use flag.TextVar for --rewrite flag

main.go

@@ -118,14 +118,15 @@ func listcmd(args []string) error {
 }
 
 func getcmd(args []string) error {
-	var dir, rewrite string
+	var rewrite regexp.Regexp
+	var dir string
 	var pre, cached, major bool
 	fset := flag.NewFlagSet("get", flag.ExitOnError)
 	fset.BoolVar(&pre, "pre", false, "allow non-v0 prerelease versions")
 	fset.BoolVar(&major, "major", false, "only get newer major versions")
 	fset.StringVar(&dir, "dir", ".", "working directory")
 	fset.BoolVar(&cached, "cached", true, "only fetch cached content from the module proxy")
-	fset.StringVar(&rewrite, "rewrite", "", "exact package version to upgrade")
+	fset.TextVar(&rewrite, "rewrite", regexp.MustCompile(".*"), "only rewrite imports matching this regex")
 	fset.Usage = func() {
 		fmt.Fprintln(os.Stderr, "Usage: gomajor get <pathspec>")
 		fset.PrintDefaults()
@@ -220,24 +221,17 @@ func getcmd(args []string) error {
 	if err := cmd.Run(); err != nil {
 		return err
 	}
-	var rewriteRegex *regexp.Regexp
-	if rewrite != "" {
-		if rewriteRegex, err = regexp.Compile(rewrite); err != nil {
-			return err
-		}
-	}
 	// rewrite imports
 	err = importpaths.RewriteModule(dir, importpaths.RewriteModuleOptions{
 		PkgDir:     pkgdir,
 		Prefix:     modprefix,
 		NewVersion: version,
 		OnRewrite: func(pos token.Position, oldpath, newpath string) error {
-			if rewriteRegex != nil && !rewriteRegex.MatchString(oldpath) {
+			if !rewrite.MatchString(oldpath) {
 				return importpaths.ErrSkip
 			}
 
 			fmt.Printf("%s %s\n", pos, newpath)
-
 			return nil
 		},
 	})