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