Implement BytesHex type of argument (#115)

BytesHex is an []byte represented as HEX-string

--bytes=010203040506070809 states for []bytes{1,2,3,4,5,6,7,8,9}

2 files changed, 177 insertions, 0 deletions

diff --git a/bytes.go b/bytes.go
new file mode 100644
index 0000000..12c58db
--- /dev/null
+++ b/bytes.go
@@ -0,0 +1,105 @@
+package pflag
+
+import (
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// BytesHex adapts []byte for use as a flag. Value of flag is HEX encoded
+type bytesHexValue []byte
+
+func (bytesHex bytesHexValue) String() string {
+	return fmt.Sprintf("%X", []byte(bytesHex))
+}
+
+func (bytesHex *bytesHexValue) Set(value string) error {
+	bin, err := hex.DecodeString(strings.TrimSpace(value))
+
+	if err != nil {
+		return err
+	}
+
+	*bytesHex = bin
+
+	return nil
+}
+
+func (*bytesHexValue) Type() string {
+	return "bytesHex"
+}
+
+func newBytesHexValue(val []byte, p *[]byte) *bytesHexValue {
+	*p = val
+	return (*bytesHexValue)(p)
+}
+
+func bytesHexConv(sval string) (interface{}, error) {
+
+	bin, err := hex.DecodeString(sval)
+
+	if err == nil {
+		return bin, nil
+	}
+
+	return nil, fmt.Errorf("invalid string being converted to Bytes: %s %s", sval, err)
+}
+
+// GetBytesHex return the []byte value of a flag with the given name
+func (f *FlagSet) GetBytesHex(name string) ([]byte, error) {
+	val, err := f.getFlagType(name, "bytesHex", bytesHexConv)
+
+	if err != nil {
+		return []byte{}, err
+	}
+
+	return val.([]byte), nil
+}
+
+// BytesHexVar defines an []byte flag with specified name, default value, and usage string.
+// The argument p points to an []byte variable in which to store the value of the flag.
+func (f *FlagSet) BytesHexVar(p *[]byte, name string, value []byte, usage string) {
+	f.VarP(newBytesHexValue(value, p), name, "", usage)
+}
+
+// BytesHexVarP is like BytesHexVar, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) BytesHexVarP(p *[]byte, name, shorthand string, value []byte, usage string) {
+	f.VarP(newBytesHexValue(value, p), name, shorthand, usage)
+}
+
+// BytesHexVar defines an []byte flag with specified name, default value, and usage string.
+// The argument p points to an []byte variable in which to store the value of the flag.
+func BytesHexVar(p *[]byte, name string, value []byte, usage string) {
+	CommandLine.VarP(newBytesHexValue(value, p), name, "", usage)
+}
+
+// BytesHexVarP is like BytesHexVar, but accepts a shorthand letter that can be used after a single dash.
+func BytesHexVarP(p *[]byte, name, shorthand string, value []byte, usage string) {
+	CommandLine.VarP(newBytesHexValue(value, p), name, shorthand, usage)
+}
+
+// BytesHex defines an []byte flag with specified name, default value, and usage string.
+// The return value is the address of an []byte variable that stores the value of the flag.
+func (f *FlagSet) BytesHex(name string, value []byte, usage string) *[]byte {
+	p := new([]byte)
+	f.BytesHexVarP(p, name, "", value, usage)
+	return p
+}
+
+// BytesHexP is like BytesHex, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) BytesHexP(name, shorthand string, value []byte, usage string) *[]byte {
+	p := new([]byte)
+	f.BytesHexVarP(p, name, shorthand, value, usage)
+	return p
+}
+
+// BytesHex defines an []byte flag with specified name, default value, and usage string.
+// The return value is the address of an []byte variable that stores the value of the flag.
+func BytesHex(name string, value []byte, usage string) *[]byte {
+	return CommandLine.BytesHexP(name, "", value, usage)
+}
+
+// BytesHexP is like BytesHex, but accepts a shorthand letter that can be used after a single dash.
+func BytesHexP(name, shorthand string, value []byte, usage string) *[]byte {
+	return CommandLine.BytesHexP(name, shorthand, value, usage)
+}
diff --git a/bytes_test.go b/bytes_test.go
new file mode 100644
index 0000000..cc4a769
--- /dev/null
+++ b/bytes_test.go
@@ -0,0 +1,72 @@
+package pflag
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+func setUpBytesHex(bytesHex *[]byte) *FlagSet {
+	f := NewFlagSet("test", ContinueOnError)
+	f.BytesHexVar(bytesHex, "bytes", []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}, "Some bytes in HEX")
+	f.BytesHexVarP(bytesHex, "bytes2", "B", []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}, "Some bytes in HEX")
+	return f
+}
+
+func TestBytesHex(t *testing.T) {
+	testCases := []struct {
+		input    string
+		success  bool
+		expected string
+	}{
+		/// Positive cases
+		{"", true, ""}, // Is empty string OK ?
+		{"01", true, "01"},
+		{"0101", true, "0101"},
+		{"1234567890abcdef", true, "1234567890ABCDEF"},
+		{"1234567890ABCDEF", true, "1234567890ABCDEF"},
+
+		// Negative cases
+		{"0", false, ""},   // Short string
+		{"000", false, ""}, /// Odd-length string
+		{"qq", false, ""},  /// non-hex character
+	}
+
+	devnull, _ := os.Open(os.DevNull)
+	os.Stderr = devnull
+
+	for i := range testCases {
+		var bytesHex []byte
+		f := setUpBytesHex(&bytesHex)
+
+		tc := &testCases[i]
+
+		// --bytes
+		args := []string{
+			fmt.Sprintf("--bytes=%s", tc.input),
+			fmt.Sprintf("-B  %s", tc.input),
+			fmt.Sprintf("--bytes2=%s", tc.input),
+		}
+
+		for _, arg := range args {
+			err := f.Parse([]string{arg})
+
+			if err != nil && tc.success == true {
+				t.Errorf("expected success, got %q", err)
+				continue
+			} else if err == nil && tc.success == false {
+				// bytesHex, err := f.GetBytesHex("bytes")
+				t.Errorf("expected failure while processing %q", tc.input)
+				continue
+			} else if tc.success {
+				bytesHex, err := f.GetBytesHex("bytes")
+				if err != nil {
+					t.Errorf("Got error trying to fetch the IP flag: %v", err)
+				}
+				if fmt.Sprintf("%X", bytesHex) != tc.expected {
+					t.Errorf("expected %q, got '%X'", tc.expected, bytesHex)
+				}
+			}
+		}
+	}
+}