rust-inspired option type

2022-11-11 16:25:18 +01:00
parent aac37e5101
commit c4f63ce3be
2 changed files with 69 additions and 0 deletions
--- a/Engine/Engine/Scripts/Utilities/Option.cs
+++ b/Engine/Engine/Scripts/Utilities/Option.cs
@@ -0,0 +1,66 @@
+using System;
+
+namespace Escape_Room_Engine.Engine.Scripts.Utilities
+{
+    /// <summary>
+    /// Optional type with a subset of the functionality of the one described in the Rust documentation at https://doc.rust-lang.org/std/option/enum.Option.html.
+    /// </summary>
+    public interface IOption<T>
+    {
+        public bool IsSome();
+        public bool IsNone();
+        public T Expect(string message);
+        public T Unwrap();
+        public T UnwrapOr(T def);
+        public T UnwrapOrElse(Func<T> f);
+        public IOption<T> And(IOption<T> other);
+        public IOption<T> Or(IOption<T> other);
+        public bool Contains(T value);
+        public T Match(Func<T, T> some, Func<T> none);
+        public void Match(Action<T> some, Action none);
+        public void Match(Action<T> some);
+        public void Match(Action none);
+    }
+
+    public class Some<T> : IOption<T>
+    {
+        private readonly T _value;
+        
+        private Some(T value) => _value = value;
+
+        public bool IsSome() => true;
+        public bool IsNone() => false;
+        public T Expect(string message) => _value;
+        public T Unwrap() => _value;
+        public T UnwrapOr(T def) => _value;
+        public T UnwrapOrElse(Func<T> f) => _value;
+        public IOption<T> And(IOption<T> other) => other;
+        public IOption<T> Or(IOption<T> other) => this;
+        public bool Contains(T value) => _value.Equals(value);
+        public T Match(Func<T, T> some, Func<T> none) => some(_value);
+        public void Match(Action<T> some, Action none) => some(_value);
+        public void Match(Action<T> some) => some(_value);
+        public void Match(Action none) {}
+
+        public static IOption<T> Of(T value) => new Some<T>(value);
+    }
+
+    public class None<T> : IOption<T>
+    {
+        public bool IsSome() => false;
+        public bool IsNone() => true;
+        public T Expect(string message) => throw new Exception(message);
+        public T Unwrap() => throw new Exception("Tried to unwrap None.");
+        public T UnwrapOr(T def) => def;
+        public T UnwrapOrElse(Func<T> f) => f();
+        public IOption<T> And(IOption<T> other) => this;
+        public IOption<T> Or(IOption<T> other) => other;
+        public bool Contains(T value) => false;
+        public T Match(Func<T, T> some, Func<T> none) => none();
+        public void Match(Action<T> some, Action none) => none();
+        public void Match(Action<T> some) {}
+        public void Match(Action none) => none();
+
+        public static IOption<T> New() => new None<T>();
+    }
+}