Pchp.Library.Arrays.array_flip C# (CSharp) Method

        public static PhpArray array_flip(PhpArray array)
        {
            if (array == null)
            {
                //PhpException.ArgumentNull("array");
                //return null;
                throw new ArgumentNullException();
            }

            PhpArray result = new PhpArray(array.Count);

            var iterator = array.GetFastEnumerator();
            while (iterator.MoveNext())
            {
                var entry = iterator.Current;
                // dereferences value:
                var val = entry.Value.GetValue();
                switch (val.TypeCode)
                {
                    case PhpTypeCode.Int32:
                    case PhpTypeCode.Long:
                    case PhpTypeCode.String:
                    case PhpTypeCode.WritableString:
                        var askey = val.ToIntStringKey();
                        result[askey] = PhpValue.Create(entry.Key);
                        break;
                    default:
                        // PhpException.Throw(PhpError.Warning, LibResources.GetString("neither_string_nor_integer_value", "flip"));
                        throw new ArgumentException();
                }
            }

            // no need to deep copy because values are ints/strings only (<= keys were int/strings only):
            return result;
        }