feat(main): implement []string flag valuer

Implement flag.Value to automnatically split strings into an array at
their spaces.

Change-Id: Ia9139e23d74a30acfc74cb65935bb7fc2b322aec

1 files changed, 34 insertions, 0 deletions

diff --git a/internal/flag/flag.go b/internal/flag/flag.go
new file mode 100644
index 0000000..7c7d977
--- /dev/null
+++ b/internal/flag/flag.go
@@ -0,0 +1,34 @@
+package flag
+
+import (
+	"fmt"
+	"strings"
+)
+
+// A StringsValue is a command-line flag that interprets its argument
+// as a space-separated list of strings.
+type StringsValue []string
+
+// Set implements the flag.Value interface by spliting the provided string at
+// spaces.
+func (v *StringsValue) Set(s string) error {
+	if s == "" {
+		*v = []string{}
+		return nil
+	}
+
+	*v = strings.Fields(s)
+
+	return nil
+}
+
+// Get implements the flag.Getter interface by returning the contents of this
+// value.
+func (v *StringsValue) Get() interface{} {
+	return []string(*v)
+}
+
+// String returns a string
+func (v *StringsValue) String() string {
+	return fmt.Sprintf("%s", *v)
+}