CSharp: Iterator Pattern in donet core 6

资源都来源于互联网

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241

/// <summary>    /// 迭代器模式  Iterator Pattern    /// </summary>    public interface IIterableCollection    {        /// <summary>        ///        /// </summary>        /// <returns></returns>        IIterator CreateIterator();    }    /// <summary>    /// 迭代器模式  Iterator Pattern    /// </summary>    public class FestivalCollection : IIterableCollection    {          /// <summary>        ///        /// </summary>        private readonly List<MusicFestival> _festivals = new();        /// <summary>        ///        /// </summary>        public int Count => _festivals.Count;        /// <summary>        ///        /// </summary>        /// <param name="festival"></param>        public void Add(MusicFestival festival) => _festivals.Add(festival);        /// <summary>        ///        /// </summary>        /// <param name="index"></param>        /// <returns></returns>        public MusicFestival Get(int index) => _festivals[index];        /// <summary>        ///        /// </summary>        /// <returns></returns>        public IIterator CreateIterator() => new FestivalIterator(this);        }      /// <summary>    ///  迭代器模式  Iterator Pattern    /// </summary>    public interface IIterator    {        /// <summary>        ///        /// </summary>        int Step { get; set; }        /// <summary>        ///        /// </summary>        /// <returns></returns>        MusicFestival First();        /// <summary>        ///        /// </summary>        /// <returns></returns>        MusicFestival Current();        /// <summary>        ///        /// </summary>        /// <returns></returns>        bool MoveNext();        /// <summary>        ///        /// </summary>        void Reset();      }   /// <summary>    ///  迭代器模式  Iterator Pattern    /// </summary>    public class FestivalIterator : IIterator    {          /// <summary>        /// /        /// </summary>        private readonly FestivalCollection _collection;        /// <summary>        ///        /// </summary>        private int _position;        /// <summary>        /// /        /// </summary>        private int _step;        /// <summary>        ///        /// </summary>        /// <param name="collection"></param>        public FestivalIterator(FestivalCollection collection)        {            _collection = collection;            _position = -1;            _step = 1;        }          // It's probably more logical to have a method for changing the step.        // However, for demo purposes the idea was to show that iterator interface can contain properties too.        /// <summary>        ///        /// </summary>        public int Step        {            get => _step;            set            {                if (value <= 0)                {                    throw new ArgumentOutOfRangeException(nameof(value), "步长只能是正值。当前迭代器不支持倒退.");                }                  _step = value;            }        }        /// <summary>        ///        /// </summary>        /// <returns></returns>          public MusicFestival First()        {            _position = 0;            return Current();        }        /// <summary>        ///        /// </summary>        /// <returns></returns>        public MusicFestival Current() => _collection.Get(_position);        /// <summary>        ///        /// </summary>        /// <returns></returns>        public bool MoveNext()        {            var updatedPosition = _position + _step;              if (updatedPosition < _collection.Count)            {                _position = updatedPosition;                return true;            }              return false;        }        /// <summary>        ///        /// </summary>        public void Reset() => _position = -1;    }    /// <summary>    ///    /// </summary>    public class MusicFestival    {          /// <summary>        ///  迭代器模式  Iterator Pattern        /// </summary>        /// <param name="name"></param>        /// <param name="country"></param>        public MusicFestival(string name, string country)        {            Name = name;            Country = country;        }        /// <summary>        ///        /// </summary>        public string Name { get; set; }        /// <summary>        ///        /// </summary>        public string Country { get; set; }        /// <summary>        ///        /// </summary>        /// <returns></returns>        public override string ToString()        {            return $"姓名：{this.Name} 国家： {this.Country}";        }    }      /// <summary>    /// 迭代器模式  Iterator Pattern    /// </summary>    public static class MusicFestivalsExecutor    {          /// <summary>        ///  迭代器模式  Iterator Pattern        /// </summary>        public static void Execute()        {            ConsoleExtension.WriteSeparator(" 迭代器模式  Iterator Pattern:Music festivals demo");              var collection = new FestivalCollection();              collection.Add(new MusicFestival("春", "中国"));            collection.Add(new MusicFestival("四季之歌", "比利时"));            collection.Add(new MusicFestival("春", "英国"));            collection.Add(new MusicFestival("夏", "美国"));            collection.Add(new MusicFestival("冬", "中国"));              var iterator = collection.CreateIterator();              Console.WriteLine("初始遍历.");            Traverse(iterator);              iterator.Reset();            iterator.Step = 2;              Console.WriteLine("\nT应跳过所有其他元素的第二个遍历.");            Traverse(iterator);        }        /// <summary>        ///        /// </summary>        /// <param name="iterator"></param>        private static void Traverse(IIterator iterator)        {            while (iterator.MoveNext())            {                var festival = iterator.Current();                Console.WriteLine($"音乐节 {festival.Name} 发生在{festival.Country}.");            }        }    }

　　

调用：

?

1	Geovin.Du.DuIterator.MusicFestivals.MusicFestivalsExecutor.Execute();

　　

输出：

?

1 2 3 4 5 6 7 8 9 10 11 12

迭代器模式  Iterator Pattern:Music festivals demo -------------------------------------------------- 初始遍历. 音乐节 春 发生在中国. 音乐节 四季之歌 发生在比利时. 音乐节 春 发生在英国. 音乐节 夏 发生在美国. 音乐节 冬 发生在中国.   T应跳过所有其他元素的第二个遍历. 音乐节 四季之歌 发生在比利时. 音乐节 夏 发生在美国.