41 lines
778 B
Go
41 lines
778 B
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build !go1.13
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// +build !go1.13
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package errors
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import "reflect"
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// Is is a copy of Go 1.13's errors.Is for use with older Go versions.
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func Is(err, target error) bool {
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if target == nil {
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return err == target
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}
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isComparable := reflect.TypeOf(target).Comparable()
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for {
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if isComparable && err == target {
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return true
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}
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if x, ok := err.(interface{ Is(error) bool }); ok && x.Is(target) {
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return true
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}
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if err = unwrap(err); err == nil {
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return false
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}
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}
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}
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func unwrap(err error) error {
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u, ok := err.(interface {
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Unwrap() error
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})
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if !ok {
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return nil
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}
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return u.Unwrap()
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}
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