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//go:build !go1.20
// +build !go1.20
package jwt
import (
"errors"
"fmt"
)
// Is implements checking for multiple errors using [errors.Is], since multiple
// error unwrapping is not possible in versions less than Go 1.20.
func (je joinedError) Is(err error) bool {
for _, e := range je.errs {
if errors.Is(e, err) {
return true
}
}
return false
}
// wrappedErrors is a workaround for wrapping multiple errors in environments
// where Go 1.20 is not available. It basically uses the already implemented
// functionality of joinedError to handle multiple errors with supplies a
// custom error message that is identical to the one we produce in Go 1.20 using
// multiple %w directives.
type wrappedErrors struct {
msg string
joinedError
}
// Error returns the stored error string
func (we wrappedErrors) Error() string {
return we.msg
}
// newError creates a new error message with a detailed error message. The
// message will be prefixed with the contents of the supplied error type.
// Additionally, more errors, that provide more context can be supplied which
// will be appended to the message. Since we cannot use of Go 1.20's possibility
// to include more than one %w formatting directive in [fmt.Errorf], we have to
// emulate that.
//
// For example,
//
// newError("no keyfunc was provided", ErrTokenUnverifiable)
//
// will produce the error string
//
// "token is unverifiable: no keyfunc was provided"
func newError(message string, err error, more ...error) error {
// We cannot wrap multiple errors here with %w, so we have to be a little
// bit creative. Basically, we are using %s instead of %w to produce the
// same error message and then throw the result into a custom error struct.
var format string
var args []any
if message != "" {
format = "%s: %s"
args = []any{err, message}
} else {
format = "%s"
args = []any{err}
}
errs := []error{err}
for _, e := range more {
format += ": %s"
args = append(args, e)
errs = append(errs, e)
}
err = &wrappedErrors{
msg: fmt.Sprintf(format, args...),
joinedError: joinedError{errs: errs},
}
return err
}
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