using System.Collections.Generic;

namespace Plane.Collections
{
    public static class DictionaryExtensions
    {
        /// <summary>
        /// 尝试返回字典中与指定的键对应的值，若此键不存在则返回指定的默认值。
        /// </summary>
        /// <typeparam name="TKey">键的类型。</typeparam>
        /// <typeparam name="TValue">值的类型。</typeparam>
        /// <param name="dictionary">源字典。</param>
        /// <param name="key">键。</param>
        /// <param name="defaultValue">默认值。</param>
        /// <returns>若字典中包含指定的键，返回其对应的值；否则返回指定的默认值。</returns>
        public static TValue GetValue<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key, TValue defaultValue = default(TValue))
        {
            var value = defaultValue;
            dictionary.TryGetValue(key, out value);
            return value;
        }
    }
}