实现通用的 ToConcurrentDictionary 扩展方法

Question

I Was trying to add some type safe dictionary logic to my app and tried to look around for an implementation to convert a given dictionary to a concurrent one. After searching for a while with no luck, I ended up implementing a version of my own with some hacked up code. below is the version I have come up with:

    public static class Extensions
      {
        public static ConcurrentDictionary<TKey, TValueResult> ToConcurrentDictionary<TKey, TValueInput, TValueResult>(this IEnumerable<KeyValuePair<TKey, TValueInput>> input)
        {
          var result = new ConcurrentDictionary<TKey, TValueResult>();
          foreach (var kv in input)
          {
            if (typeof(TValueInput).IsDictionaryType())
            {
              var mi = MethodInfo.GetCurrentMethod() as MethodInfo;
              var valGenericArgs = typeof(TValueInput).GetGenericArguments();
              if (valGenericArgs.Length > 0 && valGenericArgs.Last().IsDictionaryType())
              {
                Type generic = typeof(ConcurrentDictionary<,>);
                var conDicType = generic.MakeGenericType(typeof(TValueResult).GetGenericArguments().Last().GetGenericArguments());
                valGenericArgs = valGenericArgs.Concat(new Type[] { conDicType }).ToArray();
              }
              else
              {
                valGenericArgs = valGenericArgs.Concat(new Type[] { valGenericArgs.Last() }).ToArray();
              }
              var genMi = mi.MakeGenericMethod(valGenericArgs);
              var newDic = genMi.Invoke(null, new object[] { kv.Value });
              result.TryAdd(kv.Key, (TValueResult)newDic);
            }
            else
            {
              result.TryAdd(kv.Key, (TValueResult)Convert.ChangeType(kv.Value, typeof(TValueResult)));
            }
          }
          return result;
        }

        public static bool IsDictionaryType(this Type type)
        {
          return type.FullName.StartsWith("System.Collections.Generic.IDictionary`")
            || type.GetInterfaces().Any(t => t.FullName.StartsWith("System.Collections.Generic.IDictionary`"));
        }
}

Using the method is like below:

  var dic1 = new Dictionary<string, Dictionary<int, IDictionary<string, int>>> 
    { 
        {"one", new Dictionary<int, IDictionary<string, int>>
                {
                    {11, new Dictionary<string,int>
                                {
                                    {"one-one-one", 10000}
                                }
                    }
                }
        }
    };
  var dic2 = new Dictionary<int, IDictionary<int, IDictionary<int, string>>> 
    { 
        {1, new Dictionary<int, IDictionary<int, string>>
                {
                    {11, new Dictionary<int,string>
                                {
                                    {111, "one-one-one"}
                                }
                    }
                }
        }
    };

  var dic3 = new Dictionary<int, string> 
                                {
                                    {111, "one-one-one"}
                                };

  var cd1 = dic1.ToConcurrentDictionary<string, Dictionary<int, IDictionary<string, int>>, ConcurrentDictionary<int, ConcurrentDictionary<string, int>>>();
  var cd2 = dic2.ToConcurrentDictionary<int, IDictionary<int, IDictionary<int, string>>, ConcurrentDictionary<int, ConcurrentDictionary<int, string>>>();
  var cd3 = dic3.ToConcurrentDictionary<int, string, string>();

Any suggestions to improve this method or any better alternatives to achieve the same results?

Answer 1

Looking at MSDN there is a constructor for ConcurrentDictionary that accepts an IEnumerable of KeyValuePairs. Would this achieve what you're looking for?

public static ConcurrentDictionary<TKey, TValue> ToConcurrentDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> input)
{
        return new ConcurrentDictionary<TKey, TValue>(input);
}

Answer 2

//Translate A to B
var a = new Dictionary<Dictionary<string, string>>();
var b = a.SerializeJson()
         .DeserializeJson<ConcurrentDictionary<ConcurrentDictionary<string,string>>();

Answer 3

I know this is an old thread, but looking at the Microsoft source code for ToDictionary, I was able to make an extender for ToConcurrentDictionary and ToConcurrentBag

public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
    {
        return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance, null);
    }

    public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
    {
        return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance, comparer);
    }

    public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
    {
        //return ToConcurrentDictionary<TSource, TKey, TElement>(source, keySelector, elementSelector, null);
        if (source == null) throw new Exception("Source is null");
        if (keySelector == null) throw new Exception("Key is null");
        if (elementSelector == null) throw new Exception("Selector is null");

        ConcurrentDictionary<TKey, TElement> d = new ConcurrentDictionary<TKey, TElement>();
        foreach (TSource element in source) d.TryAdd(keySelector(element), elementSelector(element));
        return d;
    }

    public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
    {
        if (source == null) throw new Exception("Source is null");
        if (keySelector == null) throw new Exception("Key is null");
        if (elementSelector == null) throw new Exception("Selector is null");

        ConcurrentDictionary<TKey, TElement> d = new ConcurrentDictionary<TKey, TElement>(comparer);
        foreach (TSource element in source) d.TryAdd(keySelector(element), elementSelector(element));
        return d;
    }
    public static ConcurrentBag<TSource> ToConcurrentBag<TSource>(this IEnumerable<TSource> source)
    {
        if (source == null) throw new Exception("Source is null");
        return new ConcurrentBag<TSource>(source);
    }