Import of https://github.com/ciena/voltctl at commit 40d61fbf3f910ed4017cf67c9c79e8e1f82a33a5

Change-Id: I8464c59e60d76cb8612891db3303878975b5416c
diff --git a/vendor/github.com/spf13/pflag/golangflag.go b/vendor/github.com/spf13/pflag/golangflag.go
new file mode 100644
index 0000000..d3dd72b
--- /dev/null
+++ b/vendor/github.com/spf13/pflag/golangflag.go
@@ -0,0 +1,105 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pflag
+
+import (
+	goflag "flag"
+	"reflect"
+	"strings"
+)
+
+// flagValueWrapper implements pflag.Value around a flag.Value.  The main
+// difference here is the addition of the Type method that returns a string
+// name of the type.  As this is generally unknown, we approximate that with
+// reflection.
+type flagValueWrapper struct {
+	inner    goflag.Value
+	flagType string
+}
+
+// We are just copying the boolFlag interface out of goflag as that is what
+// they use to decide if a flag should get "true" when no arg is given.
+type goBoolFlag interface {
+	goflag.Value
+	IsBoolFlag() bool
+}
+
+func wrapFlagValue(v goflag.Value) Value {
+	// If the flag.Value happens to also be a pflag.Value, just use it directly.
+	if pv, ok := v.(Value); ok {
+		return pv
+	}
+
+	pv := &flagValueWrapper{
+		inner: v,
+	}
+
+	t := reflect.TypeOf(v)
+	if t.Kind() == reflect.Interface || t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+
+	pv.flagType = strings.TrimSuffix(t.Name(), "Value")
+	return pv
+}
+
+func (v *flagValueWrapper) String() string {
+	return v.inner.String()
+}
+
+func (v *flagValueWrapper) Set(s string) error {
+	return v.inner.Set(s)
+}
+
+func (v *flagValueWrapper) Type() string {
+	return v.flagType
+}
+
+// PFlagFromGoFlag will return a *pflag.Flag given a *flag.Flag
+// If the *flag.Flag.Name was a single character (ex: `v`) it will be accessiblei
+// with both `-v` and `--v` in flags. If the golang flag was more than a single
+// character (ex: `verbose`) it will only be accessible via `--verbose`
+func PFlagFromGoFlag(goflag *goflag.Flag) *Flag {
+	// Remember the default value as a string; it won't change.
+	flag := &Flag{
+		Name:  goflag.Name,
+		Usage: goflag.Usage,
+		Value: wrapFlagValue(goflag.Value),
+		// Looks like golang flags don't set DefValue correctly  :-(
+		//DefValue: goflag.DefValue,
+		DefValue: goflag.Value.String(),
+	}
+	// Ex: if the golang flag was -v, allow both -v and --v to work
+	if len(flag.Name) == 1 {
+		flag.Shorthand = flag.Name
+	}
+	if fv, ok := goflag.Value.(goBoolFlag); ok && fv.IsBoolFlag() {
+		flag.NoOptDefVal = "true"
+	}
+	return flag
+}
+
+// AddGoFlag will add the given *flag.Flag to the pflag.FlagSet
+func (f *FlagSet) AddGoFlag(goflag *goflag.Flag) {
+	if f.Lookup(goflag.Name) != nil {
+		return
+	}
+	newflag := PFlagFromGoFlag(goflag)
+	f.AddFlag(newflag)
+}
+
+// AddGoFlagSet will add the given *flag.FlagSet to the pflag.FlagSet
+func (f *FlagSet) AddGoFlagSet(newSet *goflag.FlagSet) {
+	if newSet == nil {
+		return
+	}
+	newSet.VisitAll(func(goflag *goflag.Flag) {
+		f.AddGoFlag(goflag)
+	})
+	if f.addedGoFlagSets == nil {
+		f.addedGoFlagSets = make([]*goflag.FlagSet, 0)
+	}
+	f.addedGoFlagSets = append(f.addedGoFlagSets, newSet)
+}