1 files changed, 63 insertions, 0 deletions
diff --git a/scalar.go b/scalar.go
new file mode 100644
index 0000000..a3bafe4
--- /dev/null
+++ b/scalar.go
@@ -0,0 +1,63 @@
+package arg
+
+import (
+	"encoding"
+	"fmt"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+var (
+	durationType        = reflect.TypeOf(time.Duration(0))
+	textUnmarshalerType = reflect.TypeOf([]encoding.TextUnmarshaler{}).Elem()
+)
+
+// set a value from a string
+func setScalar(v reflect.Value, s string) error {
+	if !v.CanSet() {
+		return fmt.Errorf("field is not exported")
+	}
+
+	// If we have a time.Duration then use time.ParseDuration
+	if v.Type() == durationType {
+		x, err := time.ParseDuration(s)
+		if err != nil {
+			return err
+		}
+		v.Set(reflect.ValueOf(x))
+		return nil
+	}
+
+	switch v.Kind() {
+	case reflect.String:
+		v.SetString(s)
+	case reflect.Bool:
+		x, err := strconv.ParseBool(s)
+		if err != nil {
+			return err
+		}
+		v.SetBool(x)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		x, err := strconv.ParseInt(s, 10, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetInt(x)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		x, err := strconv.ParseUint(s, 10, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetUint(x)
+	case reflect.Float32, reflect.Float64:
+		x, err := strconv.ParseFloat(s, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetFloat(x)
+	default:
+		return fmt.Errorf("not a scalar type: %s", v.Kind())
+	}
+	return nil
+}