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package errutil
import "strings"
// Multi combines multiple errors into one:
//
// - If all errors are nil, it returns nil.
//
// - If there is one non-nil error, it is returned.
//
// - Otherwise, the return value is an error whose Error methods contain all
// the messages of all non-nil arguments.
//
// If the input contains any error returned by Multi, such errors are flattened.
// The following two calls return the same value:
//
// Multi(Multi(err1, err2), Multi(err3, err4))
// Multi(err1, err2, err3, err4)
func Multi(errs ...error) error {
var nonNil []error
for _, err := range errs {
if err != nil {
if multi, ok := err.(multiError); ok {
nonNil = append(nonNil, multi...)
} else {
nonNil = append(nonNil, err)
}
}
}
switch len(nonNil) {
case 0:
return nil
case 1:
return nonNil[0]
default:
return multiError(nonNil)
}
}
type multiError []error
func (me multiError) Error() string {
var sb strings.Builder
sb.WriteString("multiple errors: ")
for i, e := range me {
if i > 0 {
sb.WriteString("; ")
}
sb.WriteString(e.Error())
}
return sb.String()
}
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