khenaidoo | 5fc5cea | 2021-08-11 17:39:16 -0400 | [diff] [blame] | 1 | // Copyright 2020 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
Joey Armstrong | ba3d9d1 | 2024-01-15 14:22:11 -0500 | [diff] [blame] | 5 | //go:build !go1.13 |
khenaidoo | 5fc5cea | 2021-08-11 17:39:16 -0400 | [diff] [blame] | 6 | // +build !go1.13 |
| 7 | |
| 8 | package errors |
| 9 | |
| 10 | import "reflect" |
| 11 | |
| 12 | // Is is a copy of Go 1.13's errors.Is for use with older Go versions. |
| 13 | func Is(err, target error) bool { |
| 14 | if target == nil { |
| 15 | return err == target |
| 16 | } |
| 17 | |
| 18 | isComparable := reflect.TypeOf(target).Comparable() |
| 19 | for { |
| 20 | if isComparable && err == target { |
| 21 | return true |
| 22 | } |
| 23 | if x, ok := err.(interface{ Is(error) bool }); ok && x.Is(target) { |
| 24 | return true |
| 25 | } |
| 26 | if err = unwrap(err); err == nil { |
| 27 | return false |
| 28 | } |
| 29 | } |
| 30 | } |
| 31 | |
| 32 | func unwrap(err error) error { |
| 33 | u, ok := err.(interface { |
| 34 | Unwrap() error |
| 35 | }) |
| 36 | if !ok { |
| 37 | return nil |
| 38 | } |
| 39 | return u.Unwrap() |
| 40 | } |