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// Copyright (c) 2017-2023 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//go:build !go1.20
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// +build !go1.20
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package multierr
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import "errors"
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// Versions of Go before 1.20 did not support the Unwrap() []error method.
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// This provides a similar behavior by implementing the Is(..) and As(..)
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// methods.
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// See the errors.Join proposal for details:
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// https://github.com/golang/go/issues/53435
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// As attempts to find the first error in the error list that matches the type
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// of the value that target points to.
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//
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// This function allows errors.As to traverse the values stored on the
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// multierr error.
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func (merr *multiError) As(target interface{}) bool {
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	for _, err := range merr.Errors() {
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		if errors.As(err, target) {
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			return true
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		}
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	}
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	return false
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}
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// Is attempts to match the provided error against errors in the error list.
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//
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// This function allows errors.Is to traverse the values stored on the
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// multierr error.
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func (merr *multiError) Is(target error) bool {
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	for _, err := range merr.Errors() {
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		if errors.Is(err, target) {
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			return true
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		}
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	}
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	return false
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}
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func extractErrors(err error) []error {
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	if err == nil {
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		return nil
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	}
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	// Note that we're casting to multiError, not errorGroup. Our contract is
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	// that returned errors MAY implement errorGroup. Errors, however, only
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	// has special behavior for multierr-specific error objects.
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	//
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	// This behavior can be expanded in the future but I think it's prudent to
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	// start with as little as possible in terms of contract and possibility
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	// of misuse.
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	eg, ok := err.(*multiError)
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	if !ok {
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		return []error{err}
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	}
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	return append(([]error)(nil), eg.Errors()...)
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}
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