func reifySliceMerge()

in reify.go [542:587]

• 37 lines of code
• 9 McCabe index (conditional complexity)

func reifySliceMerge(
	opts fieldOptions,
	old reflect.Value,
	tTo reflect.Type,
	val value,
) (reflect.Value, Error) {
	arr, err := castArr(opts.opts, val)
	if err != nil {
		return reflect.Value{}, err
	}

	arrMergeCfg := opts.configHandling()

	l := len(arr)
	start := 0
	cpyStart := 0

	withOld := old.IsValid() && !old.IsNil()
	if withOld {
		ol := old.Len()

		switch arrMergeCfg {
		case cfgReplaceValue:
			// do nothing

		case cfgArrAppend:
			l += ol
			start = ol

		case cfgArrPrepend:
			cpyStart = l
			l += ol

		default:
			if l < ol {
				l = ol
			}
		}
	}
	tmp := reflect.MakeSlice(tTo, l, l)

	if withOld {
		reflect.Copy(tmp.Slice(cpyStart, tmp.Len()), old)
	}
	return reifyDoArray(opts, tmp, tTo.Elem(), start, val, arr)
}