// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package errors

import (
	
)

// 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 ( error) error {
	,  := .(interface {
		() error
	})
	if ! {
		return nil
	}
	return .()
}

// Is reports whether any error in err's tree matches target.
// The target must be comparable.
//
// The tree consists of err itself, followed by the errors obtained by repeatedly
// calling its Unwrap() error or Unwrap() []error method. 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.
func (,  error) bool {
	if  == nil ||  == nil {
		return  == 
	}

	 := reflectlite.TypeOf().Comparable()
	return is(, , )
}

func is(,  error,  bool) bool {
	for {
		if  &&  ==  {
			return true
		}
		if ,  := .(interface{ (error) bool });  && .() {
			return true
		}
		switch x := .(type) {
		case interface{ () error }:
			 = .()
			if  == nil {
				return false
			}
		case interface{ () []error }:
			for ,  := range .() {
				if (, , ) {
					return true
				}
			}
			return false
		default:
			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.
//
// For most uses, prefer [AsType]. As is equivalent to [AsType] but sets its target
// argument rather than returning the matching error and doesn't require its target
// argument to implement error.
//
// The tree consists of err itself, followed by the errors obtained by repeatedly
// calling its Unwrap() error or Unwrap() []error method. 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(any) 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.
func ( error,  any) bool {
	if  == nil {
		return false
	}
	if  == nil {
		panic("errors: target cannot be nil")
	}
	 := reflectlite.ValueOf()
	 := .Type()
	if .Kind() != reflectlite.Ptr || .IsNil() {
		panic("errors: target must be a non-nil pointer")
	}
	 := .Elem()
	if .Kind() != reflectlite.Interface && !.Implements(errorType) {
		panic("errors: *target must be interface or implement error")
	}
	return as(, , , )
}

func as( error,  any,  reflectlite.Value,  reflectlite.Type) bool {
	for {
		if reflectlite.TypeOf().AssignableTo() {
			.Elem().Set(reflectlite.ValueOf())
			return true
		}
		if ,  := .(interface{ (any) bool });  && .() {
			return true
		}
		switch x := .(type) {
		case interface{ () error }:
			 = .()
			if  == nil {
				return false
			}
		case interface{ () []error }:
			for ,  := range .() {
				if  == nil {
					continue
				}
				if (, , , ) {
					return true
				}
			}
			return false
		default:
			return false
		}
	}
}

var errorType = reflectlite.TypeOf((*error)(nil)).Elem()

// AsType finds the first error in err's tree that matches the type E, and
// if one is found, returns that error value and true. Otherwise, it
// returns the zero value of E and false.
//
// The tree consists of err itself, followed by the errors obtained by
// repeatedly calling its Unwrap() error or Unwrap() []error method. When
// err wraps multiple errors, AsType examines err followed by a
// depth-first traversal of its children.
//
// An error err matches the type E if the type assertion err.(E) holds,
// or if the error has a method As(any) bool such that err.As(target)
// returns true when target is a non-nil *E. In the latter case, the As
// method is responsible for setting target.
func [ error]( error) (, bool) {
	if  == nil {
		var  
		return , false
	}
	var  * // lazily initialized
	return asType(, &)
}

func asType[ error]( error,  **) ( ,  bool) {
	for {
		if ,  := .();  {
			return , true
		}
		if ,  := .(interface{ (any) bool });  {
			if * == nil {
				* = new()
			}
			if .(*) {
				return **, true
			}
		}
		switch x := .(type) {
		case interface{ () error }:
			 = .()
			if  == nil {
				return
			}
		case interface{ () []error }:
			for ,  := range .() {
				if  == nil {
					continue
				}
				if ,  := (, );  {
					return , true
				}
			}
			return
		default:
			return
		}
	}
}