refactor: goexports use go template.

cmd/goexports/goexports.go

@@ -1,36 +1,57 @@
-// This program generates code to register binary program symbols to
-// the interpeter.
+// This program generates code to register binary program symbols to the interpreter.
 // See stdlib.go for usage
 
 package main
 
 import (
-	"bufio"
-	"fmt"
+	"bytes"
+	"go/format"
 	"go/importer"
 	"go/types"
+	"io/ioutil"
 	"log"
 	"os"
-	"os/exec"
 	"path"
 	"strings"
+	"text/template"
 	"unicode"
 )
 
-func genfile(dest, pkgName, ofile string) error {
+const model = `package {{ .Dest }}
+
+// CODE GENERATED AUTOMATICALLY BY 'goexports {{ .PkgName }}'.
+// THIS FILE MUST NOT BE EDITED.
+
+import (
+	"{{ .PkgName }}"
+	"reflect"
+)
+
+func init() {
+	Value["{{ .PkgName }}"] = map[string]reflect.Value{
+		{{range .Val -}}
+			{{if forceUint $.Pkg . -}}
+				"{{.}}": reflect.ValueOf(uint({{ $.Pkg }}.{{.}})),
+			{{else -}}
+				"{{.}}": reflect.ValueOf({{ $.Pkg }}.{{.}}),
+			{{ end -}}
+		{{end -}}
+	}
+
+	Type["{{ .PkgName }}"] = map[string]reflect.Type{
+		{{range .Typ -}}
+			"{{.}}": reflect.TypeOf((*{{ $.Pkg }}.{{.}})(nil)).Elem(),
+		{{end -}}
+	}
+}
+`
+
+func genContent(dest, pkgName string) ([]byte, error) {
 	p, err := importer.Default().Import(pkgName)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	f, err := os.Create(ofile)
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-
-	out := bufio.NewWriter(f)
-
 	var typ []string
 	var val []string
 	sc := p.Scope()
@@ -49,43 +70,43 @@ func genfile(dest, pkgName, ofile string) error {
 		}
 	}
 
-	pkg := path.Base(pkgName)
+	base := template.New("goexports")
+	base.Funcs(template.FuncMap{
+		"forceUint": forceUint,
+	})
 
-	// Print header
-	fmt.Fprintln(out, `package `+dest+`
-// Code generated by 'goexports `+pkgName+`'. DO NOT EDIT.
-
-import (
-	"`+pkgName+`"
-	"reflect"
-)
-
-func init() {`)
-
-	// Print values
-	fmt.Fprintln(out, `Value["`+pkgName+`"] = map[string]reflect.Value{`)
-	for _, v := range val {
-		if (pkgName == "math" && v == "MaxUint64") ||
-			(pkgName == "hash/crc64" && v == "ECMA") ||
-			(pkgName == "hash/crc64" && v == "ISO") {
-			// go build will fail with overflow error if this const is untyped. Fix this.
-			fmt.Fprintln(out, "\""+v+"\": reflect.ValueOf(uint("+pkg+"."+v+")),")
-		} else {
-			fmt.Fprintln(out, "\""+v+"\": reflect.ValueOf("+pkg+"."+v+"),")
-		}
+	parse, err := base.Parse(model)
+	if err != nil {
+		return nil, err
 	}
-	fmt.Fprintln(out, "}")
 
-	// Print types
-	fmt.Fprintln(out, `Type["`+pkgName+`"] = map[string]reflect.Type{`)
-	for _, t := range typ {
-		fmt.Fprintln(out, `"`+t+`": reflect.TypeOf((*`+pkg+"."+t+")(nil)).Elem(),")
+	data := map[string]interface{}{
+		"Dest":    dest,
+		"PkgName": pkgName,
+		"Pkg":     path.Base(pkgName),
+		"Val":     val,
+		"Typ":     typ,
 	}
-	fmt.Fprintln(out, "}")
 
-	fmt.Fprintln(out, "}")
+	b := &bytes.Buffer{}
+	err = parse.Execute(b, data)
+	if err != nil {
+		return nil, err
+	}
 
-	return out.Flush()
+	// gofmt
+	source, err := format.Source(b.Bytes())
+	if err != nil {
+		return nil, err
+	}
+	return source, nil
+}
+
+// go build will fail with overflow error if this const is untyped. Fix this.
+func forceUint(pkgName, v string) bool {
+	return (pkgName == "math" && v == "MaxUint64") ||
+		(pkgName == "hash/crc64" && v == "ECMA") ||
+		(pkgName == "hash/crc64" && v == "ISO")
 }
 
 func main() {
@@ -96,15 +117,15 @@ func main() {
 	dest := path.Base(dir)
 
 	for _, pkg := range os.Args[1:] {
-		oFile := strings.Replace(pkg, "/", "_", -1) + ".go"
-		if err := genfile(dest, pkg, oFile); err != nil {
+		content, err := genContent(dest, pkg)
+		if err != nil {
 			log.Fatal(err)
 		}
 
-		cmd := exec.Command("gofmt", "-w", oFile)
-		output, err := cmd.CombinedOutput()
+		oFile := strings.Replace(pkg, "/", "_", -1) + ".go"
+
+		err = ioutil.WriteFile(oFile, content, 0666)
 		if err != nil {
-			log.Println(output)
 			log.Fatal(err)
 		}
 	}

stdlib/syscall.go

@@ -1,6 +1,7 @@
 package stdlib
 
-// Code generated by 'goexports syscall'. DO NOT EDIT.
+// CODE GENERATED AUTOMATICALLY BY 'goexports syscall'.
+// THIS FILE MUST NOT BE EDITED.
 
 import (
 	"reflect"
@@ -2116,6 +2117,7 @@ func init() {
 		"Write":                            reflect.ValueOf(syscall.Write),
 		"XCASE":                            reflect.ValueOf(syscall.XCASE),
 	}
+
 	Type["syscall"] = map[string]reflect.Type{
 		"Cmsghdr":              reflect.TypeOf((*syscall.Cmsghdr)(nil)).Elem(),
 		"Conn":                 reflect.TypeOf((*syscall.Conn)(nil)).Elem(),