1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/github.com/go-errors/errors/error_backward.go b/vendor/github.com/go-errors/errors/error_backward.go
new file mode 100644
index 000000000..80b0695e7
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/error_backward.go
@@ -0,0 +1,57 @@
+// +build !go1.13
+
+package errors
+
+import (
+	"reflect"
+)
+
+type unwrapper interface {
+	Unwrap() error
+}
+
+// As assigns error or any wrapped error to the value target points
+// to. If there is no value of the target type of target As returns
+// false.
+func As(err error, target interface{}) bool {
+	targetType := reflect.TypeOf(target)
+
+	for {
+		errType := reflect.TypeOf(err)
+
+		if errType == nil {
+			return false
+		}
+
+		if reflect.PtrTo(errType) == targetType {
+			reflect.ValueOf(target).Elem().Set(reflect.ValueOf(err))
+			return true
+		}
+
+		wrapped, ok := err.(unwrapper)
+		if ok {
+			err = wrapped.Unwrap()
+		} else {
+			return false
+		}
+	}
+}
+
+// Is detects whether the error is equal to a given error. Errors
+// are considered equal by this function if they are the same object,
+// or if they both contain the same error inside an errors.Error.
+func Is(e error, original error) bool {
+	if e == original {
+		return true
+	}
+
+	if e, ok := e.(*Error); ok {
+		return Is(e.Err, original)
+	}
+
+	if original, ok := original.(*Error); ok {
+		return Is(e, original.Err)
+	}
+
+	return false
+}