add vendor data

vendor/github.com/dunglas/httpsfv/item.go

@@ -0,0 +1,73 @@
+package httpsfv
+
+import (
+	"strings"
+)
+
+// Item is a bare value and associated parameters.
+// See https://httpwg.org/specs/rfc9651.html#item.
+type Item struct {
+	Value  interface{}
+	Params *Params
+}
+
+// NewItem returns a new Item.
+func NewItem(v interface{}) Item {
+	assertBareItem(v)
+
+	return Item{v, NewParams()}
+}
+
+func (i Item) member() {
+}
+
+// marshalSFV serializes as defined in
+// https://httpwg.org/specs/rfc9651.html#ser-item.
+func (i Item) marshalSFV(b *strings.Builder) error {
+	if i.Value == nil {
+		return ErrInvalidBareItem
+	}
+
+	if err := marshalBareItem(b, i.Value); err != nil {
+		return err
+	}
+
+	return i.Params.marshalSFV(b)
+}
+
+// UnmarshalItem parses an item as defined in
+// https://httpwg.org/specs/rfc9651.html#parse-item.
+func UnmarshalItem(v []string) (Item, error) {
+	s := &scanner{
+		data: strings.Join(v, ","),
+	}
+
+	s.scanWhileSp()
+
+	sfv, err := parseItem(s)
+	if err != nil {
+		return Item{}, err
+	}
+
+	s.scanWhileSp()
+
+	if !s.eof() {
+		return Item{}, &UnmarshalError{off: s.off}
+	}
+
+	return sfv, nil
+}
+
+func parseItem(s *scanner) (Item, error) {
+	bi, err := parseBareItem(s)
+	if err != nil {
+		return Item{}, err
+	}
+
+	p, err := parseParams(s)
+	if err != nil {
+		return Item{}, err
+	}
+
+	return Item{bi, p}, nil
+}