1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package errors
import (
"errors"
"fmt"
)
// A Wrapper provides context around another error.
type Wrapper interface {
// Unwrap returns the next error in the error chain.
// If there is no next error, Unwrap returns nil.
Unwrap() error
}
// Opaque returns an error with the same error formatting as err
// but that does not match err and cannot be unwrapped.
func Opaque(err error) error {
return noWrapper{err}
}
type noWrapper struct {
error
}
func (e noWrapper) FormatError(p Printer) (next error) {
if f, ok := e.error.(Formatter); ok {
return f.FormatError(p)
}
p.Print(e.error)
return nil
}
// Unwrap returns the result of calling the Unwrap method on err, if err's
// type contains an Unwrap method returning error.
// Otherwise, Unwrap returns nil.
func Unwrap(err error) error {
return errors.Unwrap(err)
}
// Cause returns first recorded Frame.
func Cause(err error) (f Frame, r bool) {
for {
we, ok := err.(*wrapError)
if !ok {
return f, r
}
f = we.frame
r = r || ok
err = we.err
}
}
type wrapError struct {
msg string
err error
frame Frame
}
func (e *wrapError) Error() string {
return fmt.Sprint(e)
}
func (e *wrapError) Format(s fmt.State, v rune) { FormatError(e, s, v) }
func (e *wrapError) FormatError(p Printer) (next error) {
p.Print(e.msg)
e.frame.Format(p)
return e.err
}
func (e *wrapError) Unwrap() error {
return e.err
}
// Wrap error with message and caller.
func Wrap(err error, message string) error {
frame := Frame{}
if Trace() {
frame = Caller(1)
}
return &wrapError{msg: message, err: err, frame: frame}
}
// Wrapf wraps error with formatted message and caller.
func Wrapf(err error, format string, a ...interface{}) error {
frame := Frame{}
if Trace() {
frame = Caller(1)
}
msg := fmt.Sprintf(format, a...)
return &wrapError{msg: msg, err: err, frame: frame}
}
// Is reports whether any error in err's chain matches target.
//
// The chain consists of err itself followed by the sequence of errors obtained by
// repeatedly calling Unwrap.
//
// An error is considered to match a target if it is equal to that target or if
// it implements a method Is(error) bool such that Is(target) returns true.
//
// An error type might provide an Is method so it can be treated as equivalent
// to an existing error. For example, if MyError defines
//
// func (m MyError) Is(target error) bool { return target == fs.ErrExist }
//
// then Is(MyError{}, fs.ErrExist) returns true. See syscall.Errno.Is for
// an example in the standard library.
func Is(err, target error) bool {
return errors.Is(err, target)
}
// As finds the first error in err's chain that matches target, and if so, sets
// target to that error value and returns true. Otherwise, it returns false.
//
// The chain consists of err itself followed by the sequence of errors obtained by
// repeatedly calling Unwrap.
//
// An error matches target if the error's concrete value is assignable to the value
// pointed to by target, or if the error has a method As(interface{}) bool such that
// As(target) returns true. In the latter case, the As method is responsible for
// setting target.
//
// An error type might provide an As method so it can be treated as if it were a
// different error type.
//
// As panics if target is not a non-nil pointer to either a type that implements
// error, or to any interface type.
func As(err error, target interface{}) bool { return errors.As(err, target) }
|
