/*
 * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
 *
 * 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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package errors

// llgo:skipall
import (
	_ "unsafe"
)

// 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].
func Unwrap(err error) error {
	u, ok := err.(interface {
		Unwrap() error
	})
	if !ok {
		return nil
	}
	return u.Unwrap()
}

// New returns an error that formats as the given text.
// Each call to New returns a distinct error value even if the text is identical.
func New(text string) error {
	return &errorString{text}
}

// errorString is a trivial implementation of error.
type errorString struct {
	s string
}

func (e *errorString) Error() string {
	return e.s
}

// ErrUnsupported indicates that a requested operation cannot be performed,
// because it is unsupported. For example, a call to [os.Link] when using a
// file system that does not support hard links.
//
// Functions and methods should not return this error but should instead
// return an error including appropriate context that satisfies
//
//	errors.Is(err, errors.ErrUnsupported)
//
// either by directly wrapping ErrUnsupported or by implementing an Is method.
//
// Functions and methods should document the cases in which an error
// wrapping this will be returned.
var ErrUnsupported = New("unsupported operation")