Simple Cache

using System;
using System.Collections.Concurrent;

namespace Common.Utilities
{
    /// <summary>
    /// Very simple caching using a <seealso cref="System.Collections.Concurrent.ConcurrentDictionary"/>
    /// </summary>
    public class SimpleCache
    {
        static SimpleCache _default = new SimpleCache();

        public static SimpleCache Default
        {
            get { return _default; }
        }

        readonly ConcurrentDictionary<string, object> s_cache = new ConcurrentDictionary<string, object>();

        /// <summary>
        /// Returns the cached item or call the valueFactory() delegate to insert the results into the cache
        /// </summary>
        public T GetOrAdd<T>(string key, Func<string, T> valueFactory, bool enabled = true) where T : class
        {
            if (!enabled)
                return valueFactory(key);

            object raw = s_cache.GetOrAdd(key, valueFactory: (arg) =>
            {
                return valueFactory(arg);
            });

            T ret = raw as T;
            return ret;
        }

        /// <summary>
        /// Returns the cached item or call the valueFactory() delegate to insert the results into the cache
        /// </summary>
        public object GetOrAdd(string key, Func<string, object> valueFactory, bool enabled = true)
        {
            return GetOrAdd<object>(key, valueFactory, enabled);
        }

        public void Clear()
        {
            s_cache.Clear();
        }
    }
}