mirror of https://go.googlesource.com/go
63 lines
1.3 KiB
Go
63 lines
1.3 KiB
Go
// Copyright 2022 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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package errors
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import (
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"unsafe"
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)
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// Join returns an error that wraps the given errors.
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// Any nil error values are discarded.
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// Join returns nil if every value in errs is nil.
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// The error formats as the concatenation of the strings obtained
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// by calling the Error method of each element of errs, with a newline
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// between each string.
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//
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// A non-nil error returned by Join implements the Unwrap() []error method.
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func Join(errs ...error) error {
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n := 0
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for _, err := range errs {
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if err != nil {
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n++
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}
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}
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if n == 0 {
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return nil
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}
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e := &joinError{
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errs: make([]error, 0, n),
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}
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for _, err := range errs {
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if err != nil {
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e.errs = append(e.errs, err)
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}
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}
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return e
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}
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type joinError struct {
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errs []error
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}
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func (e *joinError) Error() string {
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// Since Join returns nil if every value in errs is nil,
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// e.errs cannot be empty.
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if len(e.errs) == 1 {
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return e.errs[0].Error()
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}
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b := []byte(e.errs[0].Error())
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for _, err := range e.errs[1:] {
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b = append(b, '\n')
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b = append(b, err.Error()...)
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}
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// At this point, b has at least one byte '\n'.
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return unsafe.String(&b[0], len(b))
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}
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func (e *joinError) Unwrap() []error {
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return e.errs
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}
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