GetFriendlyName.cs

using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;

namespace K4os.Fx;

internal static class ReflectionExtensions
{
	private static readonly ConcurrentDictionary<Type, string> FriendlyNamesCache = new();
	
	public static string GetFriendlyName(this Type? type) => 
		type is null ? "<null>" : FriendlyNamesCache.GetOrAdd(type, BuildFriendlyName);

	private static string BuildFriendlyName(Type? type)
	{
		if (type is null) return "<null>";

		var typeName = type.Name;
		if (!type.IsGenericType)
			return typeName;

		var length = typeName.IndexOf('`');
		if (length < 0) length = typeName.Length;

		return new StringBuilder()
			.Append(typeName, 0, length)
			.Append('<')
			.Append(string.Join(",", type.GetGenericArguments().Select(GetFriendlyName)))
			.Append('>')
			.ToString();
	}

	public static string GetObjectFriendlyName(this object? subject) =>
		subject is null 
			? "<null>" 
			: $"{subject.GetType().GetFriendlyName()}@{RuntimeHelpers.GetHashCode(subject):x}";
}