Dictionary Extensions

DictionaryExtensions.cs

using System;
using System.Linq;

namespace System.Collections.Generic
{
    public static class DictionaryExtensions
    {
        public static TValue GetOrAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, Func<TKey, TValue> valueFactory)
        {
            TValue v;

            if (dictionary.TryGetValue(key, out v))
            {
                return v;
            }
            else
            {
                v = valueFactory(key);
                dictionary.Add(key, v);
                return v;
            }
        }

        public static TValue GetOrAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue value)
        {
            TValue v;

            if (dictionary.TryGetValue(key, out v))
            {
                return v;
            }
            else
            {
                dictionary.Add(key, value);
                return value;
            }
        }

        public static TValue AddOrUpdate<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, Func<TKey, TValue> addValueFactory, Func<TKey, TValue, TValue> updateValueFactory)
        {
            TValue v;
            TValue newValue;

            if (dictionary.TryGetValue(key, out v))
            {
                newValue = updateValueFactory(key, v);
                dictionary[key] = newValue;
            }
            else
            {
                newValue = addValueFactory(key);
                dictionary.Add(key, newValue);
            }

            return newValue;
        }

        public static TValue AddOrUpdate<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue addValue, Func<TKey, TValue, TValue> updateValueFactory)
        {
            TValue v;
            TValue newValue;

            if (dictionary.TryGetValue(key, out v))
            {
                newValue = updateValueFactory(key, v);
                dictionary[key] = newValue;
            }
            else
            {
                newValue = addValue;
                dictionary.Add(key, newValue);
            }

            return newValue;
        }
    }
}