EnumDescription

IEnumDescription describes an enum type.

/// <summary>Description of an enum type.</summary>
/// <remarks>See Avalanche.Message.Localization for localizing <see cref="IEnumDescription"/>.</remarks>
public interface IEnumDescription
{
    /// <summary>Underlying type</summary>
    Type ItemType { get; set; }
    /// <summary>Flag operations. Null if enum is not [Flags] usable.</summary>
    IEnumFlagOperations<object>? Flags { get; set; }
    /// <summary>Details about each item.</summary>
    IList<IEnumItem<object>> Items { get; set; }
}

IEnumFlagOperations describes an enum flag operations.

/// <summary>Enumeration flag operations</summary>
public interface IEnumFlagOperations<T>
{
    /// <summary>Underlying type</summary>
    Type Type { get; set; }
    /// <summary>Get-or-create default value.</summary>
    T Default { get; set; }
    /// <summary>Test whether <paramref name="enumValue"/> has any of the flags in <paramref name="flags"/>.</summary>
    bool HasAny(T @enumValue, T flags);
    /// <summary>Test whether <paramref name="enumValue"/> has all of the flags in <paramref name="flags"/>.</summary>
    bool HasAll(T @enumValue, T flags);
    /// <summary>Intersection of <paramref name="value1"/> and <paramref name="value2"/></summary>
    T Intersection(T value1, T value2);
    /// <summary>Union of <paramref name="value1"/> and <paramref name="value2"/></summary>
    T Union(T value1, T value2);
}

IEnumItem describes an enum item.

/// <summary>Enum item description</summary>
public interface IEnumItem<T>
{
    /// <summary>Key, typically "Class:Field".</summary>
    string Key { get; set; }
    /// <summary>Enumeration item name, part of full key.</summary>
    string Name { get; set; }
    /// <summary>Object that prints label when ToString() is called. May implement <see cref="IFormattable"/> or <see cref="ISpanFormattable"/> for culture specific formatting.</summary>
    object Label { get; set; }
    /// <summary>Value, such as <see cref="string"/>.</summary>
    T Value { get; set; }
}

EnumDescription.CreateForEnumType(type) creates description for an enum type.

// Create IEnumDescription
IEnumDescription enumDescription = EnumDescription.CreateForEnumType(typeof(LanguageEnum));
// Print items
foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);

[Flags]
public enum LanguageEnum
{
    Finnish = 1 << 0,
    Swedish = 1 << 1,
    Norwegian = 1 << 2
}

[EnumOf] indicates that type contains an enum.

public record MyRecord200
{
    [EnumOf<string, Languages>(isFlags: true)]
    public string Languages { get; set; } = "Finnish";
}

public class Languages : IEnumerable<IEnumItem<object>>
{
    IEnumItem<object>[] content = new IEnumItem<object>[] {
        new EnumItem("Languages:Finnish", "Finnish", "Finnish", "Finnish"),
        new EnumItem("Languages:Swedish", "Swedish", "Swedish", "Swedish"),
        new EnumItem("Languages:Norwegian", "Norwegian", "Norwegian", "Norwegian"),
    };

    public IEnumerator<IEnumItem<object>> GetEnumerator() => ((IEnumerable<IEnumItem<object>>)content).GetEnumerator();
    IEnumerator IEnumerable.GetEnumerator() => content.GetEnumerator();
}

EnumDescription.CreateForEnumOf(enumOfAttribute) creates description for [EnumOf<,>] attribute.

// Get [EnumOf]
EnumOfAttribute enumOf = typeof(MyRecord200)
    .GetProperty(nameof(MyRecord200.Languages))!
    .GetCustomAttribute<EnumOfAttribute>()!;
// Create IEnumDescription
IEnumDescription enumDescription = EnumDescription.CreateForEnumOf(enumOf, null);
// Print items
foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);

If EnumOfAttribute enumerable is interface, then enum items can be supplied to dependency injection.

// Create dependency injection
IServiceProvider services = new ServiceCollection()
    .AddSingleton<ICountries, Countries>()
    .BuildServiceProvider();
// Get [EnumOf]
EnumOfAttribute enumOf = typeof(MyRecord203)
    .GetProperty(nameof(MyRecord203.Countries))!
    .GetCustomAttribute<EnumOfAttribute>()!;
// Create IEnumDescription
IEnumDescription enumDescription = EnumDescription.CreateForEnumOf(enumOf, services);
// Print items
foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);

public record MyRecord203
{
    [EnumOf<string, ICountries>(isFlags: true)]
    public string Countries { get; set; } = "Finland";
}

public interface ICountries : IEnumerable<IEnumItem<object>> { }

public class Countries : ICountries
{
    IEnumItem<object>[] content = new IEnumItem<object>[]
    {
        new EnumItem<string>("Countries:Finland", "Finland", "Finland", "Finland"),
        new EnumItem<string>("Countries:Sweden", "Sweden", "Sweden", "Sweden"),
        new EnumItem<string>("Countries:Norway", "Norway", "Norway", "Norway"),
    };

    public IEnumerator<IEnumItem<object>> GetEnumerator() => ((IEnumerable<IEnumItem<object>>)content).GetEnumerator();
    IEnumerator IEnumerable.GetEnumerator() => content.GetEnumerator();
}

IEnumFlagOperations can create unions, intersections and test flags.

// Get cached IEnumDescription
IEnumDescription enumDescription = EnumDescription.Cached[typeof(LanguageEnum)];
// Choose one item
LanguageEnum language = (LanguageEnum)enumDescription.Items[0].Value;
// Take union
LanguageEnum language2 = (LanguageEnum)enumDescription.Flags!.Union(enumDescription.Items[0].Value, enumDescription.Items[1].Value);
// Take intersection
LanguageEnum language3 = (LanguageEnum)enumDescription.Flags!.Intersection(language, language2);
// Test flag
bool gotOne = enumDescription.Flags!.HasAny(language2, enumDescription.Items[1].Value);
bool gotAll = enumDescription.Flags!.HasAll(language2, enumDescription.Items[1].Value);

Full Example

Full example

using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using Avalanche.Utilities;
using Microsoft.Extensions.DependencyInjection;

public class enumdescription
{
    public static void Run()
    {
        {
            // <01>
            // Create IEnumDescription
            IEnumDescription enumDescription = EnumDescription.CreateForEnumType(typeof(LanguageEnum));
            // Print items
            foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);
            // </01>
        }
        {
            // <02>
            // Get [EnumOf]
            EnumOfAttribute enumOf = typeof(MyRecord200)
                .GetProperty(nameof(MyRecord200.Languages))!
                .GetCustomAttribute<EnumOfAttribute>()!;
            // Create IEnumDescription
            IEnumDescription enumDescription = EnumDescription.CreateForEnumOf(enumOf, null);
            // Print items
            foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);
            // </02>
        }
        {
            // <03>
            // Create dependency injection
            IServiceProvider services = new ServiceCollection()
                .AddSingleton<ICountries, Countries>()
                .BuildServiceProvider();
            // Get [EnumOf]
            EnumOfAttribute enumOf = typeof(MyRecord203)
                .GetProperty(nameof(MyRecord203.Countries))!
                .GetCustomAttribute<EnumOfAttribute>()!;
            // Create IEnumDescription
            IEnumDescription enumDescription = EnumDescription.CreateForEnumOf(enumOf, services);
            // Print items
            foreach (IEnumItem<object> item in enumDescription.Items) Console.WriteLine(item.Name);
            // </03>
        }
        {
            // <04>
            // Get cached IEnumDescription
            IEnumDescription enumDescription = EnumDescription.Cached[typeof(LanguageEnum)];
            // Choose one item
            LanguageEnum language = (LanguageEnum)enumDescription.Items[0].Value;
            // Take union
            LanguageEnum language2 = (LanguageEnum)enumDescription.Flags!.Union(enumDescription.Items[0].Value, enumDescription.Items[1].Value);
            // Take intersection
            LanguageEnum language3 = (LanguageEnum)enumDescription.Flags!.Intersection(language, language2);
            // Test flag
            bool gotOne = enumDescription.Flags!.HasAny(language2, enumDescription.Items[1].Value);
            bool gotAll = enumDescription.Flags!.HasAll(language2, enumDescription.Items[1].Value);
            // </04>
        }
    }
}

// <02B>
public record MyRecord200
{
    [EnumOf<string, Languages>(isFlags: true)]
    public string Languages { get; set; } = "Finnish";
}

public class Languages : IEnumerable<IEnumItem<object>>
{
    IEnumItem<object>[] content = new IEnumItem<object>[] {
        new EnumItem("Languages:Finnish", "Finnish", "Finnish", "Finnish"),
        new EnumItem("Languages:Swedish", "Swedish", "Swedish", "Swedish"),
        new EnumItem("Languages:Norwegian", "Norwegian", "Norwegian", "Norwegian"),
    };

    public IEnumerator<IEnumItem<object>> GetEnumerator() => ((IEnumerable<IEnumItem<object>>)content).GetEnumerator();
    IEnumerator IEnumerable.GetEnumerator() => content.GetEnumerator();
}
// </02B>

// <01B>
[Flags]
public enum LanguageEnum
{
    Finnish = 1 << 0,
    Swedish = 1 << 1,
    Norwegian = 1 << 2
}
// </01B>

// <03B>
public record MyRecord203
{
    [EnumOf<string, ICountries>(isFlags: true)]
    public string Countries { get; set; } = "Finland";
}

public interface ICountries : IEnumerable<IEnumItem<object>> { }

public class Countries : ICountries
{
    IEnumItem<object>[] content = new IEnumItem<object>[]
    {
        new EnumItem<string>("Countries:Finland", "Finland", "Finland", "Finland"),
        new EnumItem<string>("Countries:Sweden", "Sweden", "Sweden", "Sweden"),
        new EnumItem<string>("Countries:Norway", "Norway", "Norway", "Norway"),
    };

    public IEnumerator<IEnumItem<object>> GetEnumerator() => ((IEnumerable<IEnumItem<object>>)content).GetEnumerator();
    IEnumerator IEnumerable.GetEnumerator() => content.GetEnumerator();
}
// </03B>