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| 1 | +using System; |
| 2 | + |
| 3 | +namespace PatternMatching |
| 4 | +{ |
| 5 | + |
| 6 | + /// <summary> |
| 7 | + /// Pattern Matching |
| 8 | + /// https://docs.microsoft.com/en-us/archive/msdn-magazine/2019/may/csharp-8-0-pattern-matching-in-csharp-8-0 |
| 9 | + /// https://docs.microsoft.com/en-us/dotnet/csharp/pattern-matching |
| 10 | + /// https://docs.microsoft.com/en-us/dotnet/csharp/tutorials/pattern-matching |
| 11 | + /// https://github.com/dotnet/roslyn/blob/master/docs/features/patterns.md |
| 12 | + /// </summary> |
| 13 | + class Program |
| 14 | + { |
| 15 | + static void Main(string[] args) |
| 16 | + { |
| 17 | + IInstrument stock01 = new Stock(); |
| 18 | + Console.WriteLine($"Stock volatility is {GetVolatilityUsingifBlock(stock01)}"); |
| 19 | + |
| 20 | + IInstrument bond01 = new Bond(); |
| 21 | + Console.WriteLine($"Bond volatility is {GetVolatilityUsingifBlock(bond01)}"); |
| 22 | + |
| 23 | + SNP500IndexFund sNP500 = new SNP500IndexFund(); |
| 24 | + Console.WriteLine($"SNP500IndexFund volatility is {GetVolatilityUsingSwitchBlock(sNP500)}"); |
| 25 | + |
| 26 | + EmergingMarketFund emergingMarketFund = new EmergingMarketFund(); |
| 27 | + Console.WriteLine($"EmergingMarketFund volatility is {GetVolatilityUsingSwitchBlock(emergingMarketFund)}"); |
| 28 | + |
| 29 | + Console.WriteLine($"Authorize is {Authorize("123",string.Empty, false)}"); |
| 30 | + Console.WriteLine($"Authorize is {Authorize(string.Empty, string.Empty, true)}"); |
| 31 | + Console.WriteLine($"Authorize is {Authorize(string.Empty, string.Empty, false)}"); |
| 32 | + |
| 33 | + Stock stock02 = new Stock(920.12); |
| 34 | + Console.WriteLine($"Stock should be price {ShouldBuy(stock02, 170)}"); |
| 35 | + |
| 36 | + Stock stock03 = new Stock(920.12); |
| 37 | + Console.WriteLine($"Stock should be price {ShouldBuy(stock03, 1200.10)}"); |
| 38 | + } |
| 39 | + |
| 40 | + static VolatilityType GetVolatilityUsingifBlock(IInstrument instrument) |
| 41 | + { |
| 42 | + // csharp-7.0 |
| 43 | + if (instrument is Stock s) |
| 44 | + { |
| 45 | + return s.Volatility; |
| 46 | + } |
| 47 | + |
| 48 | + if (instrument is Bond b) |
| 49 | + { |
| 50 | + return b.Volatility; |
| 51 | + } |
| 52 | + |
| 53 | + return VolatilityType.Unknown; |
| 54 | + } |
| 55 | + |
| 56 | + static VolatilityType GetVolatilityUsingSwitchBlock(IInstrument instrument) |
| 57 | + { |
| 58 | + // csharp-7.0 |
| 59 | + switch (instrument) |
| 60 | + { |
| 61 | + case Stock s when s is SNP500IndexFund: |
| 62 | + return s.Volatility; |
| 63 | + case Stock s when s is EmergingMarketFund: |
| 64 | + return s.Volatility; |
| 65 | + } |
| 66 | + |
| 67 | + return VolatilityType.Unknown; |
| 68 | + } |
| 69 | + |
| 70 | + // csharp-7.0 |
| 71 | + static VolatilityType GetVolatilityUsingSwitchBlockV2(IInstrument instrument) => |
| 72 | + instrument switch |
| 73 | + { |
| 74 | + Stock s when s is SNP500IndexFund => s.Volatility, |
| 75 | + Stock s when s is EmergingMarketFund => s.Volatility, |
| 76 | + _ => VolatilityType.Unknown |
| 77 | + }; |
| 78 | + |
| 79 | + // csharp-8.0 - tupe-switch |
| 80 | + static bool Authorize(string apiKey, string authToken, bool isAuthTokenValid) => |
| 81 | + (apiKey, authToken, isAuthTokenValid) switch |
| 82 | + { |
| 83 | + ("123", _, _) => true, |
| 84 | + (_,_,true)=> true, |
| 85 | + (_, _, false) => false, |
| 86 | + }; |
| 87 | + |
| 88 | + // csharp-8.0 |
| 89 | + static bool ShouldBuy(Stock stock, double maxPrice) => |
| 90 | + (stock, maxPrice) switch |
| 91 | + { |
| 92 | + var (Volatility, price) when price < maxPrice => true, |
| 93 | + var (Volatility, price) when price > maxPrice => false, |
| 94 | + _=>false |
| 95 | + }; |
| 96 | + |
| 97 | + public interface IInstrument |
| 98 | + { |
| 99 | + VolatilityType Volatility { get; set; } |
| 100 | + } |
| 101 | + |
| 102 | + public enum VolatilityType |
| 103 | + { |
| 104 | + Unknown = 0, |
| 105 | + Low = 1, |
| 106 | + High = 2 |
| 107 | + } |
| 108 | + |
| 109 | + public class Stock : IInstrument |
| 110 | + { |
| 111 | + public VolatilityType Volatility { get; set; } = VolatilityType.High; |
| 112 | + |
| 113 | + public double Price { get; set; } |
| 114 | + |
| 115 | + public Stock(double price) => (price) = (Price); |
| 116 | + |
| 117 | + public Stock() |
| 118 | + { |
| 119 | + |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + public class Bond : IInstrument |
| 124 | + { |
| 125 | + public virtual VolatilityType Volatility { get; set; } = VolatilityType.Low; |
| 126 | + } |
| 127 | + |
| 128 | + public class SNP500IndexFund : Bond |
| 129 | + { |
| 130 | + |
| 131 | + } |
| 132 | + |
| 133 | + public class EmergingMarketFund : Bond |
| 134 | + { |
| 135 | + public override VolatilityType Volatility { get; set; } = VolatilityType.High; |
| 136 | + } |
| 137 | + } |
| 138 | +} |
| 139 | + |
| 140 | + |
| 141 | + |
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