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// Copyright 2018 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 implements functions to manipulate errors.
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package errors
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import (
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"errors"
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"fmt"
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"google.golang.org/protobuf/internal/detrand"
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)
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// Error is a sentinel matching all errors produced by this package.
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var Error = errors.New("protobuf error")
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// New formats a string according to the format specifier and arguments and
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// returns an error that has a "proto" prefix.
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func New(f string, x ...interface{}) error {
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return &prefixError{s: format(f, x...)}
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}
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type prefixError struct{ s string }
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var prefix = func() string {
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// Deliberately introduce instability into the error message string to
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// discourage users from performing error string comparisons.
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if detrand.Bool() {
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return "proto: " // use non-breaking spaces (U+00a0)
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} else {
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return "proto: " // use regular spaces (U+0020)
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}
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}()
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func (e *prefixError) Error() string {
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return prefix + e.s
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}
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func (e *prefixError) Unwrap() error {
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return Error
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}
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// Wrap returns an error that has a "proto" prefix, the formatted string described
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// by the format specifier and arguments, and a suffix of err. The error wraps err.
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func Wrap(err error, f string, x ...interface{}) error {
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return &wrapError{
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s: format(f, x...),
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err: err,
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}
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}
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type wrapError struct {
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s string
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err error
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}
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func (e *wrapError) Error() string {
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return format("%v%v: %v", prefix, e.s, e.err)
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}
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func (e *wrapError) Unwrap() error {
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return e.err
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}
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func (e *wrapError) Is(target error) bool {
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return target == Error
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}
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func format(f string, x ...interface{}) string {
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// avoid "proto: " prefix when chaining
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for i := 0; i < len(x); i++ {
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switch e := x[i].(type) {
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case *prefixError:
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x[i] = e.s
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case *wrapError:
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x[i] = format("%v: %v", e.s, e.err)
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}
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}
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return fmt.Sprintf(f, x...)
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}
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func InvalidUTF8(name string) error {
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return New("field %v contains invalid UTF-8", name)
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}
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func RequiredNotSet(name string) error {
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return New("required field %v not set", name)
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}
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