カスタム Enum.TryParse

基になる数値の文字列表現はパースできません。

速度については、これまた測定していません。

EnumHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

class Program
{
    static void Main(string[] args)
    {
        var enumType = typeof(FooBar);
        var helper = (EnumHelperBase)Activator.CreateInstance(typeof(EnumHelper<>).MakeGenericType(enumType));
        TestParse(helper, "");
        TestParse(helper, "Default");
        TestParse(helper, "Foo");
        TestParse(helper, "Bar");
        TestParse(helper, "Baz");
        TestParse(helper, "Fizz");
        TestParse(helper, "Buzz");
        TestParse(helper, "FizzBuzz");
    }

    private static void TestParse(EnumHelperBase helper, string value)
    {
        object result;
        bool success = helper.TryParse(value, out result);
        Console.WriteLine("Success={0}, Result={1}", success, result);
    }
}

public enum FooBar
{
    Default = 0,
    Foo = 0,
    Bar = 3,
    Baz = 6,
    Fizz = 3,
    Buzz = 5,
    FizzBuzz = 15,
}

public abstract class EnumHelperBase
{
    public abstract bool TryParse(string value, out object result);
}

public class EnumHelper<T> : EnumHelperBase where T : struct
{
    private readonly Dictionary<string, T> table;
    public EnumHelper()
    {
        Type t = typeof(T);
        if (!t.IsEnum)
        {
            throw new InvalidOperationException("Type parameter is not enum.");
        }
        var fields = t.GetFields(BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic);
        table = fields.ToDictionary(x => x.Name, x => (T)x.GetRawConstantValue());
    }

    public bool TryParse(string value, out T result)
    {
        return table.TryGetValue(value, out result);
    }

    public override bool TryParse(string value, out object result)
    {
        T enumResult;
        bool success = this.TryParse(value, out enumResult);
        result = enumResult;
        return success;
    }
}