: c.Packages,
 			Plugins:    c.Plugins,
@@ -182,8 +183,8 @@ func main() {
 
 		if override, ok := overrides[importDirPath]; ok {
 			// selectively apply the overrides to the protoc structure.
-			if override.Generator != "" {
-				protoc.Name = override.Generator
+			if len(override.Generators) > 0 {
+				protoc.Names = override.Generators
 			}
 
 			if override.Plugins != nil {

protoc.go

@@ -30,12 +30,16 @@ var (
 		{{if $index}}` + string(filepath.ListSeparator) + `{{end -}}
 			{{.}}
 	{{- end -}}
-	{{- if .Descriptors}} --include_imports --descriptor_set_out={{.Descriptors}}{{- end }} --
-	{{- .Name -}}_out={{if .Plugins}}plugins={{- range $index, $plugin := .Plugins -}}
-		{{- if $index}}+{{end}}
-		{{- $plugin}}
+	{{- if .Descriptors}} --include_imports --descriptor_set_out={{.Descriptors}}{{- end -}}
+
+	{{- range $index, $name := .Names }} --{{- $name -}}_out=
+		{{- if $.Plugins}}plugins={{- range $index, $plugin := $.Plugins -}}
+			{{- if $index}}+{{end}}
+			{{- $plugin}}
+		{{- end -}},{{- end -}}
+		import_path={{$.ImportPath}}
 	{{- end -}}
-	,{{- end -}}import_path={{.ImportPath}}
+
 	{{- range $proto, $gopkg := .PackageMap -}},M
 		{{- $proto}}={{$gopkg -}}
 	{{- end -}}
@@ -46,7 +50,7 @@ var (
 
 // protocParams defines inputs to a protoc command string.
 type protocCmd struct {
-	Name        string // backend name
+	Names       []string
 	Includes    []string
 	Plugins     []string
 	Descriptors string

protoc_test.go

@@ -0,0 +1,57 @@
+/*
+   Copyright The containerd Authors.
+
+   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 main
+
+import "testing"
+
+func TestMkcmd(t *testing.T) {
+	testcases := []struct {
+		name     string
+		cmd      protocCmd
+		expected string
+	}{
+		{
+			name:     "basic",
+			cmd:      protocCmd{Names: []string{"go"}},
+			expected: "protoc -I --go_out=import_path=:",
+		},
+		{
+			name:     "plugin",
+			cmd:      protocCmd{Names: []string{"go"}, Plugins: []string{"grpc"}},
+			expected: "protoc -I --go_out=plugins=grpc,import_path=:",
+		},
+		{
+			name:     "use protoc-gen-go-grpc instead of plugins",
+			cmd:      protocCmd{Names: []string{"go", "go-grpc"}},
+			expected: "protoc -I --go_out=import_path= --go-grpc_out=import_path=:",
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			cmd := &tc.cmd
+
+			s, err := cmd.mkcmd()
+			if err != nil {
+				t.Fatalf("err must be nil but %+v", err)
+			}
+
+			if s != tc.expected {
+				t.Fatalf(`s must be %q, but %q`, tc.expected, s)
+			}
+		})
+	}
+}