return errors.New("nbf: Expected number")
				}
				c.NotBefore, err = jsonparser.ParseInt(value)
				return err
			}
		case 's':
			if string(key) == "sub" {
				if dataType != jsonparser.String {
					return errors.New("sub: Expected string")
				}
				c.Subject, err = jsonparser.ParseString(value)
				return err
			}
		}
		// Ignore unknown fields
		return nil
	})
}

	Primary *PrimaryTerm `parser:"| @@"`
}

// NegatedTerm has a leading minus sign.
type NegatedTerm struct {
	Term *PrimaryTerm `parser:"\"-\" @@"`
}

// PrimaryTerm represents a Value, Path expression, a Sub-expression
// or a function call.
type PrimaryTerm struct {
	Value         *LitValue   `parser:"  @@"`
	JPathExpr     *JSONPath   `parser:"| @@"`
	ListExpr      *ListExpr   `parser:"| @@"`