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nullable.go
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nullable.go
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package nullable
import "reflect"
// Nullable is an interface with an IsNull method
type Nullable interface {
// IsNull returns true if the implementing value is considered null.
IsNull() bool
}
// Zeroable is an interface with an IsZero method
type Zeroable interface {
// IsZero returns true if the implementing value is considered zero.
IsZero() bool
}
// ReflectIsNull returns if a reflect.Value contains either a nil value
// or implements the Nullable interface and returns true from IsNull
// or implements the Zeroable interface and returns true from IsZero.
// It's safe to call ReflectIsNull on any reflect.Value
// with true returned for the zero value of reflect.Value.
func ReflectIsNull(v reflect.Value) bool {
switch v.Kind() {
case reflect.Pointer:
if v.IsNil() {
return true
}
v = v.Elem()
case reflect.Map, reflect.Slice, reflect.Interface, reflect.Chan, reflect.Func, reflect.UnsafePointer:
if v.IsNil() {
return true
}
case reflect.Invalid:
return true
}
nullable, _ := v.Interface().(Nullable)
if nullable == nil && v.CanAddr() {
nullable, _ = v.Addr().Interface().(Nullable)
}
if nullable != nil {
return nullable.IsNull()
}
zeroable, _ := v.Interface().(Zeroable)
if zeroable == nil && v.CanAddr() {
zeroable, _ = v.Addr().Interface().(Zeroable)
}
if zeroable != nil {
return zeroable.IsZero()
}
return false
}