// Copyright 2017, 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.md file.

package value

import (

	"math"

	"reflect"

)

// IsZero reports whether v is the zero value.

// This does not rely on Interface and so can be used on unexported fields.

func IsZero(v reflect.Value) bool {

	switch v.Kind() {

	case reflect.Bool:

		return v.Bool() == false

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:

		return v.Int() == 0

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:

		return v.Uint() == 0

	case reflect.Float32, reflect.Float64:

		return math.Float64bits(v.Float()) == 0

	case reflect.Complex64, reflect.Complex128:

		return math.Float64bits(real(v.Complex())) == 0 && math.Float64bits(imag(v.Complex())) == 0

	case reflect.String:

		return v.String() == ""

	case reflect.UnsafePointer:

		return v.Pointer() == 0

	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:

		return v.IsNil()

	case reflect.Array:

		for i := 0; i < v.Len(); i++ {

			if !IsZero(v.Index(i)) {

				return false

			}

		}

		return true

	case reflect.Struct:

		for i := 0; i < v.NumField(); i++ {

			if !IsZero(v.Field(i)) {

				return false

			}

		}

		return true

	}

	return false

}