new generator helper package, implements main()

cmd/libs/go2idl/args/args.go

+/*
+Copyright 2015 The Kubernetes 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 args has common command-line flags for generation programs.
+package args
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"k8s.io/kubernetes/cmd/libs/go2idl/generator"
+	"k8s.io/kubernetes/cmd/libs/go2idl/namer"
+	"k8s.io/kubernetes/cmd/libs/go2idl/parser"
+
+	"github.com/spf13/pflag"
+)
+
+// Default returns a defaulted GeneratorArgs. You may change the defaults
+// before calling AddFlags.
+func Default() *GeneratorArgs {
+	return &GeneratorArgs{
+		OutputBase:       DefaultSourceTree(),
+		GoHeaderFilePath: filepath.Join(DefaultSourceTree(), "k8s.io/kubernetes/hack/boilerplate/boilerplate.go.txt"),
+	}
+}
+
+// GeneratorArgs has arguments common to most generators.
+type GeneratorArgs struct {
+	// Which directories to parse.
+	InputDirs []string
+
+	// Source tree to write results to.
+	OutputBase string
+
+	// Package path within the source tree.
+	OutputPackagePath string
+
+	// Where to get copyright header text.
+	GoHeaderFilePath string
+}
+
+func (g *GeneratorArgs) AddFlags(fs *pflag.FlagSet) {
+	fs.StringSliceVarP(&g.InputDirs, "input-dirs", "i", g.InputDirs, "Comma-separated list of import paths to get input types from.")
+	fs.StringVarP(&g.OutputBase, "output-base", "o", g.OutputBase, "Output base; defaults to $GOPATH/src/ or ./ if $GOPATH is not set.")
+	fs.StringVarP(&g.OutputPackagePath, "output-package", "p", g.OutputPackagePath, "Base package path.")
+	fs.StringVarP(&g.GoHeaderFilePath, "go-header-file", "h", g.GoHeaderFilePath, "File containing boilerplate header text. The string YEAR will be replaced with the current 4-digit year.")
+}
+
+// LoadGoBoilerplate loads the boilerplate file passed to --go-header-file.
+func (g *GeneratorArgs) LoadGoBoilerplate() ([]byte, error) {
+	b, err := ioutil.ReadFile(g.GoHeaderFilePath)
+	if err != nil {
+		return nil, err
+	}
+	b = bytes.Replace(b, []byte("YEAR"), []byte(strconv.Itoa(time.Now().Year())), -1)
+	return b, nil
+}
+
+func (g *GeneratorArgs) NewBuilder() (*parser.Builder, error) {
+	b := parser.New()
+	for _, d := range g.InputDirs {
+		if err := b.AddDir(d); err != nil {
+			return nil, fmt.Errorf("unable to add directory %q: %v", d, err)
+		}
+	}
+	return b, nil
+}
+
+// DefaultSourceTree returns the /src directory of the first entry in $GOPATH.
+// If $GOPATH is empty, it returns "./". Useful as a default output location.
+func DefaultSourceTree() string {
+	paths := strings.Split(os.Getenv("GOPATH"), string(filepath.ListSeparator))
+	if len(paths) > 0 && len(paths[0]) > 0 {
+		return filepath.Join(paths[0], "src")
+	}
+	return "./"
+}
+
+// Execute implements main().
+// If you don't need any non-default behavior, use as:
+// args.Default().Execute(...)
+func (g *GeneratorArgs) Execute(nameSystems namer.NameSystems, defaultSystem string, pkgs func(*generator.Context, *GeneratorArgs) generator.Packages) error {
+	g.AddFlags(pflag.CommandLine)
+	pflag.Parse()
+
+	b, err := g.NewBuilder()
+	if err != nil {
+		return fmt.Errorf("Failed making a parser: %v", err)
+	}
+
+	c, err := generator.NewContext(b, nameSystems, defaultSystem)
+	if err != nil {
+		return fmt.Errorf("Failed making a context: %v", err)
+	}
+
+	packages := pkgs(c, g)
+	if err := c.ExecutePackages(g.OutputBase, packages); err != nil {
+		return fmt.Errorf("Failed executing generator: %v", err)
+	}
+
+	return nil
+}

cmd/libs/go2idl/generator/execute.go

@@ -84,6 +84,7 @@ func (f *file) assemble(w io.Writer) {
 
 	if len(f.imports) > 0 {
 		fmt.Fprint(w, "import (\n")
+		// TODO: sort imports like goimports does.
 		for i := range f.imports {
 			if strings.Contains(i, "\"") {
 				// they included quotes, or are using the