add vendor data

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

@@ -0,0 +1,71 @@
+package httpsfv
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+// isExtendedTchar checks if c is a valid token character as defined in the spec.
+func isExtendedTchar(c byte) bool {
+	if isAlpha(c) || isDigit(c) {
+		return true
+	}
+
+	switch c {
+	case '!', '#', '$', '%', '&', '\'', '*', '+', '-', '.', '^', '_', '`', '|', '~', ':', '/':
+		return true
+	}
+
+	return false
+}
+
+// ErrInvalidTokenFormat is returned when a token format is invalid.
+var ErrInvalidTokenFormat = errors.New("invalid token format")
+
+// Token represents a token as defined in
+// https://httpwg.org/specs/rfc9651.html#token.
+// A specific type is used to distinguish tokens from strings.
+type Token string
+
+// marshalSFV serializes as defined in
+// https://httpwg.org/specs/rfc9651.html#ser-token.
+func (t Token) marshalSFV(b io.StringWriter) error {
+	if len(t) == 0 {
+		return fmt.Errorf("a token cannot be empty: %w", ErrInvalidTokenFormat)
+	}
+
+	if !isAlpha(t[0]) && t[0] != '*' {
+		return fmt.Errorf("a token must start with an alpha character or *: %w", ErrInvalidTokenFormat)
+	}
+
+	for i := 1; i < len(t); i++ {
+		if !isExtendedTchar(t[i]) {
+			return fmt.Errorf("the character %c isn't allowed in a token: %w", t[i], ErrInvalidTokenFormat)
+		}
+	}
+
+	_, err := b.WriteString(string(t))
+
+	return err
+}
+
+// parseToken parses as defined in
+// https://httpwg.org/specs/rfc9651.html#parse-token.
+func parseToken(s *scanner) (Token, error) {
+	if s.eof() || (!isAlpha(s.data[s.off]) && s.data[s.off] != '*') {
+		return "", &UnmarshalError{s.off, ErrInvalidTokenFormat}
+	}
+
+	start := s.off
+	s.off++
+
+	for !s.eof() {
+		if !isExtendedTchar(s.data[s.off]) {
+			break
+		}
+		s.off++
+	}
+
+	return Token(s.data[start:s.off]), nil
+}