1package multierr
 2
 3// Copyright 2022 The Go Authors. All rights reserved.
 4// Use of this source code is governed by a BSD-style
 5// license that can be found in the LICENSE file.
 6
 7// Join returns an error that wraps the given errors.
 8// Any nil error values are discarded.
 9// Join returns nil if errs contains no non-nil values.
10// The error formats as the concatenation of the strings obtained
11// by calling the Error method of each element of errs, with a newline
12// between each string.
13func Join(errs ...error) error {
14	n := 0
15	for _, err := range errs {
16		if err != nil {
17			n++
18		}
19	}
20	if n == 0 {
21		return nil
22	}
23	e := &joinError{
24		errs: make([]error, 0, n),
25	}
26	for _, err := range errs {
27		if err != nil {
28			e.errs = append(e.errs, err)
29		}
30	}
31	return e
32}
33
34type joinError struct {
35	errs []error
36}
37
38func (e *joinError) Error() string {
39	var b []byte
40	for i, err := range e.errs {
41		if i > 0 {
42			b = append(b, '\n')
43		}
44		b = append(b, err.Error()...)
45	}
46	return string(b)
47}
48
49func (e *joinError) Unwrap() []error {
50	return e.errs
51}