135 lines
4.0 KiB
Go
135 lines
4.0 KiB
Go
package errors
|
|
|
|
import (
|
|
_ "unsafe"
|
|
)
|
|
|
|
// Is reports whether any error in err's tree matches target.
|
|
//
|
|
// The tree consists of err itself, followed by the errors obtained by repeatedly
|
|
// calling Unwrap. When err wraps multiple errors, Is examines err followed by a
|
|
// depth-first traversal of its children.
|
|
//
|
|
// An error is considered to match a target if it is equal to that target or if
|
|
// it implements a method Is(error) bool such that Is(target) returns true.
|
|
//
|
|
// An error type might provide an Is method so it can be treated as equivalent
|
|
// to an existing error. For example, if MyError defines
|
|
//
|
|
// func (m MyError) Is(target error) bool { return target == fs.ErrExist }
|
|
//
|
|
// then Is(MyError{}, fs.ErrExist) returns true. See [syscall.Errno.Is] for
|
|
// an example in the standard library. An Is method should only shallowly
|
|
// compare err and the target and not call Unwrap on either.
|
|
//
|
|
//go:linkname Is errors.Is
|
|
func Is(err error, target error) bool
|
|
|
|
// IsV2 calls Is(err, target) for each target within targets.
|
|
func IsV2(err error, targets ...error) bool {
|
|
for _, target := range targets {
|
|
if Is(err, target) {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// As finds the first error in err's tree that matches target, and if one is found, sets
|
|
// target to that error value and returns true. Otherwise, it returns false.
|
|
//
|
|
// The tree consists of err itself, followed by the errors obtained by repeatedly
|
|
// calling Unwrap. When err wraps multiple errors, As examines err followed by a
|
|
// depth-first traversal of its children.
|
|
//
|
|
// An error matches target if the error's concrete value is assignable to the value
|
|
// pointed to by target, or if the error has a method As(interface{}) bool such that
|
|
// As(target) returns true. In the latter case, the As method is responsible for
|
|
// setting target.
|
|
//
|
|
// An error type might provide an As method so it can be treated as if it were a
|
|
// different error type.
|
|
//
|
|
// As panics if target is not a non-nil pointer to either a type that implements
|
|
// error, or to any interface type.
|
|
//
|
|
//go:linkname As errors.As
|
|
func As(err error, target any) bool
|
|
|
|
// AsV2 is functionally similar to As(), instead
|
|
// leveraging generics to handle allocation and
|
|
// returning of a concrete generic parameter type.
|
|
func AsV2[Type any](err error) Type {
|
|
var t Type
|
|
var ok bool
|
|
errs := []error{err}
|
|
for len(errs) > 0 {
|
|
// Pop next error to check.
|
|
err := errs[len(errs)-1]
|
|
errs = errs[:len(errs)-1]
|
|
|
|
// Check direct type.
|
|
t, ok = err.(Type)
|
|
if ok {
|
|
return t
|
|
}
|
|
|
|
// Look for .As() support.
|
|
as, ok := err.(interface {
|
|
As(target any) bool
|
|
})
|
|
|
|
if ok {
|
|
// Attempt .As().
|
|
if as.As(&t) {
|
|
return t
|
|
}
|
|
}
|
|
|
|
// Try unwrap errors.
|
|
switch u := err.(type) {
|
|
case interface{ Unwrap() error }:
|
|
errs = append(errs, u.Unwrap())
|
|
case interface{ Unwrap() []error }:
|
|
errs = append(errs, u.Unwrap()...)
|
|
}
|
|
}
|
|
return t
|
|
}
|
|
|
|
// Unwrap returns the result of calling the Unwrap method on err, if err's
|
|
// type contains an Unwrap method returning error.
|
|
// Otherwise, Unwrap returns nil.
|
|
//
|
|
// Unwrap only calls a method of the form "Unwrap() error".
|
|
// In particular Unwrap does not unwrap errors returned by [Join].
|
|
//
|
|
//go:linkname Unwrap errors.Unwrap
|
|
func Unwrap(err error) error
|
|
|
|
// UnwrapV2 is functionally similar to Unwrap(), except that
|
|
// it also handles the case of interface{ Unwrap() []error }.
|
|
func UnwrapV2(err error) []error {
|
|
switch u := err.(type) {
|
|
case interface{ Unwrap() error }:
|
|
if e := u.Unwrap(); err != nil {
|
|
return []error{e}
|
|
}
|
|
case interface{ Unwrap() []error }:
|
|
return u.Unwrap()
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Join returns an error that wraps the given errors.
|
|
// Any nil error values are discarded.
|
|
// Join returns nil if every value in errs is nil.
|
|
// The error formats as the concatenation of the strings obtained
|
|
// by calling the Error method of each element of errs, with a newline
|
|
// between each string.
|
|
//
|
|
// A non-nil error returned by Join implements the Unwrap() []error method.
|
|
//
|
|
//go:linkname Join errors.Join
|
|
func Join(errs ...error) error
|