Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 1 | // Copyright (C) MongoDB, Inc. 2017-present. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 4 | // not use this file except in compliance with the License. You may obtain |
| 5 | // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 |
| 6 | |
| 7 | package internal |
| 8 | |
| 9 | import ( |
| 10 | "fmt" |
| 11 | ) |
| 12 | |
| 13 | // WrappedError represents an error that contains another error. |
| 14 | type WrappedError interface { |
| 15 | // Message gets the basic message of the error. |
| 16 | Message() string |
| 17 | // Inner gets the inner error if one exists. |
| 18 | Inner() error |
| 19 | } |
| 20 | |
| 21 | // RolledUpErrorMessage gets a flattened error message. |
| 22 | func RolledUpErrorMessage(err error) string { |
| 23 | if wrappedErr, ok := err.(WrappedError); ok { |
| 24 | inner := wrappedErr.Inner() |
| 25 | if inner != nil { |
| 26 | return fmt.Sprintf("%s: %s", wrappedErr.Message(), RolledUpErrorMessage(inner)) |
| 27 | } |
| 28 | |
| 29 | return wrappedErr.Message() |
| 30 | } |
| 31 | |
| 32 | return err.Error() |
| 33 | } |
| 34 | |
| 35 | //UnwrapError attempts to unwrap the error down to its root cause. |
| 36 | func UnwrapError(err error) error { |
| 37 | |
| 38 | switch tErr := err.(type) { |
| 39 | case WrappedError: |
| 40 | return UnwrapError(tErr.Inner()) |
| 41 | case *multiError: |
| 42 | return UnwrapError(tErr.errors[0]) |
| 43 | } |
| 44 | |
| 45 | return err |
| 46 | } |
| 47 | |
| 48 | // WrapError wraps an error with a message. |
| 49 | func WrapError(inner error, message string) error { |
| 50 | return &wrappedError{message, inner} |
| 51 | } |
| 52 | |
| 53 | // WrapErrorf wraps an error with a message. |
| 54 | func WrapErrorf(inner error, format string, args ...interface{}) error { |
| 55 | return &wrappedError{fmt.Sprintf(format, args...), inner} |
| 56 | } |
| 57 | |
| 58 | // MultiError combines multiple errors into a single error. If there are no errors, |
| 59 | // nil is returned. If there is 1 error, it is returned. Otherwise, they are combined. |
| 60 | func MultiError(errors ...error) error { |
| 61 | |
| 62 | // remove nils from the error list |
| 63 | var nonNils []error |
| 64 | for _, e := range errors { |
| 65 | if e != nil { |
| 66 | nonNils = append(nonNils, e) |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | switch len(nonNils) { |
| 71 | case 0: |
| 72 | return nil |
| 73 | case 1: |
| 74 | return nonNils[0] |
| 75 | default: |
| 76 | return &multiError{ |
| 77 | message: "multiple errors encountered", |
| 78 | errors: nonNils, |
| 79 | } |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | type multiError struct { |
| 84 | message string |
| 85 | errors []error |
| 86 | } |
| 87 | |
| 88 | func (e *multiError) Message() string { |
| 89 | return e.message |
| 90 | } |
| 91 | |
| 92 | func (e *multiError) Error() string { |
| 93 | result := e.message |
| 94 | for _, e := range e.errors { |
| 95 | result += fmt.Sprintf("\n %s", e) |
| 96 | } |
| 97 | return result |
| 98 | } |
| 99 | |
| 100 | func (e *multiError) Errors() []error { |
| 101 | return e.errors |
| 102 | } |
| 103 | |
| 104 | type wrappedError struct { |
| 105 | message string |
| 106 | inner error |
| 107 | } |
| 108 | |
| 109 | func (e *wrappedError) Message() string { |
| 110 | return e.message |
| 111 | } |
| 112 | |
| 113 | func (e *wrappedError) Error() string { |
| 114 | return RolledUpErrorMessage(e) |
| 115 | } |
| 116 | |
| 117 | func (e *wrappedError) Inner() error { |
| 118 | return e.inner |
| 119 | } |