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//go:build !go1.13
// +build !go1.13
package errors
import (
"reflect"
)
type unwrapper interface {
Unwrap() error
}
// As assigns error or any wrapped error to the value target points
// to. If there is no value of the target type of target As returns
// false.
func As(err error, target interface{}) bool {
targetType := reflect.TypeOf(target)
for {
errType := reflect.TypeOf(err)
if errType == nil {
return false
}
if reflect.PtrTo(errType) == targetType {
reflect.ValueOf(target).Elem().Set(reflect.ValueOf(err))
return true
}
wrapped, ok := err.(unwrapper)
if ok {
err = wrapped.Unwrap()
} else {
return false
}
}
}
// Is detects whether the error is equal to a given error. Errors
// are considered equal by this function if they are the same object,
// or if they both contain the same error inside an errors.Error.
func Is(e error, original error) bool {
if e == original {
return true
}
if e, ok := e.(*Error); ok {
return Is(e.Err, original)
}
if original, ok := original.(*Error); ok {
return Is(e, original.Err)
}
return false
}
// Disclaimer: functions Join and Unwrap are copied from the stdlib errors
// package v1.21.0.
// Join returns an error that wraps the given errors.
// Any nil error values are discarded.
// Join returns nil if every value in errs is nil.
// The error formats as the concatenation of the strings obtained
// by calling the Error method of each element of errs, with a newline
// between each string.
//
// A non-nil error returned by Join implements the Unwrap() []error method.
func Join(errs ...error) error {
n := 0
for _, err := range errs {
if err != nil {
n++
}
}
if n == 0 {
return nil
}
e := &joinError{
errs: make([]error, 0, n),
}
for _, err := range errs {
if err != nil {
e.errs = append(e.errs, err)
}
}
return e
}
type joinError struct {
errs []error
}
func (e *joinError) Error() string {
var b []byte
for i, err := range e.errs {
if i > 0 {
b = append(b, '\n')
}
b = append(b, err.Error()...)
}
return string(b)
}
func (e *joinError) Unwrap() []error {
return e.errs
}
// 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.
//
// Unwrap only calls a method of the form "Unwrap() error".
// In particular Unwrap does not unwrap errors returned by [Join].
func Unwrap(err error) error {
u, ok := err.(interface {
Unwrap() error
})
if !ok {
return nil
}
return u.Unwrap()
}
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