Add option to show digit map only

This is intended to allow users to easily view the digit maps of many
different radices at once by running the program multiple times.

2 files changed, 17 insertions, 2 deletions

diff --git a/args.go b/args.go
index d0f5da9..2adb076 100644
--- a/args.go
+++ b/args.go
@@ -16,6 +16,7 @@ type args struct {
 	FullMap        bool
 	ExactMTCLarge  bool
 	TotativeDigits bool
+	DigitMapOnly   bool
 	// If true, exit the program immediately after parsing args.
 	Exit bool
 }
@@ -23,6 +24,8 @@ type args struct {
 func parseArgs() (args, error) {
 	var a args
 	flag.BoolVar(&a.Compact, "c", false, "Compact the output display")
+	flag.BoolVar(&a.DigitMapOnly, "d", false,
+		"Show only the digit map; incompatible with -m and -t")
 	flag.BoolVar(&a.FullMap, "f", false,
 		fmt.Sprintf("Show full digit map (up to %d) for every radix",
 			maxSmallRadix))
@@ -45,6 +48,8 @@ func parseArgs() (args, error) {
 		return args{Exit: true}, nil
 	} else if a.Compact && a.TotativeDigits {
 		return args{}, errors.New("You cannot use both -t and -c at the same time.")
+	} else if a.DigitMapOnly && (a.TotativeDigits || a.ExactMTCLarge) {
+		return args{}, errors.New("You cannot use both -d and -t or -m at the same time.")
 	} else {
 		if flag.NArg() == 1 {
 			if radix, err := strconv.ParseUint(flag.Arg(0), 0, 0); err == nil {
diff --git a/radix_info.go b/radix_info.go
index f495905..befc25d 100644
--- a/radix_info.go
+++ b/radix_info.go
@@ -14,9 +14,19 @@ func main() {
 	if err == nil {
 		factorInfo := getFactorInfo(args)
 		if args.Compact {
-			factorInfo.writeToCompact(os.Stdout)
+			if args.DigitMapOnly {
+				fmt.Printf("Radix %02d ", args.Radix)
+				writeDigitMapCompact(os.Stdout, factorInfo.DigitMap)
+			} else {
+				factorInfo.writeToCompact(os.Stdout)
+			}
 		} else {
-			factorInfo.writeTo(os.Stdout)
+			if args.DigitMapOnly {
+				fmt.Printf("Radix %d Digit Map:\n", args.Radix)
+				writeDigitMap(os.Stdout, factorInfo.DigitMap)
+			} else {
+				factorInfo.writeTo(os.Stdout)
+			}
 		}
 	} else {
 		fmt.Fprintln(os.Stderr, err)