cmd/gomobile: subcommand flag support

Several standard Go tool flags are not supported yet, those will
come in followup CLs.

Change-Id: I1d98afccf3063d7a3313f66b9fd57067fcfa5297
Reviewed-on: https://go-review.googlesource.com/4450
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

cmd/gomobile/build.go

@@ -9,7 +9,6 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"errors"
-	"flag"
 	"fmt"
 	"go/build"
 	"io"
@@ -42,14 +41,12 @@ are copied into the APK file.
 
 These build flags are shared by the build, install, and test commands.
 For documentation, see 'go help build':
-TODO:
 	-a
 	-tags 'tag list'
 `,
 }
 
 // TODO: -n
-// TODO: -v
 // TODO: -x
 // TODO: -mobile
 
@@ -58,12 +55,13 @@ func runBuild(cmd *command) error {
 	if err != nil {
 		panic(err)
 	}
+	args := cmd.flag.Args()
 
-	switch len(flag.Args()) {
-	case 1:
+	switch len(args) {
+	case 0:
 		pkg, err = ctx.ImportDir(cwd, build.ImportComment)
-	case 2:
-		pkg, err = ctx.Import(flag.Args()[1], cwd, build.ImportComment)
+	case 1:
+		pkg, err = ctx.Import(args[0], cwd, build.ImportComment)
 	default:
 		cmd.usage()
 		os.Exit(1)
@@ -133,6 +131,9 @@ func runBuild(cmd *command) error {
 		`-i`, // TODO(crawshaw): control with a flag
 		`-ldflags="-shared"`,
 		`-o`, libPath)
+	if buildV {
+		gocmd.Args = append(gocmd.Args, "-v")
+	}
 	gocmd.Stdout = os.Stdout
 	gocmd.Stderr = os.Stderr
 	gocmd.Env = []string{
@@ -228,6 +229,29 @@ func runBuild(cmd *command) error {
 	return apkw.Close()
 }
 
+// "Build flags", used by multiple commands.
+var (
+	buildA bool // -a
+	buildV bool // -v
+)
+
+func addBuildFlags(cmd *command) {
+	cmd.flag.BoolVar(&buildA, "a", false, "")
+	cmd.flag.Var((*stringsFlag)(&ctx.BuildTags), "tags", "")
+}
+
+func addBuildFlagsNXV(cmd *command) {
+	// TODO: -n, -x
+	cmd.flag.BoolVar(&buildV, "v", false, "")
+}
+
+func init() {
+	addBuildFlags(cmdBuild)
+	// TODO: addBuildFlags(cmdInstall)
+	addBuildFlagsNXV(cmdBuild)
+	addBuildFlagsNXV(cmdInit)
+}
+
 // A random uninteresting private key.
 // Must be consistent across builds so newer app versions can be installed.
 const debugCert = `

cmd/gomobile/init.go

@@ -79,9 +79,14 @@ func runInit(cmd *command) error {
 		return err
 	}
 
+	url := "http://dl.google.com/android/ndk/" + ndkName
+
+	if buildV {
+		fmt.Fprintf(os.Stderr, "fetching %s\n", url)
+	}
+
 	// TODO(crawshaw): The arm compiler toolchain compresses to 33 MB, less than a tenth of the NDK. Provide an alternative binary download.
-	// TODO(crawshaw): extra logging with -v
-	resp, err := http.Get("http://dl.google.com/android/ndk/" + ndkName)
+	resp, err := http.Get(url)
 	if err != nil {
 		return err
 	}
@@ -102,7 +107,9 @@ func runInit(cmd *command) error {
 	inflate.Dir = tmpdir
 	out, err := inflate.CombinedOutput()
 	if err != nil {
-		os.Stderr.Write(out) // TODO(crawshaw): only in verbose mode?
+		if buildV {
+			os.Stderr.Write(out)
+		}
 		return err
 	}
 	srcSysroot := filepath.Join(tmpdir, "android-ndk-r10d", "platforms", "android-15", "arch-arm", "usr")
@@ -145,8 +152,11 @@ func runInit(cmd *command) error {
 	if v := goEnv("GOROOT_BOOTSTRAP"); v != "" {
 		make.Env = append(make.Env, `GOROOT_BOOTSTRAP=`+v)
 	}
+	if buildV {
+		fmt.Fprintf(os.Stderr, "building android/arm cross compiler\n")
 		make.Stdout = os.Stdout
 		make.Stderr = os.Stderr
+	}
 	if err := make.Run(); err != nil {
 		return err
 	}

cmd/gomobile/main.go

@@ -50,6 +50,8 @@ func main() {
 
 	for _, cmd := range commands {
 		if cmd.Name == args[0] {
+			cmd.flag.Usage = cmd.usage
+			cmd.flag.Parse(args[1:])
 			if err := cmd.run(cmd); err != nil {
 				msg := err.Error()
 				if msg != "" {
@@ -95,6 +97,7 @@ var commands = []*command{
 
 type command struct {
 	run   func(*command) error
+	flag  flag.FlagSet
 	Name  string
 	Usage string
 	Short string

cmd/gomobile/strings_flag.go

@@ -0,0 +1,62 @@
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+type stringsFlag []string
+
+func (v *stringsFlag) Set(s string) error {
+	var err error
+	*v, err = splitQuotedFields(s)
+	if *v == nil {
+		*v = []string{}
+	}
+	return err
+}
+
+func isSpaceByte(c byte) bool {
+	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
+}
+
+func splitQuotedFields(s string) ([]string, error) {
+	// Split fields allowing '' or "" around elements.
+	// Quotes further inside the string do not count.
+	var f []string
+	for len(s) > 0 {
+		for len(s) > 0 && isSpaceByte(s[0]) {
+			s = s[1:]
+		}
+		if len(s) == 0 {
+			break
+		}
+		// Accepted quoted string. No unescaping inside.
+		if s[0] == '"' || s[0] == '\'' {
+			quote := s[0]
+			s = s[1:]
+			i := 0
+			for i < len(s) && s[i] != quote {
+				i++
+			}
+			if i >= len(s) {
+				return nil, fmt.Errorf("unterminated %c string", quote)
+			}
+			f = append(f, s[:i])
+			s = s[i+1:]
+			continue
+		}
+		i := 0
+		for i < len(s) && !isSpaceByte(s[i]) {
+			i++
+		}
+		f = append(f, s[:i])
+		s = s[i:]
+	}
+	return f, nil
+}
+
+func (v *stringsFlag) String() string {
+	return "<stringsFlag>"
+}