/// <summary>
/// 获取指定枚举的描述对象数组。
/// </summary>
/// <param name="enumType">要获取的枚举类型，可为<seealso cref="System.Nullable"/>类型。</param>
/// <param name="underlyingType">是否将生成的 <seealso cref="EnumEntry"/> 元素的 <seealso cref="EnumEntry.Value"/> 属性值置为 enumType 参数对应的枚举项基类型值。</param>
/// <param name="nullValue">如果参数<paramref name="enumType"/>为可空类型时，该空值对应的<seealso cref="EnumEntry.Value"/>属性的值。</param>
/// <param name="nullText">如果参数<paramref name="enumType"/>为可空类型时，该空值对应的<seealso cref="EnumEntry.Description"/>属性的值。</param>
/// <returns>返回的枚举描述对象数组。</returns>
public static EnumEntry[] GetEnumEntries(Type enumType, bool underlyingType, object nullValue, string nullText)
{
if (enumType == null)
{
throw new ArgumentNullException(nameof(enumType));
}
Type underlyingTypeOfNullable = Nullable.GetUnderlyingType(enumType);
if (underlyingTypeOfNullable != null)
{
enumType = underlyingTypeOfNullable;
}
EnumEntry[] entries;
int baseIndex = (underlyingTypeOfNullable == null) ? 0 : 1;
var fields = enumType.GetFields(BindingFlags.Public | BindingFlags.Static);
if (underlyingTypeOfNullable == null)
{
entries = new EnumEntry[fields.Length];
}
else
{
entries = new EnumEntry[fields.Length + 1];
entries[0] = new EnumEntry(enumType, string.Empty, nullValue, nullText, nullText);
}
for (int i = 0; i < fields.Length; i++)
{
var alias = fields[i].GetCustomAttributes(typeof(AliasAttribute), false).OfType <AliasAttribute>().FirstOrDefault();
var description = fields[i].GetCustomAttributes(typeof(DescriptionAttribute), false).OfType <DescriptionAttribute>().FirstOrDefault();
entries[baseIndex + i] = new EnumEntry(enumType, fields[i].Name,
underlyingType ? System.Convert.ChangeType(fields[i].GetValue(null), Enum.GetUnderlyingType(enumType)) : fields[i].GetValue(null),
alias == null ? string.Empty : alias.Alias,
description == null ? string.Empty : ResourceUtility.GetString(description.Description, enumType.Assembly));
}
return(entries);
}
