1 // Copyright (c) 2017-2023 Uber Technologies, Inc.
2 //
3 // Permission is hereby granted, free of charge, to any person obtaining a copy
4 // of this software and associated documentation files (the "Software"), to deal
5 // in the Software without restriction, including without limitation the rights
6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 // copies of the Software, and to permit persons to whom the Software is
8 // furnished to do so, subject to the following conditions:
9 //
10 // The above copyright notice and this permission notice shall be included in
11 // all copies or substantial portions of the Software.
12 //
13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19 // THE SOFTWARE.
20 21 //go:build !go1.20
22 // +build !go1.20
23 24 package multierr
25 26 import "errors"
27 28 // Versions of Go before 1.20 did not support the Unwrap() []error method.
29 // This provides a similar behavior by implementing the Is(..) and As(..)
30 // methods.
31 // See the errors.Join proposal for details:
32 // https://github.com/golang/go/issues/53435
33 34 // As attempts to find the first error in the error list that matches the type
35 // of the value that target points to.
36 //
37 // This function allows errors.As to traverse the values stored on the
38 // multierr error.
39 func (merr *multiError) As(target interface{}) bool {
40 for _, err := range merr.Errors() {
41 if errors.As(err, target) {
42 return true
43 }
44 }
45 return false
46 }
47 48 // Is attempts to match the provided error against errors in the error list.
49 //
50 // This function allows errors.Is to traverse the values stored on the
51 // multierr error.
52 func (merr *multiError) Is(target error) bool {
53 for _, err := range merr.Errors() {
54 if errors.Is(err, target) {
55 return true
56 }
57 }
58 return false
59 }
60 61 func extractErrors(err error) []error {
62 if err == nil {
63 return nil
64 }
65 66 // Note that we're casting to multiError, not errorGroup. Our contract is
67 // that returned errors MAY implement errorGroup. Errors, however, only
68 // has special behavior for multierr-specific error objects.
69 //
70 // This behavior can be expanded in the future but I think it's prudent to
71 // start with as little as possible in terms of contract and possibility
72 // of misuse.
73 eg, ok := err.(*multiError)
74 if !ok {
75 return []error{err}
76 }
77 78 return append(([]error)(nil), eg.Errors()...)
79 }
80