1 // +build go1.13
2 3 package errors
4 5 import (
6 stderrors "errors"
7 )
8 9 // Is reports whether any error in err's chain matches target.
10 //
11 // The chain consists of err itself followed by the sequence of errors obtained by
12 // repeatedly calling Unwrap.
13 //
14 // An error is considered to match a target if it is equal to that target or if
15 // it implements a method Is(error) bool such that Is(target) returns true.
16 func Is(err, target error) bool { return stderrors.Is(err, target) }
17 18 // As finds the first error in err's chain that matches target, and if so, sets
19 // target to that error value and returns true.
20 //
21 // The chain consists of err itself followed by the sequence of errors obtained by
22 // repeatedly calling Unwrap.
23 //
24 // An error matches target if the error's concrete value is assignable to the value
25 // pointed to by target, or if the error has a method As(interface{}) bool such that
26 // As(target) returns true. In the latter case, the As method is responsible for
27 // setting target.
28 //
29 // As will panic if target is not a non-nil pointer to either a type that implements
30 // error, or to any interface type. As returns false if err is nil.
31 func As(err error, target interface{}) bool { return stderrors.As(err, target) }
32 33 // Unwrap returns the result of calling the Unwrap method on err, if err's
34 // type contains an Unwrap method returning error.
35 // Otherwise, Unwrap returns nil.
36 func Unwrap(err error) error {
37 return stderrors.Unwrap(err)
38 }
39