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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package internal
import (
"fmt"
)
// WrappedError represents an error that contains another error.
type WrappedError interface {
// Message gets the basic message of the error.
Message() string
// Inner gets the inner error if one exists.
Inner() error
}
// RolledUpErrorMessage gets a flattened error message.
func RolledUpErrorMessage(err error) string {
if wrappedErr, ok := err.(WrappedError); ok {
inner := wrappedErr.Inner()
if inner != nil {
return fmt.Sprintf("%s: %s", wrappedErr.Message(), RolledUpErrorMessage(inner))
}
return wrappedErr.Message()
}
return err.Error()
}
//UnwrapError attempts to unwrap the error down to its root cause.
func UnwrapError(err error) error {
switch tErr := err.(type) {
case WrappedError:
return UnwrapError(tErr.Inner())
case *multiError:
return UnwrapError(tErr.errors[0])
}
return err
}
// WrapError wraps an error with a message.
func WrapError(inner error, message string) error {
return &wrappedError{message, inner}
}
// WrapErrorf wraps an error with a message.
func WrapErrorf(inner error, format string, args ...interface{}) error {
return &wrappedError{fmt.Sprintf(format, args...), inner}
}
// MultiError combines multiple errors into a single error. If there are no errors,
// nil is returned. If there is 1 error, it is returned. Otherwise, they are combined.
func MultiError(errors ...error) error {
// remove nils from the error list
var nonNils []error
for _, e := range errors {
if e != nil {
nonNils = append(nonNils, e)
}
}
switch len(nonNils) {
case 0:
return nil
case 1:
return nonNils[0]
default:
return &multiError{
message: "multiple errors encountered",
errors: nonNils,
}
}
}
type multiError struct {
message string
errors []error
}
func (e *multiError) Message() string {
return e.message
}
func (e *multiError) Error() string {
result := e.message
for _, e := range e.errors {
result += fmt.Sprintf("\n %s", e)
}
return result
}
func (e *multiError) Errors() []error {
return e.errors
}
type wrappedError struct {
message string
inner error
}
func (e *wrappedError) Message() string {
return e.message
}
func (e *wrappedError) Error() string {
return RolledUpErrorMessage(e)
}
func (e *wrappedError) Inner() error {
return e.inner
}
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