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0868329936
My favorite part of generics. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
89 lines
2.1 KiB
Go
89 lines
2.1 KiB
Go
// Copyright (c) 2021 Tailscale Inc & 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 multierr provides a simple multiple-error type.
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// It was inspired by github.com/go-multierror/multierror.
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package multierr
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import (
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"errors"
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"strings"
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)
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// An Error represents multiple errors.
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type Error struct {
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errs []error
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}
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// Error implements the error interface.
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func (e Error) Error() string {
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s := new(strings.Builder)
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s.WriteString("multiple errors:")
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for _, err := range e.errs {
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s.WriteString("\n\t")
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s.WriteString(err.Error())
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}
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return s.String()
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}
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// Errors returns a slice containing all errors in e.
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func (e Error) Errors() []error {
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return append(e.errs[:0:0], e.errs...)
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}
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// New returns an error composed from errs.
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// Some errors in errs get special treatment:
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// * nil errors are discarded
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// * errors of type Error are expanded into the top level
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// If the resulting slice has length 0, New returns nil.
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// If the resulting slice has length 1, New returns that error.
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// If the resulting slice has length > 1, New returns that slice as an Error.
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func New(errs ...error) error {
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dst := make([]error, 0, len(errs))
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for _, e := range errs {
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switch e := e.(type) {
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case nil:
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continue
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case Error:
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dst = append(dst, e.errs...)
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default:
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dst = append(dst, e)
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}
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}
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// dst has been filtered and splatted.
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switch len(dst) {
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case 0:
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return nil
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case 1:
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return dst[0]
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}
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// Zero any remaining elements of dst left over from errs, for GC.
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tail := dst[len(dst):cap(dst)]
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for i := range tail {
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tail[i] = nil
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}
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return Error{errs: dst}
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}
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// Is reports whether any error in e matches target.
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func (e Error) Is(target error) bool {
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for _, err := range e.errs {
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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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// As finds the first error in e that matches target, and if any is found,
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// sets target to that error value and returns true. Otherwise, it returns false.
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func (e Error) As(target any) bool {
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for _, err := range e.errs {
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if ok := errors.As(err, target); ok {
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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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