add vendor data

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

@@ -0,0 +1,49 @@
+package httpsfv
+
+import (
+	"errors"
+	"io"
+)
+
+// ErrInvalidBooleanFormat is returned when a boolean format is invalid.
+var ErrInvalidBooleanFormat = errors.New("invalid boolean format")
+
+// marshalBoolean serializes as defined in
+// https://httpwg.org/specs/rfc9651.html#ser-boolean.
+func marshalBoolean(bd io.StringWriter, b bool) error {
+	if b {
+		_, err := bd.WriteString("?1")
+
+		return err
+	}
+
+	_, err := bd.WriteString("?0")
+
+	return err
+}
+
+// parseBoolean parses as defined in
+// https://httpwg.org/specs/rfc9651.html#parse-boolean.
+func parseBoolean(s *scanner) (bool, error) {
+	if s.eof() || s.data[s.off] != '?' {
+		return false, &UnmarshalError{s.off, ErrInvalidBooleanFormat}
+	}
+	s.off++
+
+	if s.eof() {
+		return false, &UnmarshalError{s.off, ErrInvalidBooleanFormat}
+	}
+
+	switch s.data[s.off] {
+	case '0':
+		s.off++
+
+		return false, nil
+	case '1':
+		s.off++
+
+		return true, nil
+	}
+
+	return false, &UnmarshalError{s.off, ErrInvalidBooleanFormat}
+}